The most commonly prescribed infertility drugs are clomiphene citrate, gonadotropins, gonadotropin releasing hormone agonists and progesterone and progesterone-like substances. The following is a brief overview of each class of medication and how they are used.
Ovulation induction medications:
Clomiphene citrate is the most commonly used drug to induce ovulation. It is relatively inexpensive and highly effective. If the lack of ovulation is the only cause of infertility and the woman responds to clomiphene citrate with ovulation, a majority of couples will achieve a pregnancy within the first four to six months. Those who do not achieve a pregnancy likely have other issues complicating their situation. An intact hypothalamic-pituitary- ovarian axis is required for clomiphene citrate to work. Clomiphene citrate binds to estrogen receptors and causes the hypothalamus to perceive low estrogen levels. The hypothalamus in turn signals the pituitary to increase the release of gonadotropins [ FSH and LH]. The gonadotropins cause ovarian follicular development which also produces more estrogen. Side effects of the medication include hot flashes during use, and multiple pregnancies in five to eight percent of pregnancies (normal one to two percent). Rarely patients have visual disturbances while on the medication. These visual disturbances uniformly resolve after discontinuation.
Human menopausal gonadotropins (hMG) and recombinant human FSH (r-FSH) are injectable gonadotropins.
hMG is a human urinary product (with both FSH and LH components) which is given by intramuscular injection. r-FSH (pure FSH) is a synthetic (man-made) product which can be given by subcutaneous injection. These medications are extremely potent and should be only administered by physicians with extensive training and experience in the use of these medications. Board certified reproductive endocrinologists have such training and experience. These medications induce ovarian follicular development (creation of estradiol mature egg). Ovarian follicular development is monitored with serial ultrasound evaluations and serum estradiol (E2) levels as necessary.
Gonadotropin releasing hormone agonist (GnRHa)
These medications are synthetic substances which mimic the structure of gonadotropin hormone releasing hormone (GnRH) and therefore bind to the receptor. In binding they can cause the release of gonadotropins (FSH and LH) initially (flare effect), but then desensitize and downregulate the normal actions of GnRH and cause gonadotropin levels to be suppressed. The suppression of gonadotropins results in menopausal levels of estrogen. These drugs are used in women with endometriosis and for assisted reproductive procedures.
Progesterone and progestins:
Progesterone is the steroid hormone which is produced by the corpus luteum after ovulation. It is critical to the development of an endometrial (uterine) lining, capable of accepting and sustaining the implantation and growth of a developing embryo. There are many forms and routes of administration for natural progesterone and synthetic progesterone-like substances (progestins).
Revision date: July 3, 2011
Last revised: by David A. Scott, M.D.