Summary
A new oral drug, Letrozole (also known as Femara) is being used to help women with fertility issues. It works similarly to Clomid, but has fewer side effects.
The dose of Letrozole is 2.5-12.5 mg. daily, days 3-7 of the menstrual cycle. It can cause a woman to ovulate, or in some cases produce more than one egg for ovulation.
Letrozole is completely gone from your body in 9 days, which means it is not in your bloodstream by the time pregnancy occurs. When used in this manner for infertility, Letrozole does not increase the risk of miscarriage or birth defects.
Letrozole is also used to treat women with breast cancer, but using a different dose and a different schedule for administration.
Please note that there is a warning about using this drug during pregnancy. Do not be alarmed, as Letrozole will be cleared from your system before the baby implants. However, it is important to never take Letrozole, Clomid, or any other fertility drug during pregnancy unless told to by your doctor. This is why we ask you to check a home pregnancy test before you begin any of these drugs.
Discussion
One of the key aspects of achieving fertility is the process of ovulation, by which an egg grows, matures, and is ejected from the ovary on a regular (usually monthly) basis. Several medications are used by infertility specialists to enhance fertility, and frequently they work by affecting ovulation. Such drugs include injectable formulations (Follistim, Gonal-F, Menapur) as well as oral medications (Clomid). Oral medications are often preferred as initial therapy due to their minimal expense, need for infrequent monitoring, and few side effects. For this reason, Clomid has long been a popular early treatment for infertile couples suffering from ovulation failure or unexplained infertility.
Unfortunately, Clomid has several important drawbacks that make it less than ideal as a fertility drug. One component of Clomid can stay in the bloodstream for more than a month, and causes the uterine lining to grow poorly and the cervical mucus to thicken in consistency. To compensate for these adverse effects, we must give you a second drug (estrogen) just after completion of the Clomid; unfortunately, this remedy is not always effective.
Recently, a new drug, Letrozole (also called Femara) has been used as an oral fertility drug much the way that Clomid has been traditionally used. This drug, from a group of drugs called aromatase inhibitors, was first used as a long-term daily treatment for certain types of breast cancer. However, when used for brief periods (5 days, days 3-7 of the menstrual cycle) Letrozole works nearly identically to Clomid. This drug, in daily doses of 2.5-12.5 mg., will frequently cause women to ovulate when they normally do not, or in the normally ovulatory woman cause 2, 3 or even more mature eggs to develop. Thus, it is excellent therapy for both ovulation failure and unexplained infertility, the same indications for which we use Clomid. However, a big advantage of Letrozole is its short lifespan after consumption. Half of the Letrozole you take will be gone in 43 hours, and it should be completely eliminated from the system in just over 9 days. This means that the side effects often seen with Clomid, especially those seen with repeated or high doses, are less frequently encountered with Letrozole. It also means that Letrozole is completely out of your system by the time pregnancy occurs.
There are various reports in the medical literature and on the internet of adverse effects upon pregnancy by Letrozole and related drugs; in particular, there have been claims that the drug is related to an increased risk of malformations at birth. However, this is true of any drug that alters hormones when taken during pregnancy for prolonged periods of time, including Clomid. When used as outlined above for fertility treatment, Letrozole does not increase the risk of miscarriage or birth defects. In fact, no long-term side effects have been reported for this drug when used to treat infertility. For these reasons, we believe Letrozole to be a valuable addition to the group of fertility drugs we have at our disposal to enhance your chances of conceiving.
Letrozole is approved for use by the Food and Drug Administration as a treatment for breast cancer. However, it is administered in lower doses continuously to treat this disease, a far different treatment schedule than is used for infertility. Furthermore, it is not like traditional chemotherapy for cancer: it does not work by directly attacking cancer cells (and other normal cells in the body). Instead, it works by lowering estrogen production in the body. This treats cancers that are dependent upon estrogen for growth, such as some types of breast cancer. It will also affect body tissues that require estrogen. However, these effects only occur if the medication is used every day for a long period of time. When used briefly (5 days) each month, side effects from this drug are infrequent and mild.
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