Transdermal Delivery Field, of thejnvention

This invention relates to the field of transdermal delivery, in particular, of hormones.

Background of the Invention

Progestins, or combinations of progestins and estrogens, are used to inhibit ovulation, and to induce other physiological changes in the female reproductive system, and thereby to reduce the risk of pregnancy.

Various dosing regimens have been used to administer such hormones. These include for example, self-administration by oral delivery of a progestin and an estrogen for 21 days, followed by a 7 day "rest" interval, during which the woman typically experiences withdrawal (i.e., menstrual) bleeding. Other dosing regimens can also be used, including dosing regimens that involve longer durations of administration of a progestin and dosing regimens that involve use of low dose hormone during a non-treatment interval.

An important aspect of any effective contraceptive dosing regimen is that the regimen is convenient so as to facilitate compliance and that the doses delivered are effective to prevent or reduce the risk of pregnancy without exposing the woman to unnecessary risks of side effects. Side effects can include hormone-related adverse events and cycle control irregularities, particularly "breakthrough" bleeding.

A transdermal hormone delivery device for administering a progestin and an estrogen via a patch, and a skin permeation enhancer combination for use therein, are disclosed, e.g., in U.S. 7,045,145 and U.S. 20040054901, both of which are incorporated herein by reference as though fully set forth.

Summary of the Invention

The instant invention provides a flexible dosing regimen for administration of a progestin and, optionally, an estrogen. More specifically, the invention relates to a method of preventing pregnancy, i.e., reducing the risk of pregnancy, in a woman that comprises, transdermally administering an effective amount of a progestin and, optionally, an estrogen, over a variable treatment interval, followed by a variable rest interval, whereby the length of each treatment interval and of each rest interval can be varied throughout the course of treatment, i.e., throughout the duration of time when the woman is undergoing contraception.

In illustrative embodiments, the invention provides a method of inhibiting conception, i.e., preventing (reducing the risk of) pregnancy, in a woman that comprises:

(A) consecutively applying multiple transdermal hormone delivery treatment devices to the skin of the woman during an extended treatment interval, i.e., greater than 4 weeks, e.g., at least about 4-1/2 weeks, each device delivering an effective amount of a progestin and, optionally, of an estrogen, followed by a rest interval that typically is up to about 7 days, e.g., 3-1/2 or 7 days; and

(B) optionally applying a rest interval device during at least a portion of the rest interval, wherein the rest interval device comprises (i) low dose progestin, (ii) low dose estrogen, (iii) low dose progestin and low dose estrogen, or (iv) no hormone.

In more specific illustrative embodiments, the method comprises consecutively applying transdermal hormone delivery devices, each intended for wear for Vz week; the treatment interval is 4-1/2, 5, 5-1/2, 6, 6-1/2, 7, 7-1/2, 8, 8-1/2, 9, 9-1/2, 10, 10-1/2, 11, 11-1/2, 12, 12-1/2, 13, 13- 1/2, 14, 14-1/2, 15, 15-1/2, 16, 16-1/2, 17, 17-1/2, 18, 18-1/2, 19, 19-1/2, 20, 20-1/2, 21, 21-1/2, 22, 22-1/2, 23, 23-1/2, 24, 24-1/2, 25, 25-1/2, or 26 weeks; and the rest interval is, e.g., V ₂ week or 1 week.

In other illustrative embodiments, the method comprises consecutively applying transdermal hormone delivery devices, each intended for wear for 1 week; the treatment interval is 5, 6, 7, 8, % 10, 11, 12, 13, 14, 15, 16, 17, 8, 19, 20, 2I ₅ 22, 23, 24, 25, or 26 weeks; and the rest interval is, e.g., Vz week or 1 week.

If a treatment interval is only 3 weeks, such that the rest interval would exceed about 7 days, particularly if the rest interval would exceed 8 days or would exceed 9 days, then a rest interval device comprising low dose hormone would typically be used during all or at least a portion of the rest interval, as illustrated, e.g., by Figure Id. Brief Description of the Figures

Figure 1 illustrates hormone serum concentrations during and after a single treatment cycle comprising a treatment interval of 21 or 24-1/2 days with or without a hormone containing patch in the rest interval. The figures have been drawn to 31 days for illustrative purposes only and do not illustrate hormone serum concentrations during a succeeding treatment cycle. Figure Ia illustrates EE serum concentration levels over 31 days resulting from administration of 7 patches each for 3-1/2 days. Figure Ib illustrates EE serum concentration levels over 31 days resulting from administration of 7 patches each for 3-1/2 days, followed by administration of a rest interval device (1/2 patch) for 3-1/2 days. Figure Ic illustrates EE serum concentration levels over 31 days resulting from administration of 3 patches each for 7 days. Figure Id illustrates EE serum concentration levels over 31 days resulting from administration of 3 patches each for 7 days, followed by administration of a rest interval device (1/2 patch) for 7 days.

Figure 2 illustrates an exploded cross-section of an illustrative dermal delivery system of the invention.

Detailed Description of the Invention

In accordance with illustrative embodiments of the present invention, a single treatment interval, during which a woman is treated by transdermally administering to the woman an effective amount of a progestin and, optionally, an estrogen, is variable.

