A Prospective Randomized Trial Comparing Clomiphene Citrate with Tamoxifen for Ovulation Induction in Anovulatory Women

Abstract

Objective: To evaluate the rates of ovulation and pregnancy in a cohort of anovulatory women with infertility randomized to treatment with either Tamoxifen (TMX) or Clomiphene Citrate (CC). Design: Prospective randomized non-crossover trial. Materials and Methods: From August 1997 through November 1999, 95 anovulatory women were enrolled in the investigation. A total of 86 subjects had appropriate follow up for evaluation, 46 in the TMX arm and 40 in the CC arm. The mean age of the TMX group was 26.6 (±4.2) years and that of the CC group was 26.5 (±4.3) years. The mean years of infertility and Body Mass Index were also similar; 3.5 (±2.9) years and 30.9 (±6.0) kg/m2 for the TMX group and 3.7 (±2.5) years and 30.2 (±6.2) kg/m2 for the CC group (P>.05). Subjects were randomized to receive either 20 mg of TMX or 50 mg of CC cycle days 5–9. Ovulation was defined as a mid-luteal progesterone of 3.0 ng/mL or higher. If ovulation failed to occur, the dose of the medication was sequentially increased in each subsequent treatment cycle. The daily dose of TMX was increased to 40 mg and then 60 mg and the dose of CC to 100 mg and then 150 mg. A total of 113 evaluable TMX cycles and 91 CC cycles were available for interpretation. Results: The overall rate of ovulation in the TMX group was 50/113 cycles (44.2%) and in the CC group 41/91 cycles (45.1%), P>0.05. The ovulatory rate per cycle in subjects who received 20 mg of TMX was 56.5% and in subjects who received 50 mg of CC was 46.0%. Ovulatory rates per cycle with 40 mg of TMX or 100 mg of CC were 27.6% and 39.3% respectively, and with use of 60 mg of TMX or 150 mg of CC were 20.0% and 53.9%. Ten of 13 (76.9%) subjects receiving 60 mg of TMX failed to ovulate and 6 of 11 (54.5%) subjects receiving 150 mg of CC failed to ovulate, P>0.05. There were 10 pregnancies in the TMX group and 6 pregnancies in the CC group. The fecundability with TMX was 20.0% (10/50) per ovulatory cycle and the fecundability with CC was 14.6% (6/41) per ovulatory cycle (P>0.05). Conclusions: In a cohort of anovulatory women, the overall rate of ovulation and pregnancy were similar with TMX and CC. We conclude that TMX is an acceptable alternative ovulation induction agent to CC.