Gonadotropin releasing hormone analogs for female contraception by inhibition of ovulation.

One hundred and one healthy regularly ovulating women used two superactive GnRH agonists, Buserelin and Nafarelin, for contraception for 3-26 months. The superagonists were administered once daily by a nasal spray. The treatment was initiated on one of the first 3 days of the menstrual cycle. Seventy-one volunteers used 200, 400 or 600 micrograms of Buserelin for contraception for 3-26 months. Normal ovulation was disturbed in all but 3 of 628 treatment months. No pregnancy occurred. Fifty-three women had regular or sparse menstrual-like bleedings during treatment while 18 developed amenorrhea. Normal ovulation and fertility rapidly returned after cessation of therapy. Thirty women received 125 or 250 micrograms of Nafarelin intranasally once daily for 3 months. The treatment consistently inhibited ovulation without serious side effects. The inhibition of ovulation by prolonged continuous intranasal GnRH agonist therapy is a promising new lead to peptide contraception in women.