A double-blind study comparing the contraceptive efficacy, acceptability and safety of two progestogen-only pills containing desogestrel 75 micrograms/day or levonorgestrel 30 micrograms/day. Collaborative Study Group on the Desogestrel-containing Progestogen-only Pill.

OBJECTIVE

To compare the contraceptive efficacy, bleeding pattern, acceptability and safety of desogestrel 75 micrograms/day (Cerazette) as a progestogen-only formulation to levonorgestrel 30 micrograms/day in healthy female subjects.

METHODS

In a double-blind, randomized, group-comparative, multicenter trial, 989 subjects were randomized to desogestrel 75 micrograms/day and 331 to levonorgestrel 30 micrograms/day. The women were observed during 13 consecutive treatment periods of 28 days.

RESULTS

The Pearl indices for in-treatment pregnancies, excluding gross non-compliance, were 0.14 (one pregnancy in 727 woman-years) in the desogestrel group and 1.17 (three pregnancies in 257 woman-years) in the levonorgestrel group. Using the 90-day reference period for assessing the bleeding pattern, desogestrel users had a higher incidence of amenorrhea and infrequent bleeding on the one hand, and of frequent bleeding and prolonged bleeding on the other hand, at the beginning of the study period. In contrast to the levonorgestrel group, a tendency towards less bleeding over time was observed in the desogestrel group. The frequency and pattern of adverse experiences were comparable for desogestrel 75 micrograms/day and levonorgestrel 30 micrograms/day.

CONCLUSIONS

Desogestrel 75 micrograms/day is a reliable and safe progestogen-only pill with a contraceptive efficacy superior to levonorgestrel 30 micrograms/day. These was a similar overall acceptability of desogestrel 75 micrograms/day and levonorgestrel 30 micrograms/day.