Corifollitropin is a new drug developed for controlled ovarian stimulation, mainly used in a GnRH antagonist protocol. One single subcutaneous injection on the 2nd day of your menstrual cycle can replace a whole week (7 days) of daily FSH injections. On the 5th day of your menstrual cycle your doctor will prescribe you an antagonist. You may need to continue treatment with extra FSH injections until enough follicles of the adequate size are present.For further details click here