Abstract:
A method for the vaporization of particulate material ( 10 ) includes providing one or more containers ( 15 ) each containing possibly distinct particulate materials ( 10 ) each having at least one component, fluidizing the particulate material ( 10 ) in at least one of the containers ( 15 ), and providing a vaporization zone ( 50 ) that is thermally isolated from at least one of the containers ( 15 ). The method further includes delivering particulate material received from each container ( 15 ) to the vaporization zone ( 50 ), and applying heat to vaporize the delivered particulate materials ( 10 ) at the vaporization zone ( 50 ).

Description:
This application is a National Stage Application of International Application Number PCT/GB2006/000874, filed Mar. 13, 2006; which claims priority to Great Britain Application No. 0505058.8, filed Mar. 11, 2005. 
     FIELD OF THE INVENTION 
     This invention relates to dispensing systems for use in patient care and in particular but not exclusively to dispensing metered doses of medicinal or therapeutic products. One aspect of the invention relates to a dispensing system for sublingual delivery of a pain-relieving drug, but other applications of the invention relate to other fields such as inhalation delivery. 
     BACKGROUND OF THE INVENTION 
     There are many different dispensers which are utilised to dispense a metered dose of a product such that the dose can be self-administered, by the patient, under the direction of a physician, such dispensers including primarily aerosol dispensers relying upon a pressurised dispensing container having a metering valve and pump dispensers having a pump chamber arranged to dispense a metered dose. It is important to regulate use of the dispenser, to avoid overdosing where the product is a potentially dangerous or expensive drug. 
     Lock-out mechanisms have been disclosed, for example in U.S. Pat. No. 4,934,358, for preventing actuation of an inhalation dispenser other than in accordance with a predetermined dosing schedule. Similarly, GB2368061A discloses a locking mechanism to prevent further dispensing until electronically released in accordance with a desired dispensing program. 
     It is also known from WO03/097141, for a dispensing system to be provided with a control circuit which can be programmed to provide a dosing regime in accordance with the requirements of a physician. 
     SUMMARY OF THE INVENTION 
     The present invention seeks to provide improvements in such dispensing systems with a view to providing a practical solution in a marketable product. It can be used, for example, to dispense a formulation of a drug such as fentanyl, as described in WO2004/080382. 
     In one aspect of the invention, a dispenser includes a lock having a resilient self-locking mechanism for placing the lock into a locked state after each dose is dispensed. A sensor is provided to sense when the lock is in this locked state and a control circuit is responsive to the sensor and operable after a lock-out period to energise a lock actuator to return the lock to an unlocked state. 
     In another aspect, a lock is included with first and second retaining means that are operable independently of a lock actuation, so that the actuator requires to be engaged only when changing the lock from the locked to the unlocked state, or vice versa. 
     In a preferred embodiment, a push-push mechanism enables the lock to be responsive to the control circuit for both locking and unlocking, in addition to constituting the resilient self-locking mechanism. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective external view of a dispenser; 
         FIG. 2  is a sectional elevation of a dispensing system in accordance with a first embodiment, in which an actuator is in a rest position and the system includes a lock which is in an unlocked state; 
         FIG. 3  is a plan view of the system of  FIG. 2 , illustrating components of the lock; 
         FIG. 4  is an enlarged elevation sectioned to show detail of  FIG. 2 ; 
         FIG. 5  is a view corresponding to  FIG. 4 , showing the actuator partially depressed and the lock primed for self-locking action; 
         FIG. 6  is a view corresponding to  FIG. 5 , showing full depression of the actuator to release a dose; 
         FIG. 7  is a view corresponding to  FIG. 6 , after partial release of the actuator; 
         FIG. 8  is a view corresponding to  FIG. 7 , after the actuator has fully returned to its rest position and the lock has entered the locked state; 
         FIG. 9  is a further view of the embodiment of preceding figures, showing the energising of a lock actuator to return the lock to its unlocked state; 
         FIG. 10  is a sectional elevation of a dispensing system in accordance with a second embodiment having a push-push mechanism and showing the lock in its unlocked state; 
         FIG. 11  is an enlarged view of the lock of  FIG. 10 ; 
         FIG. 12  is a view corresponding to  FIG. 11  showing the actuator fully depressed and dispensing a dose; 
         FIG. 13  is a view corresponding to  FIG. 12  showing the actuator having returned to its rest position; 
         FIG. 14  is a plan view showing detail of the push-push mechanism in the unlocked state of the lock; 
         FIG. 15  is a corresponding view showing the push-push mechanism in an intermediate position; 
         FIG. 16  is a corresponding view showing the push-push mechanism in the locked state; and 
         FIG. 17  is a perspective view showing a cam track of the push-push mechanism. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings. 
