Libido-lifting nasal spray could help women with sexual desire disorder

by: SHERYL UBELACKER
While men have such drugs as Viagra to give them a boost in the bedroom, there's really nothing on pharmacists' shelves for sexual disorders that commonly affect women. So a drug that makes female rats rev up their "Do it to me now" signals is offering hope for their human counterparts.
The drug, a synthetic hormone called PT-141, appears to work within the brain to fan the flames of sexual desire, says James Pfaus of Concordia University in Montreal, who began testing PT-141 on laboratory rats in 2001.
An estimated 30 per cent of North American and European women suffer sexual desire disorders, which include poor libido, low ability to become aroused, inability to have an orgasm and painful intercourse.
"Right now, there's nothing in the arsenal for women to treat a desire disorder," Pfaus, an associate professor of psychology and neuroscience, said in an interview from Montreal on Monday. "There's no drug out there other than estrogen, which carries with it - especially for postmenopausal women - its own problems. (Those include increased risks of certain cancers.)
"I think this is the first salvo in our efforts to be able to treat female desire disorder."
Pfaus's research team began testing PT-141 on female rats at the behest of Palatin Technologies, a New Jersey-based pharmaceutical company which hopes to get FDA approval for PT-141 in a nasal spray to help men with erectile dysfunction and women with sexual desire disorders.
Female rats injected with PT-141, which mimics a naturally occurring hormone in the body, increased solicitation behaviour around males, which includes hopping and darting, as well as running away, then coming back - a female rat's way of sending flirtatious "come-hither" messages, he said.
"Think of solicitation as an indication that the animal wants sex - now," said Pfaus, whose study appears this week in the Proceedings of the National Academy of Sciences.
"Obviously humans are going to do it a little bit differently. We may express it in our own very typically human way, but the neurochemical underpinning of that is probably very similar between the species."
Annette Shadiack, a director of research for Palatin, said from Cranberry, N.J., that unlike "vasodilators" such as Viagra - which increase blood flow to the genital area - PT-141 acts on centres in the brain to jump-start desire, which in turn can cause increased genital blood flow in men and women alike.
PT-141 could work for men with erectile dysfunction who can't take the Viagra-like drugs, either because they don't work for them or because of other health conditions such as hypertension, Shadiack said. The vasodilators can cause a drop in blood pressure, which could be dangerous in a man taking blood pressure-lowering medications, she added.
Palatin Technologies has done preliminary studies of PT-141 in women and more advanced studies in men. They hope to have approval for a nasal spray - so far unnamed - for men by 2007, she said. One for women could follow within the next few years.
The desire-enhancing spray did pose one potential problem for the Concordia researchers, which Pfaus said they included in their investigations: "What's to stop people from doing the old Spanish fly thing and putting PT-141 inside somebody's Dristan? Would the drug make animals like something that they don't like, or make them like more something that they would typically like?
"As it turned out, it didn't have any effect," Pfaus said. "So nobody's going to put this in the air supply at a club and hope they're going to have their proverbial orgy, because it's not going to happen.
"The end result here is the drug doesn't make you do something you don't want to do. When the circumstances are appropriate, it makes you want it more."
Still, Shadiack warned that PT-141 is not intended "as a magic bullet" to fix female sexual dysfunction, which she called an often complex disorder.
"We're hoping that PT-141 will be part of an overall therapy for these women to help break the vicious cycle . . . that would help put a woman on a more normal track."