AN IMPOTENCE drug that may work even when Viagra fails has proved effective
in tests on rats. 鈥淭he initial results were astounding,鈥� says Kanchan Chitaleyn
of the Medical College of Georgia in Augusta. The drug blocks an enzyme called
rho-kinase that helps muscles contract. When injected into the penis, the drug
relaxes the muscles that normally keep the blood vessels constricted. An
erection results within minutes (Nature Medicine, vol 7, p 119). The
researchers hope to develop a cream or pill.
Viagra works by enhancing the action of nitric oxide, which makes the blood
vessels dilate. But it takes hours to work and is effective in only 60 per cent
of cases. This may be because people whose nerve ends are damaged produce no
nitric oxide.