The Yuzpe method of emergency contraception is a highly effective way of preventing pregnancy if initiated within 72 hours of unprotected intercourse. The treatment consists of administration of 100 μg of ethinyl estradiol plus 500 μg of levonorgestrel and a repeat dose 12 hours later. Unfortunately, the effectiveness and acceptability of this regimen are limited by the side effects of nausea and vomiting. More than 40 percent of patients have nausea, and 16 percent report vomiting in conjunction with this treatment. Pretreatment with an antiemetic may help reduce these side effects, but little is known about the effectiveness of this approach. Raymond and colleagues tested the efficacy of incorporating meclizine into the Yuzpe protocol to reduce the incidence of nausea and vomiting.

Women between 18 and 45 years of age who presented to a center with a request for emergency contraception were invited to participate in the study if they met criteria for the Yuzpe method and had no contraindications to any of the study medications. Participants who met the study criteria were randomized to one of three groups: no pretreatment, pretreatment using 50 mg of meclizine, or placebo given one hour before the first contraceptive dose. Following an initial assessment, participants were asked to complete symptom questionnaires at 12, 24 and 48 hours after the first contraceptive dose.

Of the 343 women who were enrolled, 325 completed the study. Demographic information was similar across groups. During the two days that symptoms were monitored, nausea was reported by 64 percent of women in the placebo and control groups compared with 47 percent in the group taking meclizine. Nausea was moderate or severe in 37 and 41 percent of the placebo and control groups, respectively, compared with 24 percent of those taking meclizine. Vomiting was reported by 18 percent of the placebo group, 13 percent of the control group and 5 percent of the women in the treatment group. In addition, women taking meclizine reported significantly lower rates of abdominal pain, systemic chills and fever. Meclizine, however, was associated with significantly greater rates of drowsiness and related symptoms. Drowsiness was reported by 31 percent of the meclizine group compared with 13 to 16 percent of the other groups. The incidence of other side effects did not differ significantly across groups.

The authors conclude that meclizine averted about 25 percent of nausea and 74 percent of vomiting in this study. Although meclizine can cause significant drowsiness, it is effective in reducing nausea and vomiting during the Yuzpe regimen of emergency contraception and may contribute significantly to the effectiveness of the method. Women should be advised to anticipate drowsiness.

editor's note: Public awareness of emergency contraception is increasing, but it remains an uncomfortable ethical area for some physicians because of concerns that the mechanism is used predominately to prevent implantation of a fertilized ovum. If acceptable to physician and patient, emergency contraception can provide a welcome relief to concerns about an unintended pregnancy, including conceptions resulting from rape. This study confirms the high rates of nausea and vomiting associated with the traditional Yuzpe method and validates the common practice of providing an antiemetic. Newer methods of emergency contraception based on progesterone eventually may replace the Yuzpe method.—a.d.w.