New Product Review (April 2003) Desogestrel-only Pill (Cerazette)

Faculty of Family Planning and Reproductive Health Care Clinical Effectiveness Unit

A unit funded by the FFPRHC and supported by the University of Aberdeen and SPCERH to provide guidance on evidence-based practice

Journal of Family Planning & Reproductive Health Care 29(3):p 162-164, July 2003.

Evidence from a randomised trial has shown that a 75 μg (microgrammes) desogestrel pill inhibits ovulation in 97% of cycles. Thus, on theoretical grounds, we would expect the desogestrel pill to be more effective than existing progestogenonly pills (POPs). However, Pearl indices from clinical trials comparing it to a levonorgestrel POP were not significantly different. Therefore an evidence-based recommendation cannot be made that the desogestrel pill is different from other POPs in terms of efficacy, nor that it is similar to combined oral contraception (COC) in this respect. An evidence-based recommendation can be made that the desogestrel-only pill is similar to other POPs in terms of side effects and acceptability. The desogestrel-only pill is not recommended as an alternative to COC in routine practice, but provides a useful alternative for women who require oestrogen-free contraception.

In clinical trials:

Ovulation was inhibited in 97% of cycles at 7 and 12 months after initiation.
The Pearl index was 0.41 per 100 woman-years, which was not significantly different from a levonorgestrel-only pill. However, the trial providing these data was too small to detect a clinically important difference. Pearl indices of the desogestrel POP and of COC have not been compared directly.
Variable bleeding was more common than with levonorgestrel-only pills but by 11–13 months of use almost 50% of women using desogestrel had infrequent bleeding or amenorrhoea compared to 10% in the levonorgestrel group.
Despite relatively greater desogestrel concentrations being used, reported side effects were no different than with a levonorgestrel-only pill due to desogestrel's low affinity for androgen receptors.
There were no significant alterations in metabolic or haemostatic parameters with desogestrel use, and volume and composition of breast milk were unchanged.

Women experiencing unacceptable bleeding patterns on conventional POPs are unlikely to fare any better on the desogestrel-only pill. The desogestrel-only pill should be taken as for other POPs, ideally no more than 27 hours after the previous dose and without a pill-free week