By "variable," is meant that the duration of each treatment interval can be varied by the user during the period during which contraception is desired. For example, a woman may elect at any time to allow herself to menstruate by suspending use of treatment devices at any time, e.g., because she is experiencing breakthrough bleeding or because for other reasons she wants to allow her body to proceed through menses or wants to reduce the likelihood that she will experience bleeding at a given time. For example, if a woman is planning a vacation, she may elect to initiate a rest interval sufficiently in advance of the vacation to make it unlikely that she will experience menstrual bleeding. Thus., "variable" can mean adjusting the duration of a treatment interval so as to avoid (i.e., minimize the chances of) menstrual bleeding during a given time interval. A treatment interval is typically 21 days or longer. In some embodiments, the treatment interval is extended and flexible. By "extended," is meant that the treatment interval is extended beyond four weeks.

Thus, this invention provides a woman with flexibility to decide, within safe and effective bounds, how long a given treatment interval should be, how long a given rest interval should be (if any), whether or not to use a rest interval device during a given rest interval and, if so, for what part of the rest interval, etc.

For example, in a given treatment cycle comprising a treatment interval and a rest interval, a woman can decide to enter a rest interval of 1 to about 7 days after a treatment interval of 21 days. In accordance with this invention, the woman would ordinarily not choose successive 21 day treatment intervals. For example, she may then decide that the succeeding treatment interval will end after a different number of days, e.g., 43 days, to be followed by a rest interval of the same or a different number of days as the previous rest interval. Succeeding treatment intervals can be of longer or shorter duration as previous treatment intervals and succeeding rest intervals can be of longer or shorter duration than previous rest intervals. In other words, it is not necessary that each treatment interval be of the same duration as the previous ones or that each rest interval be of the same duration as the previous ones.

In an alternative, each treatment interval can be a minimum of 4-1/2 weeks, or a minimum of 9 weeks, e.g., 3 or 6 months.

In another alternative, a woman may find it more convenient to stay on a regular schedule for a length of time, whereby each treatment interval is the same length of time and is at least 4-1/2 weeks, or at least about 9 weeks, e.g., 3 months or 6 months, and each rest interval is of the same length of time as other rest intervals.

In some embodiments of the invention, the rest interval is 0 days, i.e., a treatment device is worn throughout the period of time during which contraception is desired. This is typically the case when the treatment device comprises a progestin without an estrogen.

The woman may also choose to vary whether or not she uses a rest interval device and, if so, for what part of the rest interval. She may also have the option of choosing whether or not the rest interval device is a placebo or contains a low dose of a progestin, a low dose of an estrogen, or a low dose of both a progestin and an estrogen. By "low dose" is meant a dose that is not effective for contraception if used throughout a treatment interval.

Conveniently, transdermal delivery is accomplished by means of transdermal hormone delivery devices, i.e., "patches," that are worn consecutively throughout the treatment interval, for a wear interval of ¹ A week or 1 week.

Each Vz week period is about 3 to about 4 days. For example, a single H-week device can be worn for 2-1/2 or 3 days of a given week, in which case the other %-week device would be worn for 4-1/2 or 4 days of that week, respectively, or each device can be worn for 3-1/2 days each. Each one week period can similarly be 6, 6-1/2, 7-1/2, and 8 days, although it is preferable to fix one day per week such that a week is 7 days.

In illustrative embodiments that employ ¹ A week patches, each treatment interval can independently be 4-1/2, 5, 5-1/2, 6, 6-1/2, 7, 7-1/2, 8, 8-1/2, 9, 9-1/2, 10, 10-1/2, 11, 11-1/2, 12, 12-1/2, 13, 13-1/2, 14, 14-1/2, 15, 15-1/2, 16, 16-1/2, 17, 17-1/2, 18, 18-1/2, 19, 19-1/2, 20, 20- 1/2, 21, 21-1/2, 22, 22-1/2, 23, 23-1/2, 24, 24-1/2, 25, 25-1/2, or 26 weeks, or longer.

In illustrative embodiments that employ 1 week patches, each treatment interval can independently be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 8, 19, 20, 21, 22, 23, 24, 25, or 26 weeks, or longer.

In any event, at the end of each treatment interval, there follows a rest interval that is variable and would typically be ¹ A week or 1 week. So, for example, if the treatment interval is 12 weeks, as in the case of 12 devices each worn for one week, or 24 devices each worn for one-half week, the rest interval would likely be ¹ A week or 1 week, although it could be varied shorter or longer. While a rest interval of up to 7 days is typical, the rest interval can also be extended, e.g., to 10, 12, or 14 or more days. In such cases, it may be advantageous to administer low dose hormone during all or a portion of the extended rest interval. At the other end, a rest interval can be as little as a single day or two days but is more typically at least 3 days, e.g., 3, 4, 5, 6, or 7 days. A woman can choose, e.g., to have a rest interval from 1 up to about 12 times per year.

A woman may choose to begin wearing the first patch of the first treatment interval on, or about on, the first day of the woman's period, i.e., on the first day of menstrual bleeding. In this case, the woman can employ a longer or shorter initial treatment interval or initial rest interval, in order to get her on to a schedule that is convenient for her. In embodiments of the invention, only a progestin is administered during treatment intervals. In other embodiments, the progestin is administered in combination with an estrogen during treatment intervals, for all or a portion of each treatment interval. In either case, a progestin or an estrogen or both can but is not necessarily administered during all or a portion of the rest interval, as described below.

