Gonal-F, Follistim

Gonal-F Follistim and other FSH products stimulate the ovarian follicles directly. Remember that clomiphene stimulates the ovary indirectly via the hypothalamic-pituitary interactions. Externally administered FSH is physiologically identical to the FSH produced by the pituitary.

Gonal-F is administered by subcutaneous injection in conjunction with assisted reproductive technologies and intrauterine insemination where multiple eggs are needed. Multiple egg development occurs because of the stimulatory effect of FSH on the follicles. Some women who have very low FSH levels (hypogonadotropic) and functional ovaries have an excellent response to FSH resulting in high pregnancy rates. Gonal-F is usually administered at home by the patient or her partner.

Repronex and Humegon contain FSH and small amounts of leutinizing hormone whereas Gonal-F and Follistim are pure FSH made with recombinant DNA technology. There is debate as to which class of these products (pure FSH vs. FSH/LH) is the most effective. Many embryologists believe higher quality eggs are obtained from pure FSH cycles.

The most serious potential side effect of the gonadotropins is ovarian hyperstimulation syndrome (OHSS). In this condition, the ovaries become enlarged and there is a "shift" of body fluid into the abdomen and pelvic cavity after ovulation. The decrease in fluid resulting from this "shift" can reduce blood perfusion and result in clots and poor circulation to the internal organs. The best predictor of hyperstimulation is elevated estrogen levels. Fortunately, the incidence of OHSS is low (approximately 5%).

Use of gonadotropins significantly increases the chances of multiple births, usually twins. The incidence of higher order births is reduced when the drugs are properly administered and monitored. These products should only be administered by a physician specially trained in their use. Much experience is required to become familiar with variable patient responses, interpret stimulation markers, adjust dosages, and prevent unwanted side effects. Reproductive endocrinologists undergo an additional two years of fellowship training after completing their OB/GYN residency.