Viagra (sildenafil)

Universitat Autònoma de Barcelona researchers have discovered that Viagra® drastically reduces multiple sclerosis symptoms in animal models with the disease.

The research, published in Acta Neuropathologica, demonstrates that a practically complete recovery occurs in 50% of the animals after eight days of treatment. Researchers are confident that clinical trials soon will be carried out in patients given that the drug is well tolerated and has been used to treat sexual dysfunction in some multiple sclerosis patients.

Multiple sclerosis is the most common chronic inflammatory disease of the central nervous system and one of the main causes of disability among young adults. The disease is caused by the presence of multiple focuses of demyelination (loss of myelin sheaths around the axons, affecting the ability of neurons to communicate) and neurodegeneration in different areas of the central nervous system. There is currently no cure for the disease, although some drugs have proven effective in fighting symptoms and preventing it from progressing.

A research team from the UAB Institute of Biotechnology and Biomedicine directed by Dr Agustina García, in collaboration with the research team directed by Dr Juan Hidalgo from the UAB Institute of Neurosciences, has studied the effects of a treatment using sildenafil, sold as Viagra®, in an animal model of multiple sclerosis known as experimental autoimmune encephalomyelitis (EAE). Researchers demonstrated that a daily treatment with sildenafil after disease onset quickly reduced clinical signs, with a practically complete recovery in 50% of the cases after eight days of treatment. Scientists observed how the drug reduced the infiltration of inflammatory cells into the white matter of the spinal cord, thus reducing damage to the nerve cell's axon and facilitating myelin repair.

Sidenafil, together with tadalafil (Cialis®) and vardenafil (Levitra®), form part of a group of vasodilator drugs known as phosphodiesterase type 5 (PDE5) inhibitors, used in the treatment of erectile dysfunction and pulmonary arterial hypertension. Recent studies in animal models of central nervous system pathologies already pointed to the fact that in addition to vasodilation, these drugs could contain other neuroprotective actions and suggest their usefulness as possible treatments of both acute (cerebrovascular stroke) and chronic (Alzheimer's) neuropathologies. In fact, in a research published in 2010 in the Journal of Neurochemistry, the same research group from UAB demonstrated that one of these inhibitors reduced neuroinflammation and neuronal damage in animal models of traumatic brain injury.

Source: News-Medical.net (19/05/11)

A cream allowing erectile dysfunction drugs to be applied directly to the skin could one day make them safer to use, say New York scientists.

Studies in rats suggest that Viagra, Levitra and Cialis could pass through the skin in tiny capsules, they say.

The research, published in the Journal of Sexual Medicine, could mean fewer side-effects, and even significantly speed up the drug's action.

However, it could be a decade before creams are fully ready for use.

The arrival of erectile dysfunction treatments in tablet form has been one of the success stories of the modern pharmaceutical industry, with some estimates suggesting that tens of millions of men worldwide have used them.

However, although they have worked for many men, they also carry the risk of side-effects such as headaches, blurred vision or upset stomachs.

In addition, men with severe heart problems, or who have just suffered a stroke, are advised to avoid the tablets altogether or use them with extreme caution.

Less risk

For many, this could be solved by the development of the cream, with would confine more of the active ingredients of the drug to a single area of the body, rather than circulating them widely.

The research team at the Albert Einstein College of Medicine at Yeshiva University, in New York, used nanoparticles, each much smaller than a grain of pollen, and found a way to encapsulate particles of the drug inside.

Their early tests involved just a few rats bred to have erectile dysfunction later in life.

Of these, 11 were treated with nanoparticles containing Cialis, a newer erectile dysfunction drug called sialorphin, and nitric oxide, a chemical also needed to widen blood vessels and produce an erection, often reduced in men with diabetes.

All of the rats showed improvement, unlike seven rats given empty nanoparticles instead.

Dr Kelvin Davies, one of the researchers, said: "The response time to the nanoparticles was very short, just a few minutes, which is basically what people want in an erectile dysfunction medication.

"In both rats and humans, it can take 30 minutes to one hour for oral erectile dysfunction medications to take effect."

The researchers found no signs of local inflammation or damage caused by the nanoparticles, and no evidence of wider side-effects.

Clinical studies in humans could begin in a few years if animal studies continued to suggest the treatment was safe, they said.

However, finally getting the drug approved for widescale use could take 10 years or more, they said.

Source: BBC News © British Broadcasting Corporation 2009 (22/09/09)

The etiology of multiple sclerosis (MS)-emergent erectile dysfunction (ED) is still matter of debate, since both organic and psychological factors have been implicated.

There is an association between sexual dysfunction (SD) and destructive lesions in the pons, in MS patients. Central and peripheral nerves systems play a key role in the erectile process. The innervation of the penis is both autonomic (sympathetic and parasympathetic) and somatic (sensory and motor). Pudendal nerves have a central role in erection. Tactile stimulation of the penile shaft activates parasympathetic fibers, which travel in the pudendal nerve and function through the spinal reflex arc from S2 to S4. Neural signals originating in the brain are transmitted to a thoracolumbar erection center and trigger the psychogenic erection associated with either fantasy or viewing erotic material.

