EP0544900A4

EP0544900A4 - Transdermal nicotine absorption dosage unit and process

Info

Publication number: EP0544900A4
Application number: EP19920915353
Authority: EP
Inventors: Chin-Chih Chiang; Jhili Wu
Original assignee: TBS Laboratories Inc
Current assignee: TBS Laboratories Inc
Priority date: 1991-06-26
Filing date: 1992-06-24
Publication date: 1993-12-01
Also published as: TW221970B; WO1993000057A1; EP0544900A1; AU2294192A; CN1067811A; CA2094913A1

Abstract

Provided by this invention is a transdermal dosage unit for administering nicotine for reducing the desire or craving for smoking tobacco. The dosage unit reduces or substantially eliminates the reddening of the skin at the site of the nicotine absorption commonly associated with transdermal absorption of nicotine. Also, provided is a dosage unit which has present an agent for increasing skin wearability of the transdermal dosage unit. Additionally, provided is a method for reducing the desire or craving of a subject for smoking tobacco by use of the provided transdermal dosage unit.

Description

TRANSDERMAL NICOTINE ABSORPTION DOSAGE UNIT AND PROCESS

TECHNICAL FIELD

This invention relates to a novel transdermal absorp¬ tion dosage unit adapted for administration of nicotine wherein adverse reaction in the skin at the site of the absorption, such as a reddening of the absorption site, caused by said transdermal administration of nicotine, is prevented or substantially reduced. Incorporated into the dosage unit is an agent which is also transdermally absorbed, which reduces or prevents this adverse reaction to the transdermal absorption of nicotine. Also preferably included in the dosage unit is an ingredient which increases skin wearability of the dosage units and desirably also reduces the amount of nicotine lost during the production of the dosage units and preferably a further ingredient is dis¬ persed in the dosage unit which will reduce any oxidation of nicotine during storage. Additionally, this invention relates to a method for reducing the desire by those persons who smoke or have smoked tobacco to continue that smoking habit.

BACKGROUND ART

It has been found that the principal agent in tobacco which creates the habit or craving for the continuity of smoking tobacco is nicotine. However, it has been found that the greatest damage to the human system by smoking tobacco does not emanate from the introduction of nicotine to the body by smoking, but rather by the various other chemical entities which enter into the human body during smoking, principally into the lungs. These chemical entities include various tars and hydrocarbons. It is understood that these chemical entities can do considerable damage to various tissues throughout the human body including certainly to the lung tissues. Recent studies have given evidence that these chemical entities which enter into the lungs of humans who smoke tobacco can cause gene changes within the lung cells of certain persons who smoke resulting at times in an abnormal growth or carcinomas with- in the lungs.

It has been found that if nicotine is introduced into the body in an alternative way to smoking, nicotine can assist in the withdrawal by such smokers from the smoking habit. Nicotine has been introduced into the body by various means, such as by oral administration. Also, cer¬ tain administration has been proposed by transdermal admin¬ istration of nicotine. However, there have been certain side-effects that have been caused by certain of these pro¬ posed means of nicotine administration by transdermal means, such as reddening of the skin at the absorption site.

It would be highly advantageous to provide an improved transdermal dosage unit for administration of nicotine which would substantially reduce or prevent such side-effects. It would also be highly advisable and desired to have such improved transdermal dosage units for administration of nicotine which would provide an improved means to help a human subject to cease the habit of smoking tobacco.

SUMMARY OF INVENTION

Provided by this invention is a transdermal nicotine absorption dosage unit which has the advantage of providing very substantial reduction or prevention of the side-effect of reddening of the skin site at which the nicotine is transdermally absorbed. The nicotine transdermal dosage units of this invention comprise the following elements: 1) a backing layer substantially impervious to the ingre¬ dients of the dosage unit;

2) an effective amount of nicotine to provide a daily dose of nicotine to diminish the desire for smoking;

3) an amount of a biocompatible salicylate ester effective to reduce substantially or to prevent a reddening of the skin at the site of the absorption of nicotine from the dosage unit;

4) a biocompatible adhesive layer adhered to said backing layer;

5) optionally a polymer matrix layer separating said adhe¬ sive layer and said backing layer wherein the backing layer is adhered to one side of the polymer matrix layer and the adhesive layer is adhered to the opposite side of the matrix layer; said nicotine and said salicylate ester being distri¬ buted in said adhesive layer or said polymer matrix layer or both.

