Viagra, sildenafil. Poke, V
What is Viagra?
Viagra is the trade name of sildenafil, an anti-impotence drug, belonging to a new group of drugs known as phosphodiesterase type 5 (PDE5) inhibitors. Developed originally as a treatment for angina, patients prescribed with Viagra reported erections as an unexpected side effect.
How does it work?
As an inhibitor, the drug works by improving the blood flow to the penis by stopping the degradation of cyclic guanosine monophosphate (cGMP) - a chemical released during sexual stimulation which relaxes the smooth muscle in the penis. Once these muscles have been relaxed, blood vessels are able to dilate, allowing the blood flow to the penis to increase.
By selectively inhibiting the breakdown of cGMP, Viagra uniquely promotes the flow of blood into the penis at times of sexual stimulation, therefore facilitating an erection, though not causing one. Viagra therefore does not increase sexual desire (although a side effect may be an increase in confidence which in turn may increase sexual desire).
It follows also that those who do not suffer from impotence caused by insufficient blood flow may gain little from taking the drug. Viagra is not the first drug for treating impotence.
However, the drug's ease of administration, its lack of obvious side-effects and its apparent success rate have meant that it has found favour among a number of recreational users such as clubbers, gay men, those experimenting sexually with the drug, and by impotent men and women self-medicating.
and youths who use the club drug ecstasy are mixing it with the anti-impotency drug Viagra, leading drug-abuse specialists to warn about the health risks of a combination that users say fuels all-night dancing and marathon sex.The combined drugs - known in the club scene as "sextasy" - began as a fad among youths in England and Australia. About a year ago, officials of the U.S. Drug Enforcement Administration began hearing reports that the mixture had become popular in this country's gay party culture.
Doctors warn that combining the two drugs can cause heart problems or erections that don't subside for more than four hours, possibly leading to anatomical damage. There have been scattered reports of such injuries across the US, officials say.
Currently the drug is only available free on the NHS from hospital specialists and not from GPs. The drug however has been available on private prescription since it was given authorisation by the European Medicines Evaluation Agency in September 1998.
The drug can be purchased via other means, primarily on the Internet, a practice the Medicines Control Agency has tried to prevent (as a medicine the drug can only be legally dispensed by chemists on receipt of a prescription). Viagra can also be obtained illegally on the streets, in clubs and reportedly outlets such as sex or head shops at £10 a tablet.
Side effects vary, but can include flushing and headaches, and less commonly indigestion, and muscle pain caused by the drug's vasodilator properties. At higher doses visual disturbances such as a blue haze around objects, are caused by the inhibition of a chemical similar to PDE5 in the retina, involved in turning light into sight.In addition to these mild side effects, there have been worrying reports of it reacting badly with other medicines.
The drug interactions to be aware of are anti-HIV drugs (there have been worrying reports from the US of it leading to an increase in blood levels of the protease inhibitor Ritonavir); and poppers (there have been reports from the US of deaths when the two are used together). Ecstasy, cocaine and speed also have an impact on heart rates, and it may be risky to use them with Viagra, particularly as they may have been cut with substances containing nitrates.
What we do.
Prof. Robert F. Schmidt Ausgewählte Publikationen (ältere Arbeiten, bis einschließlich 1999) Schmidt, R.F. : Physiologie kompakt. 3. Auflage, Heidelberg: Springer, pp 1-347 Heppelmann, B., Pawlak, M., Schmidt, R.F: Projection areas of the posterior articular nerve in the rat cortex. Europ J Physiol Suppl 437: R131 Schmidt, R.F. : Neurophysiologie. In: Berlit, P. (Hrsg.) Klinische
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