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© AFP/File Filippo MonteforteApril 17, 2009, (Sawf News) - One need not live with male sexual dysfunction anymore thanks to the treatment options abound. But the same does not hold true for treating female sexual disorders (FSD), a complex and multi-layered problem.
A team of researchers has undertaken a new approach in the lab to understanding how and why FSD occurs in general, and the impact of the vasculature (the vessels in the body that carry blood, such as arteries and veins) in particular. The findings of their latest study suggest that the drugs that help men may some day also address some forms of female sexual dysfunction.
The study, Phosphodiesterase Type 5 Inhibitors Relax Female Rat Internal Pudendal Arteries: Potential Treatment for Female Sexual Dysfunction, was conducted by Kyan J. Allahdadi, Rita C. Tostes, and R. Clinton Webb, all of the Medical College of Georgia, Augusta, GA.
The Study
New evidence suggests that female sexual dysfunction may be, in part, the result of inadequate supply of blood to the female genitals and may be addressed with erectile dysfunction drugs. Originally developed as therapy for hypertension, these drugs work by dilating blood vessels sufficiently to produce erections in males. These drugs have not been fully explored in females.
The researchers used an animal model and compared the effects of three drugs used for erectile dysfunction (the phosphodiesterase 5 inhibitors (PDE5I, such as Viagra® (sildenafil); Levitra® (vardenafil); and Cialis® (tadalafil)). PDE5I was used and analyzed in female and male rat internal pudendal arteries. The internal pudendal artery supplies blood to the penis in men and to the vagina and clitoris in women. Arterial segments were contracted with phenylephrine then submitted to increasing concentrations of one of the PDE5 inhibitors.
The internal pudendal arteries of both male and female rats (n=10 to12) were measured for constriction/dilation.
The researchers found the following results:
Percent maximum relaxation (Top), effective concentration to relax 50% (Bottom)
Sildenafil
Female Arteries Concentration/Dependency: 105.00±7.73; 6.60±1.7 Male Arteries Concentration/Dependency: 103±0.9; 5.67±0.9
Vardenafil
Female Arteries Concentration/Dependency: 115.6±11.63; 6.67±0.24 Male Arteries Concentration/Dependency: 105.1±89.88; 6.4±0.23
Tadalafil
Female Arteries Concentration/Dependency: 80.13±5.39; 7.98±0.24 Male Arteries Concentration/Dependency: 102.3±23.65; 5.4±0.23
* All the PDE5I inhibitors relaxed both female and male rat internal pudendal arteries, indicating that these arteries from both female and male rats are sensitive to PDE5I. However, female internal pudendal arteries were more sensitive to sildenafil at a lower concentration, which suggests it may be effective at a lower dose than vardenafil.
* Male internal pudendal arteries reacted more effectively to vardenafil. Female internal pudendal arteries also reacted differently in comparison to the male arteries in that they demonstrated an oscillatory behavior by both dilating and contracting, suggesting that PDE5I may have a different mechanism of action in females.
Conclusions
According to Dr. Allahdadi, “PDE5I may be useful in the treatment of female sexual dysfunction caused by inadequate blood supply through the internal pudendal artery. The significant difference in how male and female pudendal arteries react to PDE5 inhibitors merits further study.”
The study team is currently exploring the different relaxation profile observed between female and male rat internal pudendal arteries as well as functional abnormalities in internal pudendal arteries from diabetic rats.
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