Abstract:
Disclosed is a method and device for rapid heating of a substance. One embodiment includes a substance including a drug to be vaporized for inhalation therapy. A sealed fuel cell containing a combustible filament is placed in a heat exchange relationship with the substance. An igniter is operatively associated with the combustible element. The substance may be vaporized inside of a housing to allow the vaporized drug to aerosolize and be inhaled by a user.

Description:
RELATED APPLICATIONS 
     This application is a continuation application of U.S. application Ser. No. 10/146,086, filed May 13, 2002, entitled “Method And Apparatus For Vaporizing A Compound”, which is incorporated by reference herein in its entirety for any purpose. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to methods and devices for delivery of an aerosol through an inhalation route. Specifically, the present invention relates a method and device for producing aerosols containing active drugs that are used in inhalation therapy. 
     BACKGROUND 
     It is known to aerosolize a drug for delivery by inhalation. For example, U.S. Pat. No. 5,099,861 to Clearman et al. for an Aerosol Delivery Article (“Clearman et al.”) discloses a device including a substrate carrying a flavor or a drug. The substrate is heated by burning a fuel element which can be an “extruded carbonaceous material”. Heating the substrate causes the flavor or drug to aerosolize which allows the user to inhale the flavor or drug. However, because the device disclosed in Clearman et al. burns a carbonaceous material to generate heat, heating and aerosol generation can be relatively slow. Additionally, the user must use a separate implement, such as a lighter or match, to ignite the fuel element. Also, the fuel element may generate undesirable products such as odor and smoke which may irritate the user or bystanders. These drawbacks to the Clearman et al. device can make the device relatively inconvenient. 
     U.S. Pat. No. 4,693,868 to Katsuda at al. for a Thermal Fumigator for Drugs (“Katsuda et al.”) also discloses a device which can be used to vaporize a drug for inhalation delivery. As Clearman et al., Katsuda et al. also uses heat to vaporize the drug. However Katsuda et al. discloses ignition of a volatile fuel such as alcohol, petroleum or ether to generate the heat required to cause vaporization of a drug. The volatile fuel held by a container and is ignited by a metal catalyst included with the device. However, while combustion of the fuels disclosed in Katsuda is typically much more rapid than the combustion of the carbonaceous material fuel disclosed in Clearman et al., ignition of the fuels disclosed in Katsuda et al. can still be relatively slow. Additionally, the fuels disclosed in Katsuda et al. generate gaseous products upon combustion. Thus, if the fuel is contained in a sealed container, the pressure in the container may increase and cause a rupture. Additionally, even if a valve is provided for escape of the excess gas upon combustion, the escaping gas may generate an unpleasant odor. 
     SUMMARY OF THE INVENTION 
     The present invention includes a method and apparatus for providing inhalation delivery of a drug from a self contained unit. A method and device of the present invention allows rapid heating of a coated drug to produce a vapor. The rapid heating is followed by cooling and condensation of the vapor to provide an aerosol, also referred to as a condensation aerosol, which can be inhaled by a user to deliver a dose of the drug. The method and apparatus of the present invention achieves such rapid heating by using a sealed fuel cell having a combustible element. Because the fuel cell is sealed, there are advantageously no unpleasant combustion products released into the surrounding atmosphere. Additionally, the combustion of the element is relatively rapid and preferably does not generate gaseous products which would cause an increase in pressure in the sealed fuel cell. 
     A device for rapid heating of a coated substance in accordance with the present invention preferably includes a substrate which has an interior surface surrounding an interior region and an exterior surface upon which the coated substance is to be adhered. Though the substrate is preferably metallic, it does not need to be. A combustible element is placed in the interior region of the substrate and an igniter is connected to the combustible element. The igniter is for initiating oxidation of the combustible element. Preferably, the coated substance includes a drug to be vaporized inside of a housing to allow the vaporized drug to be inhaled by a user. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view showing internal detail of a device for vaporizing a drug including a sealed fuel cell in accordance with the present invention. 
         FIG. 2  is a top view showing internal detail of a distal portion of the device shown in  FIG. 1 . 
         FIG. 3  is a perspective view showing the external surface of the distal portion of the device shown in  FIG. 1 . 
         FIG. 4  is a perspective view showing the external surface of the device shown in  FIG. 1 . 
         FIG. 5  is a detail side sectional view of the device shown in  FIG. 1 . 
         FIG. 6  is a flow chart illustrating a method of delivering a drug via inhalation in accordance with the present invention. 
         FIG. 7  is a side view of an alternate embodiment of the sealed fuel cell and substrate useable with the housing illustrated in  FIG. 1  in accordance with the present invention. 
