Clinical Review

Transdermal contraception: update on clinical management

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With efficacy rates at least as high as those of the pill, and even greater patient compliance, the patch significantly broadens the contraceptive armamentarium.


 

References

KEY POINTS
  • The transdermal contraceptive system is a combination hormonal patch that contains 6 mg norelgestromin and 0.75 mg ethinyl estradiol (EE2) in a stable adhesive, and delivers a daily dose of 150 μg norelgestromin and 20 μg EE2to the bloodstream.
  • Three large contraceptive trials, in which 3,319 women used the contraceptive patch worldwide, reported low pregnancy rates, with an overall Pearl index of 0.88.
  • The primary goals of management are increasing correct and consistent use and effectively counseling and educating women about adverse effects, thereby enhancing continuation rates.
  • In studies involving more than 70,000 patches, only 4.7% were replaced because of partial or complete detachment. In 1 health-club study, with physical exertion and variable temperature and humidity, only 1 of 87 patches became completely detached.
  • Treatment-limiting events were reported in 1% to 2.4% of women in clinical trials and included nausea and/or vomiting, application-site reaction, breast symptoms, headache, and emotional lability.

The delivery of hormones via a transdermal patch is not a new development. Estrogen and estrogen-progestin transdermal systems have been used for a number of years to treat the symptoms of menopause.1-3 However, until now, no patch-delivery system was able to administer sufficient hormones to prevent pregnancy.

Transdermal delivery systems are warranted for drugs that are highly potent and lipophilic.4 Published studies demonstrate some patient preference for transdermal systems over oral dosing, particularly drug-in-adhesive transdermal systems (as opposed to first-generation reservoir systems).5,6 In 1 study, drug-in-adhesive systems were rated as having better cosmetic appearance, better skin adhesion, greater comfort, and less skin irritation.6 These traits also apply to the contraceptive patch. In clinical studies, the transdermal contraceptive system was shown to have statistically better patient compliance than oral contraceptives (OCs); in 1 trial, compliance was better across all age groups (FIGURE 1).7 This may be due in part to the weekly, rather than daily, dosing regimen.

FIGURE 1 Compliance by age group


The basic product

The transdermal contraceptive system is a combination hormonal patch that contains 6 mg norelgestromin and 0.75 mg ethinyl estradiol (EE2) in a stable adhesive, and delivers a daily dose of 150 μg norelgestromin and 20 μg EE2 to the bloodstream.8 The progestin component, norelgestromin, is the primary active metabolite of norgestimate.

The transdermal contraceptive patch is a thin, matrix-type system consisting of 3 layers. The backing, composed of a flexible beige film, provides structural support. It also protects the middle layer from the environment. The middle layer contains the adhesive and active hormones. The third layer is the release liner, which protects the adhesive layer during storage and is removed just prior to application. This matrix system allows for lower delivery doses and bypasses the first-pass hepatic metabolism of oral administration.

Efficacy

The efficacy of the contraceptive patch is well-established. Three large contraceptive trials, in which 3,319 women used the contraceptive patch worldwide, reported low pregnancy rates, with an overall Pearl index of 0.88 (TABLE 1).9 In 1 randomized clinical trial, 811 women who wore the patch (5,240 cycles) had an overall pregnancy rate of 1.2 per 100 woman-years, compared with 605 women who took an OC (4,167 cycles), with an overall pregnancy rate of 2.18 per 100 woman-years.10 This difference is not statistically significant, but it does indicate that the patch performs at least as well as the OC.10,11 This is important when counseling patients, since women are not used to relying on a transdermal system to prevent pregnancy and may be skeptical that a patch can be effective.

For maximum efficacy, the transdermal system should be initiated as directed. That is, the first patch should be applied on the first day of menses. Another start day, such as Sunday (i.e., the first Sunday after menses begins), can be chosen instead. However, the woman then must use a backup method of contraception for the first 7 days of patch use.

TABLE 1

Contraceptive patch efficacy: pregnancies per 100 woman-years

STUDYCYCLES (N)PREGNANCIES (N)PEARL INDICES
OVERALL PEARL*METHOD PEARL**
Smallwood et al1610,99460.710.59
Hedon et al115,92140.880.66
Audet et al105,24051.240.99
TOTAL22,155150.880.70
* User failure plus method failure
** Failure when taken as directed
Source: Zieman M, et al. Contraceptive efficacy and cycle control with the Ortho Evra/Evra transdermal system. Fertil Steril. 2002;76:S13.

Patient management

The primary goals of management are increasing correct and consistent use and effectively counseling and educating women about adverse effects, thereby enhancing continuation rates.

Although the theoretical pregnancy rate for oral hormonal contraception is extremely low (0.1% for combination pills), the typical annual pregnancy rate is much higher (8%).12 This difference between perfect and typical use derives mainly from patient errors, such as skipping or delaying pills. In addition, the starting and stopping of hormonal contraception may lead to times during which a woman believes she is protected but is actually at risk for pregnancy. In clinical studies, the difference between the transdermal system’s overall failure and method failure probabilities of pregnancy was only 0.2%.9 In other words, when failures occurred, they were seldom due to patient error. This would suggest that typical-use pregnancy rates for the patch are lower than for combination OCs. Typical-use pregnancy rates are usually based on population surveys and studies; these data are not yet available for the patch.

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