Drugs such as finasteride (Propecia) and dutasteride (Avodart) may produce significant side effects in some people, including loss of libido, erectile dysfunction (ED), ejaculatory dysfunction and potential depression, according to a recent study.

These drugs belong to a group called 5a-reductase inhibitors (5a-RIs). They have been approved to treat lower urinary tract symptoms due to enlarged prostate, and have shown marked efficacy, the researchers said in a statement released today by Boston University Medical Center. They also may prevent hair loss , and finasteride is approved to treat this condition as well.

However, the new findings suggest that extreme caution should be exercised prior to prescribing 5a-RIs to patients for hair growth or for urinary tract symptoms, the researchers said.

Although the adverse side effects of these drugs are thought to be minimal, the magnitude of adverse effects on sexual function, gynecomastia (the development of breast tissue in men), depression, and quality of life remains ill-defined, the researchers said.

To determine the potential extent of this problem, the researchers examined data from previous clinical studies. They found that in a subset of men, prolonged adverse effects on sexual function such as erectile dysfunction and diminished libido were reported, raising the possibility of a causal relationship.

The researchers said the adverse side effects of 5a-RIs on sexual function, gynecomastia and overall health have received minimal attention. However, in some patients, these side effects are persistent with regard to sexual function, and have taken an emotional toll.

"The potential widespread use of 5a-RIs for treatment of BPH [Benign Prostatic Hyperplasia, or an enlarged prostate], prostate cancer and male pattern hair loss may produce undesirable adverse side effects on overall health and in particular, vascular health and sexual function in a subgroup of susceptible patients, " said study researcher Abdulmaged M. Traish, a professor of biochemistry and professor of urology at the medical center. "Furthermore, treatment of hair loss, a benign condition, with 5a-RIs may produce persistent side effects in a number of young patients."

"Honest and open discussion with patients to educate them on these serious issues must be pursued prior to commencing therapy because, in some patients, these adverse effects are persistent and may be prolonged and patients do not recover well after discontinuation from drug use," Traish said.

The researchers said additional clinical and preclinical studies are warranted to determine why some of these adverse effects persist in some people.

The findings are currently published on-line in Journal of Sexual Medicine.