Oct. 19 (Bloomberg) -- Pfizer Inc.’s Viagra, Eli Lilly & Co.’s Cialis and Bayer AG’s Levitra should be used in men with erectile dysfunction, while treatment with hormones such as testosterone may not help, a doctors’ group said.

There isn’t enough data to determine whether hormonal therapies improve erectile dysfunction, the American College of Physicians said in new guidelines published today in the Annals of Internal Medicine. Viagra and other drugs -- known as phosphodiesterase-5, or PDE-5, inhibitors -- have been proven effective, according to the report.

The number of men with erectile dysfunction may increase to about 322 million worldwide by 2025 from 152 million in 1995, the report said, citing advanced age, chronic diseases and depression as some causes. The report examined 191 studies published from 1966 to April 2009 evaluating the efficacy and safety of drugs such as Viagra, Cialis and Levitra, as well as the benefits of hormonal testing and treatment.

“With the aging general population, increased life expectancy and increased prevalence of diabetes and cardiovascular diseases, the health-care burden associated with erectile dysfunction is going to increase,” said Amir Qaseem, senior medical associate at the American College of Physicians and a lead author of the report, in a telephone interview today. Increased prevalence of erectile dysfunction led the group to establish guidelines for its treatment, Qaseem said.

Treatment Cost

The cost to treat erectile dysfunction in the U.S. could reach $15 billion annually if all affected men sought care, according to the report, which cited estimates from the National Health and Nutrition Examination Survey. Heart disease and stroke, the first- and third-leading causes of death in the U.S., are projected to cost more than $475 billion this year, according to the Centers for Disease Control and Prevention.

Erectile dysfunction should be evaluated and possibly treated once it has persisted for three months, the report recommended.

The physicians’ group says clinicians should start therapy for erectile dysfunction with a PDE-5 inhibitor for men who don’t have unstable heart disease and who aren’t taking nitrate medication, which are contraindications to taking the drugs. “High-quality evidence” from previous trials shows the drugs improve sexual intercourse by 69 percent, compared with 35 percent improvement in patients who took a placebo, according to the report. They improve erections as much as 89 percent, versus as much as 35 percent with placebo, the study said.

Patient Preference

Doctors should choose among the drugs based on patients’ preferences on ease of use, cost and side effects. Existing data isn’t strong enough to recommend one drug over another based on efficacy, Qaseem said. Side effects of the treatments included headache, nausea and vomiting.

The report doesn’t take a position on routine hormonal blood tests or hormonal treatment for erectile dysfunction, citing insufficient evidence to determine benefits and potential harmful effects.

“The trials were small, low-quality, and inconsistent,” Qaseem said. Hormonal therapies tested included pills, gels, creams, injections and patches, according to the report.

More research should be done on hormonal testing and treatment, Qaseem said. The higher quality of drug studies may be because more than 70 percent of the PDE-5 inhibitor trials reviewed were industry-funded, according to the report. The American College of Physicians, which publishes the Annals of Internal Medicine, funded the development of the guidelines.

Sales Figures

Viagra, New York-based Pfizer’s fifth best-selling drug, generated $1.93 billion in 2008. Cialis drew $1.45 billion last year, also the fifth best-seller for Indianapolis-based Lilly. Levitra had $341 million in 2008 sales for Germany-based Bayer, and is sold in the U.S. by Kenilworth, New Jersey-based Schering-Plough Corp. and London-based GlaxoSmithKline Plc.

Drugmakers developing testosterone treatments include Endo Pharmaceuticals Holdings Inc., based in Chadds Ford, Pennsylvania. The company is seeking to sell Fortesta, its gel containing 2 percent testosterone, in the U.S. for men with low levels of the hormone, a condition called hypogonadism. Endo received a letter today from the U.S. Food and Drug Administration seeking more details on the therapy, the company said in a statement.

To contact the reporter on this story: Meg Tirrell in New York at mtirrell@bloomberg.net.

Last Updated: October 19, 2009 17:00 EDT