         FIG. 8  is a side view of an alternate embodiment of the sealed fuel cell and substrate useable with the housing illustrated in  FIG. 1  in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As used herein, the term “Aerosol” refers to a suspension of solid or liquid particles in a gas and the term “Vapor” refers to a gas, and “vapor phase” refers to a gas phase. The term “thermal vapor” refers to a vapor phase, aerosol, or mixture of aerosol-vapor phases, formed preferably by heating. 
       FIG. 1  is a side view showing internal construction of a preferred embodiment of a drug delivery device  10  that rapidly heats a drug using an exothermic reaction in accordance with the present invention. Drug delivery device  10  includes a fuel cell  12  for containing an exothermic reaction surrounded by a substrate  20  which is to be coated with a drug  15  or compound containing a drug. In the embodiment shown in  FIG. 1 , fuel cell  12  and substrate  20  are surrounded by a housing  30  having a distal end section  30   a , a proximal end section  30   b  and including an airway  32  and mouthpiece  34 . Airway  32  provides a path for aerosolized drug from the central region of housing  30  to mouthpiece  34 , which facilitates inhalation of the aerosolized drug. Preferably, drug delivery device  10  includes two sections; a proximal end section  30   b  and a distal end section  30   a  which can be separated from each other along a division  90  as will be discussed in greater detail below. 
     In the embodiment shown in  FIG. 1 , fuel cell  12  includes two sealed bulbs  14   a  and  14   b  containing combustible elements  16   a  and  16   b , respectively. Though  FIG. 1  shows two bulbs  14   a  and  14   b , it is also considered to include only a single bulb containing a single combustible element in fuel cell  12 . Fuel cell  12  can essentially include standard flashbulbs, or a single standard flashbulb, of the type used for still photography. Preferably, the atmosphere inside each bulb  14   a ,  14   b  may contain a relatively high percentage of oxygen; preferably from 60% to 100% oxygen and more preferably from 75% to 95% oxygen. Preferably the pressure inside bulbs  14   a  and  14   b  is greater than atmospheric pressure and more preferably the pressure is between 5 and 10 atmospheres. Bulbs  14   a  and  14   b  are preferably formed from glass and may, but need not, be coated on an exterior surface with a polymer (not shown in  FIG. 1 ) to contain glass particles if the glass shatters upon ignition of fuel cell  12 . Such polymer coatings can include, without limitation, various laquers, cellulose-acetate, polyamides or Teflon®. Preferably, the thickness of such polymer coatings is between 0.01 mm and 1.0 mm. Bulbs suitable for use in a method and apparatus of the present invention have been available for several decades as articles of commerce manufactured by major bulb suppliers such as Osram Sylvania of Danvers, Mass. (under the brand name Blue Dot® flash bulbs), General Electric and Philips Corporation. Formation of a polymer coating useful for a glass bulb such as bulbs  14   a  and  14   b  is understood in the art and disclosed, for example, in U.S. Pat. No. 4,198,200 to Fonda et al. for Damage-Preventive Coatings which is hereby incorporated by reference in its entirety. 
     Combustible elements  16   a  and  16   b  are contained within sealed bulbs  14   a  and  14   b , respectively. Preferably, combustible elements  16   a  and  16   b  include filaments formed from combustible metal such as aluminum, magnesium or zirconium formed into “wool” strands as is understood by those skilled in the art. However, combustible elements  16   a  and  16   b  could be formed from any combustible filament such as, without limitation, polymer filaments impregnated with combustible metal. 
     In the embodiment shown in  FIG. 1 , combustible element  16   a  is exposed to a set of metal electrodes  18   a  and  18   b , across which a primer-coated resistive element is connected and which protrude through bulb  14   a  and are connected to an ignition power source  40  as described below. Electrodes  18   a  and  18   b  are preferably formed from copper but can be formed from any electrically conductive material such as, without limitation, aluminum. Power source  40  is preferably a relatively small, portable power source such as, without limitation a dry cell battery. If a dry cell battery is used as power source  40 , the voltage of the battery is preferably between 1.5 and 9 volts. Electrodes  18   a  and  18   b  are connected to power source  40  through conductive lines  21   a  and  21   b  as described below. 
     As can be seen in  FIG. 2 , which is a top view of the distal end section  30   a  of housing  30  showing the interior construction, power source  40  preferably includes two 1.5 volt dry cell batteries  40   a  and  40   b . It is to be understood that other types of power sources may be used with a drug delivery device in accordance with the present invention including, without limitation, a standard 9v battery. Batteries  40   a  and  40   b  are preferably connected in series via electrodes  60  and  62 . Electrode  62  is preferably a substantially flat plate that is positioned between a base  31  of distal section  30   a  of housing  30  and batteries  40   a  and  40   b . Electrode  60  preferably includes a moving section  60   a  in contact with battery  40   a  and separated by a gap  60   c  from a static section  60   b , which is in contact with battery  40   b . Moving section  60   a  and static section  60   b  are each formed into a hook shape and manufactured from an elastic conductive material such that section  60   a  can be elastically deformed to close gap  60   c  between moving section  60   a  and static section  60   b  to close a series circuit including batteries  40   a  and  40   b.    