The amount of hormone in each treatment device, e.g., each 3-1/2 day patch or 7 day patch, can be varied from patch to patch, or week to week, to provide a multiphasic treatment regimen. For example, the amounts of hormone can be varied so as to provide a triphasic delivery regimen such as, e.g., the triphasic oral contraceptive disclosed in U.S. 6,214,815 (Ortho-McNeil). Either or both of the progestin and the estrogen can be varied (or maintained) independently of each other. Alternatively, the amount of the progestin and of the estrogen can be the same in all patches used in a given treatment cycle or in all treatment cycles.

It is desirable that each treatment device result in an average progestin serum concentration level equivalent to at least about 750 pg/ml of levonorgestrel during the entire treatment interval. In some embodiments, the average progestin serum concentration level is equivalent to at least about 500 pg/ml of levonorgestrel during week 1 of the treatment interval and/or is at least about 750 pg/ml during week 2 and week 3 of each treatment interval, it being understood, however, that such levels may not be achieved during the entire first treatment cycle. In particular, for example, such levels may not be achieved during the first week of the first treatment cycle.

In addition, serum concentrations of a progestin, as well as of an estrogen, can vary from patient to patient. Thus, when considering average serum concentrations achieved during treatment intervals, it is useful to refer to a population of subjects, e.g., 10 or more, 25 or more, 50 or more, 75 or more, or 100 or more. Thus, the concentration values, and peak-trough relationships, expressed herein may be achieved in a population of subjects but not necessarily in every subject within a given population.

The amount of estrogen delivered during each treatment interval can be an amount that results in serum concentration levels equivalent to about 5 to about 80, e.g., about 15 to about 65, pg/ml of ethinyl estradiol during the entire treatment interval, or about 20 to about 30 pg/ml. Serum concentration levels that average about 20 to about 30 pg/ml ethinyl estradiol equivalent can be achieved during week 2 and week 3 of each treatment interval. In an illustrative embodiment of the invention, low (or lower) dose hormone(s) can be delivered during all or a part of the rest interval. The amount of hormone delivered during the rest interval is no more than about 80%, e.g., about 20% to about 80%, of the amount delivered during the treatment interval. For example,, the amount of hormone(s) delivered during the rest interval can be about 3/4, about 2/3, about 1/2, about 1/3, or about 1/4 of the amount delivered during an equivalent amount of time during the treatment interval. Such amount may attenuate, i.e., lessen the severity of, symptoms of menstruation, which can include excessive vaginal bleeding, mood changes, headaches, dysmenorrhea and other symptoms associated with hormone withdrawal, especially sudden hormone withdrawal, or otherwise.

Such rest interval patch, or rest interval device, can conveniently be made in the same manner as the treatment device but with a reduced amount of hormone(s). The amount of hormone(s) can be reduced, for example, by reducing the size of the patch. For example, if a treatment patch has a surface area of 20 cm ² and it is desired to deliver 50% of the hormones during the rest interval, then the rest interval device can be the same as the treatment interval device but reduced in size to have a surface area of 10 cm ² . Such rest interval device could be referred to as a "half patch." Similarly, one could administer a "quarter patch" to deliver 25% of the hormones, or a patch of any other fraction of the size of the treatment patch. Alternatively, the size (surface area) of the rest interval device can be the same as the size of the treatment device, in which case it would be loaded with reduced amounts of hormones and/or enhancers.

The rest interval device can be worn for any part or the whole of the rest interval. So, for example, a half patch can be worn for the full rest interval.

Figure 1 shows illustrative hormone serum concentration levels over 31 days. In accordance with the practice of this invention, of course, a fresh device can be applied on Day 29.

As illustrated in Figure 1 , patches can be designed so as to deliver varying amounts of hormone(s) during the period of wear of each patch, such that there is a peak serum concentration level that occurs after the patch is applied and a trough serum concentration level that occurs at the time the patch is removed. This characteristic can be usefully employed to deliver an amount of a progestin or an estrogen, or both, during the rest interval that declines as the end of the rest interval approaches such that the amount of hormone delivered by the end of the rest interval is decreased relative to peak levels during wear of the rest interval device and, in some embodiments, relative to serum concentration levels on the day that the rest interval device is applied. Such device can be referred to as a descending dose device.

Use of such rest interval device can have several advantages. In one embodiment, the rest interval device is a placebo and is used as a matter of convenience, e.g., so that the woman stays in the habit of removing and applying a patch every 3-12 days or every 7 days. In another embodiment, low dose hormone is delivered such that the woman experiences menstruation but with attenuated symptoms. In such embodiment, also, hormone serum concentration levels are adjusted gradually rather than "all or nothing".

