PDE5 inhibitors - pharmacology and clinical applications 20 years after sildenafil discovery.

The discovery of the nitric oxide/cGMP pathway was the basis for our understanding of many normal physiological functions and the pathophysiology of several diseases. Since the discovery and introduction of sildenafil, inhibitors of PDE5 have been the first-line therapy for erectile dysfunction (ED). The success of sildenafil in the treatment of ED stimulated research in the field of PDE5 inhibition and led to many new applications, such as treatment of lower urinary symptoms, and pulmonary arterial hypertension, which are now approved indications. However, PDE5 inhibitors have also been used in several other disorders not discussed in this review, and the fields of clinical use are increasing. In the present review, the pharmacological basis of the NO/cGMP pathway and the rationale and clinical use of PDE5 inhibitors in different diseases are discussed.