Potent and long-acting stimulatory analogues to the hypothalamic gonadotrophin-releasing
hormone (
GnRH) were originally developed for profertility purposes. Paradoxically they proved to possess anti-fertility properties. Their anti-gonadal properties are at present being utilized for therapeutic purposes, e.g.
contraception, treatment of
central precocious puberty and sex
steroid-dependent benign and malignant diseases of the reproductive organs, predominantly metastatic
prostatic cancer. This review will be limited to the potential use of superactive
GnRH agonists for
contraception in women and men. Inhibit ion of ovulation by continuous
GnRH agonist administration has been studied most extensively and will be dealt with in more detail. Other approaches to interfere with corpus luteum function (induction of in adequate luteal function, luteolysis or early abortion) have so far proved less successful. In males, complete
azoospermia has not been consistently achieved by chronic high dose
GnRH superagonist
therapy alone.
Testosterone supplementation is mandatory to avoid the unacceptable side effects associated with
GnRH superagonist
therapy, namely loss of libido and potency. Thus, to date, inhibition of ovulation by repeated intranasal
GnRH agonist administration seems to have the greatest potential as a future
contraceptive method. In long-term clinical trials, this new lead to
birth control has already proved to provide safe, reliable and reversible
contraception in women.