       FIG. 3  is a perspective view of the exterior of distal end section  30   a  of housing  30 . As shown, distal end section  30   a  includes a upper notch  72  adjacent to base  31  and a lower notch  70 , opposite upper notch  72  and also adjacent to base  31 . As shown in  FIGS. 1  and/or  3 , electrode  62  extends through housing  30  at upper notch  72  on distal end section  30   a  of housing  30  and electrode  60  extends through housing  30  at lower notch  70 . 
     As shown in  FIG. 5 , which is a sectional side view of drug delivery device  10  showing detail near a portion of device  10  where it separates into two sections, housing  30  includes an upper fin portion  82  and a lower fin portion  80  which interconnect with upper notch  72  and lower notch  70 , respectively, as shown on  FIG. 3 . Upper fin portion  82  includes a connecting electrode  86  which contacts electrode  62  when distal end portion  30   a  is engaged with proximal end portion  30   b . Additionally, lower fin portion  80  includes a connecting electrode  84  which contacts electrode  60  when distal end portion  30   a  is engaged with proximal end portion  30   b . Electrode  18   a  is preferably connected to electrode  62  through connecting electrode  86  and electrode  18   b  is preferably connected to electrode  60  through connecting electrode  84 . Referring again to  FIG. 2 , in the embodiment shown, device  10  includes a button  63  in contact with a flattened portion of moving section  60   a  of electrode  60 . Button  63  can be depressed by a user to close the circuit including batteries  40   a  and  40   b  and provide power to electrodes  60  and  62 , respectively. In another embodiment of a fuel cell, the combustible element can be ignited by a piezoelectric crystal (or phosphor) which is in turn caused to discharge (or ignited by) a mechanical striker. 
     Referring again to  FIG. 1 , as noted above, the atmosphere inside sealed bulbs  14   a  and  14   b  preferably includes a high percentage of oxygen. Thus, if combustible elements  16   a  and  16   b  include a combustible metal such as magnesium or zirconium, providing a voltage from power source  40 , causes the combustible element  16   a  to ignite and rapidly oxidize. The heat and light given off by the combustion of combustible element  16   a  causes sympathetic ignition of combustible element  16   b . The exothermic combustion of elements  16   a  and  16   b  gives up heat to the surrounding atmosphere and to substrate  20 . Preferably, each combustible element  16   a ,  16   b  is made up of approximately 1 mMole of metallic wool. Using this amount of wool, the exothermic reaction typically takes from 20 to 30 milliseconds. The heat provided by the exothermic reaction to substrate  20  causes vaporization of the drug coated onto substrate  20 . As noted above, because the combustion of combustible elements  16   a  and  16   b  takes place in sealed bulbs  14   a  and  14   b , respectively, no unpleasant combustion products escape into the surrounding atmosphere. Additionally, oxidation of a metal, such as occurs in combustion of combustible elements  16   a  and  16   b , does not create gaseous products. As such, the pressure inside bulbs  14   a  and  14   b  does not increase excessively beyond that increase caused by the temperature rise after oxidation of combustible elements  16   a  and  16   b  has occurred. 
     Substrate  20  is preferably formed as a substantially cylindrical sheath having an opening in one end of the cylinder to allow insertion of bulbs  14   a  and  14   b . The opposite end of the cylindrical sheath is preferably closed but may also be open. The cylindrical sheath forming substrate  20  is preferably tightly fit around bulbs  14   a  and  14   b . Preferably, substrate  20  is machined from a rod of aluminum to form a cylinder of between approximately 0.05 mm and approximately 0.15 mm thickness. Substrate  20  may also be extruded, stamped or may be formed in any manner including rolling a sheet of aluminum or using aluminum foil and may be any suitable thickness. As shown in  FIG. 1 , substrate  20  can be formed with one or more increased thickness sections  25  to increase the rigidity of substrate  20 . If used, increased thickness sections  25  are preferably located at areas of substrate  20  that do not contact bulbs  14   a  and  14   b . To securely fit bulbs  14   a  and  14   b  inside substrate  20 , substrate  20  can be slightly heated to expand the diameter of the cylinder. Bulbs  14   a  and  14   b  can then be positioned inside substrate  20  which will fit snugly around bulbs  14   a  and  14   b  upon cooling. Preferably, bulbs  14   a  and  14   b  are approximately lcm in diameter. As such, the inner diameter of substrate  20  is also close to 1 cm. 
