New data released underscores safety of dedicated continuous-use pill

Prepare to counsel women on continuous-use oral contraceptive

New research released on Lybrel, the first dedicated continuous use oral contraceptive (OC) (Wyeth Pharmaceuticals; Collegeville, PA), underscores the safety of the new drug.1,2 Now on U.S. pharmacy shelves, a four-week supply of 28 tablets costs about $57 at CVS and Wal-Mart, similar to the cost of other birth control pills.3 The pill was approved by the Food and Drug Administration in May 2007.

What is the status of insurance coverage for Lybrel? Wyeth has been working with the major health care plans and pharmacy benefit management companies to ensure access for the pill, says company spokeswoman Danielle Halstrom. At this time, most health care plans and pharmacy benefit management companies are providing access to Lybrel as an option for their participants, she reports.

Other contraceptive pill regimens have placebo or pill-free intervals lasting four to seven days that stimulate a menstrual cycle. Lybrel is designed to be taken without the placebo or pill-free time interval. While the concept of using pills in a continuous manner is not a new concept for family planners, Lybrel represents the first dedicated product in that category.

For many years, the progestin-containing pill, also called the mini-pill, has been used on a daily continuous basis as an oral contraceptive, points out Julia Johnson, MD, professor and vice chair of gynecology in the Division of Reproductive Endocrinology and Infertility in the Department of Obstetrics and Gynecology at the University of Vermont College of Medicine in Burlington. The newest continuous pill differs in that it also contains a low dose of estrogen (20 mcg ethinyl estradiol) in addition to a commonly used contraceptive progestin (90 mcg levonorgestrel), says Johnson.

Johnson and other researchers performed a substudy of Lybrel's Phase III trial to evaluate the effect of Lybrel on endometrial histology. Findings of the substudy, designed to evaluate the effect of the continuous daily regimen pill on endometrial histology, indicate the pill has a good endometrial safety profile.1

The safety of continuous contraceptives, with or without adding a small amount of estrogen, is well established, says Johnson. The impact on the endometrial lining with any progestin-containing contraceptive is thinning and atrophy of the endometrium, she notes. Women are reassured when they learn that the lack of menses is not because the lining cannot shed, but because there is no lining to shed. Johnson says this effect on the endometrium is expected by all progestin contraceptives: oral, injectable, implant, or intrauterine systems.

"The advantage of having an inactive endometrium is the suppression of menses for women with dysmenorrhea or menorrhagia; in addition, the estrogen component of these pills also suppresses the ovary and prevents functional cyst formation, as seen with progestin-only contraceptives," says Johnson. "Future studies are needed, but continuous oral contraceptives may also improve other common gynecologic disorders, such as premenstrual syndrome."

Will periods return?

Women who are interested in using Lybrel will want to know about the ability to menstruate and become pregnant after discontinuation of the pill. Results from a new study indicate that most women who use the drug return to their regular bleeding pattern after they stop use of the pill. Of the 187 women who completed the study, 185 (98.9%) returned to spontaneous menses (181) or became pregnant2 within 90 days after pill use. For the two women who did not experience menses during the study interval, one reported menses on Day 124 and the other at approximately two months after the study ended.2

To perform the observational study, researchers enrolled women ages 18-49 with a history of regular menstrual cycles who had participated for at least six months in an open-label trial of the drug. The median time to return to menses in the women who completed the study was 32 days, and the incidence of spontaneous menses or pregnancy at day < 90 was 98.9%. Researchers report that the duration of amenorrhea during drug use before stopping treatment was unrelated to the time to the return to menses.

Lybrel is similar to other oral contraceptive pills in that when women stop taking them, they are at risk of pregnancy, says the paper's lead author, Anne Davis, MD, MPH, FACOG, assistant professor of clinical obstetrics and gynecology at Columbia Presbyterian Medical Center in New York City. There is no delayed return to fertility. In contrast, in a study of return to fertility among users of DMPA conducted in Thailand, women conceived nine months on average after the last injection, or 5.5 months after discontinuing, which the researchers assumed to be 15 weeks after the last injection.4

All of the women in the current study had regular menstrual periods prior to taking Lybrel, Davis points out. For women who have irregular cycles, use of Lybrel will not "correct" the cycle, she notes. Women will return to their previous mode of menstruation when they stop taking the drug, says Davis.

Data back safety

As clinicians more frequently prescribe extended/continuous OCs and other hormonal contraceptives, some clinicians and women may be concerned that extended/continuous exposure to the sex steroids in the contraceptives may be associated with delayed return to fertility and/or endometrial disease, observes Andrew Kaunitz, MD, professor and associate chair in the Obstetrics and Gynecology Department at the University of Florida College of Medicine — Jacksonville. Research indicates this is not the case, he notes.

Kaunitz points to a study of continuous OC use conducted in Oregon, where one woman conceived within one week of stopping pills after six months of continuous use.5 The findings of a separate study provide similar data. In a study of 30 women who discontinued a one-year Phase III trial of continuous-use pills in order to conceive, 57% had become pregnant by three months, and 81% had become pregnant by 12 months. The overall pregnancy rate at 13 months was 86%.6

References

  1. Johnson JV, Grubb GS, Constantine GD. Endometrial histology following 1 year of a continuous daily regimen of levonorgestrel 90 micro g/ethinyl estradiol 20 micro g. Contraception 2007; 75:23-26.
  2. Davis AR, Kroll R, Soltes B, et al. Occurrence of menses or pregnancy after cessation of a continuous oral contraceptive. Fertil Steril 2007; [Epub ahead of print].
  3. Kotz D. Two new contraceptives reach store shelves. U.S. News & World Report 2007. Accessed at: health.usnews.com.
  4. Pardthaisong T. Return of fertility after use of the injectable contraceptive Depo-Provera: Updated data analysis. J Biosocial Science 1984; 16:23-34.
  5. Kwiecien M, Edelman A, Nichols MD, et al. Bleeding patterns and patient acceptability of standard or continuous dosing regimens of a low-dose oral contraceptive: A randomized trial. Contraception 2003; 67:9-13.
  6. Barnhart K, Mirkin S, Grubb G, et al. Return of fertility after cessation of a continuous oral contraceptive. Fertil Steril 2006; 86:S15.