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Propecia and Erectile Dysfunction

Propecia is the brand name of a drug (finasteride) manufactured by Merck to treat male pattern baldness. Finasteride, also available in a larger dosage under the brand-name Proscar, is used to treat prostate enlargement. Propecia was approved by the FDA (Food and Drug Administration) in 1997 after clinical trials demonstrated success in stimulating and preserving an increase in hair count.

By 2010, Propecia was established as a blockbuster drug, reportedly bringing in around half a billion dollars a year in revenue. The warning label downplayed the risk of Propecia sexual side effects, claiming that “a small number of men had sexual side effects, with each occurring in less than 2% of men.” Along with Propecia erectile dysfunction (ED), the label listed the possibility of side effects such as impotencediminished libido and reduced semen volume. Merck’s label assured users that all of these sexual problems were not only incredibly rare, but would also disappear once men stopped using the drug.

Escalating reports from men about sexual problems — including permanent side effects lasting long after use of the drug is discontinued—prompted a number of post-marketing studies, whose concerning results have compelled Merck to increase warnings on the drug’s labels.

Sexual side effects from Propecia

Propecia is a type II 5α-reductase inhibitor; it works by inhibiting an enzyme in the body that converts testosterone to dihydrotestosterone. Interfering with this conversion process has slowed the rate of hair loss in many men, but in some it has also caused impotence and related Propecia sexual side effects, as well as cognitive complications, including depression, brain fog, and memory loss.

Erectile dysfunction (ED) is a form of sexual dysfunction in which a man repeatedly struggles to get or sustain an erection. Though ED is a physical condition, it can in some cases result from psychological, emotional, or other sources. Finasteride use is just one of many factors associated with erectile dysfunction.

Other common causes of erectile dysfunction include:

  • Prescribed use of SSRI antidepressants (such as Zoloft, Paxil, and Prozac)
  • Smoking / nicotine
  • Neurological disorders
  • Cardiovascular disease
  • Hormonal insufficiency
  • Stress and/or performance anxiety
  • Aging
  • Kidney failure
  • Diabetes
  • Obesity
  • Anti-inflammatory drugs (non-steroidal)
  • Surgical complications

Diagnosing ED

There are a number of diagnostic tests used to determine whether the cause of erectile dysfunction is physiological or psychological in nature. Just because a patient takes Propecia, and at the same time experiences erectile dysfunction, does not necessarily mean that the two are causally related.

Doctors may use any of a number of diagnostic tests to pinpoint the problems causing ED:

  • Snap Gauge Test: Also known as a nocturnal penile tumescence test (NPT), this method involves fastening a plastic ring device around the patient’s penis before he goes to sleep at night. The plastic ring is designed to snap off if the pressure of an erection is exerted against it. The majority of men experience anywhere from 3 to 5 full erections during deep R.E.M. sleep. As a result, any patient who experiences erections while sleeping can likely not point to a physical cause for his erectile dysfunction—in other words, the ED is unlikely to be the result of Propecia side effects.
  • Rigiscan: Another NPT test. Rigiscan is an electronic monitoring device that records the frequency of the patient’s erections and calculates their rigidity and tumescence.
  • Penile Brachial Index (PBI): A Doppler ultrasound machine measures PBI scores by recording the speed and direction of blood flow in the penis. Sometimes the PBI test is performed after the penis is injected with a vasoactive drug to stimulate an erection.
  • Bulbocavernosus reflex test: A manual test that analyzes blood flow and possible calcification of erectile tissue. The head of the penis (glans) is squeezed by the doctor, while the response time of the contraction of the anus is observed to determine if nerve function is normal.
  • MRA (magnetic resonance angiography): Similar to MRIs, MRAs utilize magnetic fields and radio waves to create comprehensive images of blood vessels in the penis.

Treatment for erectile dysfunction

Though an untold number of scientifically unfounded impotence cures and virility tonics have been peddled to the public over the centuries, there are a variety of established medical treatments for erectile dysfunction.

Treatments for ED vary depending on the underlying problem, but may include:

  • Psychotherapy / counseling: Used to treat underlying psychological causes of ED, such as anxiety or stress.
  • Medication: Can be taken orally or in rarer cases injected directly into the penis. The most popular are phosphodiesterase (PDE) type 5 inhibitors. These include Viagra (sildenafil), Cialis (tadalafil), and Levitra (vardenafil hydrochloride). Usually taken an hour or so before sexual activity commences, PDE-5 inhibitors relax muscles in the penis to improve blood flow and enable erections.
  • Injections: A drug called alprostadil may be injected directly into the side of the penis, or inserted into the urethra in pellet form, to improve blood flow.
  • Penis pump: A vacuum device may be used to manually suction blood into the penis, while an elastic ring can be placed around the base of the penis after an erection is achieved, to delay the loss of blood.

Propecia sexual problems: clinical studies & FDA warnings

A number of studies have sought to investigate Propecia impotence and other sexual problems linked to the hair loss drug.

  • 2006: The Swedish Medical Products Agency began investigating reports of permanent Propecia side effects, including sexual problems that persisted long after use of the drug was discontinued.
  • 2008: Merck revised the Propecia product label in Sweden to reflect the potential for persistent erectile dysfunction, but deliberately chose not make an equivalent change to the label in the United States.
  • 2009: A study by the United Kingdom’s Medical and Healthcare Products Regulatory Agency (MHRA) focused on the risk of male breast cancer with the use of finasteride, but also noted that patients in the study had reported persistent Propecia erectile dysfunction and other forms of sexual dysfunction.
  • 2011: A George Washington University study found that 96% of men who reported experiencing Propecia sexual side effects continued to suffer from sexual dysfunction at least one year after quitting the drug. Out of a test group of 54 males, 86% reported side effects such as Propecia impotence & ED, low libido, diminished sex drive, genital numbness, reduced volume and quality of ejaculate, and inability to achieve orgasm. Lead researcher Dr. Michael Irwig concluded in the Journal of Sexual Medicine that, “In most men who developed persistent sexual side effects (more than 3 months) despite the discontinuation of finasteride, the sexual dysfunction continued for many months or years.”

Dr. Irwig stated to ABC News that, “Our findings make me suspicious that this drug may have done permanent damage to these men.”

FDA strengthens Propecia warning label

In June 2011, Merck made a slight change to the product information packet, indicating that some patients had experienced erectile dysfunction that persisted “after discontinuation of treatment.” In April of 2012, however, the FDA ordered Merck to strengthen the Propecia warning label and expand the list of sexual adverse events. The FDA also required Merck to indicate that some Propecia sexual side effects were reported to endure after patients stopped taking the drug. The FDA reviewed 421 reports of sexual dysfunction from 1998 to 2011 that were related to Propecia. Of these, 59 cases reported the condition lasted longer than three months after drug discontinuation.

New forms of sexual dysfunction added to the Propecia label include “libido disorders, ejaculation disorders, and orgasm disorders that continued after discontinuation of the drug.”

The FDA alerted consumers and the medical community that, “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.”

Merck responded to the FDA’s label changes, stating in a press release that: “Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.”