Drug delivery articles utilizing electrical energy

Drug delivery articles employ an electrical resistance heating element and an electrical power source to provide a dose of a drug in aerosol form. The articles advantageously comprise a disposable portion and a reusable controller. The disposable portion, normally includes a drug and an air permeable resistance heating element having a surface area greater than 1 m.sup.2 /g, which usually carries an aerosol forming material. The reusable controller normally includes a puff-actuated current actuation means, a time-based current regulating means to control the temperature of the heating element, and a battery power supply.

BACKGROUND OF THE INVENTION 
The present invention relates to drug delivery articles which employ an 
electrical resistance heating element and an electrical power source to 
deliver a drug in aerosol form. As used herein, the term "drug" includes 
articles and substances intended for use in the diagnosis, cure, 
mitigation, treatment or prevention of disease; and other substances and 
articles referred to in 21 USC 321(g)(1). 
Over the years, there have been proposed numerous smoking products, flavor 
generators and medicinal inhalers which utilize electrical energy to 
vaporize or heat a volatile material for delivery to the mouth of the 
user. 
U.S. Pat. No. 2,057,353 to Whittemore, Jr. proposed a vaporizing unit. In 
particular, a wick reportedly carried liquid medicament by capillary 
action to a point where the liquid was vaporized by an electrical 
resistance heating element. 
U.S. Pat. No. 2,104,266 to McCormick proposed an article having a pipe bowl 
or cigarette holder which included a resistance coil (i) wound on an 
insulating and heat resisting material, and (ii) contained in an insulated 
chamber. Prior to use of the article, the pipe bowl was filled with 
tobacco or the holder was fit with a cigarette. Current then was passed 
through the resistance coil. Heat produced by the resistance coil was 
transmitted to the tobacco in the bowl or holder, resulting in the 
volatilization of various ingredients from the tobacco. A thermostatic 
switch was employed to maintain a predetermined temperature range to which 
the tobacco was heated. 
U.S. Pat. No. 3,200,819 to Gilbert proposed a smokeless, non-tobacco 
cigarette having a flavor cartridge, such as a porous substrate 
impregnated with mentholated water. The article included a battery for 
powering a tube or bulb which was illuminated before assembly. The bulb 
was placed in a tubular liner, which was in turn located within a tube of 
plastic having the size, color and form of a cigarette. In use, the 
illuminated bulb reportedly heated the flavored air drawn through passages 
formed between the bulb and the tubular liner. As such, warm, moist, 
flavored air was delivered to the user. 
French Patent Publication No. 2,128,256 to Ribot et al. proposed an article 
for delivering denicotinized smoke. The proposed article included a sealed 
ampule which contained pressurized denicotinized smoke. An electric 
resistor was immersed in the smoke. In use, the terminals of the resistor 
were pushed into contact with a microbattery causing the resistor to 
generate heat and heat the smoke within the ampule. Draw by the user 
reportedly caused warm smoke to exit a valve near the mouthend of the 
article. 
Japanese Patent Publication No. 8231/73 to Takeda proposed a cigar-shaped 
inhaler which included a battery powered Nichrome wire to heat air that, 
in turn, evaporated an essence from an essence container. The Nichrome 
wire was energized by either a manually-actuated or a draw actuated 
"on-off" switch. 
West German Patent Application No. 2,653,133 to Kovacs proposed a smoking 
simulator having an internal battery which could accelerate or control the 
vaporization or emission of aromatic substances for delivery to the user. 
In supplemental West German Patent Application No. 2,704,218, Kovacs 
described the use of a vacuum or draw-actuated switch to switch "on" the 
battery operated heating coil. 
A draw actuated, pressure transducer switch was described in U.S. Pat. No. 
4,246,913 to Ogden et al., as part of a smoke aversion therapy article 
which delivered a small electrical shock to a smoker whenever the smoker 
drew on a cigarette. 
U.S. Pat. No. 4,141,369 to Burruss proposed an article similar to the 
previously discussed McCormick articles. Burruss proposed a container 
which was electrically heated to a temperature sufficient to volatilize 
desired components from smoking material inserted therein. Heated air 
passing through the container during draw reportedly carried volatilized 
materials to the mouth of the user. 
U.S. Pat. No. 4,303,083 to Burruss proposed a pipe having an electrical 
resistance heating element, a manually operated "on-off" power switch, and 
an opening above the resistance element for the addition of volatile 
compound. During use, the volatile compound was applied, using a squeeze 
tube or eye dropper, to a heated surface within the pipe, apparently on a 
puff-by-puff basis. The volatile compounds reportedly were vaporized, 
mixed with air drawn into the pipe, and inhaled by the user. 
PCT Publication No. WO 86/02528 to Nilsson et al. proposed an article 
similar to that described by McCormick. Nilsson et al proposed an article 
for releasing volatiles from a tobacco material which had been treated 
with an aqueous solution of sodium carbonate. The article resembled a 
cigarette holder and reportedly included a battery operated heating coil 
to heat an untipped cigarette inserted therein. A switch was activated to 
supply current to the heating coil. A temperature sensor reportedly 
disconnected and reconnected the battery in order to maintain the 
temperature generated by the device in a narrow temperature range. Air 
drawn through the device reportedly was subjected to elevated temperatures 
below the combustion temperature of tobacco and reportedly liberated 
tobacco flavors from the treated tobacco contained therein. 
U.S. Pat. No. 4,735,217 to Gerth et al. proposed a "cigarette-shaped" 
medicament dosing article having a pellet of vaporizable medicament and a 
Nichrome resistance heating element connected in series with a battery 
power source and a draw actuated switch. In their only working example, 
the Nichrome heating element allegedly achieved a temperature in the range 
of 190+ F. to 220+ F. (90.degree. C. to 105.degree. C.) within a two 
second puff, which apparently was sufficient to volatilize menthol from a 
menthol pellet. At Column 8, lines 43-63, Gerth et al. went on to 
speculate that their article could be used to vaporize nicotine from a 
nicotine-containing pellet and that they believed it feasible to coat the 
heating element with a nicotine-containing compound in lieu of using a 
vaporizable pellet. 
However, it is believed that it would not be possible to coat a Nichrome 
heating element, of the type described by Gerth et al., with enough 
vaporizable liquid material to deliver sufficient volatile material to the 
user, over a 6 to 10 puff life. It also is believed that the article of 
Gerth et al. would not be able to provide enough electrical energy to (i) 
vaporize volatile material until near the end of a typical two second 
puff, or (ii) provide a high enough temperature (eg., 150.degree. C. to 
350.degree. C.) to vaporize many volatile materials within a two second 
puff, including many desirable aerosol forming substances and many 
volatile flavor components. In addition, even with only a single AA 
battery, the article described by Gerth et al. is more than 3 times the 
diameter and many times heavier than a typical cigarette and is provided 
with a relatively imprecise draw actuated control switch and with no means 
of regulating the current or heat during the puff. 
Despite many years of interest and effort, none of the foregoing articles 
employing electrical energy has ever realized any significant commercial 
success, and it is believed that none has ever been widely marketed. 