     The embodiment of  FIG. 1  comprises a dispensing system  1  suitable for sublingual delivery of a narcotic product for use in pain relief. A housing  2  is closed at its upper end by a button  3  which can be manually depressed relative to the housing by a user wishing to dispense a dose of a product held in a container. The button  3  is located above the container, and is constrained from being removed from the housing by internal stop features. The button  3  also defines an aperture through which a dispensing nozzle  5  delivers an aerosol spray of product. 
     A window  6  is formed in the housing  2 , through which the presence and/or amount of product in the container can be inspected. The button  3  includes a port  7  through which an indicator for verifying the current status of an internal lock can be viewed. A removable dust cap may be provided so as to clip onto the housing in a manner which shields the button from the ingress of debris prior to use. 
     The shape and size of the viewing window  6  may be varied, e.g. depending on the length of the container. 
       FIG. 2  shows the internal construction of the dispensing system  1 , including a glass-walled container  21  and an actuator  22  for delivering an aerosol spray through dispensing nozzle  5  when the actuator is depressed. The button  3  is located on the actuator  22  by protrusions  23  and  24 , the actuator having a generally cylindrical outer surface engaged peripherally by the protrusion  23  and an aperture located by the protrusion  24 . Depressing the button  3  relative to the housing  2  causes depression of the actuator, along the longitudinal axis of the container to provide a dispensing stroke of the dispenser. The location of the protrusion  24  in an aperture formed in the upper end of the actuator  22  prevents mis-alignment of the actuator relative to the button  3 , thereby maintaining the dispensing nozzle  5  in alignment with the opening defined by the applicator  4 , to ensure unimpeded delivery. 
     The button  3  is prevented from being removed from the housing by cooperating stop formations  9 . The housing  2  includes a chassis  10  connected by snap-fit connectors to side wall portions of the housing. 
     The dispenser also includes a lock  25  for selectively preventing actuation of the actuator  22  and a control circuit  26  for electrically releasing the lock  25 . 
       FIG. 2  shows also a primary battery  27  for energising the lock and a secondary battery  28  for the operation of the control circuit  26 , and a capacitor  29 . 
     The lock  25  comprises a locking member  30  which is slidable in a direction normal to the direction of depression of the actuator, so as to be movable into and out of a locking position in which an end portion  31  of the locking member limits travel of the actuator  22 , to prevent completion of a dispensing stroke. 
     In  FIG. 2 , the locking member  30  is shown in a position in which the lock  25  is unlocked and the end portion  31  does not impede axial movement of the actuator  22 . 
     A spring  32  in the form of a compression coil spring biases the locking member  30  towards the actuator  22 . When the lock  25  is in the unlocked state and the button  3  is in the rest position, as shown in  FIG. 2 , the locking member  30  is retained against action of the spring  32  by a latch  33  which, as shown more clearly in  FIG. 3 , projects into an aperture  34  formed in the locking member. The latch  33  comprises a domed head mounted on a cylindrical piston  35  which is slidable within a fixed cylinder  36  and upwardly biased by a second spring  37  into latching engagement with the locking member  30 . 