The amount of nicotine to be administered to the human subject can vary but ordinarily the amount of nicotine found to be effective has been found to be in the range of about

10 mg to about 40 mg, ordinarily about 24 mg being adequate and satisfactory. It is preferable that the nicotine be released from the dosage unit and transdermally absorbed on a continuous basis throughout a 24-hour period in order to provide consistent systemic levels of nicotine effective to reduce the desire for the subject to smoke.

The amount of salicylate ester, suitably methyl salicy¬ late, to be present in the dosage unit will vary depending upon the particular dosage unit, the length of time the dosage unit is designed for administering nicotine and other factors. Ordinarily, a continuously delivered amount of methyl salicylate in the range of about 5 mg to about 20 mg has been found effective and an amount presently preferred is i_n the range of about 10 mg to about 15 mg per day.

It has also been found advantageous to have present and mutually distributed in the dosage unit along with the nico- tine and salicylate ester an amount of an antioxidant that is biologically acceptable and compatible with the nicotine and the salicylate ester of the dosage unit and effective in inhibiting oxidation of nicotine. Further, it has been found advantageous to have present an agent that will increase or promote the wearability of the dosage unit. By wearability is meant the degree of adhesion of the dosage unit, to the skin of the subject being treated, which is biocompatible and comfortable throughout the period of treatment with the dosage unit under the normal course of life of the subject. It has been found that isopropyl myristate and certain other agents providing the properties in the dosage units as provided by isopropyl myristate have increased or contributed to high wearability of the dosage units. It has been found that such agents as isopropyl myristate also provide the added property of reducing loss of nicotine through volatilization during the production of the transdermal dosage units of this invention.

Additionally provided by this invention is a method to assist humans having the desire or craving to smoke caused by smoking or exposure to smoking to reduce the desire or craving to smoke and thus to assist in breaking the so- called smoking habit.

DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENTS

The backing layer can be made of any suitable material which is impermeable to the nicotine and other components dispersed within the adjacent adhesive layer or the optional polymer matrix layer. The backing layer serves as a protec- tive cover for the dosage unit and provides also a support function. The backing layer can be formed so that it is essentially the same size layer as the nicotine-containing layer or it can be of larger dimension so that it can extend beyond the side of the nicotine-containing layer or overlay the side or sides of the nicotine-containing layer and then can extend outwardly in a manner that the surface of the extension of the backing layer can be a base for an adhesive to hold the dosage unit in intimate contact with subjects being treated.

In making the dosage units which reduce or prevent the unwanted reddening caused at the site of the nicotine trans¬ dermal absorption, the composition containing the nicotine can readily be coated onto a nicotine impermeable backing layer such as a composite sold under the designation Scotch Pak 1109 by 3M Company. A coating equipment unit can be used to coat the backing layer to the desired thickness. A coater which can be used is the Warner-Mathis Laboratory Coater Type LTSV with built-in laboratory dryer LTF. The thickness of the nicotine-adhesive layer can be accurately controlled to desired thickness such as to 400 microns, using such a designed coater-dryer.

The amount of nicotine added to the adhesive solution used for coating can vary so long as there is provided an effective amount of nicotine for transdermal absorption. Ordinarily it has been found that about a 5 percent amount of nicotine based upon the total weight of the coating ix- ture of adhesive, nicotine and isopropyl myristate, provides an effective amount of transdermal absorption of nicotine. The amount of nicotine can be varied depending upon the rate of absorption desired, the particular adhesive or polymer material used in making the dosage unit and other factors. The effective amount can be selected from a range of from about 1 to about 20 percent based upon the weight of the coating mixture used to make the dosage unit, a more prefer¬ able range being from about 3 to about 10 percent based on said weight.

The amount of methyl salicylate or other effective salicylate ester can also be varied so long as an effective amount is utilized to reduce greatly or eliminate the red¬ dening of the absorption site of nicotine from the trans- dermal dosage units. It has been found that an effective amount of a salicylate ester can be incorporated into the adhesive solution in making the adhesive layer or into the polymer mixture used in making a polymer matrix storage reservoir, if that is selected. It has been found prefer¬ able to use methyl salicylate, however, other effective and biocompatible esters can be selected such as other lower alkyl esters, such as ethyl salicylate, glycol salicylate, benzyl salicylate and the like esters.

