Patent Publication Number: US-7896192-B2

Title: Patient controlled timed medication dispenser

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is a continuation-in-part application claiming the benefit of the patent application assigned Ser. No. 11/125,299, filed on May 9, 2005 now U.S. Pat. No. 7,743,923, which claims the benefit of the patent application Ser. No. 10/247,427, filed on Sep. 19, 2002, now U.S. Pat. No. 7,044,302, which claims the benefit of the provisional patent application assigned Ser. No. 60/323,521 filed on Sep. 19, 2001. 
    
    
     Certain claimed elements of the present invention were developed with funds provided by the U.S. National Institutes of Health under grant number IR43NS046087-01A1. The U.S. government therefore has certain rights in these elements of the invention. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to a medication dispenser, and more particularly to a time-controlled medication dispenser for dispensing as-needed medications. 
     BACKGROUND OF THE INVENTION 
     Fifty percent of post-operative patients report inadequate pain relief. Fifty percent of all cancer patients and ninety percent of advanced cancer patients experience pain. Pain is now defined as “the fifth vital sign” as part of the mandate by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) to develop guidelines for pain management. 
     Adequate pain control requires the appropriate medication for the pain level and type reported. In a hospital setting, pain medication can be obtained only by a physician&#39;s order. Pain medications such as narcotics and nonsteroidals (and anxiety medications such as tranquilizers) are frequently ordered on an as-needed basis (referred to as prn orders). This approach requires the patient to initiate a request for each pm drug dose. The nurse determines whether the appropriate time interval has passed between doses, according to the physician&#39;s order. If the required time interval has elapsed, the nurse transports the medication to the patient&#39;s bedside and administers the medication to the patient. In some dosing regimens the patient is given a time-release pain medication at the same time(s) each day, with as-needed (prn) medications for breakthrough pain. Again the patient must request the medication for each breakthrough pain episode. A common reported patient frustration is the need to issue a request for each and every dose of prn medication. Thus a busy nurse must determine that the ordered time has elapsed from the last dosage, locate the medication and transport it to the patient in response to each request. This must also be accomplished in a timely fashion, as patients in pain must be administered to as soon as possible. 
     The as-needed approach to dosing provides the minimum amount of medication to adequately control symptoms, without the risk of abuse, overdosing and unnecessary side effects. Disadvantageously, in a hospital or institutional setting each medication that is dispensed on a prn basis requires nursing staff time and extra documentation by nursing and pharmacy staff, since the drugs can be administered only after the lapse of the predetermined time interval between doses. For example, a drug prescribed as needed every six hours may be given no more than four times in 24 hours. Such a drug may be administered from zero to four times in any given 24-hour period, depending upon patient dosage requests. If six hours have passed since the last administration of the drug, the medication is provided to the patient in response to the request. If six hours have not lapsed, the patient must wait the minimum time interval of six hours prior to receiving the next drug dose. In a home setting, the patient must remain aware of the restricted dosing schedule to safely self-administer these medications. 
     An automated bedside dispensing cabinet, requiring the nurse to enter the cabinet at times to dispense medications, is known. As with all prn medications this device requires the nurse to visit the patient&#39;s room, where the medication is removed from the cabinet for dispensing. Although such a device reduces medication errors compared to the conventional approach, it expends valuable nursing time and expense. 
     It is also known that oral medications may be provided through the use of a sealed wrist pouch. The pouch is worn by the patient and filled with two medication doses. The pouch is refilled by a nurse at the patient&#39;s request. The patient reports the time of each self-administered dose and maintains a pain control diary. As in the other prior art devices, nursing staff time is required for refills and nursing staff availability may disrupt timely refilling of the pouch. 
     Drug delivery devices that remind the patient to take a medication at preset time intervals are known. These devices provide the reminder through a variety of signaling indicators, such as audible alarms, and promote compliance to a scheduled dosing regimen, but do not control nor prevent patient access to the medications at intervals shorter than prescribed. 
     Known PCA (patient controlled analgesia) intravenous pumps allow patients to self-medicate with pain medications. Using a PCA pump, under a physician&#39;s order, a patient receives a single dose of intravenous medication by activating a bedside button. The actuation starts a pump that delivers a measured dose of the intravenous drug (a narcotic, for example) at allowable time intervals. If the button is activated during a time interval in which an allowable dose has already been administered, the pump is “locked out” and unable to deliver the dose until the appropriate time interval has passed. This prevents the patient from taking more than a maximum allowable dose of medication during a measured time interval. The PCA device records the drug volume delivered over time. A nurse can query the device to chart the volume of drug delivered over a given time interval and the number of doses administered. 
     Two other dosing devices are available using the same principal as the intravenous PCA. These include pumps that deliver narcotic medications subcutaneously and epidural catheters that deliver pain medications near the spinal canal. Cancer patients experiencing both acute and chronic pain use such intravenous PCA pumps. 
     A randomized study of pain management in a post-operative setting using patient controlled analgesia (that is, the PCA pump) versus conventional pain therapy CPT (i.e., a request to the nurse for each administered dose), has been reported in the medical literature. Patient satisfaction for pain management in the PCA group was significantly better than that reported in the CPT group. Note the only difference between the two study groups was the ability of the PCA group to easily and promptly self-control the medication dosing. 
     Multiple factors prevent the timely dosing of pain medication and other as-needed medications to the patient bedside according to conventional pain therapy techniques. A national survey of pharmacy practice in acute care settings in 1999 indicated that 75% of pharmacies still practice centralized pharmacy distribution systems. In some situations, these centralized pharmacies extend the time required to deliver medications to each patient area. A future medication-delivery trend includes automated medication dispensing stations in each patient area. Although this is a trend for the future, it is not as yet reality except in large, sophisticated, primarily academic hospitals. Currently there is a shortage of pharmacists and the existing staffs are over-burdened, creating further delays in drug delivery to the patient bedside. 
     In about 98% of the cases, nurses directly administer medications to patients. A time and motion study has reported that each prn oral medication delivered by a nurse to a hospital patient requires 18.42 minutes, which includes the unlocking of the narcotics cabinet to sign out the medication, transporting it to the patient&#39;s bedside, and documenting (charting) the time the dose is given. Like the pharmacy staff, nursing staffs are short-handed, while the number of complex hospitalized patients is growing. These patients have increasingly more complex diagnoses with more medication requirements. 
     Improved patient pain control leads to better patient outcomes in the hospital setting. This has been well documented in the surgical literature in the post-operative setting, with fewer post-operative complications, earlier rehabilitation, and shorter hospital stays for patients with better pain management. Better pain management is also highly cost effective since earlier discharges and fewer complications save health care dollars and staff time. 
     BRIEF SUMMARY OF THE INVENTION 
     According to one embodiment, the present invention comprises a medication dispenser for permitting access to medication doses after a minimum dosing interval between doses. The dispenser comprises a medication tray comprising medication retention areas, wherein a medication dose is disposed in each retention area and further comprising blank areas; a cover disposed over the medication tray, the cover defining a dose opening therein through which a dose in a retention area can be accessed; a controller for authenticating a person to access a medication dose, the controller further aligning the dose opening with a retention area to present a medication dose through the dose opening after the minimum dosing interval has elapsed and the person has been authenticated, and wherein the controller aligns the dose opening with a blank area between minimum dosing intervals. 
     According to another embodiment, the present invention comprises a medication dispenser for providing medication doses for administration to a patient with a minimum dosing interval between successive doses. The medication dispenser comprises a substantially circular medication tray comprising medication retention areas and blank regions about a periphery thereof; an enclosure for supporting the medication tray, wherein the enclosure defines an opening, and wherein the medication doses are accessed through the opening; a controller for controlling a relative position of the medication tray and the opening to align one of the medication retention areas with the opening responsive to authentication of a person to access the medication dose and after the minimum dosing interval from an immediately previous presentation of one of the medication doses and wherein after a time when the opening is aligned with one of the medication retention areas the controller aligns a blank region with the opening. 