     At its end  42  distant from the actuator  22 , the locking member  30  is pivotally connected to one end of a lever  43  whose other end is connected to a plunger  44  of a pull solenoid  45 . The lever  43  is pivoted about a pivot pin  46  located so as to apply a 2:1 leverage ratio, thereby amplifying movement applied to the locking member  30  by solenoid plunger  44 . This amplified movement is applied to provide sliding motion of the locking member  30  when the solenoid  45  is energised. Since the solenoid  45  is a pull solenoid, energising the solenoid results in the plunger  44  being retracted within the solenoid and, by lever action, the locking member  30  being urged outwardly with respect to the actuator  22 . 
     One leg or a pair of legs  47  project from the button  3  into abutment with the top surface of the latch  33  so that depression of the button  3  results in the latch  33  being pushed against action of the second spring  37  in a direction which retracts the domed head of the latch  33  from the aperture  34  and releases the locking member  30 . As described below, this release occurs only after the actuator  22  has been depressed to a point beyond the limit of travel available when locked, so that the released locking member cannot yet advance fully to its locked position. 
     Electrical contact pins (not shown) are located in fixed positions adjacent to the lever  43  and are contactable by a resilient contact  49  mounted on the lever and arranged to make electrical contact between the pins whenever the lock  25  is in the locked state as described below. 
       FIG. 4  shows part of the dispenser in the same state as in  FIG. 2 . In this configuration, the lock  25  is in an unlocked state with the locking member  30  latched in a fully retracted position. The contact  49  is not touching the contact pins. 
       FIG. 5  illustrates partial depression of the button  3 , resulting in motion of the actuator  22  towards the container  21  to a position where a shoulder  60  defined by the actuator  22  is able to pass beyond the position of the locking member  30 , while the locking member  30  is retained by action of the latch  33  from limiting travel of the actuator. 
     Having passed this position, the legs  47  depress the latch  33  to the point where the locking member is free to advance with a sliding motion towards the actuator  22  under action of the spring  33 . This sliding motion eventually causes the locking member  33  to come into sliding contact with the cylindrical surface of the actuator  22  as the actuator continues to travel. 
       FIG. 5  therefore shows the lock  25  in an unlocked state but in which the locking member  30  is unlatched and therefore primed to provide self-locking action during the return stroke of the button  3  as described further below. The contact  49  is still not touching the contact pins. 
       FIG. 6  illustrates the position of the button at its maximum degree of travel, at which point the dispenser causes a dose of spray in aerosol form to be dispensed via the dispensing nozzle  5 . The dispenser is of a type which can dispense only a single dose in response to one actuating displacement of the actuator  22  e.g., through a stroke of 6 mm. The initial portion of the travel, e.g. the first 2 mm of depression, does not produce spray output and constitutes a degree of over-travel in the movement of the actuator. Following the release of the metered dose, no further discharge is possible immediately. When the actuator  22  has been allowed to return to within the initial portion of travel from its rest position, as shown in  FIG. 4 , a further dispensing stroke may be completed depressing the actuator  22  to the position shown in  FIG. 6 . 
     In the fully depressed position shown in  FIG. 6 , the locking member  30  is still in sliding contact with the cylindrical surface of the actuator  22 . The lock  25  therefore continues to be in an unlocked state, with the locking member primed ready for self-locking action. The contact  49  is still not touching the contact pins. 
       FIG. 7  illustrates a further position in which the button  3  has been partially released and the button together with actuator  22  is in the process of returning to its rest position. This return stroke motion is achieved by the presence of a resilient mechanism within the container  21 , which generally requires the presence of a coil spring biasing a valve stem on which the actuator is mounted into an extended position in which the actuator  22  is fully raised. 
     In  FIG. 7 , the locking member  30  maintains sliding contact with the cylindrical surface of the actuator  22  as the actuator progressively moves upwardly and away from the container  21 . The position of the shoulder  60  eventually rises to a level where it clears the upper surface of the locking member  30  which then is able to travel under the influence of the spring  32  into a locking position as shown in  FIG. 8 . The contact  49  remains not touching the contact pins. 