     Substrate  20  is supported at the interior of housing  30  in a cylindrical sleeve  37  which encloses substrate  20  along a fraction of the length thereof. Sleeve  37  is preferably formed unitarily with housing  30  and attaches to housing  30  at a base (not shown on  FIG. 1 ) of front proximal end section  30   b  of housing  30 . Substrate  20  can be affixed into sleeve  37  using known adhesives or simply by friction fit. Sleeve  37  includes a socket  59  supporting ends of conductive lines  21   a  and  21   b  of  FIG. 1  and in which a base of bulb  14   a  can be plugged to allow electrodes  18   a  and  18   b  to contact conducting lines  21   a  and  21   b  in a known manner. In this way, power from power source  40  can be provided to combustible element  16   a  via conductive lines  21   a  and  21   b . The opposite end of substrate  20 , the end nearest to mouthpiece  34 , is preferably closed and includes an increased thickness section  25 . 
     It is contemplated that substrate  20  can be formed in a variety of shapes. For example, the substrate could also be in the shape of a rectangular box. Preferably, the substrate provides a large surface to volume ratio (e.g., greater than 100 per meter) and a large surface to mass ratio (e.g., greater than 1 cm 2  per gram). Additionally, a number of different materials can be used to construct the substrate. Classes of such materials include, without limitation, metals, inorganic materials, and polymers. The following are examples of the material classes: aluminum, silver, gold, stainless steel, copper and tungsten; silica, glass, silicon and alumina; graphite, porous carbons, carbon yarns and carbon felts; polytetrafluoroethylene and polyethylene glycol. Combinations of materials and coated variants of materials can be used as well. Examples of silica, alumina and silicon based materials include amorphous silica S-5631 (Sigma, St. Louis, Mo.), BCR171 (an alumina of defined surface area greater than 2 m 2 /g from Aldrich, St. Louis, Mo.) and a silicon wafer as used in the semiconductor industry. Carbon yarns and felts are available from American Kynol, Inc., New York, N.Y. Chromatography resins such as octadecycl silane chemically bonded to porous silica are exemplary coated variants of silica. 
     As shown in  FIG. 1 , substrate  20  includes an interior surface  20   a , which is preferably, though not necessarily, in contact with the exterior of bulbs  14   a  and  14   b , and an exterior surface  20   b . As noted above, heat given off during the ignition of combustible element  16  is absorbed by substrate  20  resulting in vaporization of a drug coated onto exterior surface  20   b  of substrate  20 . To improve absorption of heat by substrate  20 , the interior surface  20   a  of substrate  20  is preferably anodized or otherwise coated to create a relatively dark surface. 
     It is also contemplated that a substrate can be coated onto bulbs  14   a  and  14   b . If bulbs  14   a  and  14   b  do not include a polymer coating, the substrate can be coated directly onto the glass surface of bulbs  14   a  and  14   b  using known evaporation or electroplating techniques. If bulbs  14   a  and  14   b  do include a polymer coating, the substrate can be coated onto the polymer coating using known evaporation or electroplating techniques. If the substrate is coated onto bulbs  14   a  and  14   b , any of the above mentioned materials which are useable with known evaporation or electroplating techniques, such as, without limitation, aluminum or stainless steel, may be used to form the substrate. 
     It is also considered that substrate  20  shown in  FIG. 1  be eliminated and the glass forming the bulb act as the substrate. In such an embodiment, the drug can be coated directly onto the glass of the bulb.  FIG. 7  is a diagram illustrating an embodiment of a fuel cell  212  that includes a sealed glass bulb  214  directly coated with a drug  215 . At the interior of glass bulb  214  is combustible element  216 , which can be substantially the same as combustible element  16  shown in  FIG. 1 . Fuel cell  212  also includes electrodes  218   a  and  218   b , which can be substantially the same as electrodes  18   a  and  18   b  shown in  FIG. 1 . Combustible element  216  is exposed to electrodes  218   a  and  218   b  such that if a voltage is place across electrodes  218   a  and  218   b , combustible element  216  will ignite. If such an embodiment in used, the bulb is preferably manufactured relatively thicker than if a separate metallic substrate such as substrate  20  is used or if the bulb is coated with a polymer coating. Thus, glasses that are resistant to thermal shock, such as Pyrex®, may be used at a thickness that prevents shattering upon ignition of combustible elements  216 . Drug  215  is preferably coated onto the exterior of bulb  216  as discussed below. 