     According to yet another embodiment, the present invention comprises a medication dispenser for providing medication doses for administration to a patient. The dispenser comprises a medication tray carrying a plurality of medication doses to be administered on an as needed basis with a minimum dosing interval between each dose; a housing supporting the medication tray; a controlled-access opening within the housing for providing access to one of the plurality of medication doses, wherein the controlled access opening is controllable to a dose-accessible condition permitting access to the medication does therethrough and a controller for controlling the controlled-access opening to allow withdrawal of the medication dose therethrough responsive to the minimum dosing interval and further responsive to authentication of the patient. 
     According to another embodiment, the present invention comprises a medication dispenser for providing medication doses for administration to a patient with a minimum dosing interval between successive doses. The medication dispenser comprises a housing having an opening therein; a medication tray received within the opening and comprising medication retention areas, wherein a medication dose is disposed in one or more of the retention areas, and further comprising blank regions between the medication retention areas; a cover lockably disposed to close the opening; a lock in the housing locking the cover within the opening, wherein in an unlocked condition the cover is removable from the opening; a controller for authenticating a patient and the controller further controlling the medication tray to align one of the plurality of retention areas containing a medication dose with the opening after the minimum dosing interval has elapsed, thereby making the medication dose available to an authenticated patient. 
     According to another embodiment, the invention comprises a method for dispensing a medication dose from a medication dispenser to a patient. The method comprises (a) determining that a minimum dosing interval has elapsed, (b) indicating to a user that the minimum dosing interval has elapsed, (c) authenticating the user, and responsive to the steps (a) and (c) causing a medication-containing medication retention area of the medication dispenser to align with an opening in the medication dispenser, allowing the authenticated user to remove the medication dose from the retention area through the opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features of the invention will be apparent from the following more particular description of the invention, as illustrated in the accompanying drawings, in which like reference characters refer to the same parts throughout the different figures. The figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
         FIG. 1  is an exploded view of a medication on demand device constructed according to the teachings of the present invention. 
         FIG. 2  is a block diagram of the control components of the medication on demand device of  FIG. 1 . 
         FIG. 3  is another exploded view of a medication on demand device constructed according to the teachings of the present invention. 
         FIGS. 4 and 5  are top and bottom views, respectively, of the medication on demand device of  FIGS. 1 and 2 . 
         FIG. 6  is a top view of another embodiment of the medication on demand device. 
         FIGS. 7 ,  8  and  9  illustrate various patient authentication devices for use with the medication on demand device of the present invention. 
         FIG. 10  is a perspective view of another embodiment of a medication on demand device according to the teachings of the present invention. 
         FIG. 11  is an exploded view of another embodiment of a medication on demand device constructed according to the teachings of the present invention. 
         FIGS. 12 and 13  illustrate another embodiment of a medication on demand device according to the teachings of the present invention, in a “on” and “off” condition respectively. 
         FIG. 14  is an exploded view of the embodiment of  FIGS. 12 and 13 . 
         FIGS. 15 and 16  are a respective top and side view of the carousel of the medication on demand device of the present invention. 
         FIGS. 17 and 18  illustrate certain components for rotating the carousel of the medication on demand device of the present invention. 
         FIG. 19 ,  20 ,  21  and  22  depict elements for locking a cover to a base of the medication on demand device of the present invention. 
         FIG. 23  illustrates a medication tray insert for use with the medication on demand device of the present invention. 
         FIG. 24  illustrates a functional block diagram of the controlling and the controlled components according to one embodiment of the present invention. 
         FIG. 25  illustrates an alternative activation element for the medication on demand device of the present invention. 
         FIG. 26  is a flow chart illustrating operation of one embodiment of the medication on demand device of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Before describing in detail the particular medication dispenser in accordance with the present invention, it should be observed that the present invention resides primarily in a novel combination of hardware and software elements related to a medication dispenser. Accordingly, the elements have been represented by conventional elements in the drawings, showing only those specific details that are pertinent to the present invention, so as not to obscure the disclosure with structural details that will be readily apparent to those skilled in the art having the benefit of the description herein. 
     A medication on demand device  10  constructed according to the teachings of the present invention is illustrated in the exploded view of  FIG. 1 , comprising an upper assembly  12  for mating with a lower assembly  14  and capturing a medication tray  16  there between. The medication tray  16  is received by an upper surface enclosure  17  of the lower assembly  14 . In one embodiment a motor (not shown in  FIG. 1 ) is located within the upper surface enclosure  17 . A gear  18  attached to a motor shaft protrudes from the vertical surface  19  of the upper surface enclosure  17  for drivingly mating with a circumferential gear track  21  disposed on an inner surface  22  of the medication tray  16 . Thus rotation of the gear in response to the application of electricity to the motor causes rotation of the medication tray  16 . 
     The upper assembly  12  includes a passage  23  for receiving a door (not shown in  FIG. 1 ) providing access to one of a plurality of medication retention areas  20  of the medication tray  16 . Once the patient has opened and closed the door to remove the medication, a timing sequence is initiated and during that sequence the medication tray  16  is locked in place. After the dosing interval has elapsed, the medication tray  16  is rotated, through action of the motor and associated gearing, through an arc segment to align the passage  23  with the next one of the plurality of medication retention areas  20 . As described further below, the medication tray  16  is controllably rotated after a predetermined time interval has elapsed since the last dosage and responsive to entry of a patient code on a keypad of the device  10 . The patient can then remove the next dosage for self-administration. 
     In the embodiment of  FIG. 1  each one of the plurality of equally-sized medication retention areas  20  carries a medication dose for administration to the patient. Preferably, the upper assembly  12  is translucent or transparent and the lower assembly  14  is opaque to provide a color contrast, making the medication dose easily visible within the plurality of medication retention areas  20 . In another embodiment a color-coded medication tray serves as an indicator of the drug type carried there within. In the pharmacy, the medication tray  16  can be loaded with medications, labeled to identify the patient and the minimum-dosing interval, and provided to the patient&#39;s attendant. While being transported, the medication tray  16  can be covered with a disposable cover. 
     A controller  30  (see  FIG. 2 ) and its associated components control rotation of the medication tray  16  and allow patient access to the medications. In one embodiment the controller  30  comprises a microchip-based controller (or a general purpose microprocessor) programmed to perform the various functions described herein. When the medication tray  16  is loaded into the device  10 , the attendant or pharmacy staff enters the physician ordered dosing interval via an input device  34 , comprising in one embodiment one or more manually operable switches. The controller  30  is responsive to the input device  34  for receiving and storing the dosing interval. The attendant also enters an authorization code, via the input device  34 , that is stored in the controller  30 , for later use to limit medication access only to the patient for whom the medications are intended. 
     The description herein generally refers to an attendant as the party exercising control over the operation of the device  10 . This function can be performed by any third party controlling the patient&#39;s medication dosing, such as an in-home care giver, medical technician, pharmacy staff member, physician, family member, nurse, etc. 
     The controller  30  is further bi-directionally responsive to a timer  36  for monitoring the time interval between permitted doses, and to a door sensor  38  (see  FIG. 1  for the physical location thereof) for determining the door position. From the door position information, the controller  30  determines the times when the door is opened and closed by the patient to receive the medication for self-administration. After the patient has sequenced the door through an open and close cycle to remove the medication dose, the controller  30  activates the timer  36  to begin a counting sequence representing the dosing interval. When the timer  36  times out, the dosing interval has elapsed and the patient is permitted to administer the next dose. In response thereto, the controller  30  illuminates an indicator  41  (see also  FIG. 1 ) indicating that the dosing interval has elapsed. In one embodiment the indicator  41  (an unlocked indicator) comprises a light emitting diode. The embodiment illustrated in  FIG. 1  includes a second optional indicator  40  (a locked indicator) that is illuminated during the time between permitted doses, serving as an indication that the patient is not permitted to administer the next medication dose. 
