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EVRA: The contraceptive transdermal patch

posted Nov 24, 2009, 12:52 AM by DERC 藥物教育資源中心

(Originally posted on 2004-11-11)

Introduction

Hormonal contraceptive agents are administered to the body through a variety of routes. The most common delivery methods are oral tablet, depot injection, implants and intrauterine device. EVRA, a contraceptive patch, that delivers an estrogen and a progestin via a transdermal route, has been launched in Hong Kong recently. It offers an additional choice to users and can enhance compliance by once weekly administration.

Description

EVRA is a combination transdermal contraceptive patch containing 6 mg norelgestromin (NGMN) and 600 mcg ethinyl estradiol (EE). The average daily dose absorbed into the systemic circulation is 150 mcg NGMN and 20 mcg EE.

Administration

A new patch is applied on the same day of each week for three consecutive weeks. The first patch is applied during the first 24 hours of the menstrual period. It also can begin on the first Sunday after a menstrual period starts. However, a non-hormonal contraception should be used for the first week of the cycle. The fourth week is patch-free. Withdrawal bleeding is expected to begin during this time. In no case should there be more than 7 consecutive patch-free days.

The patch may be applied to the upper torso (front and back, excluding the breasts), upper outer arm, abdomen or the buttocks. A different application area should be chosen when putting on each new patch. It should not be placed on skin that is red, irritated or cut, or on areas of the skin where make-up, lotions, creams, powders or other products are or will be applied.

Users can maintain their usual activities, including bathing and swimming while wearing the patch. However, if the patch comes loose, partially lifts off from the skin or falls off within 24 hours, it should be re-applied to the same place or replaced with a new patch immediately. No back-up contraception is needed and the patch change day will remain the same. If it has been more than 24 hours since the patch has come off, start a new four weeks cycle immediately by putting on a new patch. The day that the new patch is applied will be the patch change day. A non-hormonal contraception method should be used for the first week of the new cycle.

Mechanism of Action

The mechanism of action of the EVRA is the same as the combination oral contraceptives. The patch delivers hormones directly through the skin and into the bloodstream. The hormonal agents inhibit ovulation via a negative feedback mechanism on the hypothalamus, which alters the normal pattern of gonadotropin secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) by the anterior pituitary. The follicular phase FSH and midcycle surge of gonadotropins are inhibited. In addition, these agents produce alterations in the genital tract, including changes in the cervical mucus, rendering it unfavorable for sperm penetration even if ovulation occurs.

Efficacy

A study has been performed in the United States and Canada with a total of 1417 healthy adult women of child-bearing potential participated. They were randomized in a ratio of 4:3 to receive either the contraceptive patch or the oral contraceptive (OC) pills. Contraceptive efficacy, cycle control, compliance, patch adhesion and safety were evaluated. The study shows that the contraceptive patch is comparable to a combination OC in contraceptive efficacy and cycle control. Compliance was better with the weekly contraceptive patch than with the OC. A total of 4.6% of all patches were replaced for either complete (1.8 %) or partial (2.8%) detachment. Both treatments were similarly well tolerated. However, application site reactions, breast discomfort, and dysmenorrhea were significantly more common in the patch group.

Contraindications

The physician should weigh the risks and benefits of using hormonal contraceptive patch as the same as the combination OC pills. It is not recommended for patients with a personal or family history of thrombosis, cardiovascular disease, severe hypertension and diabetes with vascular involvement, migraine, undiagnosed abnormal genital bleeding, hepatocellular disease with abnormal liver function and hypersensitivity to any component of the product. Moreover, analyses of phase III data suggest that EVRA may be less effective in users with body weight > 90 kg than in users with lower body weights.

Conclusions

EVRA is an easy-to-use, weekly, non-invasive form of reversible birth control that does not require surgical procedures or daily dosing. It allows the hormones to directly enter the bloodstream through the skin, which may help to reduce loss of doses due to vomiting and diarrhoea. Compliance problems with OC have been well documented. This product may help women who do not have a regular pill-taking routine. On the other hand, application site reaction, patch detachment and medication cost per cycle may be a concern if comparing with the OC pills. There are many birth control options available including hormonal and non-hormonal contraceptives. Physician should discuss with the users and help them to choose which contraceptive method is most appropriate for their individual needs and lifestyle.

References

  1. Micromedex
  2. Marie-Claude Audet, Michele Moreau, William D.Koltun, Arthur S.Waldbaum, Gary Shangold, Alan C.Fisher, George W.Creasy, for the ORTHO EVRA/EVRA 004 study group. Evaluation of Contraceptive Efficacy and Cycle Control of a Transdermal Contraceptive Patch vs an Oral Contraceptive. American Medical Association 2001. JAMA May 9,2001; Vol.285, No.18: 2347-2354.
  3. EVRA Product Information, JANSSEN-CILAG, a Johnson & Johnson company.
  4. EVRA web site, http://www.evra.com.hk/
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