     It is also within the ambit of the present invention that the drug is impregnated into a polymer substrate and the substrate coated directly onto the bulb.  FIG. 8  is a diagram illustrating an embodiment of a fuel cell  112  that includes a capsule  114  which includes an inner glass bulb  114   b  surrounded by an outer polymer substrate  114   a . At the interior of glass bulb  114   b , combustible element  116 , which can be substantially the same as one of combustible elements  16   a  and  16   b  shown in  FIG. 1 , is exposed to contacts  118   a  and  118   b , which can be substantially the same as contact  18   a  and  18   b  shown in  FIG. 1 . Fuel cell  112  can be used in housing  30  shown in  FIG. 1  in the same way fuel cell  12  is used therein except that substrate  20  is not necessary. Polymer substrate  114   a  is preferably impregnated with a drug prior to use. Preferably, a substrate such as polymer substrate  114   a  is between 0.01 mm and 1 mm thick. A drug can be impregnated into polymer substrate  114   a  by exposing substrate  114   a  to the drug. For example, fuel cell  112  can be soaked in a solution containing a drug and a solvent, or just containing a drug, for 1 or more hours. In such an embodiment, the substrate can be formed from polyamides or Teflon® or other heat stable polymers. 
       FIG. 4  is a perspective view of drug delivery device  10  showing an exterior surface of housing  30  (as shown on  FIG. 1 ). As shown, housing  30  is preferably ellipsoid in shape having an oval cross-section in a direction transverse to a long axis of device  10 . As discussed above, substrate  20  and bulbs  14   a  and  14   b  are preferably rigidly connected to housing  30  so that substrate  20  and bulbs  14   a  and  14   b  are suspended in a substantially concentric manner inside housing  30 . Proximal end section  30   b  of housing  30  preferably includes mouthpiece  34 . Additionally, upper surface of housing  30  preferably includes openings  68   a  and  68   b  which, as shown in  FIG. 1 , are in fluid connection with airway  32  to allow air to pass from an exterior of housing  30  into airway  32 . A lower surface of housing  30  preferably also contains openings, not visible in  FIG. 4 , opposite openings  68   a  and  68   b . Housing  30  can be formed from various polymers including, without limitation, biodegradable polymers such as Biomax® available from E.I. du pont de Nemours and Company or other starch based polymers. Housing  30  can be formed by injection molding a top and bottom half and assembling the two halves as is well understood in the art. Preferably, but not necessarily, the oval cross-section of housing  30  transverse to the direction of the long axis of device  10  has an inner diameter of about 2 cm in a direction of a minor axis and about 3 cm in a direction of a major axis. It is also considered that housing  30  be formed in any other size or shape, such as, without limitation, a cylinder, rectangular box, triangular box or other shape. 
     As noted above, a proximal end section  30   b  of housing  30  is separable from a distal end section  30   a  of housing  30 . As shown in  FIG. 1  and discussed above, the distal end section  30   a  includes power supply  40  and an activation button  63  for drug delivery device  10 . And, proximal end section  30   b  contains bulbs  14   a ,  14   b , and substrate  20  coated with the drug to be delivered. Accordingly, proximal end section  30   b  can be detached from distal end section  30   a  upon consumption of the dosage included in proximal end section  30   b  and discarded. Distal end portion  30   a , including power source  40 , can then be re-used with another proximal end section containing a fresh dosage of coated drug. Distal end section  30   a  can advantageously be used a number of times in this way until power source  40  is depleted. Section  30   a  and  30   b  may, as is understood in the art, be molded to snap together, twist-lock or otherwise be joined together in preparation for aerosolization of the dosage form. 
     Aerosolization of a drug coated onto substrate  20  is accomplished by pressing button  63  to close the connection between power source  40  and combustible element  16   a . Combustible element  16   a  ignites when a voltage from power source  40  is applied to it. As noted above, combustible element  16   a  is preferably a combustible metal that will rapidly oxidize in the atmosphere of fuel cell  12 . To oxidize the amount of combustible metal preferably included in fuel cell  12  typically takes from 20 to 30 milliseconds and will release from about 800 joules to about 900 joules of energy. The release of this energy will cause the exterior surface  20   b  of substrate  20  to rise to a temperature of about 350 C to about 600 C. This is generally sufficient to cause the drug on exterior surface  20   b  of substrate  20  to vaporize. Preferably, the drug vapor then cools in airway  32  to form an aerosol. Preferably, the particle size range of the aerosolized drug is from about 1 μm to about 3 μm. To receive a dosage of the aerosolized drug, a user places mouthpiece  34  up to the user&#39;s mouth, activates by pressing the button  63 , and inhales. Air will flow through openings of housing  30 , through airway  32  and into mouthpiece  34  from which the aerosolized drug can enter the user&#39;s lungs. 