It has also been found desirable to use a biocompatible agent for enhancing skin wearability of the dosage unit. It is preferable that said agent also reduces the amount of loss through volatilization of nicotine in the production of the transdermal dosage units. It presently is preferred to use isopropyl myristate. Other agents providing the proper¬ ties of isopropyl myristate can also be used for this pur¬ pose. Other effective agents can be selected as the skin wearability enhancer, for example, it can be selected from other effective and biocompatible fatty acid compounds such as other esters, alcohols and the like. Lauryl alcohol, diethyl tartrate, diethyl citrate and isopropyl adipate, have been found in illustration to be effective.

Also it has been found desirable to utilize an anti- oxidant agent to preclude any substantial amount of oxida- tion of the nicotine of the dosage units. It has been found successful and effective to use such biocompatible anti- oxidant agents as BHT (butylated hydroxy toluene) and AAP

(ascorbic acid palmitate) . The amount utilized will vary as desired so long as there is an effective reduction or pre- vention of nicotine oxidation. It has been found suitable to utilize about one percent or an effective amount in the range of about 1 mg to about 8 mg and more preferably within

**> the range of about 2 mg to about 4 mg in a 10 cm dosage unit. It has been found that the transdermal absorption rate of nicotine is approximately 13 micrograms per square centi¬ meter of skin per hour from a controlled polyacrylic adhe¬ sive matrix dosage unit with 5 percent nicotine content based upon the weight of the coating mixture described above. It has been found that the addition of isopropyl myristate or methyl salicylate or other selected salicylate esters has little or no effect on the transdermal absorption rate of nicotine at this 5 percent level. Examples of materials suitable for making the backing layer are films of high and low density polyethylene, poly¬ propylene, polyurethane, polyvinylchloride, polyesters such as poly(ethylene phthalate) , metal foils, metal foil lami¬ nates of such suitable polymer films, and the like. Prefer- ably, the materials used for the backing layer are laminates of such polymer films with a metal foil such as aluminum foil. In such laminates, a polymer film of the laminate will usually be in contact with the adhesive layer. The backing layer can be any appropriate thickness which will provide the desired protective and support functions. A suitable thickness will be from about 10 to about 200 microns. Desirably, the thickness will be from about 20 to about 150 microns, and preferably be from about 30 to about 100 microns. In making the adhesive layer, the adhesive polymer used must be biologically acceptable and compatible with the nicotine and salicylate ester and other ingredients used. Certain polyacrylic adhesive polymers (in the form of an alkyl ester, amide, free acid, or the like) are suitable and are presently preferred. Illustrative of suitable poly- acrylic adhesives for use in making the adhesive layer are represented by the following formula:

wherein x represents the number of repeating units suffi¬ cient to provide the desired properties in the adhesive polymer and R is H or lower alkyl including ethyl, butyl and 2-ethylhexyl.

Other suitable hypoallergenic pressure-sensitive con¬ tact adhesive compositions can also be used. A preferred adhesive layer is pressure-sensitive.

Depending upon pharmaceutical compatibility and other factors, if desired, the adhesive means can extend in the form of a ring attached, for example, to an extended portion of the backing layer so that the adhesive layer is adjacent to the sidewall of the nicotine-containing disc layer. The width of such adjacent adhesive ring must be adequate to hold the dosage unit securely to the subject being treated. Ordinarily, a suitable width of such adhesive ring can be about 0.1 to about 1.0 cm, preferably about 0.2 to about 0.8 cm.

The adhesive layer then is finally covered with a releasable protective film layer which is made from mate- rials which are substantially impermeable to nicotine, the salicylate ester, wearability enhancer, and any other compo- nents of the dosage unit. The polymer materials and metal foil laminates used for the backing layer may also be used to make the protective layer, provided the layer is made strippable or releasable such as by applying conventional siliconizing or Teflon coating. A suitable releasable mate- rial is Scotchpak 1022 material sold by the 3M Company or

Bio-Release Material by Dow Corning.

