Contraceptive patch

A contraceptive patch is a transdermal patch applied to the skin that releases synthetic estrogen and progestin hormones to prevent pregnancy. They are thought to have the same effectiveness as the contraceptive pill. Currently the only publicly available contraceptive patch is marketed under the brand name Ortho Evra. Use of this relatively new contraceptive is increasing rapidly, likely because it combines the high effectiveness of contraceptive pills with a more convenient and easy method of administration. Contraceptive patches are often referred to by the slang term "the patch".

Method of use

In the United States and Canada, Ortho Evra is available only by prescription and is sold in boxes of three patches. Johnson & Johnson is the largest manufacturer of these patches.

A woman applies her first patch onto her upper outer arm, buttocks, abdomen or thigh on either the first day of her menstrual cycle (day 1) or on the first Sunday following that day, whichever she prefers. The day of application is known from that point as patch change day. Seven days later, when patch change day comes again, the woman removes the patch and applies another in its place. This process is repeated again on the next patch change day. On the following patch change day, the patch is removed and not replaced. The woman waits 7 days without a patch in place, and on the next patch change day she applies a new patch.

Backup contraception

If a woman chooses to begin with her patch change day as day 1 of her menstrual cycle, the patch is able to take effect in time to prevent ovulation (see Mechanism of Action below) and no form of backup contraception is needed at all.
- In the case that a woman wishes to begin using the contraceptive patch following a first trimester abortion or miscarriage, patch application can be done immediately afterwards. This can be considered the same as a day 1 start above, and no backup contraception is required.
If a woman chooses to begin with her patch change day as the first Sunday following day 1, it is necessary to use a backup form of contraception such as spermicide or condoms for the first week of patch wear.

Mechanism of action

Contraceptive patches are synthetic hormone contraceptives, similar in action to the contraceptive pill. The contraceptive patch product Ortho Evra contains 0.75 mg ethinylestradiol and 6.0 mg norelgestromin hormones in a single patch. The gradual release of hormones over the course of each week (approximately 20 µg/day ethinylestradiol and 150 µg/day norelgestromin) act much like contraceptive pills do. Most commonly ovulation is inhibited entirely, preventing pregnancy. Less often the cervical mucus is thickened, making it more difficult for sperm to cross through the cervix and for fertilization to occur.

Interactions and Contraindications

Contraceptive effectiveness of the patch or any other hormonal contraceptive may be reduced significantly if co-administered alongside various antibiotics, antifungals, anticonvulsants, or other drugs that increase metabolism of contraceptive steroids.

However, despite the interactions with many other antibiotics, a clinical pharamacokinetic drug interaction study showed that oral administration of tetracycline HCl 500 mg for 3 days prior to and 7 days during use of Ortho Evra did not reduce effectiveness of Ortho Evra. This is a significant factor in the common decision to administer tetracycline-derived antibiotics following an abortion (preventatively to fight potential infection) when synthetic hormone contraceptives are to be used afterwards.

Drugs containing St. John's Wort are also known to affect the effectiveness of hormonal contraceptives.

Side effects

Side effects of the patch are very similar to other synthetic hormone contraceptives such as the pill. When starting to use the contraceptive patch some people may experience slight weight gain, although this depends entirely on the individual and some people experience no weight gain at all while people who are already obese or overweight may continue to gain weight. Some people also notice changes in the intensity of sexual desire, vaginal discharge and menstrual flow. Some other common side effects are: nausea; headaches; depression; vaginitis; urinary tract infection; breast changes such as tenderness, enlargement, secretion; skin problems; and gum inflammation.

Thromboembolic risks

Currently, there is ongoing research into the thromboembolic risks of Ortho Evra as compared to oral contraceptives. Data from a recent unpublished study found that users of the contraceptive patch may have a two-fold increased risk for non-fatal venous thromboembolic events compared with women who took a norgestimate-containing oral contraceptive with 35 micrograms of estrogen However, a different study published in the Journal of Contraception concludes that the risk of nonfatal venous thromboembolism for the contraceptive patch is similar to the risk for oral contraceptives containing 35 micrograms of ethinylestradiol and norgestimate ([http://download.journals.elsevierhealth.com/pdfs/journals/0010-7824/PIIS0010782406000084.pdf PDF file). The contradictory findings between the two studies is not easily resolved, because the confidence intervals for the studies are overlapping.

While these studies examined nonfatal venous thromboembolic events, previous evidence found by the Associated Press in 2004 demonstrated that the risk of death from using the patch is three times the risk of death from oral contraceptives ^*. Specifically, the death rate for oral contraceptives is 1 in 200,000 users per year, while the death rate for contraceptive patch is 3 in 200,000 users per year. However, these rates are derived from spontaneously reported adverse events, not controlled clinical studies, and the AP points out at the end of its article that, "Dr. Philip Darney, a professor of obstetrics and gynecology at the University of California, San Francisco, and a leading contraceptive researcher, cautioned that the FDA’s adverse event reports tend to be inflated for newer products like the patch."

In studies with oral contraceptives, the risk for cardiovascular disease (such as thromboembolism) is substantially increased in women over the age of 35 years who also smoke tobacco (PMID 10818409). Hence, Ortho-Evra's package insert states that "Women who use hormonal contraceptives, including ORTHO EVRA®, should be strongly advised not to smoke".

According to the manufacturer, the patches introduce a 60 percent higher level of estrogen into the bloodstream as compared to oral contraceptives; however, the clinical significance of this difference is unknown.

Lawsuit

The parents of a 14 year old have filed a lawsuit against Johnson & Johnson because they claim that she died from a blood clot that arose from her use of the patch. At the time, the manufacturer of the Ortho Evra patch did not include warnings about potentially-fatal side effects, such as blood clots, that have now been linked to the use of the patch. Such side effects have been experienced by those using a birth control pill as well, and although it appears possible that some side effects may occur more frequently in patch users no research has yet been made available to quantitatively show to what extent this is true. ^*

Religion & the patch

The Roman Catholic Church in accordance with their belief that all artificial birth control methods are against the will of God ^* condemns it as they do condoms, and the Pill, while most Protestants take a more liberal view on the matter believing instead that it is an acceptable form of birth control.

References

External links

Hormonal contraception

Kontraceptinis pleistras | Timbre contraceptif

Gourt Home::Gourt :: Contraceptive patch