Who would have thought 8 years back that sildenafil citrate, a drug used for the treatment of angina pectoris (a cardiovascular disease), could work wonders for treating male erectile dysfunction (ED)? The results were astounding. The drug was less effective for angina but provided astonishing results in treating ED. It was patented in 1996 by the drug company Pfizer and approved for use in ED by the FDA on March 27, 1998. No other drug was approved before in the US to treat ED.

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