Vardenafil is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5) and an oral therapy for the treatment of erectile dysfunction.5,6 During sexual stimulation, nitric oxide (NO) is released from nerve endings and endothelial cells in the corpus cavernosum, activating the enzyme guanylate cyclase and increasing the synthesis of cGMP in the smooth muscle cells of the corpus cavernosum. PDE5 inhibitors, such as vardenafil, inhibit the degradation of cGMP and allow increased blood flow into the penis, resulting in an erection.1,5,6. Compared to sildenafil and tadalafil, vardenafil is a more potent inhibitor of PDE5; however, its selectivity for other PDE isoforms is lower than the one detected for tadalafil.