A nonhormonal model for emergency contraception: prostaglandin synthesis inhibitor effects on luteal function and...

The purpose of this study is to determine if the use of a specific prostaglandin endoperoxide-2 inhibitor will prevent luteal development in women.

Ovulatory reproductive-aged women not using or needing hormonal contraception were prospectively followed for three menstrual cycles. Women were randomized into two groups using a crossover design [Group 1: control cycle, placebo cycle, active drug (celecoxib 400 mg orally) cycle; Group 2: control cycle, celecoxib cycle, placebo cycle]. Study drug was dosed daily until the onset of the next menses. Demographics, menstrual cycle length and twice-weekly progesterone (P) levels during the placebo and active drug cycles were recorded. End points included the change in luteal phase P levels and menstrual cycle length (days) during active drug exposure.

A total of 11 women completed the study (Group 1, n=7; Group 2, n=4). No demographic differences were found between groups [age, race, body mass index (BMI), control cycle length]. A comparison of the control and active drug cycles for all participants demonstrated a trend toward a longer menstrual cycle with active drug exposure [control, 27.2 days (SD, 2.4); study drug, 28.5 days (SD, 2.5), p=.09]. Five women had a delay in the rise of their luteal phase P levels, two women had lower peak P levels and two women had no elevation of luteal phase P levels during active drug cycle as compared to placebo cycle.

Daily administration of a prostaglandin synthesis inhibitor may delay the timing of luteal events and, therefore, fertility in women. PTGS2 inhibitors may hold potential as an emergency contraceptive.