Use of a Calcium Channel Blocker to Prevent Premature Luteinizing Hormone Surges in Infertility Patients

Nimodipine (Nimotop® Bayer Pharmaceuticals Corporation), unlike other calcium channel blockers is fat soluble and therefore is able to cross the blood-brain barrier1. Gonadotropin releasing hormone (GnRH) neurons are clustered in the hypothalamus and are dependent on calcium flux to release GnRH responsible for the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. In a natural menstrual cycle a spontaneous LH surge occurs mid-cycle which triggers ovulation. The investigators hypothesized that nimodipine, by blocking calcium channels, may effectively suppress the release of GnRH and consequently the natural LH surge. In this prospective double-blinded randomized study the investigators will evaluate the efficacy of nimodipine to inhibit the natural LH surge in women undergoing controlled ovarian stimulation (COS) and intrauterine insemination (IUI). Nimodipine, if successful, may represent an inexpensive oral medication as an alternative to the currently used GnRH agonists or GnRH antagonists in assisted reproductive technologies like IVF.