A 3-1/2 day patch can be smaller than a 7 day patch therefore making it less noticeable to the wearer and persons around her. The adhesiveness requirements are also eased because the patch is smaller and because it doesn't need to stay attached for a full week. If a 3-1/2 day patch does become dislodged, there will only be a short period of time before the next patch is due to be applied. A 3-1/2 day patch can allow for a pharmacokinetic (PK) profile having peaks and troughs during each wear period, i.e., during each 3-1/2 day period of treatment, but such peaks and troughs can be smoother relative to a 7 day patch. So, for example, peak hormone serum concentrations during the period of time in which a single treatment device (other than the first device) is worn can be at least about 1.1 times trough levels, or at least about 1.25 times the trough levels, but also can be no more than about twice the trough levels, or no more than about 1.8 times the trough levels, or no more than about 1.5 times the trough levels. Figure 1 illustrates such peak-trough PK profiles. Such PK profile can be achieved during an entire treatment interval or during at least a single wear interval, e.g., the third week, the second half of the second or third weeks, or at least 2 weeks, e.g., the second and third weeks, of each treatment interval.

Any transdermal hormone delivery device that delivers a progestin and, optionally, an estrogen, in amounts effective to effect contraception, i.e., to prevent pregnancy, can be used in the practice of the invention. "Preventing pregnancy" does not necessarily mean that such devices are 100% effective in preventing pregnancy in all cases but such devices can have, at least, approximately the same contraceptive efficacy as currently available oral contraceptives. A transdermal hormone delivery device for preventing pregnancy that delivers 17-deacetyl norgestimate and ethinyl estradiol is disclosed in US 5,876,746 (Cygnus) and is marketed as

Ortho Evra(r) (norelgestromin / ethinyl estradiol transdermal system). As shown in the prescribing information, Ortho Evra provides a more or less "flat" delivery, i.e., no or only a slight peak-trough PK profile for each period of wear of a single patch.

The invention also comprises a kit comprising multiple patches each intended to be worn for ¹ Zz week (2-1/2 to 4-1/2 days) or 1 week (6-8 days). For example, such kit may comprise nine or more 1/2 week treatment devices. Or, for example, such kit may comprise five or more 1 week treatment devices. Or, for example, such kit may comprise a combination of Vi week and 1 week devices. In each case, the kit would include instructions for use of the devices in accordance with the method of the invention.

Such kit can also comprise rest interval devices, which can be placebos (i.e., no hormone) or low dose hormone devices, as discussed above. For example, a kit that comprises 24 'Λ-week treatment devices may comprise up to 4 rest interval devices, whereby, at one end of the spectrum of treatment options, a woman may use all treatment devices without ever using a rest interval device or, at the other end of the spectrum, she may use all of the rest interval devices, each one for up to about a week and each one typically following a treatment interval of 21 days. In each case, the kit would include instructions for use of the devices in accordance with the method of the invention. Such kit would comprise instructions explaining the options for variable and extended use.. Typically, such kit would be designed on the assumption that each treatment interval would be at least 4-1/2 weeks. In certain embodiments, each rest interval device comprises (i) low dose progestin, (ii) low dose estrogen, or (iϋ) low dose progestin and low dose estrogen.

Such rest interval devices can be clearly indicated as rest interval devices, directly or on individual patch packaging, such as by size, color, shape, or markings, to avoid confusion with treatment devices. If a multiphasic hormone delivery profile is desired, then each treatment device can be marked, directly or on individual patch packaging, to minimize the risk that a user will apply patches out of order.

Figure 1 illustrates projected serum concentration levels of ethinyl estradiol (EE) resulting from administration of patches such as described in U.S. 7,045.145 and U.S. 20040054901 and hereinbelow.

The data in Figure 1 are illustrative and do not show the effect of applying a new patch on Day 29. The data are projections calculated on the basis of actual human cadaver skin flux data obtained using a device loaded with a polymeric matrix comprising LNG and EE, substantially as described below, and having a skin contact area of approximately 9.4 cm ² . The projections are calculated using an approximate in vivo clearance rate for EE. Figures Ia and Ib show EE levels on each of Days 1 through 28, with a first 3-1/2 day patch being applied on Day 0 and subsequent patches being applied on Days 4, 7, 11, 14, 18, and 21. Figures Ic and Id show EE levels on each of Days 1 through 28, with a first 7 day patch being applied on Day 0 and subsequent patches being applied on Days 7 and 14. Figures Ib and Id show the effects of administering a rest interval patch on Days 24-28, said rest interval device being V ₂ the size of, but otherwise identical to, the treatment patch.

A similar pattern of peaks/troughs can be obtained with progestins, e.g., LNG.

Note that because these data are projected from skin flux data, actual results will vary, depending, e.g., upon the skin surface area of the patch employed, the concentration of hormone(s), and the efficacy of the skin permeation enhancer.

An illustrative device that can be used in the practice of the instant invention is illustrated in Figure 2.

With reference to Figure 2, this illustrative device comprises 4 layers. One is the AI layer (6). The second is a release liner (4). The third is an internal backing layer (5). The fourth is an overlay, which in this illustrative device, itself comprises three component layers (1, 2, 3), referred to herein below as, respectively, a PSA layer (3), an intermediate layer (2), and an overlay covering or overlay coating (1). The overlay can also be described as comprising a PSA layer (3) and an overlay covering (1, 2). In any event, a feature of this device is formation of a seal between the PSA layer (3) of the overlay (1, 2, 3) and the release liner (4).