       FIG. 6  illustrates a method  300  of delivering a drug via inhalation in accordance with the present invention. In step  310  a substrate, such as substrate  20  shown in  FIG. 1 , is provided which can support a drug to be heated and vaporized as discussed above. The substrate is preferably formed to include an interior region and an exterior surface. In step  312 , the drug is preferably coated onto an exterior surface of the substrate as discussed below. In step  314 , at least one sealed bulb, such as bulb  14   a  shown in  FIG. 1 , is placed in the interior region of the substrate. As discussed above, the sealed bulb preferably contains a combustible filament including a combustible metal, such as aluminum, zirconium or magnesium. The combustible filament is preferably electrically connected to two electrodes that extend to the exterior of the bulb and which can be intermittently connected to a power supply, such as power supply  40  shown in  FIG. 1 , to allow for ignition of the combustible element. In step  316 , the electrodes are switched into the power supply circuit and the combustible element is ignited. The ignition sets off an exothermic reaction which heats the substrate and vaporizes the drug coated thereon preferably as discussed above. In step  318 , the drug is allowed to cool to form an aerosol. Preferably this cooling takes place in an airway, such as airway  32  shown in  FIG. 1  surrounding the exterior surface of the substrate. In step  320 , the aerosolized drug is inhaled by the user. In an alternate embodiment, in step  312 , rather than coating a drug onto the exterior of the substrate provided in step  310 , it is considered to impregnate the substrate with the drug to be aerosolized, as discussed above. 
     As noted above, the aerosol-forming device of the present invention rapidly heats a drug to produce a vapor, which is followed by cooling of the vapor and condensation of the vapor to provide an aerosol, also called a condensation aerosol. The drug composition is preferably heated in one of two forms: as pure active compound, or as a mixture of active compounds and pharmaceutically acceptable excipients. 
     The term “drug” as used herein means any chemical compound that is used in the prevention, diagnosis, treatment, or cure of disease, for the relief of pain, or to control or improve any physiological or pathological disorder in humans or animals. Classes of drugs include, without limitation, the following: antibiotics, anticonvulsants, antidepressants, antiemetics, antihistamines, antiparkinsonian drugs, antipsychotics, anxiolytics, drugs for erectile dysfunction, drugs for migraine headache, drugs for the treatment of alcoholism, muscle relaxants, nonsteroidal anti-inflammatories, opioids, other analgesics, stimulants and steroids. 
     Examples of antibiotics include cefmetazole, cefazolin, cephalexin, cefoxitin, cephacetrile, cephaloglycin, cephaloridine, cephalosporin c, cephalotin, cephamycin a, cephamycin b, cephamycin c, cepharin, cephradine, ampicillin, amoxicillin, hetacillin, carfecillin, carindacillin, carbenicillin, amylpenicillin, azidocillin, benzylpenicillin, clometocillin, cloxacillin, cyclacillin, methicillin, nafcillin, 2-pentenylpenicillin, penicillin n, penicillin o, penicillin s, penicillin v, chlorobutin penicillin, dicloxacillin, diphenicillin, heptylpenicillin, and metampicillin. 
     Examples of anticonvulsants include 4-amino-3-hydroxybutyric acid, ethanedisulfonate, gabapentin, and vigabatrin. 
     Examples of antidepressants include amitriptyline, amoxapine, benmoxine, butriptyline, clomipramine, desipramine, dosulepin, doxepin, imipramine, kitanserin, lofepramine, medifoxamine, mianserin, maprotoline, mirtazapine, nortriptyline, protriptyline, trimipramine, viloxazine, citalopram, cotinine, duloxetine, fluoxetine, fluvoxamine, milnacipran, nisoxetine, paroxetine, reboxetine, sertraline, tianeptine, acetaphenazine, binedaline, brofaromine, cericlamine, clovoxamine, iproniazid, isocarboxazid, moclobemide, phenyhydrazine, phenelzine, selegiline, sibutramine, tranylcypromine, ademetionine, adrafinil, amesergide, amisulpride, amperozide, benactyzine, bupropion, caroxazone, gepirone, idazoxan, metralindole, milnacipran, minaprine, nefazodone, nomifensine, ritanserin, roxindole, S-adenosylmethionine, tofenacin, trazodone, tryptophan, venlafaxine, and zalospirone. 
     Examples of antiemetics include alizapride, azasetron, benzquinamide, bromopride, buclizine, chlorpromazine, cinnarizine, clebopride, cyclizine, diphenhydramine, diphenidol, dolasetron methanesulfonate, droperidol, granisetron, hyoscine, lorazepam, metoclopramide, metopimazine, ondansetron, perphenazine, promethazine, prochlorperazine, scopolamine, triethylperazine, trifluoperazine, triflupromazine, trimethobenzamide, tropisetron, domeridone, and palonosetron. 
