WASHINGTON -- The Food and Drug Administration said Friday it is reviewing the safety of popular testosterone drugs for men in light of recent studies suggesting they can increase the risk of heart attack, stroke and death.
A study published earlier this week suggested testosterone therapy could double the risk of those problems in men older than 65. Another study published in November found that the hormone increased the risk by 30 percent.
The FDA said it is evaluating information from those studies and others but hasn't yet reached any conclusion.
The investigation comes amid an advertising blitz for testosterone gels, patches and injections marketed for low sex drive, fatigue and other age-related ailments in men.
U.S. prescriptions for testosterone have increased more than five-fold in recent years, with sales over $1.6 billion.
Testosterone injections have long been used for men with hypogonadism, a disorder defined by low testosterone caused by injury or infection to the reproductive organs.
But the latest marketing push by drugmakers is for easy-to-use gels and patches that are aimed at a much broader population of otherwise healthy older men with low levels of testosterone, the male hormone that begins to decline in the body after age 40.
Drugmakers and many doctors claim testosterone therapy can reverse some unpleasant of the signs of aging -- ranging from insomnia to erectile dysfunction. Those claims are mostly based on short-term studies.
The National Institute on Aging is currently conducting a long-term, 800-man trial to definitively answer whether testosterone therapy improves walking ability, sexual function, energy, memory and blood cell count in men 65 years and older.
Meanwhile the market for testosterone replacements has grown increasingly crowded.
The top-selling product in the field is Abbvie's Androgel, which is applied to the shoulders and arms. Watson Pharmaceuticals markets the Androderm patch, which slowly releases testosterone into the bloodstream. Fortesta is another testosterone gel from Endo Pharmaceuticals, and Eli Lilly's Axiron is an underarm gel that rolls on like deodorant.