     Returning to  FIG. 1 , note that the upper surface enclosure  17  further carries a keypad  42  comprising a plurality of user-operable keys for entering an authorization code. After the indicator  41  is illuminated indicating that the next dose is available for administration, the patient uses the keypad  42  to enter a predetermined authorization code that is supplied as an input to the controller  30 . In one embodiment, the code comprises four digits and is followed by entry of an “enter” command on the keypad  42 . If the patient-entered code matches the stored authorized code (previously entered when the medication tray  16  was loaded into the device  10  as described above), in response thereto the controller  30  energizes a motor  44  to rotate the medication tray  16 , as described above, such that the next medication retention area  20  is aligned with the passage  23 . The patient now has access to the next medication dose. In one embodiment the motor  44  comprises a stepping motor that when energized controllably rotates only through a predetermined number of turns such that the next medication retention area  20  and the passage  23  are aligned. 
     The dosing timing cycle begins again when the door sensor  38  senses the opening and closing of the door, provides representative signals to the controller  30 , and the controller  30  activates the timer  36 . 
     If the patient&#39;s pain has subsided and he does not require a medication dose at the prescribed minimum interval, i.e., when the indicator  41  is illuminated the patient can elect not to enter the prescribed authorization code. The device  10  remains in a ready condition such that whenever the code is later entered the medication tray  16  is rotated and the next dose is accessible. Only an open and closing cycle of the door restarts the timing cycle. 
     The door open and close times determined as described above, are stored within the controller  30  and displayable on a clock  48  (disposed on the bottom surface of the lower assembly  14 ) in response to commands entered into the input device  34 . For example, an attendant commands the controller  30  to control the clock  48  to display the dose administration times, (e.g., door open times) and enters the displayed times in the patient&#39;s chart. 
     In another embodiment the clock  48  is controllable to operate as a countdown clock for displaying the time remaining until the next permitted dose. The clock  48  is reset after each dose is administered. In still another embodiment, the clock  48  is operable as a real time clock in response to commands entered into the input device  34  by the attendant. 
     In another embodiment where patient records are stored in a computing mechanism and associated storage media, the controller  30  is connected via a wired or wireless network (e.g., a radio frequency communications link such as defined by an IEEE 802.11× standard or an infrared link) to the computing mechanism for automatically downloading the dose administration times and inputting them to the patient&#39;s record. The controller  30  can also be programmed for the permitted dosing interval, patient authorization code, authorized patient identification information, etc., through the wired (such as through a serial port included in the device  10 ) or the wireless network. This remote programming and querying feature avoids the need for a nurse to physically visit the location of the device  10  to execute the programming function. Instead programming of a plurality of devices  10  is performed from a central location via a wired or wireless network that allows each device  10  to be individually and uniquely accessed. 
     Although the timer  36  is described herein as a separate component of the controlling mechanism of the device  10 , those skilled in the art recognize that the timing function can be incorporated within the controller  30 . Likewise, storage of the dosing interval, authorization code, etc., is described with reference to on-board storage in an internal memory within the controller  30 . In another embodiment the device  10  includes external memory responsive to the controller  30  for storing program code and such data. 
       FIG. 2  further includes a key switch  50  for setting the operational mode for the device  10 . In one embodiment the key switch  50  comprises a three-position key switch. A mating key is required to set the position of the key switch  50 . Typically, this key is accessible only to the attendant. In a first position the upper and lower assemblies  12  and  14  are separable for loading a new medication tray  16 . Typically, the device  10  is loaded with new medications doses every 24-hour period, although other time periods may apply depending on the dosing interval and the number of medication retention areas  20  within the medication tray  16 . In a second position the device  10  is locked and ready for patient use. With the switch in the third key position the dosing interval, authorization code, etc., can be entered through the input device  34 , and the controller  30  can be queried as to the times when the door  65  (see  FIG. 3 ) was opened and closed. 
       FIG. 2  further includes a network interface  52  providing a wired or wireless connection to a remote computing device, such as a laptop or tablet computer or a personal digital assistant device. Information collected by the controller  30 , such as patient&#39;s dosing times, is supplied to the remote computing device via the network interface  52 . Additionally, the controller  30  can be programmed from the remote computing device. 
     A more detailed exploded view of the medication on demand device  10  is illustrated in  FIG. 3 , wherein the upper assembly  12  comprises a housing  60 , for receiving a cover  62  (a material for both preferably comprises plastic). A first region  63  of the passage  23  is formed within the housing  60  and a second region  64  thereof is formed within the cover  62 . A door  65  provides access to the passage  23 . A medication dose  66  rests in a medication retention area  20  of the medication tray  16 . Variously shaped and sized medication doses can be accommodated within the retention areas  20 . Although the medication dose  66  comprises an orally administered dose, the teachings of the invention can be applied to other medication types, and thus such other medication types can be held within the medication retention area  20 . 
     The lower assembly  14  further comprises a housing  70  (preferably formed from a plastic material) carrying a circuit board  72  on which the controller  30  (not shown in  FIG. 3 ) and its associated components are mounted. The motor  44 , powered by batteries  76 , is mounted within a housing  80 . The key switch  50  passes through a notch  82  in the circuit board  72  and a notch  84  in the housing  80 . The key switch  50  is electrically connected to the controller  30  as described in conjunction with  FIG. 2 . 
       FIG. 4  is a top view of the medication on demand device  10  illustrating certain of the previously discussed components. 
       FIG. 5  is a bottom view of the medication on demand device  10  illustrating several of the previously described components of the device  10 . A guide wire  110  for securing the medication on demand device  10  to a patient&#39;s bed, bedside table or tray passes through a loophole  111 . The input device  34  and the clock  48  are also shown in the bottom view of  FIG. 5 . 
     The bottom surface of the device  10  further includes a low-battery indicator  114  and a recessed region  116  for receiving, for example, a printed substrate including patient identification information, the medication type and dosage, and the minimum interval between doses. Typically, this information is recorded on adhesive-backed substrate for affixing within the recessed region  116 . The device  10  includes a stacking ring  117  for mating with a receiving recess in the upper assembly  12  of a second device  10 , thus allowing several devices  10  to be transported and stored in an efficient and stable configuration. 
     In another embodiment of the present invention, the door  65  is lockable and controllable by operation of the controller  30  (in response to an authenticated patient), such that a door lock  120  in  FIG. 6  is released only after the minimum dosing interval has elapsed. In this embodiment, rotation of the medication tray  16  by operation of the motor  44  under control of the controller  30  can occur at any time during the minimum dosing interval, as the patient cannot gain access to the medication dose  66  until the door  65  is unlocked by operation of the lock  120 . 
     Other patient authentication techniques in lieu of entering alphanumeric characters via the keypad  42  can be employed in other embodiments of the present invention. Such authentication techniques include, but are not limited to authentication based on biometric information (e.g., fingerprint, iris scan and voice print), a bar code, an RFID (radio frequency identification) tag or a smart card. 
     A biometric reader (not shown) operative in conjunction with the medication on demand device prompts the user to enter biometric information that is compared with stored biometric information of the authorized patient. A match authenticates the patient for accessing the next medication dose according to the various medication access structures and techniques of the present invention. 
     According to another embodiment, the medication on demand device comprises a bar code reader  90  (see  FIG. 4 ) for reading a unique bar code  92  (see  FIG. 7 ) assigned to the patient and printed on a patient&#39;s wristband  94  (see  FIG. 7 ). If a stored bar code matches the scanned bar code  92  the scanning party is authenticated to use the medication on demand device and access the next medication dose. A bar code process can also be used to authenticate the attendant to perform programming and override functions as described elsewhere herein. 
     In yet another embodiment, the device  10  includes an RFID reader  100  (see  FIG. 4 ). The RFID tag reader  100  communications with a unique RFID code tag  102  incorporated into a patient&#39;s wristband  104  as illustrated in  FIG. 8 . The tag reader  100  and the tag  104  operate according to any of the known RFID technologies (e.g., magnetic or electromagnetic). 
