Men with multiple sclerosis (MS) often face several sexual complications. But erectile dysfunction (ED) is, by far, the most common, according to experts.1 There are various therapies available for men with sexual difficulties, such as sildenafil (Viagra), injectable medications such as papaverine and phentolamine that boost blood flow to the penis. Other therapies include inflatable devices and implants.1
Boosting Bloodflow
Now a new study suggests that Viagra is effective for men with MS whose main sexual complication is erectile dysfunction.2
To test the safety and efficacy of Viagra for these patients, Clare Fowler, MD, in the department of Uro-Neurology at The National Hospital for Neurology and Neurosurgery in London and her colleagues recruited 217 men diagnosed with MS and ED for a double-blind, randomized clinical trial.
The effectiveness and safety of the medication was analyzed, as well as any changes in each man's quality of life after using the medication. Of the 217 patients recruited, 104 were selected at random to receive 25 to 100 mg doses of Viagra, whereas the remaining 113 were randomly selected to receive a non-therapeutic placebo, both for a total of 12 weeks.
Each patient was then given a questionnaire to answer over the course of the study about their ability to achieve and maintain an erection, as well as their perceptions of their quality of life.
Medical and Quality-of-Life Responses
After 12 weeks, those taking Viagra showed improvements in both achieving and maintaining an erection, based on answers submitted in the questionnaires compared with those taking placebo. Additionally, nearly 90 percent of the MS patients taking the medication reported improvements in their erections compared to just 24 percent of those taking a placebo.
The randomized phase of the study was followed by a nearly yearlong extension phase in which 180 men were treated with Viagra. At the end of this phase, nearly all (95 percent) of the patients taking the medication reported improved erections, Fowler and her team reported.
Men receiving Viagra also reported that much of their quality of life had significantly improved. Overall quality-of-life jumped 43% for the men taking sildenafil versus just 13% for those taking placebo, the research group reported.
"Treatment related to adverse events were predominately mild in nature," wrote Fowler's group, "and no patient discontinued due to an adverse event."
Underlying Method of Action
Viagra works by stimulating the release of nitric oxide, a blood vessel dilator, in the corpus cavernosum—erectile tissue that makes up part of the penis. In turn, nitric oxide activates an enzyme that results in smooth muscle relaxation in the penis, allowing blood to flow in.3
This study was sponsored by Pfizer, the manufacturer of Viagra.
1. National Multiple Sclerosis Society. Sexuality. Available at: http://www.nationalmssociety.org/Sourcebook-Sexuality.asp. Accessed June 3, 2005.
2. Fowler CJ, Miller JR, Sharief MK, Hussain IF, Stecher VJ, Sweeney M. A double-blind, randomized study of sildenafil citrate for erectile dysfunction in men with multiple sclerosis. J Neurol Neurosurg Psychiatry 2005 May;76(5):700-5.
3. Pfizer. Viagra (Sildenafil Citrate). Prescribing Information. Available at: http://pfizer.com/pfizer/download/uspi_viagra.pdf. Accessed June 3, 2005.
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include overseeing health news coverage for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