Moreover, it is believed that none of the foregoing electrical energy 
articles is capable of providing an acceptable delivery of a drug to the 
user, especially over a 6 to 10 puff, or greater, product life. 
Thus, it would be desirable to provide an article for delivering a drug in 
aerosol form, which utilizes electrical energy and which is capable of 
delivering acceptable quantities of a drug and aerosol over at least 6 to 
10 puffs. 
SUMMARY OF THE INVENTION 
The present invention relates to drug delivery articles which employ an 
electrical resistance heating element and an electrical power source to 
provide a drug in aerosol form. Preferred articles can produce aerosol 
almost immediately upon commencement of a puff, as well as provide the 
controlled production of aerosol throughout the puff and over a 6 to 10 
puff product life. 
In one aspect of the invention, the drug delivery article includes a 
disposable portion (eg., a cartridge) which utilizes an air permeable high 
surface area electrical resistance heating element that normally carries 
aerosol forming substance and/or a drug prior to use. This resistance 
heating element typically is a porous material having a surface area 
greater than 1 m.sup.2 /g, as determined using the Brunaver, Emmett and 
Teller (BET) method described in J. Am. Chem Soc., Vol. 60, p. 309 (1938); 
and Adsorption Surface Area and Porosity, Gregg et al., Academic Press, NY 
(1967). Preferably, the heating element is a fibrous carbon material, most 
preferably having a surface area greater than about 1,000 m.sup.2 /g. (In 
contrast, the surface area of the Nichrome metal resistance element of 
Gerth et al. is believed to be about 0.01 m.sup.2 /g.) Preferably, such 
porous heating elements are impregnated with liquid aerosol forming 
substances, such as glycerin. Such heating elements are particularly 
advantageous in that they are capable of holding and efficiently releasing 
relatively large quantities of liquid aerosol forming substances and drug 
constituents. For example, such heating elements can carry enough aerosol 
forming substances to provide aerosol for 6 to 10 puffs, or more. 
Drugs useful herein are those which can be administered in an aerosol form 
directly into the respiratory system of the user. Typical of such drugs 
are those which are used in the treatment of asthma, emphysema, 
bronchitis, epilepsy, shock, hypertension, cardiac arrhythmia, sinus 
congestion, allergies, convulsions, anxiety, schizophrenia, and the like. 
Examples of suitable drugs include ephedrine, metaproterenol, terbutaline, 
dopamine, phenytoin, diazepam, propranolol, diphenhydramine, and the like. 
Another important aspect of the invention relates to the various 
configurations of the disposable portions described herein. For example, 
in certain preferred embodiments, the disposable portion advantageously is 
provided with an electrical connection means at one end thereof. This 
electrical connection means includes means for connecting the resistance 
element to a battery or other external power source, and preferably 
includes an air passageway used in conjunction with the preferred puff 
actuated current actuation means. In other preferred embodiments, the 
disposable portion is adapted for connection to the external power source 
via connectors located on the reusable controller. In certain preferred 
embodiments, the resistance heating element is located centrally in the 
disposable portion and/or does not occupy a significant portion of the 
cross-sectional area of the disposable portion. In other preferred 
embodiments, the resistance heating element is located adjacent an end of 
the disposable portion, and/or at least substantially fills the 
cross-sectional area of the disposable portion or the air passageway 
therethrough. 
A reusable controller can be used with the disposable portions of the 
invention. This reusable controller normally includes a current actuation 
means, a separate current regulating means to control the temperature of 
the heating element, and a battery power supply. Alternatively, the 
electrical power supply can be provided separately from the current 
actuation and current regulating means; eg., as a separate battery pack or 
as normal household current stepped down by an appropriate transformer. 
The reusable controller can be in the form of a pipe, a reusable 
mouthpiece, a hand-held unit or other portable form into which the 
disposable portion can be inserted. The use of such a reusable article 
with the disposable portions of the invention is particularly advantageous 
in that it permits the use of (i) relatively large power sources, capable 
of generating 10 to 40 watts of power or more, and (ii) accurate and 
sophisticated current actuation and current regulating means that normally 
would be too costly to incorporate into a single use, disposable article. 
Preferably, the current actuation means is puff actuated, so that current 
flows through the resistance heating element to produce aerosol only 
during draw by the user. 
To use the articles of the invention, the user simply inserts the 
disposable portion containing the drug into the controller, to 
electrically connect the heating element to a circuit including the 
current actuation and current regulating means and to the battery. When 
the user draws on the mouthend of the article, the preferred current 
actuation and current regulating means permit unrestricted or 
uninterrupted flow current through the resistance heating element to 
generate heat rapidly. This heating volatilizes the aerosol forming 
substances and/or drug, which in turn form an aerosol and pass through the 
article and into the mouth of the user. At the same time, the current 
regulating means (i) regulates current flow through the heating element to 
control heating of the resistance element and the temperature experienced 
thereby, and (ii) prevents overheating and degradation of the aerosol 
former. When the user stops drawing on the article, the current actuation 
means prevents further current flow through the heating element and 
disables the current regulating means. This process continues, puff after 
puff, until the user decides to stop drawing on the article (i.e., the 
dose of the drug is complete). At that point, the disposable portion can 
be removed and discarded, and a new one inserted in its place. 
In another aspect of the invention, the current actuation means, the 
current regulating means, and/or the electrical power source may be 
incorporated into the portion of the article containing the electrical 
resistance heating element, so that the reusable controller may be reduced 
in size or even eliminated. 
Preferred articles of the invention are capable of delivering an average of 
at least 0.5 mg, more preferably at least 0.8 mg, of aerosol and/or drug 
per puff, measured as wet total particulate matter (WTPM), under 
conditions of 2 second, 35 ml puffs, taken once every 60 seconds. 
Preferred articles of the invention can deliver such material, preferably 
in visible form, for a plurality of puffs, preferably at least about 6 
puffs, more preferably at least about 10 puffs, under such conditions. 
As used herein, and only for the purposes of this application, "aerosol" is 
defined to include vapors, gases, particles, and the like, both visible 
and invisible, generated by action of heat from the resistance heating 
element upon aerosol forming substances and/or a drug located on the 
resistance element or elsewhere in the article. 
The articles of the present invention are described in greater detail in 
the accompanying drawings and in the detailed description of the invention 
which follows.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, drug delivery article 10 includes a disposable 
cartridge 12 and a reusable, hand-held controller 14. The disposable 
cartridge 12 includes electrical connection plug 16, resistance heating 
element 18 carrying an aerosol forming substance, mouth end filter 22, and 
a resilient overwrap 24. The preferred controller 14 includes a case 26, a 
puff actuated current actuation mechanism 28 having the form of a pressure 
sensitive switch, a time-based current control circuit 30, and a chamber 
32 into which battery power supply 34 (shown as batteries 34A and 34B) is 
inserted. 
The resistance heating element 18 employed in cartridge 12 preferably is a 
fibrous material having a high surface area and an adsorbant, porous, 
wettable character, in order to carry a suitable amount of aerosol forming 
substance for effective aerosol formation. Suitable heating elements 
preferably have surface areas above about 50 m.sup.2 /g, more preferably 
above about 250 m.sup.2 /g, and most preferably above about 1,000 m.sup.2 
/g. 