     In still another embodiment a patient is provided with a smart card  106  (see  FIG. 9 ) for reading by a smart card reader  107  (see  FIG. 4 ). Use of the smart card  106  and corresponding reader  107  offers another technique for authenticating the patient. 
     It is also preferable to authenticate the attendant to ensure that only authorized persons are permitted to program the medication on demand device. Such authentication can be provided by any of the authentication techniques described above, e.g., a key pad for entering an alphanumeric code, a bar code operative with a bar code scanner, an RFID tag/reader, a smart card operative with a smart card reader, a biometric reader or another authentication technique based on unique information suitable for authenticating an attendant. 
     Other personal identification techniques are known in the art and can be incorporated into an embodiment of the medication on demand device of the present invention. The use of any such techniques and their associated structural components are considered within the scope of the present invention. 
     The medication on demand device is programmed to permit dosing in accordance with the minimum dosing interval and receive patient identification information to authenticate the patient. Additional programmable features may include, a first dose time or first does interval (i.e., time from the present time until the first dose is dispensed), a medication name, and identification information for an attendant having authority to program or override the minimum dosing interval (thereby permitting the patient to receive a medication dose prior to expiration of the minimum dosing interval), and authority to access and remove the mediation carousel for replacing with a carousel carrying medication doses. The medication on demand device can also be reprogrammed to modify any previously programmed parameters. 
     According to one embodiment, the device is programmed through a separate computer or processing platform (a programming platform) such as a laptop/notebook computer or a personal digital assistant connected to the device through a communications link, such as a wired, wireless or infrared link. A software application executing on the programming platform receives input information from a programming user and in response programs the device. 
     In another embodiment, the medication on demand device is integrated with an institution&#39;s (e.g., hospital) information technology network with network computers on the hospital wards. The device is programmed through the network computers. In yet another embodiment, an interactive programming platform at the patient&#39;s bedside can be used to program the device. A television screen at the patient&#39;s bedside can serve as a display during the programming process. 
     The programming platform can also query the medication on demand device to determine information regarding self-administered medication doses, such as when doses were made available to the patient after the minimum dosing interval. The retrieved dosing (e.g., date and time) information is recorded in the patient&#39;s medical record and invoiced against the patient&#39;s financial record. Every administered medication dose is also tracked by a pharmacy inventory system such that when a dose is administered it is deleted from the pharmacy inventory. The attendant can also query the device to determine if the patient has administered all doses, a condition requiring the ordering of and installation of a filled medication tray. 
     In yet another embodiment, the medication on demand device generates and stores a record of its operation, including authentication operations, rotation of the medication tray or carousel to present doses for self-administration and override operations. 
     In another embodiment the device is programmed to determine when all medication doses in the tray have been accessed by the patient. In response thereto the device signals (through one of a communications link) the attendant or pharmacy to supply a new medication carousel. 
     The programming platform can also unlock the device, as discussed further below, permitting the attendant to replace the medication tray. 
     In an embodiment employing a wired connection between the programming platform and the medication on demand device, the programming platform is carried to the site of the device, typically the patient&#39;s bedside, and connected to the device through the wired connection. The programming application is executed on the programming platform to program and/or query the device. 
     In a wireless embodiment, the device comprises wireless communications components (not illustrated) for receiving and processing radio frequency signals transmitted by the programming platform to program and/or query the device. For use in a treatment center environment, the programming platform can be located at a nurse&#39;s station to program and query all devices in the area. In another embodiment the programming platform is carried on a medication cart to the bedside of each patient. In still another embodiment, the programming platform is in a pharmacy responsible for supplying the medication carousel. 
     According to another embodiment, an authenticated attendant can override the programmed minimum dosing interval, permitting immediate rotation of the medication tray into a position where a dose is accessible. 
       FIG. 10  illustrates an embodiment of a medication on demand device  150  including an opening  152  in a cover  153 . Unlike the embodiments described above, the embodiment of  FIG. 10  lacks the door  65 . Instead, the motor  44  under control of the controller  30 , rotates a medication retention area  154  into alignment with the opening  152  after the minimum dosing interval has elapsed and after the user has been authenticated (according to one of the identification techniques described elsewhere herein) as the authorized patient. Once the opening  152  and the medication retention area  154  containing a medication does  66  are aligned, the patient can remove the medication dose  66  from the retention area  154  through the opening  152 . Although the present description refers generally to a single medication dose within the retention area  154 , the invention is not limited to such an application, as a plurality of doses can be disposed within one retention area  154  if the area is properly sized. Also, the medication on demand device can dispense medications other than pills if the retention areas are properly sized. Further, multiple medication types can be loaded into any retention area  154 , including loading more than one medication type into any retention area  154 . 
     The medication dose  66  remains accessible through the opening  152  for patient removal for a predetermined time, about 25 seconds in one embodiment, which should be sufficient for the patient to remove the medication dose  66 . After this time has elapsed, the medication tray  16  is rotated by action of the motor  44  under control of the controller  30  to present an empty medication retention area  154  into alignment with the opening  152 . This configuration is referred to as the locked, closed or off configuration or condition. The device  150  is in an opened, on or dose configuration or condition when the medication dose  66  is accessible by the patient through the opening  152 . In one embodiment the indicator  40  illuminates during the entire locked period. 
     The medication on demand device  150  remains in the locked configuration until the timer  36  determines that the minimum dosing interval has elapsed, at which time the indicator  41  is illuminated to indicate that the patient is permitted to administer the next dose. The patient is authenticated and the medication tray  16  rotates to present another retention area  154  containing a medication dose  66  into alignment with the opening  152 . The medication tray  16  remains in this dose-accessible position for the predetermined time, after which another tiring cycle begins. To accommodate this embodiment the medication tray  16  comprises alternating empty and medication-carrying retention areas  154 . 
     According to another embodiment also illustrated in  FIG. 10 , the medication on demand device  150  further comprises an optional tray  170  locked into a closed position within the device  150  and releasable therefrom into an open or extended position as illustrated in  FIG. 10 . Various embodiments of the tray  170  comprise a display  176  and/or user-activated keys  178  for use in combination or independently to program the medication on device  150  as described above. In particular, the device  150  must be programmed with a physician-ordered dosing interval and patient identification information for use in authenticating the patient and the attendant for programming the device  150 . 
     In yet another embodiment, the device  150  is programmed using a stylus or pen interacting with the display  176  as is known in the art. After programming, the tray  170  is returned to the closed/locked position within the device  150 . Various mechanical locking devices are known for locking the tray  170  in position while permitting convenient release and extension of the tray when it is desired to program the device  150 . The display  176  and the keys  178  can also be used to query the device  150 , for example to determine when the medication doses  66  have been self-administered for recording in the patient&#39;s medical record. 
       FIG. 11  illustrates yet another embodiment of a medication on demand device  200  comprising a housing  204  for receiving a removable drug tray  202  further comprising medication retention areas  154 , with alternating retention areas holding a medication dose  66 . 
     A dome or cover  213 , comprising a transparent (in one embodiment) material having a hemispherical or planar shape, defines an opening  214  therein and overlies the drug tray  202 . The device  200  further comprises an indicator  212  for indicating that the minimum dosing interval has elapsed and thus the device can provide access to another medication dose  66  for an authenticated patient. 
     The motor  44  (hidden from view in  FIG. 11 ) drives a planetary gear or wheel  216  to incrementally rotate the tray  202  to align successive retention areas  154  with the opening  214  at the end of each incremental rotation. A bottom surface of the tray  202  further comprises a plurality of tabs or protrusions extending therefrom for depressing a lever arm  208 A of a tray indexing switch  208  as the tray  202  rotates. The tabs are spaced around the tray  202  according to a location of the medication retention areas  154  within the tray  202 . Depression of the lever arm  202 A closes (or opens in another embodiment) switch contacts. A control element determines a position of one of the medication retention areas  154  relative to the opening  214  by detecting incremental rotation of the tray  202  that closes (or opens in another embodiment) the switch contacts as the tabs depress the lever arm  208 A. In response thereto the control element controls the motor  44  to terminate tray rotation when the opening  214  is aligned with one of the medication retention areas  214 . 