In making the optional polymer matrix layer, poly- acrylic adhesive polymers as described above can also be used, such as sold under the designation Duro-Tak, and other biocompatible adhesive polymers which provide a stable environment for nicotine and the salicylate ester and permit their release, can suitably be used. Generally speaking, those polymers and adhesive polymers can be used to form the polymer matrix layer which are capable of forming thin walls or coatings through which nicotine and the salicylate ester are stable and can pass at desired controlled rates. Suit¬ able polymers and adhesive polymers are biologically and pharmaceutically compatible, non-allergenic and insoluble in and compatible with body fluids or tissues with which the device is contacted. The use of soluble polymers is to be avoided since dissolution or erosion of the matrix would affect the release rate of the components as well as the capability of the dosage unit to remain in place for con¬ venience of removal. The amount of the components used depends upon the dosage rate of nicotine and other components, especially the salicylate ester, and the duration of treatment desired in each dosage unit and the amount which can be incorporated into the polymer matrix layer to retain suitable structural, diffusion and other properties in the final polymer matrix layer. It has been found, for example, that nicotine can be satisfactorily added to the polymer used in making the poly¬ mer layer, such as polyacrylic adhesive polymer. It has been found to be preferable to add and disperse the nicotine and salicylate ester used in an amount of a selected adhe¬ sive polymer solution. The mixture of the polymer and com- ponents is then thoroughly mixed to form a homogeneous solu¬ tion or microdispersion of the nicotine in the polymer. After the mixing step, the composition can be subjected, if desired, to vacuum to remove any entrapped air.

The mixture is then applied as by solvent casting tech- nique, to a suitable substrate, like backing laminate or release liner or other suitable substrate as described above with regard to making the adhesive layer. The polymer matrix sheet desirably is about 10 to 400 microns, prefer¬ ably about 20 to about 300 microns, in thickness. The resulting polymer matrix sheet is removed from the casting machine and another layer of medicated polymer, can be further coated on the first medicated polymer layer formed by direct casting or lamination. The dosage units either with or without the optional polymer matrix layer are then covered with a transparent low-adhesion release liner (e.g., Scotch-Pak 1022/3M) . The completed dosage layers are then cut into dosage units having various shapes and sizes by using a specially- designed device cutter, such as a 10 cm² or 20 cm² rectangu¬ lar shape.

The dosage units can be tested for the effectiveness in protecting against skin irritation as caused by nicotine transdermal absorption. An acute skin irritation test can be conducted. The results are expressed in a score in the Primary Dermal Irritation Index (PDII) . The test is con¬ ducted by utilizing young female New Zealand white rabbits. The dosage units are applied to the skin of the rabbits and the absorption sites are observed during the test period for any occurrence of skin reddening. In the test, the control dosage units utilizing a controlled amount of nicotine such as 5 percent showed no acute skin irritation upon a one-day testing. The scoring system is as follows:

Primary Dermal Irritation Index (PDII) Result

0 Non-Irritant < 2 Slight Irritant

2-5 Moderate Irritant > 5 Severe Irritant

In the skin sensitization studies, a positive control was utilized containing dinitrochlorobenzene in 95 percent alcohol. The transdermal absorption of the nicotine and salicy¬ late ester from the dosage units of this invention is evaluated by using a skin specimen from human cadaver by following the procedure described by Y.W. Chien, K. Valia and U.B. Doshi in Drug Develop. & Ind. Phar . , 11(7) 1195- 1212 (1985) .

The following examples are in illustration of the invention and are not intended to be limiting.

Example 1

A composition for use in making dosage units of this invention is made by following the procedure described. An amount of 82.93 grams of material Duro-Tak solution (Duro-

Tak 80-1054 used) is added to a 4 oz. Ouorpak bottle. To that solution there is also added to the bottle 4.04 grams of nicotine, 4.49 grams of isopropyl myristate, 8.09 grams of methyl salicylate and 0.4 grams of butylated hydroxy- toluene. The mixture is mixed for ten hours to obtain a homogeneous formulation.

The composition is coated on a backing layer. The backing layer is made of Scotch Pak 1109 sold by 3M Corpora- tion.

The oven temperature of the coating machine is set at

60°C and the timer is set at 10 minutes. A coating frame number 1 is installed onto the machine. The Scotch Pak 1109 backing material is mounted on the coating frame of the machine and the position of the doctor knife is adjusted to provide a thickness of 400 microns onto the backing layer. About 20 grams of the homogeneous formulation is poured onto the backing layer and the doctor knife is pulled toward the operator to coat a thin film of formulation upon the Scotch Pak backing layer. The doctor knife is removed and the control button is activated to advance the coating frame into the drying chamber of the coating machine. The frame holding the backing layer bearing the coating is automati- cally released from the drying chamber and the coated film is removed from the coating frame.

