PDE5 inhibitor
Drug class for ED. Sildenafil, tadalafil, vardenafil, avanafil. Blocks an enzyme to maintain erection.
PDE5 inhibitors block phosphodiesterase-5, an enzyme that breaks down cGMP. With cGMP preserved, blood vessels in the penis relax and erection is maintained when sexually stimulated. Don't combine with nitrates (severe hypotension risk).