Question:
What's the difference between oral and injectable fertility drugs?
Answer:
They are completely different classes of drugs. The oral fertility drugs are called Clomid and Femara. Both of these are Estrogen receptor blockers. The brain modulates ovarian function by checking the estrogen levels. By blocking the estrogen receptors, the brain is fooled into thinking that there is inadequate estrogen production, so it increases the amount of FSH and LH hormone to stimulate the ovary. In this way, the ovary is stimulated to ovulation, in non-ovulatory patients, or to incerase the number of eggs ovulated, in ovulatory patients.
The injectable fertility drugs are FSH and LH. Previously, these were purified, human hormones, but now they have been able to be synthesized. They are the same hormones that the brain sends to stimulate the ovary, so they stimulate the ovary directly, instead of indirectly like the oral drugs. They are stronger and work better because of the direct stimulation. That is why we use these preferentially with IVF. They are more expensive.
I hope this answers your question!
Edward J. Ramirez, M.D., FACOG
Executive Medical Director
The Fertility and Gynecology Center
Monterey Bay IVF Program
Monterey, California, U.S.A.
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