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A recent article circulated by Reuter’s and seen on MSNBC and its webpage detailed the off-label use of Femara (Letrozole). The article made further reference to a 2005 Canadian study which suggested that babies born after Letrozole use had a three-fold increase risk of birth anomalies. The article went on to suggest that as much as 30% of anovulatory patients treated for infertility had been given Letrozole.

The article concluded that significant cost savings could be realized if patients could only get insurance coverage for a medication if was used for an ’on-label’ indication. In the case of Letrozole, only patients taking the drug for its original purpose (breast cancer treatment) would be eligible for reimbursement. In the mind of the writer this would discourage off-label use of the drug and also protect patients from the ill effects of the drug. Letrozole works by blocking the enzyme aromatase, which converts male hormones to estrogens. Patients taking the drug will block production of estrogen in fat, a common problem in patients with ovulatory disorders. As the circulating estrogen level falls, the pituitary escapes the suppressive effect of estrogen on FSH secretion. This in turn leads to an increase in FSH which drives egg production from the ovary. Et Voila! An egg is born…or at least released. There are problems galore with the assertion that Letrozole is a problem child of a drug. There are also many flaws in the logic that off-label use of a drug is somehow inherently bad. Similarly, there is a widespread attitude that Letrozole is preferable to the old standby Clomiphene (clomid)….which is probably not true with regard to pregnancy rates.

Patients who read articles of this nature need to remember several points. First, off-label use of drugs is remarkably common. This is generally a good thing. Lupron for instance is indicated for treatment of prostate cancer and the Depot form of Lupron for pretreatment of myomas before surgery. It is rarely used for either indication anymore. Instead, Lupron is used primarily as co-treatment with FSH in IVF and IUI stimulation protocols, for which it never received approval. Without the ability to use Lupron ‘off-label’, IVF success rates would be MUCH lower.

Thank you for the informative article. However it is interesting whether the Letrozole had any collateral effect on health which should be considered before off-label use.

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