Contraception--a look forward, Part III: Inhibin and brain-enhanced estrogen delivery

The final installment of this review examines two contraceptive methods, inhibin and brain-enhanced estrogen delivery, which are radically different from any currently available. Inhibin is a gonadal hormone that specifically inhibits pituitary production of follicle-stimulating hormone. Before it was finally isolated in 1985, inhibin was expected to be an ideal contraceptive. Recent research, however, has shown that the inhibin hormonal system is unexpectedly complex, and hopes for clinical use of inhibin must be suspended for the present. Although oral contraception is one of the most effective methods ever devised, use is limited by adverse effects of estrogen (or fears of such effects). A system known as brain-enhanced estrogen delivery specifically delivers estrogen to the brain, including the hypothalamus, there inducing suppression of the gonadotropin-releasing hormone. It has been described and tested in animals, and its successful development could replace current oral contraceptives and extend their availability to many more women.