Avana 100 tablets contain avanafil, a type 5 inhibitor of phosphodiesterase, which is used in men to treat erectile dysfunction (impotence). Nitric oxide is released in the erectile tissue of the penis during sexual stimulation, which stimulates the guanylate cyclase enzyme. This enzyme raises the levels of a chemical called cyclic guanosine monophosphate (cGMP), which relaxes the blood vessels in the penis, allowing blood to fill the erectile spongy tissues to produce an erection. Another enzyme called type 5 phosphodiesterase (PDE5) breaks down cGMP blocking blood flow into the penis, resulting in erection failure.