The AI layer

Layer 6 comprises the AI and carriers comprising skin permeation enhancers, a humectant/plasticizer, and a PSA matrix. The AI comprise a progestin, e.g., levonorgestrel, and an estrogen, e.g., ethinyl estradiol or 17-β estradiol.

Skin Permeation Enhancers; A combination of skin permeation enhancing agents is employed that comprises a mixture of (1) a pharmaceutically acceptable organic solvent, such as dimethyl sulfoxide (DMSO), (2) a fatty (C8-C20) alcohol ester of a hydroxy acid, such as lauryl lactate, (3) a lower (C1-C4) alkyl ester of a hydroxy acid, e.g., ethyl lactate, and (4) a C6-C18 fatty acid, such as capric acid. In specific embodiments, the fatty alcohol ester of lactic acid is lauryl lactate and the lower alkyl ester of lactic acid is ethyl lactate. A medium- to long-chain fatty acid in the skin permeation enhancer formulation can be employed among the skin permeation enhancers. Capric acid has been used but other C6-C18 saturated or unsaturated fatty acids include but are not limited to caproic acid, caprytϊc acid, lauric acid and myristic acid.

In a particular such embodiment, the pharmaceutically acceptable organic solvent is DMSO. Other organic solvents include but are not limited to C1-C8 branched or unbranched alcohols, such as ethanol, propanol, isopropanol, butanol, isobutanol, and the like, as well as azone (laurocapram: l-dodecylhexahydro-2H-azepin-2-one) and methyl sulfonylmethane.

The fatty alcohol ester of a hydroxy acid can be a fatty alcohol ester of lactic acid, such as lauryl lactate. However, other hydroxy acids and fatty alcohols may be utilized. Alternative hydroxy acids include but are not limited to alpha-hydroxy acids such as glycolic acid, tartaric acid, citric acid, malic acid and mandelic acid, as well as the beta-hydroxy acid, salicylic acid. Alternative fatty alcohols include any C8-C20 saturated or unsaturated fatty alcohols, such as myristyl, palmityl or oleyl alcohols, to name a few.

The lower alkyl ester of hydroxy acid can also utilize lactic acid, and can be, e.g., ethyl lactate. However, other hydroxy acids, such as glycolic acid, tartaric acid, citric acid, malic acid, mandelic acid and salicylic acid, may also be utilized. In addition isopropylmyristic acid (IPM) may be used as a substitute for the lower alkyl ester of hydroxy acid.

Hormones: LNG is a potent progestin on a weight-dose basis, which is an important factor since progestins often exhibit a much lesser degree of transdermal absorption than do estrogens. Other progestins that could be used in part or total are norgestrel, norgestimate, desogestrel, gestodene, norethindrone, nore-thynodrel, hydrogesterone, ethynodiol dicetate, hydroxyprogesterone caproate, medroxyprogesterone acetate, norethindrone acetate, progesterone, megestrol acetate, gestogen and certain others which are biocompatible and absorbable transdermally. These include biocompatible derivatives of progestins that are transdermally absorbed, some of which, advantageously, are bioconvertible after transdermal absorption to the original progestin. The progestin and other hormones selected preferably have high compatibility with each other. For combinations of progestin with estrogen, the synthetic hormone EE is particularly suitable, although natural estrogen or other analogs can be used. This hormone may be transdermally delivered in conjunction with the particularly suitable progestin, levonorgestrel, at desirable daily rates for both hormones. EE and LNG are compatible and can be dispersed in the adhesive polymer formulation.

Derivatives of 17 β-estradiol that are biocompatible, capable of being absorbed transdermally and preferably bioconvertible to 17 β-estradiol may also be used, if the amount of absorption meets the required daily dose of the estrogen component and if the hormone components are compatible. Such derivatives of estradiol include esters, either mono- or di-esters. The monoesters can be either 3- or 17- esters. The estradiol esters can be, illustratively speaking, estradiol-3, 17-diacetate; estradiol-3 -acetate; estradiol 17-acetate; estradiol-3, 17- divalerate; estradiol-3-valerate; estradiol- 17- valerate; 3-mono-, 17-mono- and 3,17-dipivϋate esters; 3- mono-, 17-mono- and 3,17-dipropionate esters; 3-mono-, 17-mono- and 3,17-dicyclo pentyl- propionate esters; corresponding cypionate, heptanoate, benzoate and the like esters; ethinyl estradiol; estrone; and other estrogenic steroids and derivatives thereof that are transdermally absorbable.

Combinations of the above with estradiol itself (for example, a combination of estradiol and estradiol- 17- valerate or further a combination of estradiol- 17- valerate and estradiol-3, 17- divalerate) can be used with beneficial results. For example, 15-80% of each compound based on the total weight of the estrogenic steroid component can be used to obtain the desired result. Other combinations can also be used to obtain desired absorption and levels of 17 β-estradiol in the body of the subject being treated.

