Conformational variations of both phosphodiesterase-5 and inhibitors provide the structural basis for the physiological effects of vardenafil and sildenafil.
Wang, H., Ye, M., Robinson, H., Francis, S.H., Ke, H.(2008) Mol Pharmacol 73: 104-110
- PubMed: 17959709 
- DOI: 10.1124/mol.107.040212
- Primary Citation of Related Structures:  
3B2R - PubMed Abstract: 
Vardenafil has higher affinity to phosphodiesterase-5 (PDE5) than sildenafil and lower administered dosage for the treatment of erectile dysfunction. However, the molecular basis for these differences is puzzling because two drugs have similar chemic ...