Preferred heating elements normally have low mass, low density, and 
moderate resistivity, and are thermally stable at the temperatures 
experienced during use. Such heating elements heat and cool rapidly, and 
thus provide for the efficient use of energy. Rapid heating of the element 
also provides almost immediate volatilization of the aerosol forming 
substance. Rapid cooling prevents substantial volatilization (and hence 
waste) of the aerosol forming substance during periods when aerosol 
formation is not desired. Such heating elements also permit relatively 
precise control of the temperature range experienced by the aerosol 
forming substance, especially when the preferred time based current 
control means described herein is employed. 
Preferred resistance heating elements include carbon filament yarns 
available from American Kynol, Inc., New York, N.Y., as Catalog Nos. 
CFY-0204-1, CFY-0204-2, and CFY-0204-3. Such yarns reportedly have surface 
areas of about 1,500 m.sup.2 /g and resistivities of about 10 to about 30 
milliohm-cm. See, Kirk-Othmer: Encycl. Chem. Tech., Vol. 16, 3rd Ed., pp. 
135"136 (1981). Representative lengths of such yarns range from about 15 
to about 50 mm. Other preferred heating elements include carbon felts and 
activated carbon felts available from American Kynol, Inc., as Catalog 
Nos. CN-157(HC), CN-210(HC), ACN-211-10, ACN-210-10, and ACN-157-10. Such 
felts typically have surface areas of about 1,500 m.sup.2 /g and 
resistivities of about 5 to about 30 milliohm-cm. Such felts can be used 
in the form of circular discs having diameters of about 4 to 8 mm, as 
described in greater detail hereinafter with reference to FIGS. 4-6. Other 
suitable heating elements include porous metal wires or films; carbon 
yarns, cloths, fibers, discs or strips; graphite cylinders, fabrics or 
paints; microporous high temperature polymers having moderate 
resistivities; porous substrates in intimate contact with resistance 
heating components; and the like. 
Preferably, the heating element 18 is impregnated with or otherwise carries 
one or more aerosol forming substance in order that the aerosol forming 
substances are in a heat exchange relationship with the electrical heating 
element. The aerosol forming substances used in this invention are capable 
of forming aerosol during periods when the heating element generates heat. 
Such substances preferably are composed of carbon, hydrogen and oxygen, 
although other material such as water can be employed. The aerosol forming 
substances can have a solid, semi-solid, or liquid form. Examples of 
suitable aerosol forming substances include water; polyhydric alcohols 
such as glycerin, propylene glycol and triethylene glycol; aliphatic 
esters of mono-,di-, or poly-carboxylic acids such as methyl stearate, 
dimethyl dodecandioate, dimethyl tetradecandioate; a drug; and the like, 
as well as mixtures thereof. 
While the loading of the aerosol forming substance can vary from substance 
to substance and from heating element to heating element, the amount of 
liquid aerosol forming substance used typically will be greater than about 
15 mg and preferably ranges from about 25 mg to about 50 mg. 
The drug can be used as an aerosol forming substance, and can be carried by 
the resistance heating element. The drug also can be placed between the 
resistance heating element and the mouth end of the cartridge, such as in 
mouthend filter 22 or in a separate chamber or cartridge located between 
the resistance heating element and the filter. In such instances, the drug 
can either form an aerosol or be eluted by the aerosol forming material. 
As with the aerosol forming substance, the loading of each drug can vary 
depending upon the particular drug and the particular dose required. 
Although drugs can be employed to form an aerosol with or without the 
aforementioned aerosol forming substances, it is desirable to employ such 
aerosol forming substances with drugs in order that an identifiable, 
visible aerosol is provided. As such, the user readily can identify when a 
dose of the drug is complete. 
A heat resistant, electrically insulative strip, tube or spacer 36, 
preferably is provided in order to maintain the heating element in place 
and to prevent the heating element from contacting itself. The insulative 
spacer 36 can be a cellulosic sheet treated with fire retardant, an 
aluminum foil having a surface coating of aluminum oxide, an insulative 
ceramic material, a heat resistant plastic material such as a polyimide, 
or the like. 
The electrical connection plug 16 preferably is manufactured from a 
resilient, electrically insulative material such as a thermoplastic 
material. The plug 16 includes two electrical connector pins or prongs 38, 
39 connected to the ends of heating element 18 via connectors 40, 41. The 
pins 38, 39 engage with electrical terminals 42, 43 located in electrical 
connection receptacle 44 of the controller 14. Plug 16 also includes a 
passageway 46 through which tube 48 from pressure sensing switch 28 
extends. As shown in FIG. 1A, pins 38, 39 and passageway 46 are offset 
with respect to the longitudinal axis of plug 16. 
A portion of the length of the electrical connection plug 16 preferably is 
circumscribed by a collar 49 having the form of a thermoplastic tube, 
which preferably is friction fit around a portion of the length of the 
plug. The collar 49 in turn is secured to the remaining portion of the 
cartridge via overwrap 24 using tipping paper 52 or other appropriate 
means such as adhesive, a friction fit, or the like. Preferably, the 
collar 49 includes one or more peripheral air inlet openings 54 which 
provide a flow of ambient air through the cartridge during draw. 
Alternatively, the air inlet can be positioned through the extreme inlet 
end of the cartridge or elsewhere through the periphery of the cartridge, 
such that drawn ambient air passing through the cartridge to the mouth of 
the user passes the resistance element. 
The mouthend filter 22 is provided for aesthetic purposes. It preferably is 
a low efficiency filter made from a melt blown thermoplastic such as 
polypropylene. For example, the filter can be manufactured by pleating a 
web of nonwoven polypropylene available from Kimberly-Clark Corp. as 
experimental melt blown, macrofiber polypropylene PP-100-F. Alternatively, 
the mouthend filter 22 can be manufactured from cellulose acetate tow, or 
the like. Preferably, the filter material is overwrapped with a paper plug 
wrap 58. 
To maximize aerosol and dose of the drug which otherwise would be diluted 
by radial (i.e., outside) air infiltration through the overwrap 24, one or 
more layers of non-porous paper can be used to envelop the cigarette. 
Examples of suitable non-porous papers are cigarette papers commercially 
available from Kimberly-Clark Corp. as KC-63-5, P878-5, P878-16-2 and 
780-63-5. If desired, the overwrap can be a resilient paperboard material, 
foil-lined paperboard, or the like; and the paperboard can be 
circumscribed by a cigarette paper wrap. 
The reusable controller 14 includes a case 26 or outer housing which 
provides a convenient and aesthetic holder for the user. The outer housing 
26 can have a variety of shapes and can be manufactured from plastic, 
metal, or the like. Controller 14 includes an insulative receptacle 44 
which includes plug-in connectors 42, 43 for engagement with prongs 38, 39 
of plug 16. Receptacle 44 also includes tube 48 which is inserted into 
passageway 46 of plug 16 to be in airflow communication with the internal 
region of the cartridge. The other end of tube 48 is in airflow 
communication with pressure sensing switch 28, so that changes in air 
pressure which occur within the cartridge during draw can be sensed by the 
switch. 