It will be appreciated that the hormones may be employed not only in the form of the pure chemical compounds, but also in a mixture with other pharmaceuticals that may be transdermally applied or with other ingredients which are not incompatible with the desired objective as listed above. Thus, simple pharmacologically acceptable derivatives of the hormones such as ethers, esters, amides, acetals, salts and the like, if appropriate, may be used. In some cases, such derivatives may be preferred. The progestin compound and the estrogenic steroid are ordinarily dispersed or dissolved concurrently in fabricating the hormone-containing adhesive polymer matrix or they may be dispersed or dissolved separately. Polymers Used as Active Patch Components: The Al-containing layer can be a polymer matrix comprising the pharmaceutically or cosmetically active ingredient. The polymer can be a PSA to form a biologically acceptable adhesive polymer matrix, preferably capable of forming thin films or coatings through which the AI can pass at a controlled rate. Suitable polymers are biologically and pharmaceutically compatible, nonallergenic, insoluble in and compatible with body fluids or tissues with which the device is contacted. The use of water soluble polymers is generally less preferred since dissolution or erosion of the matrix would affect the release rate of the AI as well as the capability of the dosage unit to remain in place on the skin. So, in certain embodiments, the polymer is non- water soluble.

Preferably, polymers used to form a polymer matrix in the Al-containing layer have glass transition temperatures below room temperature. The polymers are preferably non-crystalline but may have some crystallinity if necessary for the development of other desired properties. Cross-linking monomeric units or sites can be incorporated into such polymers. For example, cross-linking monomers that can be incorporated into polyacrylate polymers include polymethacrylic esters of polyols such as butylene diacrylate and dimethacrylate, trimethylol propane trimethacrylate and the like. Other monomers that provide such sites include allyl acrylate, allyl methacrylate, diallyl maleate and the like.

In certain transdermal drug delivery devices, there is a a permeable or rupturable barrier, rate controlling membrane, or the like interposed between the Al-containing material and the release liner such that when the release liner is removed, said barrier remains in place. The purpose of such barrier can be, e.g., to prevent the Al-containing material from flowing out of the device or to control the rate of absorption by the skin. In the device used to generate the data illustrated in Figure 1 , there is no need for a layer between the release liner and the AI layer because the polymer matrix is adhered to the remaining layers of the device and does not readily flow and because the matrix is designed to deliver adequate drug across the skin without a need to restrict the flow rate. Thus, the polymer matrix is adhered directly to the release liner and, upon administration to the skin, the polymer matrix is adhered directly to the skin across the entire surface area of the AI layer exposed by removal of the release liner,

A useful adhesive polymer formulation comprises a polyacrylate adhesive polymer of the general formula (I): wherein "X" represents the number of repeating units sufficient to provide the desired properties in the adhesive polymer and R is H or a lower (Cl-ClO) alkyl, such as ethyl, butyl, 2-ethylhexyl, octyl, decyl and the like. More specifically, it is preferred that the adhesive polymer matrix comprises a polyacrylate adhesive copolymer having a 2-ethylhexyl aery late monomer and approximately 50-60% w/w of vinyl acetate as a co-monomer. An example of a suitable polyacrylate adhesive copolymer for use in the present invention includes, but is not limited to, that sold under the tradename of Duro Tak 87-4098 by National Starch and Chemical Co., Bridgewater, N. J., which comprises a certain percentage of vinyl acetate co-monomer.

Humectant/plasticizer: Preferably, a plasticizer/humectant is dispersed within the adhesive polymer formulation. Incorporation of a humectant in the formulation allows the dosage unit to absorb moisture from the surface of skin which in turn helps to reduce skin irritation and to prevent the adhesive polymer matrix of the delivery system from failing. The plasticizer/humectant may be a conventional plasticizer used in the pharmaceutical industry, for example, polyvinyl pyrrolidone (PVP). In particular, PVP/vinyl acetate (PVP/VA) co-polymers, such as those having a molecular weight of from about 50,000, are suitable for use in the present invention. The PVP/VA acts as both a plasticizer, acting to control the rigidity of the polymer matrix, as well as a humectant, acting to regulate moisture content of the matrix. The PVP/VA can be, for example, PVP/VA S-630 which is a 60:40 PVP:VA co-polymer that has a molecular weight of 51 ,000 and a glass transition temperature of 110 C. The amount of humectant/plasticizer is directly related to the duration of adhesion of the overlay. The PVP/vinyl acetate can be PVP/VA S-630 supplied by International Specialty Products, Inc. (ISP) of Wayne, New Jersey, wherein the PVP and the vinyl acetate are each present in approximately equal weight percent. The shape of the device of the invention is not critical. For example, it can be circular, i.e., a disc, or it can be polygonal, e.g., rectangular, or elliptical. The surface area of the AI layer generally should not exceed about 60 cm ² in area. Preferably, it will be about 5 to 50 cm ² , more preferably, about 8 to about 40 cm ² . Most preferably, the discs will be about 10 to about 20 cm ² . A disc of 15 cm ² may be preferred because it is relatively small but can be capable of dispersing high levels of hormones.

Thus, an illustrative hormone-comprising polymer matrix useful for delivering an effective amount of a progestin and of an estrogen in amounts effective to prevent pregnancy in accordance with the method of the invention comprises a polyacrylate adhesive copolymer with about 3% to about 60% w/w vinyl acetate and, on a weight percentage basis of the adhesive polymer matrix: a) from about 15% to about 35% of PVP/VA; b) from about 10% to about 30% percent of a combination of skin permeation enhancing agents which is a mixture comprising from about 4% to about 12% DMSO, from about 4.2% to about 12.6% lauryl lactate, from about 0.7% to about 2.3% ethyl lactate, and from about 3% to about 9% capric acid; and c) from about _.6% to about 1.2% LNG and EE, e.g., about .87% LNG and about .77% EE.

