The hydrochloride salt form of vardenafil, a benzenesulfonamide derivative and phosphodiesterase type 5 (PDE5) inhibitor with vasodilatory activity. Vardenafil selectively inhibits PDE5, thus inhibiting the degradation of cyclic guanosine monophosphate (cGMP) found in the smooth muscle of the corpus cavernosa and corpus spongiosum of the penis. The inhibition of cGMP degradation results in prolonged muscle relaxation, vasodilation, and blood engorgement of the corpus cavernosa, thereby prolonging penile erection.