Friday, April 17, 2009

Male impotence drugs may help women

Male impotence drugs may deserve a second look in women

New studies indicate the three drugs used to treat male impotence also appear to work in females, albeit a little differently, and should give the scientific community pause to take a second look at their potential in the 40 percent of women who report sexual dysfunction, researchers say.

In one of the first studies of the effect of phosphodiesterase Type 5 inhibitors - Viagra®, Levitra® and Cialis® - on the pudendal arteries that supply the penis, vagina and clitoris the blood needed to produce a satisfying sexual experience, Medical College of Georgia researchers showed the drugs relax the artery in male and female rats.

"It shows the drugs need to be investigated more for women and small alterations could make these compounds more effective for women living with these disorders," says Dr. Kyan J. Allahdadi, postdoctoral fellow in physiology at MCG. He's presenting the findings during the 122nd Annual Meeting of the American Physiological Society held in New Orleans April 18-22 as part of the Experimental Biology 2009 scientific conference.

Although there was talk years ago of a pink pill for women to parallel the blue Viagra for men, early clinical trials found essentially no response in women.

MCG researchers decided to look again, first giving a drug to constrict the internal pudendal arteries in male and female rats – as they would be in a non-erect state – then giving doses of each impotency drug to see the impact. The arteries from male rats displayed a relatively standard concentration-dependent relaxation – the more drug they got, the more they relaxed - while in females arteries, there was an initial relaxation then an odd oscillation between relaxation and contraction with subsequent dosing.

While they don't fully understand the swing, the unique female response likely provides more evidence that sexual function is more complex in females, says Dr. R. Clinton Webb, chair of the MCG Department of Physiology and a study author. Scientists define female sexual dysfunction as a multifaceted disorder that includes anatomical, psychological, physiological and social-interpersonal aspects.

MCG researchers have shown part of that complexity may be the smooth muscle cells in the internal pudendal arteries of females communicate, agreeing to contract and relax, while male smooth muscle cells make independent decisions to just relax.

They found one other distinction: females were more sensitive to Viagra®, or sildenafil, while males were most sensitive to Levitra®, or vardenafil.

Previous studies on the effectiveness of these drugs focused on the cavernosal tissue, or penis. The internal pudendal artery actually feeds the penile artery which is buried deep in the penis where numerous caverns enable it to be flaccid when not engorged with blood. Physical stimulation of the area causes the tissue, endothelial cells and nerves to release nitric oxide, a powerful dilator of blood vessels. The system works pretty much the same way in the vagina and clitoris.

"If you have too much constriction or not enough relaxation to allow blood to go through the internal pudendal artery, you are not going to get the net effect of an erection," Dr. Allahdadi says. "That is why we wanted to begin to characterize what was going on in this blood vessel."

Perhaps as importantly, the MCG scientists and others are beginning to believe sexual dysfunction provides an early, or at least visible, clue of vascular disease. Vascular problems, that can result from diabetes, hypertension, high cholesterol and the like, are a major cause of sexual dysfunction in men and women. "You don't feel atherosclerosis but you know darn well if you are not getting an erection," Dr. Webb says. In fact, the MCG scientists are beginning to look at animal models of disease states, such as diabetes, to see what it does to these internal pudendal arteries.

"What we have seen preliminarily is there is big difference in responsiveness in these arteries. The diabetic pudendal arteries are much more sensitive to contraction," Dr. Allahdadi says. They will look at how drugs like Viagra impact that contraction in the days ahead.

In fact MCG scientists suspect one reason that many of the women participants in previous studies of Viagra did not seem to respond is because they did not have vascular problems that could have been circumvented by a drug that relaxes arteries so blood can enter. In men with a healthy vasculature, the drugs likely would still produce a longer erection.

Dr. Rita C. Tostes, associate professor in the MCG Department of Physiology, is a co-author who contributed to the design and analysis of the study.

Thursday, April 9, 2009

Premature ejaculation spray

Premature ejaculation spray enables men to last 6 times longer after penetration

Average orgasm delayed from 0.6 minutes to 3.8 minutes

Men with premature ejaculation who used a topical spray five minutes before intercourse were able to delay their orgasm six times longer than normal, according to a study in the April issue of BJU International.

Three hundred men with clinically diagnosed lifelong premature ejaculation (PE) from 31 centres in the UK, Czech Republic, Hungary and Poland, were randomised into two groups. Two hundred used the PSD502 spray, which contains 7.5mg of lidocaine and 2.5mg of prilocaine, and 100 used a placebo spray with no active ingredients.

Every time they had intercourse during the three-month study period, each couple measured the time from vaginal penetration to ejaculation with a stopwatch. The men were asked to abstain from sexual activity or masturbation for 24 hours before each recorded encounter.

The time from penetration to ejaculation increased from an average of 0.6 minutes to 3.8 minutes in the medicated group and to just 1.1 minutes in the placebo group.

When these figures were adjusted to take account of any variations between the two groups, these showed that the treatment group were able to last 6.3 times longer after penetration when they used the spray. The placebo group lasted 1.7 times longer.

"Premature ejaculation can be a very distressing condition for men and can cause distress, frustration and make them avoid sexual intimacy" says lead researcher Professor W Wallace Dinsmore from the Royal Victoria Hospital, Belfast, UK.

The research team used the evidence-based definition of lifelong PE developed by the International Society for Sexual Medicine to select their study subjects. This states that ejaculation occurs within about one minute of vaginal penetration in the majority of encounters.

"Because this definition was only launched in 2008, studies have yet to determine the prevalence of lifelong PE in the male population" says Professor Dinsmore. "But previous research suggests that as many as 40% of men will experience premature ejaculation at some time in their lives."

The 300 men who took part in the phase three, multicentre, double-blind, randomised study had an average age of 35. The majority had used other treatments before, the most common being oral antidepressants.

After three months of treatment the researchers reported that:

90% of the men in the treatment group were able to delay ejaculation for more than one minute following vaginal penetration, compared with 54% in the placebo group.
74% of men in the treatment group managed to last more than two minutes before ejaculation, compared with 22% in the placebo group.
62% of men in the treatment group said their orgasms were 'good' or 'very good' after three months, compared with 20% before the study started. The figures for the placebo group were slightly lower at the end (19%) than at the start (21%).
66% of men in the treatment group said the medication was 'good' or 'excellent' compared with 15% in the placebo group.

A significantly higher percentage of the patients and partners in the treatment group reported improvements when it came to perceived control, personal distress, satisfaction with sexual intercourse and interpersonal difficulties.

There were no serious adverse events reported during the study. Adverse treatment-related reactions were reported by five men and six women from the treatment group and one man from the placebo group. The most common problems were loss of erection and a burning sensation in the vagina.

"Our study shows that when the PSD502 spray was applied to the man's penis five minutes before intercourse it improved both sexual performance and sexual satisfaction, which are key factors in treating premature ejaculation" says Professor Dinsmore.

"It was well tolerated by both patients and their partners, with no systemic side effects and a low incidence of localised effects and was rated favourably by the majority of users.

"We believe that this shows that PSD502 offers significant advantages over other therapies being developed for the treatment of premature ejaculation."