August 31st, 2005

"FDA panel recommends more Intrinsa studies needed prior to approval"

Intrinsa is a medical patch designed to deliver small doses of testosterone through a woman’s skin to boost the level of male sex hormone in her bloodstream. The medication is intended to reenergize stalled sex drives in women, but women have proven more complex than men for drug companies trying to come up with a female version of Viagra.

All women produce testosterone, but most women will experience testosterone levels decrease with age, and surgical removal of the ovaries will cause a drop off as well. Hypoactive sexual desire disorder, of HSDD, was not formally recognized in medicine until 1999, and according to some estimates, the condition affects about 11 million American women.

Unlike men, however, women’s sex drives are more deeply affected by mood, self-esteem and relationship issues, and so far, drug companies have been unable to create a pill to improve libido. More than a year after an application for Intrinsa was sent to the FDA, the drug still has concerning safety issues, according to the agency’s advisory panel.

Proponents of the patch, including hysterectomy support groups and some gynecologists, believe the product’s bad timing influenced FDA review. After the recall of a popular painkiller Vioxx last September, there has been a much greater focus on drug safety. Other safety experts believe the patch’s failure to so far receive approval is not because of increased scrutiny but because there are very serious safety risks that must be better understood.

The FDA advisory panel recommended against the approval of Intrinsa until the safety of long-term use was better tested and understood. Though the agency does not have to accept its’ panel’s recommendations, it usually does. Members of the panel suggested that nothing short of a five-year study involving thousands of women would ease their concerns.

The panel was concerned with the immediate popularity approval of the drug could attract. As observed by drug recalls in the past, it can be years before actual side effect risks of a new drug are fully understood. Should millions of women begin using Intrinsa before cancer risks are more thoroughly assessed, the outcome could be devastating.

Many doctors adopted hormone replacement therapy as a standard treatment, but it was not until 2004 that serious side effects were observed. By then, the hormone therapy had been accepted on a widespread scale, but a study that had followed thousands of women for five years revealed the risks of boosting estrogen and progestin levels as a treatment for menopausal symptoms.

Once dubbed “the female Viagra,” two new studies in recent months concerning Intrinsa have fueled the debate regarding the safety vs. risk of the patch. Last week, the Archives of Internal Medicine published a study finding women who used the patch for 24 weeks reported, on average, a 67 percent increase in their sexual desire, compared with a 48 percent increase in desire reported by women taking a placebo.

In addition, the study also reported the number of “satisfying sexual encounters” had increased from an average of three per month to five, a slightly higher number than what was reported from placebo users. Researchers at Baylor College of Medicine in Texas also reported similar findings in May.

The findings were minimal, however, considering the potentially fatal risks the patch could carry, according to critics of Intrinsa. A blow to the drug’s makers, Procter & Gamble is hoping the agency will overstep the panel’s recommendations and consider approval anyway.