Controller 14 also preferably includes a control circuit 30, which is 
connected to a puff actuated, differential pressure sensitive switch 28 by 
electrically conductive wires (not shown), as well as to batteries 34A and 
34B via battery terminal 62. The control circuit 30 preferably is time 
based. That is, the preferred current control circuit preferably is based 
on controlling the time period during draw during which current passes 
through the resistance element. This time based control, in turn, controls 
the temperature experienced by the resistance element and by the aerosol 
forming substances. Preferred pressure sensitive switches and control 
circuits, and their connection power source 34 and resistance element 18, 
are described in greater detail hereinafter with reference to FIGS. 9 and 
10. 
While the heat needed to volatilize the aerosol forming substance (and the 
drug in appropriate cases) during a puff varies for each particular 
substance and drug, sufficient heat usually is necessary, during a puff, 
to heat the aerosol forming substance to a temperature above about 
120.degree. C. in order to volatilize an appropriate amount of the aerosol 
forming substance. More typically, a temperature above about 150.degree. 
C., often above about 200.degree. C., and sometimes as high as about 
300.degree. C. to about 350.degree. C., is necessary to volatilize 
adequate amounts of the aerosol forming substance during a puff. However, 
it is desirable to avoid heating the aerosol forming substance to 
temperatures substantially in excess of about 550.degree. C. in order to 
avoid degradation and/or excessive, premature volatilization of the 
aerosol forming substance. 
For a particular resistance heating element and a particular aerosol 
forming substance, a sufficient current is required, during each puff, to 
generate the heat necessary to volatilize enough aerosol forming substance 
to provide an adequate amount of delivered aerosol. For the preferred 
aerosol forming substances and the preferred carbon heating elements 
described herein, an 18 volt battery usually generates sufficient power 
(i.e., about 18 watts) to heat the aerosol forming substance to a suitable 
temperature to volatilize the aerosol forming material almost immediately 
after current actuation, i.e., within about 0.5 second, preferably within 
about 0.1 second. The 18 volt battery can be provided using two fully 
charged 9 volt manganese dioxide-zinc transistor batteries (as shown in 
FIG. 1) or three 6 volt lead acid batteries. Also useful is a silver-zinc 
alkaline battery using potassium hydroxide as an electrolyte and having 
about 12 to about 15 single cells connected in series, wherein the surface 
area of each positive electrode is about 3.25 cm.sup.2. Other batteries 
can include nickel-zinc or nickel-cadmium batteries. 
In use, the user inserts the plug 16 of the cartridge 12 into the 
receptacle 44 of the controller 14. Such action provides electrical 
connection of the resistance heating element 18 with the switch 28, the 
control circuit 30 and the batteries 34A and 34B. Such action also 
provides for airflow communication between the switch 28 and the inner 
portion of the cartridge. When the user puffs on the mouthend of the 
cartridge, ambient air enters the cartridge through air inlet 54. The 
pressure actuated switch 28 responds to a sensed change in air pressure 
within the cartridge during draw and permits current flow through the 
heating element 18. As a result, the heating element experiences an 
increase in temperature which in turn heats and volatilizes the aerosol 
forming substance. The volatilized aerosol forming substance mixes with 
the drawn air and forms an aerosol. The volatilized aerosol forming 
substance (in aerosol or vapor form) exits the mouthend filter 22 into the 
mouth of the user. During the puff, the preferred current control circuit 
(described in detail hereinafter) regulates the flow of current to control 
the temperature experienced by the heating element and the amount of 
aerosol forming substance which is volatilized. 
If the drug is carried by the resistance heating element, it normally 
volatilizes and passes to the respiratory system of the user in a manner 
similar to the aerosol forming substance. If not carried by the resistance 
heating element, the drug is either volatilized by heat generated by the 
resistance heating element or eluted by the aerosol forming material as 
the aerosol forming material passes through the article. 
When the user stops drawing on the cartridge, the pressure actuated switch 
28 again responds to the sensed change in air pressure within the 
cartridge, and further current flow through the heating element ceases. As 
a result, the temperature of the heating element and the aerosol former 
quickly drop below the volatilization temperature of the aerosol former, 
and aerosol formation ceases. This process continues, puff after puff, 
normally for at least about 6 puffs, until aerosol delivery drops below 
the dosing level required by the user. Then, the user can remove the 
cartridge 12 from the control pack 14, and dispose of the cartridge. The 
user then can select a new cartridge, insert the new cartridge into the 
reusable controller, and repeat the drug delivery process. 
The embodiment illustrated in FIG. 2 is generally similar to the embodiment 
of FIG. 1, except that the heating element 18 is positioned within a heat 
resistant, insulative tube 66. The insulative tube 66 preferably is 
manufactured from a ceramic, a heat resistant cellulosic, an aluminum tube 
having a surface coating of aluminum oxide, a high temperature plastic 
such as a polyimide, or the like. Preferably, a plasticized cellulose 
acetate tube 68 circumscribes the insulative tube 66, and is itself 
circumscribed by paper overwrap 24. This embodiment also includes tipping 
overwrap 70 circumscribing the mouthend of the cartridge in order to 
attach filter element 22 to the remaining portion of the cartridge. 
Referring to FIG. 3, the illustrated embodiment is generally similar to the 
embodiment of FIG. 2, except that the controller or power pack 14 includes 
a flexible, cord-like connector 72 which terminates in a plug 74 having 
prongs 76, 77 for electrical connection into a receptacle 79 at one end of 
cartridge 12. A needle-like tube 48 extends from switch 28 and extends 
through resilient overwrap 24 in order that changes in air pressure within 
the cartridge during draw can be sensed by the switch. If desired, the 
tube 48 can be incorporated into the cord-like connector 72 and extend 
into the cartridge through the receptacle 79. With such a design, it is 
possible for the user to place the control pack in a shirt pocket or on a 
table, and hold the cartridge in a normal fashion, without holding the 
added weight of the control pack in his/her hands. A light emitting diode 
81 is positioned near the differential switch 28. The diode 81 is 
electrically connected to the electrical circuitry (as described 
hereinafter) such that it emits light during draw. As such, the user has a 
visual means for identifying periods when current passes through the 
resistance heating element 18. 
Referring to FIG. 4, the illustrated embodiment is generally similar to the 
embodiment of FIG. 1, except that the heating element 18 is a circular 
disc or pad, preferably formed from an American Kynol carbon felt. The pad 
is permeable to airflow, and is disposed across an air passageway 83 in 
tubular collar 49 so that drawn air entering the cartridge 12 through 
opening 54 passes through the heating element 18. Electrical connection 
pins 85, 86 from plug 74 contact the heating element and help hold it in 
place against collar 49. In this embodiment, the collar 49 can be a 
thermoplastic material, a thermally stable plastic material, a ceramic, or 
the like. 
