text: PDE5 is expressed in clitoral corpus cavernosum and in vaginal smooth muscle and epithelium. Therefore, it is possible that PDE5 inhibitors could affect female sexual arousal disorder but further research is needed. Increased levels of cGMP have been shown to occur in human-cultured vaginal smooth muscle cells treated with a PDE5 inhibitor suggesting involvement of the NO/cGMP axis in the female sexual response.