Good news for all those whom Viagra DISAPPOINTED! According to a study – Bayer AG and GlaxoSmithKline Plc’s rival drug Levitra helped nearly half of men who did not respond to Viagra achieve successful sexual intercourse. The study was conducted on 463 patients. It showed that 46.1 percent of men who had failed at least four of the last six attempts at successful intercourse while on Viagra were successful when given Levitra. When it starts to work and how long it lasts are big issue...