The embodiment illustrated in FIG. 5 is generally similar to the embodiment 
of FIG. 1. In this embodiment, the heating element 18 is a circular disc 
or pad of carbon felt disposed across an air passageway 83 extending 
through tubular collar 49. The pad is held in place by shoulder 84 on the 
collar 49. In addition, the cartridge does not have an electrical connect 
plug. Instead, electrical connection pins 85, 86 for the heating element 
extend from a plug 74 located on the controller 14. The cartridge 12 is 
held in place relative to the controller 14 via a clip 89 extending from 
the controller, or other suitable connection means. 
The embodiment illustrated in FIG. 6 is generally similar to the embodiment 
of FIG. 5, except that the pressure sensing tube 48 also is used as one of 
the connecting pins (eg., in lieu of connection pin 86 of FIG. 5). 
Referring to FIG. 7, drug delivery article 10 has the form of a pipe. The 
pipe includes a stem 90 having an air passageway 91 and a bowl 92 into 
which a disposable cartridge 94 is inserted. The bowl and stem can be 
manufactured from briarwood, or the like. The pipe 10 includes power 
source 34, such as one or more batteries, pressure sensing switch 28, 
pressure sensing passageway 93, current control circuit 30, and electrical 
pins 85, 86 extending from the bottom of the bowl. Preferred pressure 
sensing current control circuits and their connection to power source 34 
and heating element 18 are described in greater detail hereinafter with 
reference to FIGS. 9 and 10. 
The cartridge 94 includes an outer tubular housing 96 connected to a collar 
98 which in turn supports resistance element 18 and the aerosol forming 
substance and drug at one end of the cartridge. The resistance element 18 
can be a carbon fiber felt pad which extends perpendicularly to the 
longitudinal axis of the cartridge so that drawn air passes through the 
resistance element. The disposable cartridge 94 is positioned within the 
bowl 90, with the resistance heating element 18 positioned near the bottom 
of the bowl so that the electrical connection pins 85, 86 extending from 
the bowl contact the resistance element. 
Referring to FIG. 8, the illustrated embodiment is generally similar to the 
embodiment of FIG. 7. In this embodiment, the resistance element 18 is 
positioned towards the air inlet end of the cartridge (i.e., remote from 
the bottom of the bowl) rather than near the air outlet end of the 
cartridge. In this case, the electrical connection pins 85, 86 extend from 
the bottom of the bowl to contact the resistance element 18. 
The foregoing embodiments preferably incorporate the preferred circuit 
shown schematicallY in FIG. 9. In particular, the circuit of FIG. 9 
includes a power source 34, the electrical resistance heating element 18, 
a current actuation mechanism 28, and a preferred current regulating 
circuit or means for controlling the passage of current through the 
resistance element during periods of current actuation. 
The circuit includes a puff actuated control switch 28, or some other 
suitable current actuation/deactuation mechanism, such as a manually 
actuated on-off switch, a temperature actuated on-off switch, or a lip 
pressure actuated switch. The preferred puff actuated switch 28 enables 
current to pass through the heating element 18 only during draw on the 
article. A typical puff actuated switch includes a means for sensing the 
difference in air pressure in a region within the previously described 
cigarette or disposable cartridge and an "on-off" switch responsive 
thereto. 
A preferred puff actuated switch 28 is a pressure differential switch such 
as Model No. MPL-502-V, range A, from Micro Pneumatic Logic, Inc., Ft. 
Lauderdale, Fla. Another suitable puff actuated mechanism is a sensitive 
pressure transducer (eg., equipped with an amplifier or gain stage) which 
is in turn coupled with a comparator for detecting a predetermined 
threshold pressure. Yet another suitable puff actuated mechanism is a vane 
which is deflected by airflow, the motion of which vane is detected by a 
movement sensing means. Yet another suitable actuation mechanism is a 
piezoelectric switch. Also useful is a suitably connected Honeywell 
Microswitch Microbridge Airflow Sensor, Part No. AWM 2100V from 
Microswitch Division of Honeywell, Inc., Freeport, Ill. Other suitable 
differential switches, analog pressure sensors, flow rate sensors, or the 
like, will be apparent to the skilled artisan. 
The current regulating circuit preferably is time based. Normally, such a 
circuit includes a means for permitting uninterrupted current flow through 
the heating element for an initial time period during draw, and a timer 
means for subsequently regulating current flow until draw is completed. 
Preferably, the subsequent regulation involves the rapid on-off switching 
of current flow (eg., on the order of about every 1 to 50 milliseconds) to 
maintain the heating element within the desired temperature range. 
Alternatively, the subsequent regulation involves the modulation of 
current through the heating element to maintain the heating element within 
a desired temperature range. 
One preferred time-based current regulating circuit preferably includes a 
transistor 110, a timer 112, a comparator 114, and a capacitor 116. 
Suitable transistors, timers, comparators and capacitors are commercially 
available and will be apparent to the skilled artisan. Exemplary timers 
are those available from NEC Electronics as C-1555C and from General 
Electric Intersil, Inc. as ICM7555, as well as various other sizes and 
configurations of so-called "555 Timers". An exemplary comparator is 
available from National Semiconductor as LM311. 
In the preferred circuit of FIG. 9, the means for determining the length of 
the initial time period of uninterrupted current flow includes resistors 
118, 120, 122 and 124; capacitor 116; and comparator 114. The comparator 
114 is powered by connection to entrance pin 128 and to ground pins 130, 
132. Resistors 122 and 120 constitute a voltage divider which provides a 
predetermined reference or threshold voltage at the voltage divider tap 
134 (i.e., the common point between resistors 122 and 120). The voltage 
divider tap 134 is connected to the negative entrance pin 136 of 
comparator 114. Capacitor 116 is connected in parallel with resistor 124. 
The parallel combination of capacitor 116 and resistor 124 is connected in 
series with resistor 118 at one end and to the ground reference point of 
the power source 34 at the other end. The other end of resistor 118 is 
connected to power source 34 via switch 28. The common node point between 
the resistor 118 and the parallel combination of capacitor 116 and 
resistor 124 is connected to the positive entrance pin 138 of comparator 
114. 
Resistors 118 and 124 and the capacitance of capacitor 116 are chosen so 
that the charge rate of capacitor 116 approximates the heating and cooling 
rate of the resistance heating element 18. The ratio of the resistance of 
resistor 124 to the sum of the resistances of resistors 118 and 124 sets 
the maximum voltage to which capacitor 116 can charge. Preferably, the 
resistances of voltage divider resistors 120 and 122 provide a voltage 
which is slightly below the maximum capacitor voltage set by resistors 118 
and 124. 
The timer means for regulating (or interrupting) current flow after the 
initial time period includes timer 112, diodes 140, 141, resistors 143, 
145, and capacitor 147. This timer means generates a periodic digital wave 
having a preset on-off duty cycle, which is used to rapidly switch the 
current "on" and "off" at transistor 110 after the passage of the initial 
time period, to control the temperature range experienced by the 
resistance heating element. 
Timer 112 is powered by connection through entrance pin 149 and ground pin 
151. The reset pin 153 of timer 112 is connected to output pin 155 of 
comparator 114. As a result, the comparator 114 disables timer during the 
initial period of uninterrupted current flow. A resistor 157 provides a 
so-called "pull-up" function for the reset pin 153 of timer 112. 
