abstract |
PROBLEM TO BE SOLVED: To provide a highly selective cyclic guanosine 3 ′, 5′-monophosphate-specific phosphodiesterase enzyme type 5 (PDE5) useful in a pharmaceutical product for treating sexual dysfunction and the like. Provide inhibitors. A PDE5 inhibitor, comprising: (i) The IC 50 values of inhibition for PDE5 is at least 100-fold difference in comparison with PDE6, is an IC 50 value of inhibition of (ii) PDE5, at least 1000-fold difference in comparison with PDE1C, less than (iii) 10 nM, PDE 1-20 mg of a selective PDE5 inhibitor, having an IC 50 against 5 and (iv) sufficient bioavailability to be effective at an oral dose of 1-20 mg. |