A coating frame number 2 is then installed into the coating machine. Release liner material is mounted onto a coating frame number 2. About 20 grams of the homogeneous nicotine formulation is poured upon the release liner and the doctor knife is pulled toward the operator to coat a thin film of the formulation upon the release liner. The doctor knife is again removed and the controlling button is activated to advance the coating frame bearing the release liner having coated upon it the layer of formulation into the drying chamber. The number 2 frame bearing the coated release layer is automatically released from the drying chamber of the coating machine. The coating frame number 2 with the coated release liner is removed from the frame.

Coating frame number 1 bearing the backing layer with the nicotine coating layer is reinstalled into the machine with the nicotine coating facing upward. Also, the release liner with the coated formulation from coating frame number

2 is carefully placed upon the coating layer positioned upon the backing layer with the coating layer facing downward upon the first coating layer. The two layers then become laminated to provide a backing layer having adhered thereto the nicotine adhesive layer having 9 percent nicotine, 10 percent isopropyl myristate, 18 percent of methyl salicylate and 1 percent of butylated hydroxytoluene. The final lami¬ nated layer then also has on the opposite side from the backing layer a release layer adhered to the adhesive nico¬ tine containing layer. The laminated sheet containing a backing layer the nicotine adhesive layer and the release layer are formed into 5 cm or 10 cm transdermal dosage units by using a cutting press.

Example 2

An in-vitro skin permeation procedure described in

Chien et al. referred to herein above was used to evaluate the permeability of nicotine across human cadaver skin. Skin permeation flux measurements were made at 37°C. The nicotine concentration in the receptor medium (40% aqueous- polyethylene glycol solution) was measured at various time intervals. The skin flux or transmission of the nicotine through the cadaver skin was determined and calculated for various time intervals.

The skin permeation rate of nicotine is relatively high, for example, about 13 mcg/cm /hr from a polyacrylate adhesive matrix with 5% nicotine concentration. It was determined that the addition of certain of the ingredients, such as isopropyl myristate or methyl salicylate has little or no effect on the skin permeation rate of nicotine as shown in the following Table 1:

At 5 percent nicotine loading, the addition of isopro¬ pyl myristate up to 20 percent did not substantially affect nicotine skin permeation. The slight increase in nicotine skin permeation from the patch formulation containing 30% isopropyl myristate was the result of the protective proper¬ ty of isopropyl myristate to prevent nicotine from evapora¬ tion during the drying of the dosage unit sheets as described in Example 1 and the dilution result of isopropyl myristate to the polyacrylate adhesive matrix, causing a high nicotine diffusivity in a less viscous adhesive matrix. The following experiments show that the nicotine con¬ centration can be varied from 2.5 to 10 percent. Also, it shows" that in the presence of a set amount of isopropyl myristate, 20 percent (w/w) , the nicotine skin permeation decreased with decreasing nicotine concentration in the adhesive layer of the dosage units. The data are shown in the following Table 2. Table 2. The Effect of NCT Loadings on NCT Skin Flux

Formulation Ingredients Flux Flux NCT IPM Polyacrylate fπic /cm-/hr) Ratio

10 0 90 36.39 (2.98) 1.0 10 20 70 60.50 (4.25) 1.7 7.5 20 72.5 37.23 (2.56) 1.0

5 20 75 22.50 (2.74) 0.6 2.5 20 77.5 11.21 (0.83) 0.3

When the dosage units were made using various salicy¬ late esters, such as methyl salicylate (MS) , ethyl salicy¬ late (ES) or glycol salicylate (GS) it was shown that little or no enhancing effect on skin permeation rate of nicotine resulted. The following Table 3 shows nicotine permeation from the adhesive formulations for making the dosage unit containing a constant amount of nicotine and isopropyl myristate loadings at 9 or 10 percent respectively and varied salicylate ester loadings.

