The saga began in Sandwich, England, where a team of Pfizer scientists were working to develop a treatment for angina. In clinical trials, the drug -- sildenafil citrate -- did breathtakingly little to alleviate the symptoms of coronary heart disease. The pill did, however, have one small, noticeable side effect: Some men in the study (even those who had previously been impotent) reported having erections while taking the drug.