The Internal Backing Layer

An internal backing layer can be made of any suitable material that is impermeable or substantially impermeable to the AI and to excipients of the adhesive polymer matrix. The internal backing layer serves as a protective cover for the AI layer and provides a support function. The backing layer can be formed so that it is essentially the same size as the hormone- containing adhesive polymer matrix or it can be of larger dimension so that it can extend beyond the edges of the AI- containing patch outwardly. The backing layer can be any appropriate thickness that will provide the desired protective and support functions. A suitable thickness is from about 10 to about 300 microns. More specifically, the thickness is less than about 150 microns, yet more specifically, it is less than about 100 microns, and most specifically, the thickness is less than about 50 microns. Examples of materials suitable for making the internal backing layer are films of polypropylene, polyesters such as poly(ethylene terephthalate), metal foils, metal foil laminates of such suitable polymer films, and the like. Polyester films, such as Mylar® (DuPont Teijin) and Scotchpak® 9732 (3M Company), are particularly suitable for use in the present invention.

The.Release Liner

The surface area of the release liner is greater than that of the AI layer. This can be seen in Figure 3, where the diameter (in the case of a round device) or width and length (in the case of a polygonal device) of Layer 3 is greater than that of Layers 5 and 6, such that it extends beyond the AI layer in some or all directions.

The release liner is made of any material (1) that is impermeable or substantially impermeable to the components of the AI layer, (2) to which the PSA in the overlay will adhere, as discussed further hereinbelow, and (3) that is readily removable by peeling from the AI layer and overlay PS A just prior to applying to the skin.

The release liner can have the same dimensions as the overlay, discussed below, or it can extend totally or partially beyond the edge of the patch. In one embodiment, the release liner extends partially beyond the overlay so as to form "tabs" of release liner material that extend beyond the edges of the overlay for easy separation of the release liner from the rest of the system.

It can comprise a fluorinated or siliconized polyester film or another fluorinated or siliconized polymer such as a polyacrylonitrile copolymer, or a foil lined with a siliconized or fluorinated polymer. The release liner is preferably not polystyrene because it has been shown that polystyrene will absorb DMSO. A preferred material for the release liner when the layer 4a of the overlay comprises a PIB PSA is a Scotchpak® liner (3M Company), such as Scotchpak® 1022 or Scotchpak® 9744 fluorinated polyester release liners.

The Overlay

The overlay comprises a PSA in which the solubility of the volatile components is less, preferably significantly less, than the solubility of those same components in the AI matrix. So, e.g., when the volatile component is DMSO or ethyl lactate, a PIB PSA may be chosen. With reference to Fig. 2, the PIB PSA layer is Layer 3. Generally, such PIB PSA comprises a mix of a low to medium molecular weight and a high molecular weight PIB, a plasticizer such as polybutene, and a hydrocolloid such as a cross-linked polyvinylpyrrolidine. Useful PIBs include, e.g., Oppanol® PIBs (BASF), which have average molecular weights of between 40,000 and 4,000,000.

A useful PIB PSA comprises crospovidone such as Kollidon® CLM crospovidone (BASF) (e.g., 5-45 wt %, preferably 15-30 wt %, and more preferably 20-25 wt %); a low viscosity PIB such as Oppanol® B 12 (molecular weight: 51000, viscosity at 150 C: 150 Pascal-seconds) (e.g., 10- 60 wt %, preferably 30-50 wt %); a high viscosity PIB such as Oppanol® BlOO (viscosity: approximately 1100 Pascal-seconds) (e.g., 2-15 wt %, preferably 5-15 wt %); a polybutene such as Indopol® 1900 (Innovene LLC) (molecular weight: 2500, viscosity at 100 C: 3900-4200 centistokes) (e.g., 10-60 wt %, preferably 20-40 wt %); and a mineral oil (0-20 wt %). For example, an illustrative formulation comprises about 20 wt % crospovidone, about 40 wt% of a low viscosity PIB, about 8 wt% of a high viscosity PIB and about 32 wt% of polybutene. (The term, "about," as used in this specification, means plus or minus 10%. By "low viscosity" is meant less than about 300 Pascal-seconds and by "high viscosity" is meant more than about 800 Pascal-seconds, when the viscosity is measured at 150 C.) Cross-linking of the PVP is useful because such cross-linked polymers tend to be water-swellable but water insoluble. Such PIB PSA can provide good wear stability, e.g., attachment under normal living conditions for at least 7 days.

Other rubber-based polymers that can be used in place of PIB PSA in the overlay include silicone-based PSAs, such as BIO-PSA® (Dow Corning); copolymers and terpolymers of styrene/butadiene/styrene, styrene/isoprene/styrene, and styrene-ethylene/butylenes-styrene, such as Kraton D styrene/butadiene and Kraton G styrene-ethylene/butylene-styrene or styrene- ethylene/propylene-styrene. Isoprene rubbers, such as Kraton IR linear polyisoprene homopolymers, can also be used.