     In  FIG. 8  the end portion  31  of the locking member  30  extends inwardly of the shoulder  60 . In this locked state, subsequent depression of the button  3  causes the shoulder  60  to engage axially the upper surface of the locking member  30  at the end portion  31  so that the locking member  30  will limit travel of the actuator and prevent the actuator from reaching a position where a further dose can be dispensed. 
     In the locked state as shown in  FIG. 8 , the lever  43  is tilted to a position where electrical contact is made between the contact pins and the contact  49  which thereby together provide a sensor to which the control circuit  26  is responsive. This change of status in the electrical condition of the sensor is interpreted by the control circuit  26  as indicating that a dose has been dispensed. In practice, the timing at which the sensor changes state will be momentarily after the instant at which the dose is dispensed since the lock  25  does not enter its locked state until part-way through the return stroke of the actuator  22 . Since in practice the actuator  22  will be released immediately after the dispensing of a dose, this timing delay is acceptable. 
     In the locked state of the dispensing system  1 , no further dose may be dispensed. The control circuit  26  is configured to determine, by measuring elapsed time from entering the locked state, a further time at which the lock  25  can be released to allow a further dose to be dispensed. After such a lock-out period has elapsed, the control circuit  26  unlocks the lock  25  by energising the solenoid  45 , thereby retracting the plunger  44  as shown in  FIG. 9 . This motion is communicated via the lever  43  to the locking member  30 , causing the locking member to be retracted to the position shown in  FIG. 9  at which the latch  33  can again engage the locking member. After engagement by the latch  33 , the rest state shown in  FIG. 4  is again achieved, and the lock  25  then remains in its unlocked state with the locking member  30  retracted to a position where its end portion  31  no longer limits travel of the actuator  22 . A further dose may therefore be dispensed at any time. After the further dose, the lock  25  will again be self-locking, thereby triggering the measurement of a further lock-out period by the control circuit  26  before the lock is released. The control circuit may be configured to keep track of the number of doses dispensed, to compute the frequency with which doses are dispensed, and may be configured to regulate the length of the lock-out period accordingly, in order to comply with a prescribed dosing schedule. 
     In order to energise the solenoid  45 , the control circuit  26  applies a charging voltage to the capacitor  29  and, after an appropriate charging period, connects the output voltage to the solenoid to deliver a current pulse for solenoid actuation. Since the locking member  30  is then retained by action of the latch  33 , it is sufficient to energise the solenoid only during the transition from the locked to the unlocked state of the lock  25 . The lock may thereafter be maintained in an unlocked state for an indefinite period without energy consumption. Similarly, the sensor draws current only when the lock  25  is in the locked state. However, since this will typically occur only during a lock-out period of no more than a few hours, e.g. one hour, the use of the sensor does not represent a continuous drain on the current resources of the control circuit  26 . These features contribute to prolong the shelf-life of the system  1 , typically of the order of 3 years. 
     A second embodiment will now be described. The second embodiment has a number of features in common with the first embodiment, for example the same overall appearance as shown in  FIG. 1 , and the same reference numerals will be used for internal components where corresponding or equivalent features are present. Detailed description of components in the second embodiment will be omitted where it is apparent that they correspond to features previously described with reference to the first embodiment so that parts of the description of the first embodiment may be assumed to be incorporated where appropriate. 
     The second embodiment differs from the first embodiment primarily in the detailed construction of the lock  25  and in certain aspects of operation of the control circuit  26 .  FIG. 10  is an overview. 
     As shown in enlarged view in  FIG. 11 , the lock  25  of the second embodiment has a locking member  30  having an end portion  31  adjacent a shoulder  60  of an actuator  22 . The locking member  30  has at its other end a pivotal connection to a lever  43  which serves as a pivotal linkage between the locking member and the plunger  44  of a solenoid  45 . 
