An "enhanced" version of the herb yohimbine increases vaginal blood flow in postmenopausal women and may be a treatment option for female sexual arousal disorder, researchers from the University of Texas at Austin, in association with NitroMed, Inc., announced Saturday at the 26th International Academy of Sex Research Conference in Paris, France.
　　Nitric oxide relaxes smooth muscle, such as that found in the walls of arteries. Relaxing the arterial wall can lead to increased blood flow in different parts of the body. Combining nitric oxide with the herb helps to target the action of the agent in the body.
　　"This enhanced herb called NMI-870 works by dilating the blood vessels in women's genitalia while also facilitating blood flow into the region," psychologist Dr. Cindy Meston told Reuters Health in an interview after the meeting.
　　Meston's team conducted a study of NMI-870 and compared it with regular yohimbine and with a placebo, that is, an inactive agent used for comparison purposes. In the study, 24 postmenopausal women who met psychiatric criteria for female sexual arousal disorder were tested to measure variations in their vaginal blood flow occurring in response to the medication. After an initial baseline visit, the women returned to the lab on three occasions for study participation. During these visits, measurements were again taken, the women received one of the three study pills, and then their vaginal responses were evaluated at 30-, 60-, and 90-minute intervals.
　　"We found that the drug was most effective after 60 minutes,"Meston said,"The litmus test will be measuring the effects of the medication in an actual sexual situation. Our work was done in the lab. We can show that NMI-870 works on the vaginal responses. Now we would like to determine if it increases a woman's sexual satisfaction."
　　To date, NMI-870 has only been tested in postmenopausal women who have difficulty becoming aroused. Meston hopes testing will be expanded to other ages. She is hopeful that NMI-870 will be useful in other age groups.
　　Surveys suggest that female sexual arousal disorder affects 20% to 25% of women (an estimated 30 to 45 million in the US). "Research on female sexuality has lagged about three decades behind male research. Most of the models we have to work from are based on men," Meston commented. ``That makes this study very exciting. We are not only testing a drug but we are also defining female sexuality."
　　NitroMed, Inc. has been developing nitric oxide-enhanced medications since 1997. Researchers have developed a similar version of nitric oxide-enhanced yohimbine for men with erectile dysfunction that is also in clinical trials.