The drug malegra pro is used to treat erectile dysfunction (ED) in men. sildenafil, an inhibitor of phosphodiesterase-5 (PDE-5), is the active ingredient in malegra pro. This type of drug helps men maintain erections by increasing blood flow to the penis. malegra inhibits the PDE-5 enzyme, which relaxes the muscles of the penis and increases blood flow. The increased blood flow helps the man get an erection that is powerful enough for sex. It is important to realize that malegra does not instantly result in an erection; sexual stimulation is required for the drug to work.