Ovulation Induction

clomiphene citrate (Clomid)

Advantages of clomiphene citrate are its low cost and a wealth of information regarding its effects—Clomid has been approved for ovulation induction by the FDA since 1967. This medication works to increase your own pituitary signal, follicle-stimulating hormone (FSH), to produce an egg. A follicle is simply a fluid-filled cyst that houses the developing egg in the ovary until ovulation occurs.

While Clomid can be an effective initial treatment, many women will need to move on to alternative therapies, usually due to minimal/partial response or marginal tolerance of the medication’s side effects.

letrozole (Femara)

Femara works through a slightly different mechanism than Clomid to increase the FSH signal from your pituitary and enhance follicular development. Its primary advantage is a shorter half-life than Clomid, which allows Femara to act primarily in the follicular phase, minimizing undesirable side effects. Additionally, this feature makes Femara an excellent medication to pair with the low-dose injectable FSH preparations detailed below for stronger ovulation induction protocols.

Despite its off-label use for many years, Femara has never been submitted to the FDA for approved use in ovulation induction cycles. There is reasonable supportive evidence from a large cohort of 911 infants born to mothers that took either Clomid or Femara in five Canadian centers demonstrating no increased risk of birth defects between these two medications (Tulandi T et al, Fertility and Sterility, June 2006). Please make sure that all your questions regarding the use of Femara have been answered by our physicians before beginning your treatment cycle.

gonadotropins (Bravelle, Follistim, Gonal F, Menopur)

These are the medications most frequently prescribed for ovulation induction in a reproductive endocrinology practice. Whether these drugs are synthesized directly (Follistim, Gonal F) or purified (Bravelle, Menopur) in the laboratory, they are all follicle-stimulating hormone (FSH) preparations; Menopur consists of equal amounts of FSH and LH, which is useful in certain stimulation protocols. Since both FSH and LH are protein hormones that can be broken down with changes in temperature or pH, these preparations require refrigeration (once they are in a liquid form) and administration through subcutaneous injection.

Once these medications reach the ovaries, they are strong stimulators of follicular development. As a result, they can be used in lower doses for ovulation induction with timed intercourse/intrauterine insemination, or in higher doses for stimulations preceding in vitro fertilization (IVF) cycles.

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