Timer 112 also is connected to diodes 140, 141 at discharge pin 166. Diodes 
140, 141 are in turn connected to resistors 145 and 143, respectively. In 
addition, timer 112 is connected to resistors 143 and 145, and capacitor 
147 through trigger pin 168 and threshold pin 169. Capacitor 147 is 
provided to set the overall time period of the duty cycle. Preferably 
capacitor 147 is one which charges and discharges at a rapid rate in order 
that a relatively rapid duty cycle (eg., in the order of 1 to 50 
milliseconds) is provided. 
Resistor 145 determines the charge rate of capacitor 147, and thus the 
"off" period of the duty cycle, while resistor 143 determines the 
discharge rate of the capacitor and thus the "on" period of the duty 
cycle. Diode 140 acts to allow current flow from the timer 112 through 
resistor 145 and to capacitor 147 during periods when the capacitor is 
charging, and prevents current passage through resistor 145 when the 
capacitor is discharging. Diode 141 acts to allow current flow from the 
capacitor 147 through resistor 143 and to the timer during periods when 
the capacitor is discharging, and prevents current passage through 
resistor 143 when the capacitor is charging. Thus, the relative on-off 
duty cycle of the wave form can be varied by selection of the resistances 
of resistors 143 and 145. 
The output pin 159 of timer 112 is connected to resistor 161. The resistor 
161 is in turn connected to the base of transistor 110 in order to limit 
"on" current through the base-emitter (BE) junction of the transistor. The 
transistor 110 acts to control the relatively large current which passes 
through the resistance element 18 from the power source 34 by switching 
"on" and "off" in response to current flow from the timer. 
When draw commences, the puff actuated switch 28 closes to allow current 
flow through the circuit. The normally "off" transistor switches "on" in 
response to current flow through the timer 112. This allows current to 
flow through the resistance heating element 
Simultaneously, capacitor 116 begins to charge When capacitor 116 is 
charged to the predetermined threshold voltage determined by resistors 120 
and 122, which typically occurs in about 1 second, comparator 114 
activates timer 112 through reset pin 153. This terminates the 
uninterrupted current flow to the transistor 110 by switching the 
transistor "off." At the same time, the timing means begins generating the 
periodic digital wave form having a preset on-off duty cycle at output pin 
159. Such action of the timing mean in turn causes the transistor to 
switch "on" and "off" rapidly, thus rapidly enabling and disabling current 
flow through the heating element 18. This rapid switching acts to control 
the average current flow through the heating element, thus controlling the 
temperature range experienced by the heating element during the balance of 
a puff. 
As described above, the capacitance of capacitor 147 determines the overall 
time period of the preset duty cycle, while the relative "on" and "off" 
periods of the duty cycle are determined by the relative resistances of 
resistors 143 and 145. By varying these resistances, it is possible to 
closely control the temperature range experienced by the heating element 
18, so as to provide a relatively steady state temperature range, or a 
controlled decrease or increase in the temperature range during the latter 
portion of a puff. 
When draw ceases, puff actuated switch 28 opens to prevent further current 
flow through the circuit. As a result, the transistor 110 switches to its 
normally "off" position, thus preventing further current flow through the 
heating element 18. As a result, the heating element begins to cool, and 
volatilization of the aerosol forming substance and/or the drug ceases. At 
the same time, capacitor 116 begins to discharge, preferably at about the 
same rate at which the heating element cools. 
When a subsequent draw commences, the puff actuated switch again closes, 
thus allowing current to flow through the circuit. If the subsequent draw 
is taken before the capacitor 116 has discharged completely (i.e., before 
the heating element has cooled completely), the capacitor 116 preferably 
recharges to the predetermined threshold voltage at about the same rate at 
which the heating element heats. This activates timer 112 and terminates 
the period of uninterrupted current flow at about the same time that the 
heating element 18 reaches the preferred temperature range. As such, the 
heating element is prevented from overheating during periods of rapid 
puffing by the user. 
Controllers and drug delivery articles of the invention also can 
incorporate the alternate time-based circuit shown schematically in FIG. 
10. In particular, the circuit of FIG. 10 includes a power source 34, the 
electrical resistance heating element 18, a current actuation mechanism 
28, and a current regulating circuit or means for controlling the passage 
of current through the resistance element during current actuation. 
The preferred current actuation mechanism 28 is a puff actuated control 
switch of the type described previously. 
The current regulating circuit shown in FIG. 10 is time based. This circuit 
includes timer 112, resistors 161, 176, 178 and 180, capacitor 190, and 
transistor 110. 
Exemplary timers have been described previously. The timer 112 is powered 
by connection through entrance pin 149 and ground pin 151. The output pin 
159 of the timer 112 is connected to the base of transistor 110 through 
resistor 161. The timer 112 is connected to resistor 180 through threshold 
pin 169; to the node point between resistors 180 and 178 through trigger 
pin 168; and to the node point between resistors 178 and 176 through 
discharge pin 166. The node point between resistors 180 and 178 is in turn 
connected to capacitor 190 which is connected to ground reference point of 
the power source 34. 
The sum of the resistances of resistors 178 and 176 determines the period 
of uninterrupted current flow through resistance element 18, while the 
resistance of resistor 176 determines the period during which current flow 
is prevented from passing through the resistance element. Resistor 180 
limits the voltage discharge rate of capacitor 190 so as to limit the 
initial heating time of the resistance element during a subsequent puff 
taken a short time after the preceeding puff. 
If desired, light emitting diode 81 and resistor 192 can be employed. The 
light emitting diode 81 is connected in series with resistor 192. The 
series combination of diode 81 and resistor 192 is connected in parallel 
with the resistance element 18. The light emitting diode thus illuminates 
during draw, and the user then can have a visual means for identifying 
periods when current passes through the resistance element for heat 
generation. Such light emitting diodes also can be employed in the 
preferred circuit illustrated in FIG. 9. 
When draw commences, the puff actuated switch 28 closes to allow current 
flow through the circuit of FIG. 10. The normally "off" transistor 
switches "on" in response to current flow through the timer 112, and in 
turn allows current to flow through the resistance heating element 18. 
Simultaneously, capacitor 190 begins to charge. When capacitor 190 is 
charged to the predetermined voltage determined by resistors 178 and 176, 
timer 112 acts to switch the transistor 110 and current flow through 
heating element 18 "off." However, after a further period of time 
determined by resistor 176, the timer 112 again is turned "on." This 
process repeats itself until draw ceases. As such, the temperature 
experienced by the resistance element can be controlled so as to not 
overheat during a relatively long draw period. For example, a duty cycle 
can consist of an "on" period of uninterrupted current flow immediately 
upon draw for about 1.5 to about 2 seconds, followed by an "off" period of 
about 0.5 to about 1 second. 
When draw ceases, puff actuated switch 28 opens to prevent further current 
flow through the circuit. As a result, the transistor 110 returns to its 
normally "off" position, thus preventing further current flow through the 
resistance element 18. The resistance element cools, and volatilization of 
the aerosol forming substance and/or the drug ceases. At the same time, 
capacitor 190 discharges. 