     An empty tray  202  is detected based on a number of incremental rotations equal to a number of retention areas  154  in the tray  202 . Using any of the communications techniques described elsewhere herein, an empty tray designating signal is sent from the medication on demand device  200  to a party or site (e.g., nursing station, pharmacy, medication cart) responsible for replacing the empty tray, 
     The device  200  further comprises a solenoid  215  that engages the dome  213  to prevent unauthorized tampering with or removal of the dome  213  to access the medication doses  66 . The solenoid  215  is disengagable when it is necessary to load a new tray  202  into the housing  204 . According to the embodiment including the solenoid  215 , the commands entered through a user interface (any wired or wireless communications technique) can unlock the dome  213  by disengaging the solenoid  215 . 
       FIGS. 12 and 13  illustrate another embodiment of a medication on demand device  400 , constructed according to the teachings of the present invention, comprising a housing  410 , further comprising a lower housing  410 A and an upper housing  410 B. See also the exploded view of  FIG. 14 .  FIG. 12  illustrates the device in the “off” or “closed” condition (presenting a blank area  155  disposed between two adjacent medication retention areas  154  through an opening  430 A, see  FIG. 14 ) and  FIG. 13  illustrates the device in the “dose” or “on” condition (presenting a medication dose  66  through the opening  430 A). Alternate medication retention areas  154  are empty and in the “off” condition an empty retention area is presented through the opening  430 A. 
     An opening  414  within the upper housing  410 B (see  FIG. 14 ) receives a removable medication drug tray or carousel  418  further comprising the medication retention areas  154 . In a preferred embodiment, alternating retention areas  154  carry a medication dose  66 . 
     A cover  430  having a substantially flat or slightly hemispherical shape is removably disposed over the carousel  418 . A material of the cover  430  comprises transparent, translucent or opaque material, the former two embodiments allowing visual inspection of the medication retention areas  154  to determine the existence of a medication dose  66  within the areas  154 . 
     The carousel  418  is rotated relative to the cover  430  to align an opening  430 A in the cover  430  with one of the medication retention areas  154 . In the dose or on configuration the carousel  418  is positioned to permit a patient to access a medication dose  66  in a mediation retention area  154  through the opening  430 A. See  FIG. 13 . In the off or closed configuration a blank region  155  or an empty retention area  154  is aligned with the opening  430 A and thus a drug dose is not available. See  FIG. 12 . 
     In an embodiment comprising a transparent or translucent cover  430 , the medication doses  66  are visible through the cover  430 . The attendant can correlate the remaining dose count in the tray  418  with data, as collected by the medication on demand device (as described further below) indicating the dates and times the tray was rotated to present a dose to the patient, to determine which doses were not removed from the carousel by the patient. Additionally, the medication on demand device logs tray changes (i.e., a new carousel installed), administration of override doses (i.e., the minimum dosing interval has not elapsed but the patient is permitted an intervening dose due to considerable pain) and executions of a waste tray program (i.e., the patient has been discharged or is no longer using the medication on demand device and a partially filled tray is removed and the remaining doses are “wasted” or disposed of), which must also be considered by the attendant. As further described below, this information as collected by the medication on demand device is added to the patient&#39;s medical record or chart. Review of the chart will thus also permit the attendant to correlate the remaining doses with the doses administered. 
     In a preferred embodiment, the upper housing  410 B captures the cover  430  as openings  431  (in one embodiment three openings, but only two shown in  FIG. 14 ) in the upper housing  410 B receive corresponding tabs  432  (only one shown in  FIG. 14 ) extending from a periphery of the cover  430 . Each opening  431  comprises a wider insertion region and a narrower capture region. After inserting the tabs  432  into the insertion regions of each opening  431 , the cover  430  is rotated in a first direction, capturing the tabs  432  within the capture region to attach the cover to the upper housing  410 B. Rotating the cover in an opposite second direction permits removal of the cover  430  (for example, to insert a restocked or new carousel  418 ) as the tabs  432  are displaced to the insertion region of each opening  431 . The cover  430  is further locked to the upper housing  410 B, as described below, to prohibit cove removal and access to the medication doses  66 . 
     The medication on demand device  400  further comprises illuminating elements  434  and  436 , in a preferred embodiment each comprising a light emitting diode, for indicating various states and conditions of the device. For example, one or both of the elements  434 / 436 , according to various embodiments, indicate a low battery condition, a battery-charging condition (as described below), an operating mode (e.g., the dosing interval has elapsed and the device is ready to deliver the next dose after the patient is authenticated), certain override conditions as described elsewhere herein, an inoperative mode, an empty carousel (i.e., all medication doses have been administered) and the elapsed time until the next dosing has not yet expired. 
     The medication on demand device  400  further comprises a display  460  for displaying the time remaining until the next permitted dose. Thus the display  460  displays a decrementing count from the time when the last dose was permitted, reaching a zero count when the minimum dosing interval has elapsed. When the display count reaches zero, the patient activates a control element  462  and then swipes the RFID tag proximate the RFID reader  100  (on the face of the medication on demand device) to rotate the carousel  418  and present a medication dose  66  through the access opening  430 A. See  FIGS. 12 ,  13  and  14 . The display  460  also displays a decrementing count (about  30  seconds in one embodiment) from a time when the carousel  418  is moved to the “dose” condition until the carousel  418  is rotated to the “off” condition, i.e., a dose available interval. The patient is required to remove the dose  66  during this interval, as the dose will not be available once the dose available interval has ended. 
     If the patient does not need the dose when the display count reaches zero, the patient should preferably not activate the control elements  462 . During a “lockout” period, i.e., anytime between administered doses or if a dose is skipped (by activation of the control element and swiping the RFID tag, but the dose is not removed from the retention area), the patient can request a dose from the attendant. As further explained elsewhere herein, the attendant can override the “lockout” period, permitting the carousel to rotate and present a medication does to the patient. The “lockout” dose is recorded by the medication on demand device and further the attendant should note the prior skipped dose and the “lockout” dose in the patient&#39;s record. 
     With reference to  FIG. 14 , a threaded body portion of a screw  470  passes through a washer  471 , an opening  418 A in the carousel  418 , a spindle  419  extending from the carousel  418 , an opening  474 A in a planetary gear  474 , an opening  476 A in a trip disc  476  to threadably engage an opening  560 A in a boss  560 , to assemble the elements into a unified assembly for driving by a motor  508  (see also  FIGS. 15 ,  16 ,  17  and  18 ) and its associated gearing as described below. 
     The planetary gear  474  defines one or more notches  474 B within the opening  474 A and the trip disc  476  defines one or more notches  476 B within the opening  476 A. See  FIG. 14 . The notches  474 B and  476 B engage corresponding tabs  419 A (see  FIG. 15 ) disposed on the spindle  419  to properly align the planetary gear  474  and the trip disc  476  relative to the retention areas  154  when both are received on the spindle  419 . See  FIG. 15 . 
     To ensure that the medication doses supplied in the carousel  418  are intended for the patient to whom the carousel was delivered, the carousel includes an RFID tag  477  (written or programmed in the pharmacy when the medication is loaded into the carousel) that is read by an RFID reader (e.g., the RFID reader  100 ) within the medication on demand device. The medication on demand device determines that the patient identification information included within the carousel tag  477  matches the patient identification information stored within the medication on demand device. An affirmative match enables operation of the medication on demand device. A mismatch disables the medication on demand device, preventing the patient from self administering an incorrect medication. 
     For a new patient, i.e., the carousel RFID tag  477  carries new patient identifying information and further is accompanied by the RFID wristband  104  of  FIG. 8 . The attendant loads this information to the medication on demand device by scanning the RFID tag  477  proximate the reader  100 . Once the medication on demand device is programmed with the correct patient identification information and the minimum dosing interval, the patient is given the RFID wristband  104  for later use in controlling operation of the medication on demand device. Note that the wristband  104  and the carousel tag  477  carry the same patient identifying information. 