     Examples of antihistamines include azatadine, brompheniramine, chlorpheniramine, clemastine, cyproheptadine, dexmedetomidine, diphenhydramine, doxylamine, hydroxyzine, cetrizine, fexofenadine, loratidine, and promethazine. 
     Examples of antiparkinsonian drugs include amantadine, baclofen, biperiden, benztropine, orphenadrine, procyclidine, trihexyphenidyl, levodopa, carbidopa, selegiline, deprenyl, andropinirole, apomorphine, benserazide, bromocriptine, budipine, cabergoline, dihydroergokryptine, eliprodil, eptastigmine, ergoline, galanthamine, lazabemide, lisuride, mazindol, memantine, mofegiline, pergolide, pramipexole, propentofylline, rasagiline, remacemide, spheramine, terguride, entacapone, and tolcapone. 
     Examples of antipsychotics include acetophenazine, alizapride, amperozide, benperidol, benzquinamide, bromperidol, buramate, butaperazine, carphenazine, carpipramine, chlorpromazine, chlorprothixene, clocapramine, clomacran, clopenthixol, clospirazine, clothiapine, cyamemazine, droperidol, flupenthixol, fluphenazine, fluspirilene, haloperidol, mesoridazine, metofenazate, molindrone, penfluridol, pericyazine, perphenazine, pimozide, pipamerone, piperacetazine, pipotiazine, prochlorperazine, promazine, remoxipride, sertindole, spiperone, sulpiride, thioridazine, thiothixene, trifluperidol, triflupromazine, trifluoperazine, ziprasidone, zotepine, zuclopenthixol, amisulpride, butaclamol, clozapine, melperone, olanzapine, quetiapine, and risperidone. 
     Examples of anxiolytics include mecloqualone, medetomidine, metomidate, adinazolam, chlordiazepoxide, clobenzepam, flurazepam, lorazepam, loprazolam, midazolam, alpidem, alseroxlon, amphenidone, azacyclonol, bromisovalum, buspirone, calcium N-carboamoylaspartate, captodiamine, capuride, carbcloral, carbromal, chloral betaine, enciprazine, flesinoxan, ipsapiraone, lesopitron, loxapine, methaqualone, methprylon, propanolol, tandospirone, trazadone, zopiclone, and zolpidem. 
     Examples of drugs for erectile dysfunction include tadalafil (IC351), sildenafil, vardenafil, apomorphine, apomorphine diacetate, phentolamine, and yohimbine. 
     Examples of drugs for migraine headaches include almotriptan, alperopride, codeine, dihydroergotamine, ergotamine, eletriptan, frovatriptan, isometheptene, lidocaine, lisuride, metoclopramide, naratriptan, oxycodone, propoxyphene, rizatriptan, sumatriptan, tolfenamic acid, zolmitriptan, amitriptyline, atenolol, clonidine, cyproheptadine, diltiazem, doxepin, fluoxetine, lisinopril, methysergide, metoprolol, nadolol, nortriptyline, paroxetine, pizotifen, pizotyline, propanolol, protriptyline, sertraline, timolol, and verapamil. 
     Examples of drugs for the treatment of alcoholism include acamprosate, naloxone, naltrexone, and disulfiram. 
     Examples of muscle relaxants include baclofen, cyclobenzaprine, orphenadrine, quinine, and tizanidine. 
     Examples of nonsteroidal anti-inflammatories include aceclofenac, alclofenac, alminoprofen, amfenac, aminopropylon, amixetrine, aspirin, benoxaprofen, bermoprofen, bromfenac, bufexamac, butibufen, bucloxate, carprofen, choline, cinchophen, cinmetacin, clidanac, clopriac, clometacin, diclofenac, diflunisal, etodolac, fenclozate, fenoprofen, flutiazin, flurbiprofen, ibuprofen, ibufenac, indomethacin, indoprofen, ketoprofen, ketorolac, loxoprofen, mazipredone, meclofenamate, naproxen, oxaprozin, piroxicam, pirprofen, prodolic acid, salicylate, salsalate, sulindac, tofenamate, and tolmetin. 
     Examples of opioids include alfentanil, allylprodine, alphaprodine, anileridine, benzylmorphine, bezitramide, buprenorphine, butorphanol, carbiphene, cipramadol, clonitazene, codeine, dextromoramide, dextropropoxyphene, diamorphine, dihydrocodeine, diphenoxylate, dipipanone, fentanyl, hydromorphone, L-alpha acetyl methadol, lofentanil, levorphanol, meperidine, methadone, meptazinol, metopon, morphine, nalbuphine, nalorphine, oxycodone, papaveretum, pethidine, pentazocine, phenazocine, remifentanil, sufentanil, and tramadol. 
