U.S. regulatory reviewers Wednesday said it was unclear if Procter & Gamble Co.’s testosterone patch for boosting sexual desire in women produces meaningful benefit, or is safe over the long term.
The Food and Drug Administration reviewers will ask an advisory panel Thursday if more safety studies are needed before the patch could be approved, according to a summary posted on the FDA’s Web site.
Several companies are searching for a “female Viagra,” a counterpart to Pfizer Inc.’s blockbuster male impotence treatment that could help women with sexual problems. Analysts say the market for women could top $1 billion annually.
P&G’s patch, called Intrinsa, is being developed with Watson Pharmaceuticals Inc. The patch delivers testosterone, a hormone involved in sex drive, through the skin.
Results may not be 'clinically meaningful'
Two studies showed women treated with Intrinsa had about one more satisfying sexual experience over a four-week period than women given a dummy patch, the FDA reviewers said.
“It is not clear that the differences are clinically meaningful,” said the reviewers' memo.
Long-term safety of testosterone therapy is a concern in light of findings that other hormones raised the risks of cardiovascular problems and breast cancer, the FDA reviewers said.
“It is unknown whether the addition of a different hormone, testosterone, might have similar and unanticipated adverse effects,” the memo said.
In clinical trials, Intrinsa therapy was combined with the hormone estrogen.
FDA staff will ask the advisory panel “whether there are unanswered safety questions that should be further assessed pre-approval in appropriately sized randomized trials of adequate duration, or whether these questions can be appropriately answered post-approval,” the memo said.
Long-term safety unknown
“Only a very small number of subjects” have been treated more than one year, the FDA reviewers said.
P&G spokeswoman Elaine Plummer said the questions raised by the FDA staff were “what we would expect to be asked and they will be addressed” at the advisory panel meeting.
Panels sometimes, but not always, concur with FDA staff reviews when making recommendations on approvals. The FDA makes the final decision and usually takes the advice of the panels.
P&G is seeking approval to market Intrinsa to women who have had their ovaries removed and are bothered by a lack of sexual desire. In 2005, 2 million women may fall into that category, P&G estimated. The company has not given sales estimates for Intrinsa.
Potential rivals are being developed by Vivus Inc., which is studying a testosterone spray, and Biosante Pharmaceuticals Inc., maker of an experimental testosterone gel, as well as other companies.