AT ACOG 2016

WASHINGTON (FRONTLINE MEDICAL NEWS) – A 1-week course of tamoxifen significantly reduced unscheduled bleeding in women using an etonogestrel contraceptive implant, compared with placebo.

The selective estrogen reuptake modifier cut bleeding days by half, compared with placebo, and in some women induced at least 1 month of amenorrhea, Dr. Katharine Simmons said at the annual meeting of the American College of Obstetricians and Gynecologists.

There were no real downsides to using the drug, added Dr. Simmons, an ob.gyn. in Atlanta. There were no significant differences in adverse events between the two treatment groups.

The 6-month study randomized 56 women to 10 mg tamoxifen twice daily or placebo for 7 days. Women were instructed to begin treatment on the third day of any period of unscheduled bleeding. They could use the drug once each month, for up to three cycles during the study period. Every day, the women had to complete a short bleeding diary. This was administered by a daily text message, which asked them to rate the strength of any bleeding over the last 24 hours, and whether or not they had taken the study drug on that day.

The women were young (mean age 25 years), and most were white (about 80%). More than 60% were nulliparous. They had been using the implant for a mean of 275 days. Upon randomization, those in the tamoxifen group reported more unscheduled bleeding days than did those in the placebo group (mean 23 vs. 20 per 30 days). Ten women in the tamoxifen group reported bleeding almost every day of the prior month.

Thirty days after taking the study drug, bleeding days were significantly reduced in the tamoxifen group, compared with the placebo group. Four of 28 women taking the drug experienced complete amenorrhea; 9 reported 5 days of bleeding. The tamoxifen group reported a median of 6 bleeding days after treatment, compared with 12 days in the placebo group.

The effect was sustained, Dr. Simmons said, with a median of 30 days before bleeding resumed in the tamoxifen group, compared with 8 days in the placebo group. Women taking the drug reported significantly greater levels of satisfaction than did those taking placebo. They also were less likely to discontinue the treatment (18% vs. 36%).

There were no significant differences in side effects. Headache was the most common, with 12 women in each group reporting it. Mood changes occurred in 7 taking tamoxifen and in 12 women taking placebo. Hot flashes were slightly more common in the tamoxifen group (6 vs. 4). Reports of nausea, weight gain, and fluid retention were similar.

Dr. Simmons conducted the study during her time at Oregon Health & Science University in Portland. She had no financial disclosures.

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