Anastrozole single-dose protocol in women with oligo- or anovulatory infertility: results of a randomized phase II dose–response study

Abstract

To compare the effects of anastrozole and clomiphene citrate (CC) on follicular development and ovulation in infertile women with ovulatory dysfunction. Phase II, prospective, randomized, assessor-blind, multicenter, dose-finding, noninferiority study. Outpatient. Infertile women with ovulatory dysfunction, aged 18-35 years, and body mass index <35 kg/m(2). Single-dose anastrozole at 5 mg (n = 39), 10 mg (n = 39), 20 mg (n = 39), or 30 mg (n = 38) or a 5-day course of CC at 50 mg/d (n = 39) as starting doses. The primary endpoint was the ovulation rate in the first treatment cycle (cycle 1). Ovulation was defined as a midluteal phase serum P level ≥ 10 ng/mL or clinical pregnancy. In cycle 1 the ovulation rates for a single dose of anastrozole at 5, 10, 20, and 30 mg were 46.2%, 41.0%, 23.1%, and 28.9%, respectively, whereas that for CC at 50 mg/d was 61.5%. Among women with fewer than six menses per year, the cumulative ovulation rates over three cycles were comparable in the anastrozole 5 mg (52.4%) and CC 50 mg/d (42.3%) groups. In terms of ovulation rates in cycle 1, single-dose anastrozole at 5, 10, 20, and 30 mg was not as effective as CC at 50 mg/d for 5 days (noninferiority was not shown).