     During the programming process for a new patient, in addition to programming the minimum dosing interval (also referred to as the lockout time), the attendant programs the medication on demand device with a first dose order, i.e. the time of the patient&#39;s first medication dose measured from the present time. This time can be as short as a few minutes to as long as the minimum dosing interval. The first does order provides the patient with access to a medication dose after the first dose interval has elapsed and the patient has been authenticated 
       FIGS. 15 and 16  illustrate a respective top view and side view of the carousel  418  and the trip disc  476 , including tabs  478  extending downwardly from a circumferential region of the opening  476 A. An arrowhead  479  indicates a rotational direction of the carousel  418 . 
     An emitter/sensor assembly  480  comprising an emitter  480 A, a sensor  480 B and control electronics not illustrated, utilizes a light or infrared beam emitted by the emitter  480 A and impinging the sensor  480 B to detect a trailing edge  478 A of each tab  478 . The trailing edge  478 A of each tab  478  is aligned with a center line of each medication retention area  154  as can be seen from  FIG. 15 . Trailing edge detection indicates that a medication retention area  154  is aligned with the opening  430 A in  FIG. 14 , i.e., the retention area  154  is substantially centered relative to the opening  430 A. Rotation of the motor  508  (see  FIGS. 17 and 18 ) is terminated responsive to an edge-detected control signal produced by the emitter/sensor assembly  480  in response to detection of the trailing edge  478 A. According to one embodiment, rotation of the motor  508  by manual rotation of the carousel  418  is prevented by the high gear ratio of the motor gear train described below. 
       FIGS. 17 and 18  illustrates components of a motor assembly  500 , comprising a worm gear  502  frictionally affixed to a shaft  504  of a motor  508 . The motor  508  (comprising a stepping motor in one embodiment for more precise rotation when energized and since a conventional motor produces sparks that are not permitted in certain environments where oxygen is in use) is affixed to structural ribs  510  extending from a base  514 , in one embodiment using screws  518  and mating nuts  522 . In other embodiments other structural elements and attachment components are used to attach the motor  508  to the base  514 . The emitter/sensor assembly  480  is also shown in  FIGS. 17 and 18 . 
     A gear train plate  530  (shown in outline form in  FIG. 18  to permit viewing of underlying components) is removably attached to bosses  534  by common screws  538 , each extending through an opening in the gear plate  530  to threadably engage an opening in one of the bosses  534 . 
     Controlled power is supplied to the motor  508  through power leads  540 , causing rotation of the motor shaft  504  and driving the worm gear  502 . The worm gear  502  drives a gear  550  having a common shaft  554  with a pinion gear  558  that in turn drives the planetary gear  474  (see  FIG. 14 ) attached to the carousel  418  as described in conjunction with  FIG. 14 . It is known that the interface of the worm gear  502  and the gear  550  resists manually applied forces that tend to drive the worm gear  502  in a reverse direction. Thus it is not possible for the patient to manipulate the carousel in the reverse direction to access and administer an unauthorized medication dose. 
     A boss  570  and an opening  572  of  FIG. 17  receive common screws for attaching the base  514  to the lower housing  410 A. 
       FIGS. 19-22  illustrate elements of an exemplary locking mechanism  600  for locking the cover  430  to the upper housing  410 B to prevent unauthorized access to the medication doses by removal of the cover  430 . 
     The locking mechanism comprises a solenoid  604  further comprising a coil  606  and a solenoid-driven plunger  608  having a lower portion disposed within coil  606  (in the illustrated solenoid configuration) and thus hidden from view in  FIGS. 19 and 20 , and an upper portion  608 A extending from the coil  606  as illustrated. A spring  612  biases the pin  608  to an extended position as illustrated in the detailed view of  FIG. 20 . A pin  614  terminates the upper portion  608 A. 
     To attach and lock the cover  430 , the cover is placed in the opening  414  (see  FIG. 14 ) of the upper housing  410 B such that the tabs or protrusions  432  (also illustrated in  FIG. 14 ) on an underside lip of the cover  430  (see  FIG. 14 ) are received within the respective insertion region  431 A of the openings  431 . Arrowheads  615  depicted in  FIG. 19  represent the downward movement of the cover  430  into the opening  414  and the corresponding insertion of the tabs  432  into the insertion region  431 A. See  FIG. 21  illustrating an underside view of one of the openings  431  and the tab  432  disposed therein, wherein both positions of the tab  432  are illustrated in phantom. 
     As the tabs  432  are received within the insertion regions  431 A, one of the tabs  432  deflects a leaf spring  634 , attached to the upper housing  410 B as illustrated in  FIG. 19 , in a direction away from the upper housing  410 B. An opening  634 A defined in the spring  634  receives the pin  614 . 
     Application of a rotational force (depicted by arrowheads  616  in  FIG. 19 ) displaces each of the tabs  432  from the insertion region  431 A to the capture region  431 B. See  FIGS. 19 and 20 . As the tab deflecting the leaf spring  434  rotates, the pin  614  extends upwardly into the insertion region  431 A to prevent cover rotation in a direction opposite the arrowheads  616 , locking the cover  430  within the upper housing  410 B and preventing unauthorized access to the medication doses, for example, unauthorized access between doses. 
     Supplying power to the solenoid  604  energizes the coil  606 , drawing the plunger  608  into the coil  606  and causing the pin  614  to withdraw from the opening  634 A of the leaf spring  634 . The cover lock is released and rotation of the cover  430  allows removal as described above in conjunction with  FIG. 14 . According to various embodiments of the device, the solenoid  604  can be energized through the programming software application described above and/or manually by the patient&#39;s attendant by operational features at the medication on demand device. For example, in one embodiment the attendant activates the control element  462  for a predetermined duration of about five seconds. After the duration has elapsed, one of the illuminating elements  434  or  436  is illuminated, indicating that the attendant can swipe an attendant card for reading by the RFID reader  100  (or another authentication device), supplying power to and energizing the solenoid  604  to unlock the carousel  418 . 
     As described above, the invention comprises the carousel  418  for carrying the medication doses within retention areas  154 . In another embodiment a tray insert  695  (see  FIG. 23 ), having a shape and size substantially similar to the carousel  418  overlies the carousel  418 . Retention areas  697  of the insert  695  are received within the retentions areas  154  of the carousel  418 . A material of the insert  695  comprises a relatively light weight material. According to this embodiment it is not necessary to remove the empty carousel  418  from the medication on demand, instead the insert  695  is removed and a restocked insert  695  is mated with the carousel  418 . Medication doses are placed within the dose retention areas  697  in a pharmacy and the insert covered to retain the doses within the areas  697 . The insert  695  is then supplied to the attendant for loading into the medication on demand device. In this embodiment the RFID tag discussed above in conjunction with  FIG. 14  is applied to the insert  695 . 
     In yet another embodiment, each dose  66  is enclosed within a package or wrapper carrying a bar code representing the medication type and dosage. The attendant swipes the medication bar code for reading by the bar code reader  90  (see  FIG. 4 ). The medication bar code is compared with the stored medication type and dosage information and responsive to a match operation of the medication on demand device is permitted. In an alternative embodiment, the medication is identified by an RFID code in lieu of a bar code. 
       FIG. 24  illustrates a functional block diagram of one embodiment of a controller  700 , and certain controlled components, for implementing the desired functions of the various embodiments of the medication on demand described herein, especially the embodiments of the medication on demand devices  200  ( FIG. 11) and 400  ( FIG. 14 ). Certain described control functions may not be implemented in all described embodiments. 
