A TRANSDERMAL PHARMACEUTICAL COMPOSITION COMPRISING A PHOSPHODIESTERASE TYPE-5 INHIBITOR OR A PHARMACEUTICALLY ACCEPTABLE SALT THEREOF AND A PHARMACEUTICALLY EXCIPIENT, WHEREIN THE TRANSDERMAL PHARMACEUTICAL COMPOSITION COMPRISES AN ENHANCER SELECTED FROM THE GROUP OF COCAMIDOPROPYL BETAINE, SODIUM LAUROAMPHOACETATE, QUATERNIUM-60, ISOSTEARAMIDOPROPYL MORPHOLINE LACTATE, DIPROPYLENE GLYCOL AND A COMBINATION THEREOF.