The baldness drug finasteride has left some young, otherwise healthy men with persistent impotence, diminished sex drive and depression long after they've stopped taking it, according to emerging medical studies and patient reports, as well as lawsuits filed in the United States and Canada.
Millions of men have taken 5-milligram finasteride tablets since the U.S. Food and Drug Administration in 1992 approved Merck and Co. Inc.'s Proscar for non-cancerous enlargement of the prostate gland. Millions more have taken finasteride since FDA's 1997 approval of Propecia, Merck's lower-dose (1 mg) formulation for male-pattern baldness, which affects about half of all men.
In 2002, the FDA approved GlaxoSmithKline's closely related drug dutasteride (Avodart) to shrink enlarged prostates, further expanding the market for name-brand and generic 5-alpha reductase inhibitors. The drugs block an enzyme that converts the male sex hormone testosterone to dihydrotestosterone, which is toxic to hair follicles, but important for healthy sexual functioning.
Although the generally rare sexual side effects of finasteride and dutasteride have been mentioned at urology meetings, information about potentially irreversible consequences hasn't yet reached the larger community of prescribing physicians, such as dermatologists and primary care doctors -- or their patients, said researcher Abdulmaged M. Traish, a professor of biochemistry and urology at Boston University School of Medicine.
For an article published in the March issue of the Journal of Sexual Medicine, Traish and a B.U. colleague, along with Dr. Andrew T. Guay of the Center for Sexual Function/Endocrinology at the Lahey Clinic, Northshore, in Peabody, Mass.; a reproductive medicine specialist from Muenster, Germany; and an ob-gyn from Stavanger, Norway; reviewed available scientific studies on the adverse effects of finasteride and dutasteride. Although the overall percentage of study subjects reporting sexual side effects was small, ranging from 5 percent to 23 percent, Traish said side effects never went away for half of them.
"We found out that we're really ignoring the important part, especially those in whom the problem becomes persistent," Traish said in an interview Wednesday. "That's the group that everybody forgot. We have to worry about the consequences for people who are going to suffer -- even after they discontinue the drug -- from continuous loss of libido and potential depression." Other observed effects included reduced ejaculation and smaller volume of semen.
Traish said his paper was meant to encourage doctors to "sit down and discuss this openly, candidly and honestly" with patients, and to encourage patients to consider the possibility, small as it might be, that they could potentially sacrifice a meaningful sexual life "to improve my hairline and look good in the bar while I'm watching football."
He said he gets "a number of e-mails every week from individuals who say 'this is my life story.'"
Neither patients nor physicians have received adequate warning about the possible sexual side effects associated with finasteride for hair loss, according to Alan C. Milstein, a Moorestown, N.J., attorney who filed a federal lawsuit Feb. 2 against Merck, of Whitehouse Station, N.J., on behalf of two clients whose problems continued even after they stopped taking the medication.
Across the border in Canada, Michael Miller, a Vancouver resident in his early 20s, filed a class-action lawsuit against Merck Frosst Canada Jan. 24 on behalf of countrymen who have suffered continuing sexual dysfunction after using Propecia or Proscar.
In a statement released by the law firm handling the case, Miller said that after a month of use, "I lost my interest in sex and I felt anxious in social situations for no particular reason."
Although he stopped taking Proscar for his thinning hair, "my sexual functioning has not recovered," he said. "I have seen specialists and have tried treatments, but nothing has worked."
Miller's attorney, David Klein, also of Vancouver, said that several European countries, including Sweden, Italy and Great Britain, have changed their labels "to include a warning of persistent erectile dysfunction after discontinuation of this drug but this change has not been made on the Canadian product labels."
He said there were more than 80 other Canadian men who expressed interest in participating in the class-action suit.
In October, Merck revised its Canadian label to add depression to the list of Propecia's side effects. The U.S. label was similarly revised in December. Merck says that in clinical trials fewer than 2 percent of men had sexual side effects and most of those resolved with time.
In recent years, patient websites and online forums such as Propeciahelp.com have amassed stories from men who reported that they lost their sex drive and ability to perform while pursuing a thicker head of hair. Some doctors have issued online warnings as well.
In an Oct. 17, 2010, blog posting, Dr. Andrew Rynne, a general practitioner who runs a sexual health clinic outside Dublin, Ireland, said he and "hundreds of other doctors" have observed that the side effects "do not always go away when you stop taking Propecia."
Some patients at his County Kildare clinic "continue to suffer from sexual anaesthesia," in which "all sexual pleasure and feelings have been obliterated for all time."
Dr. Michael Irwig, an endocrinologist at George Washington University, interviewed 100 healthy men, aged 21 to 46, in the past year who took finasteride for hair loss and reported sexual side effects or depression after they stopped the drug. He tracked down the men, half of whom live overseas, through the Propeciahelp.com Web site, which has been visited by more than 1,700 men with problems following finasteride use.
After excluding potential interview subjects who had a medical history of sexual dysfunction, psychiatric issues or use of prescription medicines before taking finasteride, he submitted findings for about 71 finasteride users, including their scores on a standardized measure of sexual dysfunction, to the Journal of Sexual Medicine, which will publish them Friday.
Irwig said he has seen men "who have actually been suicidal; some who have lost their jobs" because of psychological and physiological fallout after using the medication. "I had one guy in his early 20s fly all the way from Australia, who is that desperate," he said.
Irwig said there was "strong evidence" that finasteride interferes with hormones in the brain, called neurosteroids, which in turn alter levels of important chemicals called neurotransmitters that affect mood and thinking, among other critical functions.
Irwig said he was surprised at the dearth of published material, given that finasteride has been around for 10 years and "there have been guys who have had persistent side effects for 5 and 10 years already."
Although reversible effects have been well-known, he attributed the scant knowledge about persistent effects to their relative absence in medical literature until now. "A guy will go to a doctor and will say, 'I think this medicine has caused ED [erectile dysfunction] that hasn't gone away," he said.
But because the doctor hasn't been exposed to such cases, he or she will tell the patient it's supposed to go away and refer the patient to a psychiatrist.
"This will finally give evidence that this exists and will make this legitimate and doctors won't blow these patients off," Irwig said. "And now, most importantly in terms of prevention, we can have an informed discussion; men contemplating using this medicine and doctors prescribing it."