     The locking member  30  is biased by a spring  32  towards the line of motion of the actuator  22  and, in the rest position shown in  FIG. 11  in which the lock  25  is unlocked, is prevented from moving in response to the spring action by a latching mechanism  120 . The latching mechanism  120  is a push-push mechanism which provides two possible stable states of the latching mechanism. The first stable state corresponds to the unlocked state of lock  25 , as shown in  FIG. 11 . The second stable state corresponds to the locked state of the lock, as shown in  FIG. 13  in which the locking member  30  is advanced to a position in which the first end portion  31  limits travel of the actuator  22  by abutment against the actuator. 
     The latching mechanism  120  relies upon interaction between a cam follower pin  121  and surfaces of a cam track  122 . The cam follower pin  121  is resiliently biased into positive contact with the floor surfaces  126  by a leaf spring  127 , as shown in  FIG. 11 . The cam track  122  is shown schematically in  FIGS. 14 to 16 , and in more detail in  FIG. 17 . The cam track  122  defines a closed path around which a free end  123  of the cam follower pin  121  may travel, a fixed end  124  of the cam follower pin remaining stationary and such that the position of the locking member  30  relative to the actuator  22  is determined by the instantaneous location of the free end  123  relative to the track. 
     The cam track  122  defines two stable positions of the free end  123 . The first position corresponding to the unlocked state is shown in  FIG. 14 , and the second position corresponding to the locked state is shown in  FIG. 16 . 
     As illustrated schematically in  FIG. 17 , the cam track  122  is defined by side-walls  125  and ramped floor surfaces  126 , the floor surfaces being ramped in ratchet-like manner to permit travel of the free end  123  of the cam follower pin  121  in one fixed direction around the closed path circuit, so that back-tracking is not possible. 
     In order for the push-push mechanism to operate, a retraction movement of the locking member  30  (i.e. to the right as drawn) is first required in order to place the free end  123  in an intermediate portion of the cam track  122 , and a subsequent forward movement of the locking member  30  (i.e. to the left) which continues until the next available stable state of the push-push mechanism is reached. As shown in  FIGS. 14 to 16 , the retraction movement (to the right) may be initiated either by energisation of the solenoid  45  or by mechanical impetus originating from depression of the button  3 , as described below. Subsequent forward movement (to the left) is effected by action of spring  32 . 
     Referring to  FIG. 11 , the dispenser of the second embodiment is shown in its rest state, in which the lock  25  is in an unlocked state and the button  3  is fully raised. In this position, the end portion  31  of the locking member  30  is retracted so as to provide no limit against downward travel of the actuator  22 , since there is a defined radial clearance between the shoulder  60  of the actuator and the end portion. 
     The button  3  has a pair of legs  128 , each being chamfered at its lower end to provide a cam surface  129 . In the rest position, as shown in  FIG. 11 , the legs  128  remain clear of the locking member  30 . In this configuration, the looking member  30  is restrained from forward motion towards the actuator  22  by the cam follower pin  121  co-operating with the cam track  122 , as shown in  FIG. 14 . 
     When it is required to dispense a dose, the button  3  is manually depressed, thereby initiating downward travel of the actuator  22  towards the container  21 . The legs  128  move towards and come into contact with the locking member  30  and cam action occurs between the cam surfaces  129  and an upper edge of the locking member  30 , with a resulting movement of the looking member  30  in a direction away from the actuator  22 . The locking member  30  is thus retracted by cam action and moves to a position shown in  FIG. 15 , in which retraction (movement to the right of  FIG. 15 ) of the locking member  30  is accompanied by travel of the free end  123  of the cam follower  121  within the cam track  122  to an intermediate position, as shown in  FIG. 15 . 
     The dose is then dispensed, as shown in  FIG. 12 , and the button is released so as to rise towards its rest position. During this initial movement, the legs  128  project through apertures  130  in the locking member  30 , as shown in  FIGS. 14 to 16 , and the presence of the legs within the aperture prevents further movement of the locking member  30 . 
