Noncompliance among a group of women using a novel method of contraception

Toward developing a once-a-month pill: a double-blind, randomized, controlled trial of the effect of three single doses of mifepristone given at midcycle on the pattern of menstrual bleeding

OBJECTIVE

To test the feasibility of timing the administration of mifepristone as a once-a-month contraceptive pill on the 12th day before the next menses, as calculated from the length of the previous menstrual cycles.

DESIGN

Double-blind, randomized, controlled trial.

SETTING

Five family planning centers across the world.

PATIENT(S)

Three hundred ninety-nine women attending family planning clinics.

INTERVENTION(S)

Randomized to receive 10, 25, or 200 mg of mifepristone or a placebo.

MAIN OUTCOME MEASURE(S)

Lengthening or shortening of the normal menstrual cycle length following administration of the drug by at least 5 days.

RESULT(S)

The menstrual period came within 5 days of the predicted date in 88% of women receiving the placebo, 84% of women receiving 10 mg, 72% of women receiving 25 mg of mifepristone, and only 48% of women treated with 200 mg of mifepristone. Increasing the dose of mifepristone was associated with an increased chance of having a delayed period (P<.001). Only 45% of women were in the peri-ovulatory phase of the cycle according to LH and P measurements on the day of drug administration. Women treated before ovulation were more likely to have delayed menses with all three doses of mifepristone.

CONCLUSION(S)

Because of the disruption in cycle length, it appears unlikely that mifepristone administered once a month, at a calendar-based time, would provide a reliable method of contraception.

A single dose of mifepristone (200 mg) in the immediate preovulatory phase offers contraceptive potential without cycle disruption

A single dose of mifepristone is an effective emergency contraceptive and has potential as a regular "once-a-month" pill. If given in the early luteal phase, the formation of a secretory endometrium is inhibited or delayed and implantation of the embryo prevented. We have explored the effect of giving the mifepristone just prior to ovulation on the ovarian and endometrial cycle. Seven women with regular menstrual cycles were studied during a control cycle and then in a second cycle when 200 mg mifepristone was given within 24 h of ovulation, i.e., when luteinizing hormone (LH) in serum was >15 IU/L and the dominant follicle was >18 mm. Ovulation was confirmed within 48 h by ultrasound in five of the seven women. The remaining two women had luteinized unruptured follicle. Following mifepristone, menses occurred after a normal luteal phase compared to control cycle (13.7 +/- 0.7 vs. 13.7 +/- 0.9 days). In all subjects the endometrium on LH + 6 in the treatment cycle showed no, or very little, secretory changes, suggesting it was unlikely that pregnancy would have occurred. We conclude that mifepristone could be given as a "once-a-month" contraceptive pill without causing significant disruption in the menstrual cycle in the majority of women for a 4-day period from just prior to ovulation until LH + 3.

New developments in contraceptive drugs for use by women

Since the oral contraceptive pill was first marketed in 1959, advances in contraceptive drugs for women have been limited to variations on the theme of oestrogen in combination with progestogen or progestogen alone. Alterations to the pill regimen, new progestogens and new delivery systems have increased choice but while these advances significantly improve acceptability, side effects and risks remain essentially unchanged. New ideas are in short supply. Antiprogesterones offer a new approach with a variety of dose regimens but their development has been seriously hampered by the politics associated with their abortifacient action. Other hormone antagonists as contraceptives seem a long way off. Immunocontraception is still at a very early stage. Genes, whose products are uniquely concerned with reproductive processes, promise new targets but radically new contraceptive drugs for women appear distant.