Sildenafil citrate (Viagra) reduces surface roughness of human erythrocytes: Atomic-force-microscopic study.

Sildenafil citrate (Viagra) is used to treat erectile dysfunction and pulmonary arterial hypertension. The objective of this study was to analyze the action of sildenafil citrate on normal human erythrocytes at a concentration (2.5 mg/mL) higher than the prescribed for clinical conditions.