     Examples of other analgesics include apazone, benzpiperylon, benzydramine, bumadizon, clometacin, clonixin, ethoheptazine, flupirtine, nefopam, orphenadrine, propacetamol, and propoxyphene. 
     Examples of stimulants include amphetamine, brucine, dexfenfluramine, dextroamphetamine, ephedrine, fenfluramine, mazindol, methyphenidate, pemoline, phentermine, and sibutramine. 
     Examples of steroids include betamethasone, chloroprednisone, clocortolone, cortisone, desonide, dexamethasone, desoximetasone, difluprednate, estradiol, fludrocortisone, flumethasone, flunisolide, fluocortolone, fluprednisolone, hydrocortisone, meprednisone, methylprednisolone, paramethasone, prednisolone, prednisone, pregnan-3-alpha-ol-20-one, testosterone, and triamcinolone. 
     Pharmaceutically acceptable excipients may be volatile or nonvolatile. Volatile excipients, when heated, are concurrently volatilized, aerosolized and inhaled with the drug intended to be delivered. Classes of such excipients are known in the art and include, without limitation, gaseous, supercritical fluid, liquid and solid solvents. The following is a list of exemplary carriers within the classes: water; terpenes, such as menthol; alcohols, such as ethanol, propylene glycol, glycerol and other similar alcohols; dimethylformamide; dimethylacetamide; wax; and mixtures thereof. 
     Typically, the substrates of the present invention are coated with drug using a dip coating process. In such a process a solution of drug is first made. The solvent of the solution is chosen such that the drug is miscible in it at concentrations amenable to coating. Typical solvents for such a process include, but are not limited to, methylene chloride, ether, ethyl acetate and methanol. The substrate is dipped and removed from the solution at a constant rate. After dipping, solvent is allowed to evaporate and coated drug mass is calculated by subtracting the mass of the substrate from substrate plus compound. The dipping process can be repeated until the desired amount of drug is coated. Dip coaters suitable for use in implementing a method and/or apparatus of the present invention are commercially available. One such coater is the DC-2000, which can be obtained from Concoat Limited of Surry, England. 
     EXAMPLES 
     Example 1 
     Drug Aerosolization from a Polymer-Coated Flashbulb 
     A high power Sylvania® flashbulb, with its polymer coating intact, was weighed and placed in a vial of nicotine. Liquid nicotine was allowed to absorb into the polymer coating for one hour, and the excess liquid was removed by wiping with a tissue. The bulb was allowed to equilibrate overnight in a vial under an argon atmosphere. The vial was then opened and argon flowed over the bulb for 45 minutes. Re-weighing showed a total of 24.6 mg of nicotine was dissolved in the polymer coating. The bulb was enclosed in an 8 mL vial and fired by contact of its leads across the terminals of a AAA battery. A visible aerosol cloud was formed within the vial and allowed to re-condense on the walls. high performance liquid chromatography analysis of the condensate showed it to consist of 1.3 mg of pure nicotine. 
     Example 2 
     Drug Coated onto an Aluminum Substrate 
     A high-power flashcube (GE or Sylvania), which can produce 300-400 J of energy, was inserted into an anodized aluminum tube. The flashcube/tube assembly was dipped into an organic solution containing a drug and quickly removed. Evaporation of residual solvent from the assembly was performed by placing it into a vacuum chamber for 30 min. This left a film of drug coated on the exterior surface of the aluminum tube. The flashbulb assembly was electrically connected to two 1.5 V batteries and a switch using copper wires and then enclosed in a sealed, glass vial. Ignition of the flashbulb was performed by momentarily turning on the switch between the flashbulb and batteries. After ignition, the vial was kept closed for 30 minutes such that particles of volatilized drug coagulated and condensed on the inside surface of the vial. Analysis of the aerosol involved rinsing the vial with 5 mL of acetonitrile and injecting a sample of the organic solution into an high performance liquid chromatography device. Measurement with a fast thermocouple indicated that the aluminum tube heated up to 600° C. in 50 milliseconds. This translates into a heating rate of 12,000°/s. 
     One of ordinary skill in the art would understand that the experimental device detailed above could be transformed into an inhalation delivery device by excluding the sealed vial and including a housing to contain the assembly and electrical components. The housing would contain an air inlet and a mouthpiece such that, when drug volatilization occurred, an inhaled breath would carry the formed aerosol into the lungs of a subject. 
     The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and it should be understood that many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. Many other variations are also to be considered within the scope of the present invention.