As shown in Fig. 2, and like the release liner, the overlay can extend beyond the perimeter of the AI layer in all directions, typically by a margin of about 0,1 to about 1.5 cm, more specifically about 0.3 to about 1.2 cm, and yet more specifically about 0.8 cm beyond the perimeter of the AI layer. The overlay, if it comprises a PSA layer, improves adherence to the skin by supplementing the adhesion provided by the PSA in the AI layer, if present, or, in the case of an AI layer that does not comprise a PSA, it provides adherence to the skin.

In addition, the overlay adheres to the release liner around the perimeter of both layers, thereby sealing in the components of the AI layer. By properly selecting the materials that comprise the overlay and the release liner, this seal between them prevents, or substantially prevents, escape of the volatile component in the AI layer but still allows the release liner to be peeled away easily by the user prior to topical application.

The seal is formed in situ by mechanically pressing together the edges of the overlay that extend beyond the perimeter of the AI layer and the edges of the release liner that extend beyond the perimeter of the AI layer. When the first overlay layer is a PIB PSA and the release liner is a fluorinated or siliconized polyester film, a suitable seal can be made by applying pressure. The amount of pressure required to form such seal is not critical. Finger pressure is adequate. Of course, in an illustrative embodiment of the invention, it is desirable that the seal can be broken by peeling the release liner from the rest of the system by hand just prior to application to the skin.

The seal between the overlay PSA and the release liner prevents, or substantially prevents, loss of the components of the AI layer through the seal between these two layers such as during storage of the system. The seal is preferably "tight" to the internal backing layer and the AI layer such that there is minimal or no seepage of the polymer matrix into spaces between the overlay and the release liner or between the overlay and the internal backing layer or the AI layer.

The overlay can also comprise a covering (1) that does not comprise a PSA, i.e., that comprises a non-PSA layer, such that the surface of the overlay that is exposed to fingers, clothing and ambient dirt or dust is non-tacky, is flexible or malleable so as to flex with skin and muscle movements, is of an unnoticeable or attractive color and texture, and permits moisture from the skin to pass through the device owing to its being porous or otherwise permeable to water.

Thus, it may be desirable to utilize a multi-layered overlay comprising a first layer of a PSA in which the volatile component is insoluble, covered with an intermediate layer and an overlay covering having the properties described above. Such illustrative overlay is illustrated in Fig. 2 as Layers 1, 2, and 3. While a PIB PSA is useful for containing DMSO or ethyl lactate, or both, in the AI layer, the PIB PSA may flow through most overlay coverings having the properties described above. Such flow of the PIB PSA can cause the device to become tacky and discolored. Therefore, it may be desirable to use an overlay covering that itself comprises two layers, one of which is a polymeric layer interposed between the PIB PSA (an intermediate layer) and a backing layer. Such intermediate layer can be a polyacrylate PSA as described above, because such PSA will substantially prevent flow of the PIB PSA into and through the overlay covering but will substantially not itself migrate into or through the overlay covering.

The overlay is a laminate that comprises three layers: a PIB PSA layer (3, in Fig. 2); an intermediate layer that comprises a material that does not permit flow of the PIB PSA but that does permit passage of moisture (2, in Fig. 2); and an overlay covering (or backing layer) that is non-tacky, attractive, flexible, and moisture permeable (1, in Fig. 2).

Materials useful in the intermediate layer include, e.g., polyacrylates, polyurethanes, plasticized polyvinyl chlorides, and copolymers of polyethylene and ethyl vinyl acetate. Rubber-based polymers that are of very high molecular weight, e.g., at least about 150,000 Daltons can also be used, as can rubber-based polymers that can be crosslinked. Examples include the Kraton D styrene/butadiene, Kraton G styrene-ethylene/butylene-styrene or styrene-ethylene/propylene- styrene and Kraton IR linear polyisoprene homopolymers Butyl rubbers and silicone rubbers, which are cross-linkable, can also be used. The intermediate layer can comprise a PSA that binds the first overlay layer as well as the overlay covering. High molecular weight, cross-linked polymers are preferred. Preferably, such PSA is a polyacrylate such as is described above with reference to the AI layer.

Materials used in the overlay covering are not PSAs. They include, for example, a polyurethane film, foam or spun bonded structure, a polyolefin foam, a PVC foam or a woven or non-woven fabric. Illustrative wovens include KOB 051, 053 and 055 woven polyesters (Karl Otto Braun.) Illustrative non-woven fabrics include polyesters. An illustrative polyurethane material is CoTran™ 9700 melt-blown polyurethane nonwoven backing (3M), which can be colored in skin tones. Suitable materials are described, e.g., as backing layers in U.S. 6,660,295.

If the overlay covering is not porous, then it can be used without an intermediate layer. However, if the overlay covering is not porous, adhesion problems can result from a build up of moisture in the skin / PIB PSA interface. Use of a solid material, i.e., one that is not porous, but that is otherwise permeable to water, such as a thin, e.g., 1 mil (i.e., 0.001 inch), polyurethane film, can be used. However, a porous material such as a foam or fabric will, in general, better retain its shape and provide good adhesion.

The present invention is not limited to the embodiments described and exemplified above, but is capable of variation and modification within the scope of the appended claims. Published patent applications and patents referenced in this specification are incorporated herein by reference as though fully set forth.