Current regulating means which modulate current flow through the heating 
element can be employed in place of the previously described on-off 
time-based circuits. In addition, on-off and current modulating means can 
be connected to temperature sensors or other sensing means, rather than to 
a time-based circuit, in order to control the passage of current through 
the resistance heating element. Such sensors can be temperature sensors 
such as infrared sensors, piezoelectric films or the like, or thermostats 
such as bimetallic strips. Such temperature sensors can sense either the 
temperature of the resistance element directly or the temperature of the 
air passing the heating element. Alternatively, the temperature sensors 
can sense the temperature of a second "model" resistance heating element 
having a heating and cooling character related to that of the aerosol 
carrying heating element. Another type of sensor which can be employed is 
a dynamic resistance sensor which senses the change in electrical 
resistance of the heating element during the heating period. 
The following examples are provided in order to further illustrate the 
invention but should not be construed as limiting the scope thereof. 
Unless otherwise noted, all parts and percentages are by weight, and all 
sizes are approximate. 
EXAMPLE 1 
A drug delivery article substantially as shown in FIG. 2 is prepared as 
follows: 
A. Preparation of the Disposable Portion 
End plug 16 is formed from a Delrin plastic cylinder to have a 2 mm long 
section of 8 mm diameter and a 3 mm long section of 7 mm diameter. The 
plug is provided with a passageway 46 of sufficient size to receive an 18 
gauge needle 48 and two smaller passageways to receive electrical 
connector pins 38, 39. 
The electric resistance heating element 18 is formed from a 32 mm length of 
carbon filament yarn obtained from American Kynol, Inc., under Catalogue 
No. CFY-0204-1. This heating element has a resistance of about 20 ohms and 
a surface area of about 1,500 m.sup.2 /g. The heating element is 
impregnated, dropwise, with 25 ul of a liquid aerosol forming substance 
comprising a mixture of glycerin, propylene gIycol and triethylene glycol, 
and 1.25 mg of epinephrine. The aerosol forming substance consists 
primarily of glycerin. 
Two 15 mm long crimp connectors 40, 41, including pins 38, 39, are obtained 
from Black Box Corp., Pittsburgh, PA. under Catalog No GH-FA810. Crimp 
connectors 40, 41 are attached to each end of the heating element 18. Pin 
38 of the first connector 40 is inserted through one of the smaller 
passageways in the plug 16. The heating element then is folded over a 20 
mm long, 5 mm wide strip of Kapton polyimide film 36, to keep the heating 
element from contacting itself, and pin 39 of the second connector 41 then 
is inserted through the second small passageway of the plug 16. 
A 9 mm long Delrin tube 49 is fabricated from an 8 mm diameter cylinder. 
One section, 6 mm long, has a 7 mm inner diameter (I.D ), and a second 
section, 3 mm long, has a 4 mm I.D. A single air inlet hole 54 is made 
about 4 mm from the 4 mm I.D. end of the tube using a No. 64 drill bit. 
The 7 mm I.D. end of the tube 49 then is friction fit over the 7 mm end of 
plug 16. 
A 39 mm long, 4 mm outer diameter Kapton polyimide tube 66 is slipped over 
the resistance element 18 and inserted about 4 mm into the 4 mm I.D. end 
of the Delrin tube 49. A 36 mm length of a 8 mm O.D. plasticized cellulose 
acetate tube 68, SCS-1 from American Filtrona Corp., is slipped over the 
polyimide tube. This tube 68 then is overwrapped with a layer of 
Kimberly-Clark P-850-192-2 paper 24. 
A 10 mm long, low efficiency cellulose acetate filter 22 (8 denier per 
filament, 40,000 total denier) is fastened to the open end of the wrapped 
tubes with a layer of tipping paper 70. The overall length of the 
disposable portion 12 is about 55 mm. 
B. Assembly of the Controller 
A polystyrene housing for the controller is formed to provide chambers for 
a pressure sensitive switch, a current control circuit, and a battery 
power supply. 
The pressure sensitive switch is the switch portion of a Model No 
MPL-502-V, range A, differential switch obtained from Micro Pneumatic 
Logic, Inc. A 20 mm long 18 gauge steel needle 48 is inserted into the 
appropriate opening in the switch. A polymethylmethacrylate receptacle 44 
having a length of 26 mm, a height of 12 mm and a width of 9 mm is formed 
with a hole for the gauge needle and fitted with two Black Box Model No. 
GH-FA820 plug-in connectors 42, 43. The receptacle is slipped over the 
needle and inserted into an appropriately sized opening in the case. 
The control circuit employed is schematically illustrated in FIG. 9. It is 
designed to provide uninterrupted current flow through the heating element 
for 1 second after the commencement of a puff. During the balance of the 
puff, the control circuit is designed to alternately switch off for 5 
milliseconds and then on for 5 milliseconds (a 50 percent duty cycle), 
until the pressure actuated control switch opened Comparator 114 is a 
Model LM 311 obtained from National Semiconductor. As shown in FIG. 9, 
connections are made at entrance pin 128, ground pins 130 and 132, 
negative entrance pin 136, positive entrance pin 138, and output pin 155 
Timer 112 is a Model C-1555C obtained from NEC Electronics. Connections to 
timer 112 are made at trigger pin 168, threshold pin 169, output pin 159, 
discharge pin 166, entrance pin 149 and ground pin 151. Transistor 110 is 
a Model MJE 2955 from Motorola Semiconductor Products. Diodes 140 and 141 
are Type IN914 diodes from Fairchild Semiconductor Corp. Capacitor 116 has 
a capacitance of 2.2 uF. Capacitor 147 has a capacitance of 0.1 uF. The 
resistances of the resistors 118, 120, 122 and 124 are 1,000,000 ohm; 
180,000 ohm; 1,000,000 ohm; and 820,000 ohm, respectively. The resistances 
of resistors 157, 143, 145 and 161 are 120,000 ohm; 39,000 ohm; 100,000 
ohm; and 1,000 ohm, respectively. 
The control circuit is connected to the switch, the receptacle for the plug 
on the disposable portion, and the battery terminals, as schematically 
illustrated in FIG. 9. The battery supply consists of two 9 volt alkaline 
transistor batteries connected in series. 
C. Use 
The end plug 16 is placed against receptacle 44 to electrically connect the 
disposable portion to the controller and insert the needle into the 
disposable portion. The mouthend of the disposable portion is placed in 
the mouth of the user, and the article is drawn upon. The article produces 
visible aerosol and delivery of the epinephrine on all puffs for 8 
consecutive puffs. 
EXAMPLE 2 
An article similar to the article described in Example 1 is prepared, 
except that (i) the resistance element is a length of Kynol Catalogue No. 
CFY-0204-1 carbon fiber yarn having a resistance of 28.1 ohms, and (ii) 
the heating element is impregnated with 35.9 mg of glycerin. 
The article is tested under conditions of 2 second, 35 ml puffs, taken 
every 30 seconds. The article produces visible aerosol on all puffs for a 
total of 10 puffs, and yields 21.3 mg WTPM. 