     When the button position rises to the extent that the shoulder  60  of actuator  22  is clear of the end portion  31  and legs  128  rise clear of the apertures  130 , the locking member  30  is released from this restraint. By action of spring  32 , the position of the locking member  30  advances towards the actuator  22  and comes to rest in the locked position of  FIG. 16 , where the latching mechanism  120  is in its second stable state with the free end  123  of the cam follower resisting further advancement of the locking member. 
     The lock  25  is now in a locked state, as shown in  FIG. 13 , in which the end portion  31  of the locking member  30  is located so as to limit travel of the actuator  22  and thereby prevent completion of any dispensing stroke. 
     In this locked state, the position of the lever  43  is such that contact between the contact pins and the contact  49  is made. This signals to the control circuit  26  that the lock is in its locked state. 
     The control circuit  26  then initiates determination of a lock-out period during which no further actuation of the dispenser is to be allowed. At the end of the lock-out period, the control circuit energises the solenoid  45  such that the plunger  44  is pulled into the solenoid, this motion being communicated via lever  43  to apply a retracting impetus to the locking member  30 . The solenoid is then de-energised, allowing the locking member  30  to relax to a new stable state, corresponding to the configuration of  FIG. 14  in which the lock is now placed in an unlocked state. 
     Any further actuation of the dispenser will result in a repeat of the above sequence, in which the lock  25  is automatically self-locking after each dose is dispensed and subsequently unlocked only by firing of the solenoid by the control circuit  26 . 
     The control circuit  26  may additionally or alternatively be configured to provide a dosing schedule in which, if a further dose is not taken within a predetermined time interval from unlocking the lock  25 , the control circuit energises the solenoid  45  again in order to initiate a further lock-out period. By energising the solenoid  45 , an impetus is applied to retract the locking member  30 , as shown in  FIG. 15 , so that, when the solenoid is de-energised, the locking member relaxes to a new locked state, as shown in  FIG. 16 . This state will continue until the control circuit  26  again energises the solenoid  45  to change the state of the latching mechanism  120  to place the lock in an unlocked state. 
     In the second embodiment, unlike the first embodiment, the control circuit  26  is able not only to unlock the lock  25  but also to relock it, simply by energising the solenoid  45 . 
     In one example, after an initial dispensing stroke, the control circuit  26  determines a first lock-out period of four seconds, immediately following which the solenoid is energised to change the state of the lock into an unlocked state. A dose allowance period is then defined, e.g. of 15 minutes from the change of state. If a further dispensing stroke occurs within this dose allowance period, self-locking action will return the lock to its locked state and the control circuit  26  will then determine a second lock-out period, e.g. of 2 hours, before again energising the solenoid to return the lock to its unlocked state. 
     However, if no dispensing stroke occurs during the dose allowance period, the control circuit  26  energises the solenoid at the end of the second lock-out period, to return the lock to its locked state for a further lock-out period, e.g. of 1 hour 45 minutes. The control circuit  26  then energises the solenoid, to return the lock to its unlocked state to permit further doses to be dispensed. 
     Other patterns of similar or greater complexity may be devised and embodied in the control circuit  26  in accordance with a required dosing schedule. 
     The control circuit  26  is required to energise the solenoid  45  only during transitions from one state to another, thereby minimising the drain on the current resources available to the control circuit and extending battery life. The sensor similarly draws current only when the locked state of the lock  25  is sensed. 
     In each of the first and second embodiments, the control circuit  26  may optionally include a failsafe feature whereby, after each energisation of the solenoid  45 , the status of the sensor is determined and compared with the expected status of the sensor. For example, in the first embodiment, after each energisation of the solenoid  45 , the lock  25  should transit from the locked state to the unlocked state. If the sensor nevertheless indicates that the lock remains in the locked state, this can be interpreted by the control circuit  26  as being a fault condition. Remedial action implemented by the control circuit  26  may be to energise the solenoid  45  repeatedly, until the required status of the sensor is detected. A maximum number of repeat attempts may be set by the control circuit  26 , following which the control circuit may enter a failsafe mode in which no further energising of the solenoid  45  is permitted. 