In addition, the ischiocavernosus and bulbospongiosus striated muscles, which located at the penile crus, are innervated by the motor pudendal nerve. Contraction of these muscles has a definite, contributory role in penile erection. Therefore, erection is a neurovascular event, and any disease or dysfunction affecting the brain, spinal cord, or cavernous and pudendal nerves can induce ED. With respect to placebo, sildenafil produced a 16% greater success rate for vaginal penetration, and a 15% greater rate for successful intercourse. For satisfaction with erection hardness, and satisfaction with the sexual experience, sildenafil did not produce two-fold greater rates. For all efficacy variables, sildenafil had similar or slightly greater scores compared with placebo.

Although some clinical trials have demonstrated an overall success rate of greater than 70%, certain patients will be refractory to treatment with sildenafil. Sildenafil acts a potentiator of local mediators to maintain smooth muscle relaxation and thus cannot act in the absence of intact penile innervation. In this study, most of the participants had abnormal pudendal nerve cortical somatosensory evoked potentials (PEPs). The incidence of ED after non-nerve sparing radical retropubic prostatectomy is up to 97%. This is due to cavernosal nerve damage. A poor response to sildenafil in postoperative patients with unilateral or non-nerve-sparing radical retropubic prostatectomy has been demonstrated. Direct-acting medications might be expected to be efficacious in nonresponders who have nerve injury or nerve damage. Fifty percent of the post prostatectomy patients who had failed with sildenafil, reported improved EF with intraurethral alprostadil.

Sexual dysfunction is a frequent disorder associated to MS, which contributes to the worsening of quality of life of these patients. During the course of MS, prevalence of SD becomes increasingly more common, affecting, after 10 years of disease duration, 40–70% of patients.

Interactions between neural structures are essential to all phases of human sexual response and functioning. Neurophysiological studies give invaluable information on the involvement of the parts of the nervous system which are essential in the control of sexual function. The pudendal nerve and its terminal branch (dorsal nerve of the penis) provide somatosensory innervation to the genitalia in men. Sensory pathways, which are important in reflexogenic erections, transmit information to the CNS via the dorsal penile nerve and the pudendal nerve. Therefore, a neurophysiological test that assesses the pudendal nerve function such as the PEPs, has great value in an objective evaluation of SD.

We did not recommend second or third type PDE-5 inhibitors for sildenafil non-responders. All three FDA approved PDE-5 inhibitors are targeting the same site of action. Studies from the industry tend to favor preference for their own drug, whereas independent studies tend to show no major difference in preference. Multiple well-designed studies have shown that, all three available PDE-5 inhibitors, have a very similar efficacy and safety profile. In our experiences, well-educated sildenafil non-responders, seldom respond to other type of PDE-5 inhibitors.

Source: UroToday © 2008 UroToday (23/12/08)

A new supplement called ArginMax has been shown to enhance the response to Viagra in men.

A double-blind, placebo-controlled study showed that ArginMax significantly improved the sexual performance and satisfaction of men who had not responded sufficiently to Viagra previously.

Ref: American Urological Association meeting, Oct 20-25, 2002, Kauai, Hawaii

Pfizer, the drug company behind Viagra is preparing to launch the first 'orgasm pill' for women next year. Unlike Viagra, which is blue, the new pills for women will be pink.

Trials are already underway at the National Hospital in London for women with MS. The drug dramatically increases the blood flow to the nervous tissue involved in arousal and orgasm. The new compound will be similar to the original but the recommended dose is expected to change significantly.

Ref: Sunday Times - 27th Jan, 2002

A new Study has found that Viagra, the little blue pill which is prescribed to men to help with erectile dysfunction, can also significantly help women!

Almost all of the 53 women who took part in a study by the center for Sexological Research at the University of Catania requested that they be allowed to continue on the drug. Prior to the Study all the women, aged Under 40 had difficulty becoming aroused and could not achieve orgasm. After taking Viagra the number of sexual fantasies increased, the frequency of love making rose from once a week to several times a week, and the number of orgasms to once or twice a day. Pfizer, the manufacturers of Viagra described these results as interesting.

Ref: The Sunday Telegraph

For further information, refer to the original article.

Erectile Dysfunction is common problem for men with multiple sclerosis and now new research indicates that Viagra (sildenafil) is an effective and well-tolerated treatment for erectile difficulties in such patients.

In the study, 217 relatively young men were randomly assigned to Viagra or placebo for 12 weeks. The study was funded by Pfizer, Inc., which markets the drug Viagra.

"Viagra significantly improved erectile function and the ability to engage in satisfactory sexual activity in ED due to MS," Dr. Clare J. Fowler, from The National Hospital for Neurology and Neurosurgery, in London, and colleagues report.

Compared with placebo, Viagra was associated with a significant improvement in standard erection scores. Altogether, 89 percent of Viagra-treated patients reported improved erections compared with just 24 percent of those given a placebo.

The randomized phase of the study was followed by a 48-week extension phase in which 180 men were treated with Viagra. At the end of this phase, 95 percent of patients reported improved erections.

Treatment with Viagra also significantly improved quality of life of the men in the study.

Viagra was well tolerated, according to the team. No serious drug-related side effects were seen.

The findings appear in the Journal of Neurology, Neurosurgery, and Psychiatry this month.

SOURCE: Journal of Neurology, Neurosurgery, and Psychiatry (31/05/05) 

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