EXAMPLE 3 
A drug delivery article substantially as shown in FIG. 3 is prepared as 
follows: 
A. Preparation of the Disposable Portion 
Ceramic receptacle 79 is formed from a 7 mm long 4 mm diameter section of a 
ceramic cylinder having two longitudinal, 1.5 mm diameter passageways. 
The electric resistance heating element 18 is formed from a length of 
carbon filament yarn obtained from American Kynol, Inc., under Catalogue 
No. CFY-0204-2 sufficient to provide a measured resistance of 18 ohms when 
incorporated into the disposable portion. This element is impregnated with 
38 mg of a liquid aerosol forming substance comprising 20 ul of a mixture 
of glycerin, propylene glycol and triethylene glycol, and 1 mg of 
epinephrine. The polyhydric alcohol mixture consists primarily of 
glycerin. The ends of the heating element are inserted through the 
passageways of the receptacle 79 form a loop, and the ends of the element 
are folded back over the receptacle. A strip of polyimide film 36 is 
positioned within the loop to prevent the heating element from contacting 
itself. 
Over the resistance element loop and the receptacle 79 is friction fit a 
Kapton tube of 4 mm O.D. and a length of 80 mm. The length of the 
polyimide tube then is enveloped to a diameter of about 8 mm with 
insulative glass fibers 68 obtained from Owens Corning, Toledo, Oh., as 
Glass No. 6437. The glass fibers 68 are enveloped by a non-porous 
cigarette paper wrap 24, available as P-850-192-2 paper from 
Kimberly-Clark Corp. The diameter of the resulting rod is 8 mm. 
At the end of the rod remote from the ceramic receptacle is positioned a 
low efficiency cellulose acetate tow (8 denier per filament, 40,000 total 
denier) filter element 22 having a length of about 10 mm and a diameter of 
about 8 mm. The rod and filter element are held together using tipping 
paper. 
About 1 mm behind the insulative receptacle 79 are pierced several openings 
54 through the paper wrap 24 and the polyimide tube 66 to provide air 
inlet openings for aerosol formation. The perforations are of about 0.8 mm 
diameter, which is sufficient to provide the disposable portion with a 
draw resistance of about 100 mm H.sub.2 O pressure drop as determined 
using a Model No. FTS-300 pressure drop tester from Filtrona Corp. 
B. Assembly of the Controller 
The controller includes a pressure sensitive switch 28, a current control 
circuit 30, a battery power supply 34A, 34B and a flexible, electric cord 
72 which terminates in a cylindrical plug 74. 
The cord 72 is a 50 mm length of insulated copper wire. The plug 74 
includes a ceramic cylinder, having a length of 10 mm and a diameter of 4 
mm with two small passageways extending longitudinally therethrough; and a 
heat resistant bushing made from Zydar from Dartco Mfg., Inc., Augusta, 
Ga. The cylindrical plug has a diameter of about 8 mm. Copper pins 76, 77 
connected to cord 72 are inserted through the passageways in the ceramic 
cylinder to extend 10 mm beyond the face of the plug. 
The pressure sensitive switch 28 is a Model No. MPL-502-V, range A, 
differential switch obtained from Micro Pneumatic Logic, Inc. A 12 mm 
long, 18 gauge steel needle is inserted into the appropriate opening in 
the switch. 
The control circuit employed is schematically illustrated in FIG. 10. It is 
designed to provide uninterrupted current flow through the heating element 
for 2 seconds after the commencement of a puff. During the balance of the 
puff, the control circuit is designed to alternately switch off for 1 
second and then on for 2 seconds, until the pressure actuated control 
switch opens. Timer 112 is a Model C-1555C obtained from NEC Electronics. 
Connections to timer 112 are made at trigger pin 168, threshold pin 169, 
output pin 159, discharge pin 166, entrance pin 149 and ground pin 151. 
Transistor 110 is a Model MJE 2955 from Motorola Semiconductor Products. 
Capacitor 190 has a capacitance of 22 uF. The resistances of the resistors 
176, 178 and 180 were 20,000 ohm; 120,000 ohm; and 68,000 ohm, 
respectively. Resistors 161 and 192 each have resistances of 1,000 ohm. 
The control circuit is connected to the switch, the cord 72, and the 
battery terminals, as schematically illustrated in FIG. 10. The battery 
supply consists of two 9 volt alkaline transistor batteries connected in 
series. 
C. Use 
The pins 76, 77 of plug 74 are inserted into receptacle 79 to contact the 
heating element 18 and hence electrically connect the disposable portion 
to the controller by contacting each end of the resistance element 18. The 
needle 48 is pierced through the outer wrap 24 and the polyimide tube 66 
of the disposable portion. The mouthend of the disposable portion is 
placed in the mouth of the user, and the article was drawn upon. Visible 
aerosol is provided during each puff, and during each puff period, the 
indicator light illuminates. 
EXAMPLE 4 
An aerosol delivery article substantially as shown in FIG. 4 is prepared as 
follows: 
A. Preparation of the Disposable Portion 
Electrically insulative plug 16 is formed from a Delrin cylinder to have a 
2 mm long section of 8 mm diameter and a 3 mm long section of 7 mm 
diameter. The plug is provided with a passageway 46 of sufficient size to 
receive an 18 gauge needle and two smaller passageways to receive 
electrical connector pins 38, 39. 
The pins 38, 39 are gold plated copper pins which extended through the 
passageways in the plug, beyond the 8 mm O.D. end of the plug, and 3 mm 
beyond the 7 mm O.D. end. The pins have a flattened bead of silver solder 
applied at the ends which extends beyond the 7 mm O.D. end. 
An insulative collar 49 is formed from a Delrin cylinder having a length of 
9 mm and a diameter of 8 mm to a tubular form having a 3 mm segment of 4.5 
mm I.D. and a 6 mm segment of 6 mm I.D. A single air inlet 54 is made 
about 4 mm from the 6 mm I.D. end of the collar. 
The electric resistance heating element 18 is formed from a 6 mm diameter 
circular disc of carbon filament felt obtained from American Kynol as 
Kynol Activated Carbon Felt ACN-211-10. The resistance element weighs 
about 7.8 mg and has a reported resistivity of 20 to 30 ohms-cm. The felt 
has a liquid aerosol forming substance applied thereto in a dropwise 
manner. The aerosol forming substance is 35 ul of a mixture of 20 parts 
glycerin and 1 part epinephrine. 
The resistance element 18 is inserted into the 6 mm I.D. end of the collar 
49 to abut against the 4.5 mm I.D. portion of the collar. 
The 6 mm I.D. end of the collar 48 then is fit over the narrow end of plug 
16 such that the flattened silver solder ends of pins 38 and 39 each 
contact the resistance element 18. 
A resilient paperboard tube having an 8 mm O.D. and a length of 75 mm is 
abutted against the end of collar 49 opposite plug 16, and the two tubes 
are held in place using adhesive tape 52. 
B. Use 
The plug 16 is placed against receptacle 88 of the controller described in 
Example 1 to electrically connect the disposable portion to the controller 
and insert the needle 48 into the disposable portion. The mouthend of the 
disposable portion is placed in the mouth of the user, and the article is 
drawn upon. Visible aerosol and epinephrine is delivered on each puff for 
more than 6 puffs.