摘要 |
Compounds of the formula (I): wherein R<SUP>1</SUP>, R<SUP>2</SUP>, R<SUP>4 </SUP>and R<SUP>13 </SUP>are as defined or a pharmaceutically or veterinarily acceptable salt or polymorph thereof, or a pharmaceutically or veterinarily acceptable solvate or pro-drug thereof: are potent and selective inhibitors of type 5 cyclic guanosine 3',5'-monophosphate phosphodiesterase (cGMP PDE5) and have utility in the treatment of, inter alia, male erectile dysfunction (MED) and female sexual dysfunction (FSD). |