     In the second embodiment, after each energisation of the solenoid  45 , the status of the sensor should change to correspond to either the locked or unlocked state of the lock  25 , depending upon the initial state of the lock prior to energising the solenoid. If no transition of state has occurred, a defect condition may then be determined to exist by the control circuit  26  and appropriate remedial action taken, as indicated above. 
     A dispenser of the invention may include visual indicators provided on the side edge of the locking member  30 , at a position in which allows the position of the locking member to be determined by inspection through the port  7  shown in  FIG. 1 . For example, red and green dots may be applied to the locking member so that a green dot when visible indicates an unlocked state and a red dot when visible indicates a locked state. 
     In each of the above embodiments, the control circuit  26  consists of a printed circuit board on which are mounted a microprocessor, the solenoid  45 , the contact pins, and the contact  49  together with capacitor  29  and peripheral components. The microprocessor is preferably programmed with deterministic software for regulating the timing of unlocking the lock  25  and, in the case of the second embodiment, optionally relocking the lock by energising the solenoid  45 . 
     A dispenser of the invention may include means to enable the microprocessor to be reprogrammed in accordance with a new dosing schedule. The control circuit may store a dispensing history of the device which may be subsequently downloaded for analysis. 
     In each of the above embodiments, the mass of the locking member is selected to dynamically balance the mass of the solenoid plunger such that, when the system is subject to shock or impact, the effect of inertia on the locking member and the solenoid is to apply substantially equal and opposite turning moments about the pivot pin  46 , so that there is minimal net turning moment applied to the locking member. The spring  32  provides sufficient restraint to prevent any net movement of the locking member. Inadvertent change of state of the lock is thereby avoided, when the system is subject to accidental or deliberate shocks and impacts. 
     A number of variations to the disclosed embodiments are envisaged. For example, the actuator  22  and button  3  may be formed integrally. The applicator  4  may be modified to be suitable for other forms of delivery such as inhalation therapy. Alternatively, the button may be constructed so as to be connectable to a number of alternative applicators. 
     The dispenser may comprise a pump dispenser, particularly where low velocity aerosol delivery is required, as in the case of sublingual delivery, or alternatively may comprise a pressurised dispensing container, particularly where higher velocity aerosols are required, such as in the case of inhalation therapy. 
     Other forms of sensor may be used to sense the locking state of the lock. For example, the position of the locking member itself may be sensed or alternatively the position of the solenoid plunger. Sensing may be via the use of electrical contacts which are bridged to complete a circuit. Alternatively, different forms of sensor for measuring position or proximity may be utilised. 
     In the specific description of the embodiments, reference is made to springs providing bias and motion where required. Alternative spring construction may be used. For example, tension springs may be used instead of compression springs and leaf springs may be used instead of coil springs. Other resilient means including the use of magnets may be substituted where appropriate. 
     In the embodiment illustrated in  FIG. 1 , indicator port  7  is provided in the button. Alternatively, the indicator port may be provided in the housing, depending upon the shapes adopted for the housing and top button and the relative position of the components of the lock  25 . 
     In the embodiments disclosed above, the lock  25  engages a surface of the actuator  22 . Alternative embodiments are envisaged in which actuator movement is limited by the lock engaging a feature formed in the button  3 , such embodiments being equally effective since the button  3  and actuator  22  move in unison throughout the stoke of the dispenser. 
     In the arrangement of  FIG. 2 , the container  21  rests upon the chassis  10  which forms an end portion of the housing  2 . Dispensers of different length may be accommodated, e.g. by including a modification to the chassis  10  to provide a support so that the bottom end of the container stands off from the base of the housing. 
     The embodiments detailed above have two separate batteries. By appropriate modification to the circuit, a single battery may be utilised.