The nicotine permeation rate as a function of sali¬ cylate loadings in the patch is shown in the following Table 3:

Table 3. The Effect of Salicylate Loadings on NCT Skin Flux

Nicotine Skin micromol/5 cm² Flux (mcg/cm²/hr

28.02 (6.29)

28.94 (4.53)

38.39 (9.32)

46.06 (5.71)

30.13 (5.85)

32.39 (6.66)

35.56 (6.17)

37.09 (13.00)

25.93 (1.68) 31.23 (2.10) 32.26 (5.96)

Example 3

The dosage units made following the procedure of Example 1 which contain methyl salicylate with or without nicotine, placebo dosage units or active dosage units, respectively, were tested on six young female New Zealand white" rabbits to study the protective effect of salicylate ester against skin irritation (redenning) normally caused by nicotine transdermal absorption.

The following Table 4 shows the low amount of skin irritation of the dosage units of the invention having methyl salicylate in the Primary Dermal Irritation Index (PDII) . Table 4. PDII Scores in a Primary Skin Irritation Study Patch Formulation PDII Scores*

Active 0.34 Placebo 0.34

*Scoring System: PDII Result

0 Non-Irritant < 2 Slight Irritant

2 - 5 Moderate Irritant > 5 Severe Irritant

The results of the testing show that methyl salicylate containing dosage units showed little or no skin irritation at the various concentrations of nicotine. The methyl sali¬ cylate containing dosage units showed substantially the same skin irritation level exhibited by placebo dosage units, in contrast to the positive control using the standard test material dinitrochlorobenzene in 95% ethanol solution. The scoring system is as follows:

Sensitization Rate Class

0-8 Weak

9-24 Mild

29-64 Moderate

65-80 Strong

81-100 Extreme

They show that the presence of methyl salicylate in the dosage units containing nicotine eliminated irritation or sensitization of skin caused by transdermal absorption of nicotine. Example 4

Dosage units were made containing different concentra¬ tions of isopropyl myristate. The presence of isopropyl myristate and other like agents increase the wearability or adhesion of the dosage units upon the skin of the subject undergoing nicotine transdermal absorption. Also, isopropyl myristate reduces loss of nicotine during the production of the nicotine containing dosage units, such as those described in Example 1.

Dosage units made by the general procedure as described in Example 1 having a size of 5 cm were extracted with solvent to remove nicotine. Dosage units containing no iso¬ propyl myristate and dosage units containing both the 10% nicotine and 20% isopropyl myristate were extracted to determine the amount of nicotine present and the protective effect of isopropyl myristate. The following Table 6 shows that isopropyl myristate substantially improved the preven¬ tion of loss of nicotine during the preparation procedure for making the nicotine containing dosage units.

Table 6. Recovery of Nicotine from Patches With and Without IPM

Formulation Ingredients Amount of Nicotine Recovered NCT IPM Polyacrylate (mg/5 cm² Patch)

10 0 90 3.79 (0.01) 10 20 70 4.14 (0.01) Example 5

Dosage units were made containing zero and various amounts of an antioxidant, ascorbic acid palmitate or buty¬ lated hydroxytoluene. Long term stability tests were car¬ ried out. These tests showed that at high storage te pera- tures nicotine was stabilized in the presence of butylated hydroxytoluene as compared to corresponding dosage unit containing no butylated hydroxytoluene. The following Table 7 shows the loss of nicotine in the absence of the antioxi¬ dant butylated hydroxytoluene.

Table 7. Recovery of Nicotine Patches without BHT.

Temperature (°-C) Duration (Weeks) Recovery of NCT r.t. 0 100%

5 3 99.4%

45 3 90.9%

The data show that after a storage period of 3 weeks at

45° C a loss of 9% of nicotine was incurred.

Corresponding dosage units were made incorporating 1% butylated hydroxytoluene based on the weight of the nicotine composition used to make up the nicotine containing adhesive layer. The following data show that presence of butylated hydroxytoluene acted to protect nicotine against oxidative degradation. Table 8. Recovery of Nicotine from Patches with 1% BHT.

Example 6

The above dosage units are repeated using ethyl salicy- late or glycol salicylate as the anti-reddening agent. Also the above dosage units can be made using other antioxidation agents, such as ascorbic acid palmitate and other wear¬ ability enhancers instead of isopropyl myristate, which provide the benefits of isopropyl myristate.

