The Food and Drug Administration (FDA) added new warnings on Wednesday to finasteride, the drug used to treat male pattern baldness and enlarged prostate, citing sexual side effects that continue to occur even after patients stop the treatment.
The changes apply to the anti-baldness drug Propecia and the prostate medication Proscar, which both contain finasteride and are marketed by Merck & Co. The drugs already bear warnings for sexual side effects, but the FDA is updating the labels to note that some of the effects may last after the treatments are stopped.
“It’s important to note that these labeling changes are not new warnings, as characterized by other news reports. Sexual adverse events were reported in clinical trials, and this information was included in the finasteride drug labels at the time of approval,” says Stephanie Yao of the FDA Office of Public Affairs. In those clinical trials, the side effects resolved in patients who stopped using finasteride, as well as in most patients who continued therapy.
The updates are based on the FDA’s latest review of postmarketing reports of sexual dysfunction from users. The FDA reviewed 421 post-marketing reports of sexual side effects related to Propecia from 1998 to 2011. Of these, 59 cases reported adverse sexual effects that lasted longer than three months after drug discontinuation. The agency also reviewed 251 cases associated with semen quality; 13 had enough information for evaluation. For Proscar, the FDA reviewed 131 cases of erectile dysfunction and 68 cases of decreased libido from 1992 to 2010.
Finasteride labels will now warn users that Propecia’s side effects can include libido disorders, ejaculation disorders, and orgasm disorders that continue after discontinuation of the drug and that Proscar can lead to decreased libido that continues after quitting the drug. Both medications will receive a new description of reports of male infertility and poor semen quality that normalized or improved after stopping therapy.
“Despite the fact that clear causal links between finasteride (Propecia and Proscar) and sexual adverse events have not been established, the cases suggest a broader range of adverse effects than previously reported in patients taking these drugs,” the FDA said in a statement.
The FDA maintains that finasteride is safe and effective, but notified health care professionals who commonly prescribe finasteride — dermatologists, family practice professionals, internists and urologists — about the data review and warning changes.