Infertility Medications / Drugs
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).
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