English: Viagra is a commercial produced medicine containing Sildenafil citrate, which is used to treat male erectile dysfunction and pulmonary arterial hypertension.

• 中文:威而钢是辉瑞药厂所生产，一种主要成份为西地那非的药物，由于对治疗男性勃起障碍与肺动脉高血压具有相当不错的疗效，因而知名。