     In one embodiment, the functionality of the controller  700  is implemented by a data processing device (e.g., a microprocessor) operative with a memory  701  for storing and executing the commands required to implement the desired functionality. In such an embodiment the commands and control features are executed by a software program stored in the memory  701 . When implemented in a microprocessor, program code configures the microprocessor to create logical, arithmetic and control operations to implement the desired functions. The program code and the microprocessor become an apparatus for practicing the invention. 
     The memory  701  stores programming code and data (e.g., dosing interval, patient identification information) for use in executing certain functions of the medication on demand device, including dose dispensing times. Stored dosing information can be read from the memory  701  for entry into a patient&#39;s medical record via a serial port or directly via a communications device as described below. 
     The controller  700  comprises an access control function  702  responsive to a reader  704 , further comprising a bar code reader, an RFID reader, a smart card reader, a biometrics reader (e.g., finger print, iris) and/or another device for authenticating a person as an authorized patient or as an authorized attendant to program or control the medication on demand device. In an embodiment employing the RFID reader  100  of  FIGS. 4 ,  12  and  13 , a patient&#39; RFID tag  102  (see  FIG. 8 ) typically worn on the patient&#39;s wrist is scanned within a few inches of the RFID reader  100  for about seven seconds. During the scan, the RFID reader  100  interrogates the RFID tag  102  and in response the tag transmits a response signal to the reader  100 . An attendant&#39;s RFID tag is similarly scanned to authenticate the attendant to program or query the device or insert a new carousel  418 . To enable the scanning party to locate the RFID reader  100  in a dark room, an illuminating device (not shown in the Figures) is disposed proximate the RFID reader  100 . In one embodiment, one of the illuminating elements  434 / 436  provides illumination for the scanning process. 
     A motor control function  708  controls the motor  44  as described above. The emitter/sensor assembly  408  supplies a control signal to the motor control function  708  to stop motor rotation when the medication retention area  154  is aligned with the dose access opening (such as the opening  430 A in the cover  430 ). 
     In one embodiment, a stop switch  710  determines that the medication tray has stopped rotating and provides a representative signal to a lock control function  712  that in turn controls the locking mechanism  600  to an engaged condition. 
     A configuration interface  720  interfaces with the programming platform  722 , such as a laptop/tablet computer/PDA (or any of the other programming techniques and apparatuses described herein or generally known) via a serial port  721  to program the various programmable features of the controller  700 . The serial port  721  implements a wired, wireless, infrared or any other known communications technique. In alternative embodiments, other port configurations are used in lieu of the serial port  721 . 
     A timer control function  728  supplies timing signals to control the various time-dependent components of the medication on demand device. 
     An enunciator control function  734  controls a display  736  (such as the display  460  of  FIGS. 12 and 13 ) to display clock time, the time remaining (decrementing) until the next dose is permitted, i.e., accessible through the access opening and/or the time remaining until the dose retention area  154  holding a dose  66  is rotated from beneath the access opening, the device then in an “off” or closed configuration. The display resets to begin the countdown interval at the beginning of each dosing interval. When the display count reaches zero, one of the illuminating elements  434 / 436  is lit to indicate that the next dose is permitted. The patient swipes the RFID tag proximate the RFID reader and activates the control element  462  to rotate the carousel and present a medication dosage through the access opening. 
     The enunciator control function  734  also controls a buzzer/beeper  738  or another device capable of providing an aural notification when the next dose is permitted. The annunciator control function  734  also controls a visual notification device  736 , such as a flashing or solid light (such as the illuminating elements  434 / 436 ) to provide a visual notification when the next dose is permitted. 
     In another embodiment, the annunciator control function controls an aural or visual indicating device to indicate that a patient or an attendant has been authenticated to use (e.g., program or query) the device or that the authentication attempt has succeeded or failed. In yet another embodiment, the annunciator control function controls an aural or visual indicating device to indicate that an attendant&#39;s attempt to override the minimum dosing interval to access a dose for immediate administration has succeeded or failed. A device inoperative condition can also be indicated by an aural or visual indicating device. 
     Power is supplied to the device via a power supply  740 , comprising batteries (such as the batteries  76  illustrated in  FIGS. 3 and 14 ; in one embodiment the batteries comprise nickel-metal-hydride cells. Other power sources, including alternating current (rectified as required) and solar power can be used in lieu of the power supply  740 . A low battery sensor operative with the power source  740  provides an indicating signal to the annunciator control function  734  for generating an aural or visual alert when the battery charge has fallen below a predetermined threshold, at which time the batteries can be charged according to known practices. In a preferred embodiment the device comprises a back-up battery power supply  741  to retain programming code and data in the memory  701 . The batteries are accessed through a battery door  472  illustrated in  FIG. 14 . 
     The controller  700  further comprises a printer driver  748  for supplying print commands to a printer (such as a thermal printer) physically attached to or enclosed within the device. In another embodiment the printer driver  748  drives a separate printer spaced apart from the device and in communications with the medication on demand device over a wired, wireless or infrared link. In another embodiment the printer operates in conjunction with the programming platform  722  to print information regarding operation of the medication on demand device, in response to a query. For example, dosing times and related information (stored in the memory  701 ) can be printed to the printer for inclusion in the patient&#39;s medical record. The attendant can also activate the printer to print a record by operation of one or more of the switches  434 / 436  or the programming platform (after the attendant is properly authenticated). 
     In one embodiment, the controller  700  comprises a modem  752  (wired or wireless) for permitting bidirectional communications between the controller  700  of the medicine on demand device and an external communications device interfacing with a data processor, the latter for programming, querying or otherwise controlling the medication on demand device. 
     In one embodiment, the controller  700  further comprises an expansion card slot  754  for receiving an expansion printed circuit card operative with the controller  700  to reprogram the controller or add features to the medication on demand device of the present invention. 
     A switch  756  represents the various patient and attendant activated switches described above in conjunction with various embodiments of the present invention. Activation of the switch  756  indicates that an RFID device (e.g., wrist band or smart card) is ready for interrogation for patient authentication or to energize a backlight associated with the display  460 . Additionally, in one embodiment the switch  756 , when activated by the attendant or patient, supplies a signal to the controller  700  indicating that the accessible medication dose has been administered. 
     A dose presence detector  757  detects whether the dose has been removed from the retention area  154 , for example by detecting the absence of the dose weight from the retention area  154  or using an infrared emitter in the retention area  154  projecting an infrared beam to a spaced apart detector, the beam detected only when a dose is not present in the well. In another embodiment, a patient&#39;s finger inserted into the retention area  154  breaks the beam, thereby signaling removal of the medication dose. In still another embodiment, a magnetic field is created within each retention area  154 . The existence of the dose in the retention area or insertion of a finger into the retention area distorts the magnetic field. Detection of the distorted magnetic field indicates that the dose has been removed. 
     As known by those skilled in the art, the various functional attributes of the controller  700  illustrated in  FIG. 24  are in communication with other components thereof to effectuate control of the features and functions of the medication on demand device. In one embodiment of the medication on demand device  400 , the various components of the controller  700  are disposed on a board  770  as illustrated in  FIG. 14 . 
     The medication on demand device further comprises certain override features. In particular, the patient&#39;s attendant can override the minimum dosing interval, permitting dose administration prior to expiration of the minimum dosing interval. At anytime during the dosing interval, the attendant activates the override feature by activating the control element  462  and causing it to remain in a certain state for a predetermined interval (five seconds in one embodiment). In response, one of the illuminating elements  434 / 436  illuminates to indicate override operation. The attendant executes an authentication process, and once authenticated, can either activate the solenoid  606  to permit removal of the cover  430  (and replacement of the carousel  418 ) or can cause the carousel  418  to rotate, permitting administration of the next medication dose. The attendant can also command the medication on demand device (i.e., manually command without use of the programming platform) to supply a record of the patient&#39;s actual dosing regimen. 
     The various embodiments of the medication on demand device of the present invention comprise communications components providing communications capabilities to external devices (e.g., the programming platform  722 , a printer, an information technology backbone) for programming and/or querying the medication on demand device. Certain of these features have been broadly described above. These external devices communicate with the medication on demand device via the modem  752 , the serial port  721  and/or any wireless communications protocol (such as a Bluetooth communications protocol) or an infrared communications link. 