Effective and biocompatible nicotine salts, solvates and the like nicotine compounds which are transdermally absorbed can be used in making the dosage units described in the above Example. Also, other effective and biocompatible salicylate esters, isopropyl myristate substitutes, other bioacceptable antioxidants or other components can be used, so long as the resulting dosage units are effective and have the desired properties.

Example 7

Following are the steps to manufacture dosage units which comprise a backing layer-polymer matrix-adhesive- release liner: 1) Mount Scotch Pak 1109 on the coating frame and adjust the position of the doctor knife to provide a thickness of 400 microns (above the Scotch Pak) .

2) Pour approximately 20 gm of the homogeneous polymer mixture onto Scotch Pak 1109 and pull the doctor knife

(toward the operator) to coat a thin film of formula¬ tion containing nicotine, methyl salicylate and isopro- pyl myristate as defined in Example 1 on the Scotch

Pak. 3) Remove the doctor knife and push controlling button to advance the coating frame into the drying chamber.

4) As the frame is automatically released from the drying chamber, remove the coating frame with film-coated

Scotch Pak from the machine and place it aside. 5) Install the coating frame No. 2 onto the machine.

6) Pour approximately 10 gm of the adhesive only on release liner and pull the doctor knife (toward the

^•operator) to coat a thin film, 200 microns, of formula¬ tion on the release liner. 7) Remove the doctor knife and push the controlling button to advance the coating frame No. 2 into the drying chamber.

8) As the frame is automatically released from the drying chamber, remove the coating frame No. 2 and put it aside. 9) Re-install the coating frame No. 1 with the coating formulation facing upward. 10) Release the release liner from the coating frame No. 2 and carefully place it, with the coated formulation facing downward, onto the coated formulation on the backing layer and laminate the two coated formulations together. 11) Remove the coating frame No. 1 from the machine and unload the multilaminated sheet.

12) Cut the multilaminated sheet into dosage units of desired size by using a cutting press.

Claims

5

What Is Claimed Is:

1. A nicotine transdermal dosage unit for transdermal

10 administration of nicotine having

1) a backing layer impervious to the ingredients of said dosage unit,

15

2) an effective amount of nicotine to reduce the desire for smoking tobacco,

20 3) an amount of a biocompatible salicylate ester effective to reduce substantially or to prevent reddening of the skin at the site of the absorp¬

25 tion of the nicotine,

4) a biocompatible adhesive layer adhered to said ³⁰ backing layer, and

5) optionally a polymer matrix layer separating said adhesive layer and said adhesive layer which 35 adheres on one side to said backing layer and on the opposite side to said adhesive layer;

40 said nicotine and salicylate ester distributed in said adhesive layer or said polymer matrix layer or

⁴⁵ both.

2. A dosage unit of Claim 1 wherein the salicylate ester ⁵⁰ is methyl salicylate.

3. A dosage unit of Claim 1 wherein the adhesive layer is

-j ⁵⁵ a polyacrylic adhesive. 4. A dosage unit of Claim 1 having an effective amount of a skin wearability enhancer

5. A dosage unit of Claim 5 wherein said enhancer is isopropyl myristate.

6. A dosage unit of Claim 1 wherein the nicotine and salicylate ester are present in the adhesive layer and said adhesive layer is adhered to said backing layer.

7. A dosage unit of Claim 1 wherein said salicylate ester is methyl salicylate.

8. A dosage unit of Claim 7 wherein said adhesive layer is made of polyacrylic adhesive.

9. A dosage unit of Claim 8 wherein said dosage unit delivers for transdermal absorption an amount of nico¬ tine in the range of about 10 to about 40 mg.

10. A dosage unit of Claim 9 wherein said dosage unit delivers for transdermal absorption an amount of methyl salicylate in the range of about 5 mg to about 20 mg.

11. A method to reduce the desire or craving of a subject to smoke tobacco by transdermal administration of an effective amount of nicotine by use of a transdermal dosage unit of Claim 1.

12. A method of Claim 11 wherein the transdermal dosage unit has an effective amount of methyl salicylate. 13. A method of Claim 12 wherein the transdermal dosage unit administration of nicotine is an effective amount in the range of about 10 to about 40 mg and an effective amount of methyl salicylate in the range of about 5 to about 20 mg.

14. A method of Claim 13 wherein the dosage unit has an effective amount of a skin wearability enhancer.

15. A method of Claim 14 wherein said skin wearability enhancer is isopropyl myristate.