GnRH antagonist in single-dose applications

Previous studies on ovarian stimulation have confirmed the efficacy of a single dose of the gonadotrophin-releasing hormone (GnRH) antagonist, Cetrorelix, in preventing premature LH surges. The single-dose protocol is easy to use and assures patient compliance. When compared with the long protocol using a depot administration of the GnRH agonist, triptorelin, the IVF results in patients treated with Cetrorelix showed a shorter treatment duration, reduced amount of human menopausal gonadotrophin (HMG) required and a lower occurrence of ovarian hyperstimulation syndrome (OHSS). The pregnancy rates did not differ significantly between the two treatments. The use of Cetrorelix in natural cycles associated with gonadotrophins reduced the rate of premature LH surges and, therefore, the cancellation rate. The stimulation was minimal and the preliminary pregnancy rates were satisfactory. If a larger study confirms the results of the natural cycle with HMG support, the single-dose administration of GnRH antagonist could represent an interesting first-choice IVF treatment in selected indications. The tolerance of Cetrorelix was excellent in all patients, with only mild and transitory reactions at the injection site. New GnRH antagonists are already available for clinical use in some countries, and they will certainly change ovarian stimulation protocols. If the pregnancy rates are confirmed, the main advantages of these new compounds are the reduction in side-effects and complications of the stimulation protocol; a clear benefit to the patients.