     According to another embodiment, the medication on demand device comprises one element of a telemedicine system that controls the dispensing, billing, and inventory control of medication delivery devices, such as the medication on demand device of the present invention. For example, with the modem  752  connected through a communications link to a control/programming station, the medication on demand the device can be programmed to dial a specified number at predetermined times to report status items. The report can include the number of doses self-administered and the number of doses remaining in the carousel. The medication on demand device can also be queried through its communications devices from a remote site (e.g., a hospital pharmacy, a medication cart, or a nurses&#39; station) and commanded to report status items. 
     In another embodiment, the medication on demand device is assigned to patients in a drug abuse clinic, permitting drug treatments, such as methadone, to be administered at home. The medication on demand device can include a global positioning system receiver for locating and tracking the device. Further, the device comprises an asset identification indicia (tag) that can be transmitted to a receiving site for tracking the device. The location information is provided to a monitoring station either in response to a location query or on a predetermined schedule. 
     In another embodiment, the controller  700  includes radio frequency communications equipment providing a wireless link between the medication on demand device and a receiving unit. In one example, the receiving unit resides in a pharmacy cart used by nurses to dispense medications to hospital patients. The transceiver equipment on the cart can query the dispense log from the medication on demand device. The dispense log can be provided from the cart to the pharmacy. In another embodiment, the medication on demand device communicates bi-directionally directly with the pharmacy. Additionally, the dispense log is provided to the hospital accounting department for billing the patient and added to the patient&#39;s medical record. 
     In yet another embodiment, the medication on demand device of the present invention includes a passive radio frequency identification component that disables the medication on demand device when it is removed from a hospital. Hospital doorway sensors detect the presence of the passive RFID element and in response disable the medication on demand device. 
     When equipped with the proper communications components, a medication on demand device of the present invention communicates over a hospital local area network (either a wired or wireless local area network). The medication on demand device can be programmed and/or queried to provide the dispense log and other information stored within or collected by the medication on demand device. 
     In the local area network application, several medication on demand devices are likely connected to the network. It is therefore necessary to provide each device with a unique identification that allows contact of the correct device for programming and querying. 
     The modem also provides a communications link to an automated drug dispensing and inventory control system. As described above, the controller  700  can produce a tray-empty signal responsive to determined tray rotations and the number of medication retention areas  154  carrying a medication dose  66 . The controller operative with the modem  752  sends the tray-empty signal to the automated drug dispensing system to advise the pharmacist to prepare a medication carousel to replace the empty carousel. 
     With the growth of telemedicine systems, the controller  700  operative with the modem  752  (or another communications interface device) allows the medicine on demand device of the present invention to operate in a telemedicine system. 
     According to another embodiment of the invention, each of the medication retention areas  154  comprises a light source  800  (see  FIG. 15 ) to illuminate the area  154  and the dose  66  to allow the patient to see the dose in a dark room. Such a light source preferably operates at a relatively low temperature to avoid heating of the dose  66 . Further, in such an embodiment the medication on demand device comprises a light sensor to detect ambient light and disable the light source  800  during such periods. The light source can also be controlled to activate only shortly prior to the time of a dose administration. 
       FIG. 25  illustrates an alternative embodiment for the control element  462  of  FIG. 14 , comprising a plurality of control elements  850  (a plurality of membrane switches in one embodiment) spaced linearly across a region  854  on a front surface of the medication on demand device. The control elements  850  provide the patient with a mechanism for indicating pain severity, ranging from no pain, by activating a control element  850 A, to a highest or most severe pain level, by activating the control element  850 B. Additional control elements (not shown) between the control elements  850 A and  850 B allow the patient to indicate intermediate pain levels. A numeral “5” indicates the approximate midpoint of the pain scale between the control elements  850 A and  850 B. The functionality of the control elements  850  includes the functions associated with the control element  462 , i.e., the patient or attendant activates one of the control elements  850  after the dosing interval has elapsed and then presents indicia for authentication. Thus the control elements  850  provide a pain severity indication while controlling operation of the medication on demand device. 
     In one embodiment, an eleven element pain scale is implemented by the control elements  850 , comprising: a zero level (represented by the control element  850 A), levels 1-3 indicating mild pain, levels 4-6 indicating moderate pain and levels 7-10 indicating severe pain (with the control element  850 B representing a most severe pain). To assist the patient in determining his pain level, expressive facial or smile icons  855  are disposed within the region  854 , overlying the control elements  850  in one embodiment. 
     In an alternative embodiment, each of the control elements  850  comprises a sensor each producing a proximate magnetic field. Disturbance of the magnetic field by, for example, a finger inserted into the field, is detected and represents activation of the corresponding control element  850 . 
     In the embodiments described above the RFID reader  100  comprises an integrated antenna and reader/processor that tends to limit the read distance to about one inch. In another embodiment of the invention, an external RFID antenna  860  (see  FIG. 25 ) is disposed about a periphery of the region  854 . The antenna  860 , which is coupled to the RFID reader/processor (not shown), extends the read range to several inches. 
     In another embodiment of the invention, when an attendant is responsible for providing medication to the patient, rotation of the carousel or tray is responsive to authentication of both the patient and the attendant. In an application where the patient self-administers the medication dose, the medication on demand device requires authentication by only the patient to cause the carousel or tray to present the next dose. 
     In yet another embodiment, in addition to the authentication process required to activate (rotate) the carousel or tray as described above, the patient is required to perform an overt act to indicate that the medication has been administered. Administration of the dose and the administration time can be recorded by the medication on demand device for later entry into the patient&#39;s record. Such an overt act can comprise a subsequent authentication-like process or simple activation of a switch as a condition precedent to presentation of the next dose. 
       FIG. 26  illustrates a flow chart depicting operations associated with the medication on demand device of the present invention. At a step  902 , an attendant programs the various programmable features of the medication on demand device. In one embodiment, the programing elements include: a minimum dosing interval, medication type, patient identification information, attendant identification and a first dose cock time or an interval between a present time and administration of the first dose. 
     A step  904  depicts administration of the patient&#39;s first medication dose at the predetermined clock time or after an interval from the present time. 
     At a step  906  a counter or timer is initialized with the minimum dosing interval in preparation for the next dose after the minimum dosing interval. At a step  907  the counter or timer is decremented and a decision step  908  determines whether the minimum dosing interval has elapsed. Execution returns to the decrementing step  907  until the decision turns affirmative at the decision step  908 . Execution continues to a step  910  where the medication on demand device provides a visual and/or aural indication to the patient. 
     The patient is authenticated, according to the various authentication techniques described elsewhere herein, at a step  912 . (In one embodiment, authentication is preceded or followed by activation of a control element of the medication on demand device.) The carousel rotates at a step  914  and holds in the rotated position during a step  916  (about 30 seconds in one embodiment). The rotated position aligns a medication dose with the opening, allowing the patient to withdraw a dose from the carousel through the opening. Step  918  indicates that the patient has self-administered the dose. After the hold time has expired, the carousel rotates (see a step  922 ) to align a blank region between medication retention areas with the opening. In this configuration, a medication dose is not available for administration. The process returns to the step  906  where the counting or timing to the next dosage interval begins. 
     In another embodiment, the dispenser comprises a plurality of medication retention areas  154  and a cover or housing having a plurality of controlled access openings formed therein. For example, the controlled access openings comprise a plurality of doors prohibiting access to the retention areas  154  when in a closed condition and permitting access to the medication retention areas  154  when in an opened condition. A controller controls a condition of the plurality of doors to permit access to the medication doses after the minimum dosing interval. 
     While the invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalent elements may be substituted for elements thereof without departing from the scope of the present invention. The scope of the present invention further includes any combination of the elements from the various embodiments as set forth herein. In addition, modifications may be made to adapt the teachings of the present invention to a particular application without departing from its essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.