Levonorgestrel butanoate intramuscular injection does not reliably suppress ovulation for 90 days in obese and normal-BMI women: a pilot study

Abstract

Background We performed a pilot evaluation of a new formulation of levonorgestrel butanoate (LB) designed to be a long-acting injectable (6 months) contraceptive to determine pharmacodynamic end-points in normal and obese BMI women. Study design Obese (BMI ≥ 30 kg/m2) and normal BMI, otherwise healthy, women received a single intramuscular injection of LB after ovulation was confirmed in a baseline cycle. The primary outcome was return of ovulation in days. Results A total of 14 women enrolled and completed the study [normal BMI n= 9, median BMI 22.7 kg/m2 (range 19.4 – 25.8); obese n= 5, median BMI 35.7 kg/m2 (30.1–39.2)]. The first 6 subjects (normal BMI = 4/9, obese BMI = 2/5) received 40 mg of LB, and the remaining 8 received 20 mg. All women except one returned to ovulation prior to 6 months. Return to ovulation occurred earlier in the obese group; 3/5 obese and 0/9 normal BMI subjects returned to ovulation within 90 days (p = 0.03). No serious adverse events were reported during the study. Conclusion Return to ovulation was earlier than 6 months in both BMI groups but more so in the obese BMI group.

Esters of levonorgestrel and etonogestrel intended as single, subcutaneous-injection, long-lasting contraceptives

“…LB underwent several clinical trials but to this date has not been marketed [12] . A more recent study [13] found that a higher body mass index of women resulted in earlier return to ovulation, suggesting possible inconsistencies in efficacy from woman to woman.…”