Tadalafil is a highly selective phosphodiesterase 5 (PDE5) inhibitor. It increases the concentration of cGMP in the corpus cavernosum of the penis by inhibiting PDE5, relaxes vascular smooth muscle and increases blood flow, thereby improving erectile function.Its chemical name is: (6R,12aR)-6-(1,3-benzodioxol-5-yl)-2-methyl-2,3,6,7,12,12a-hexahydropyrazino[1',2':1,6]pyrido[3,4-b]indole-1,4-dione.

1. Male erectile dysfunction (ED): On-demand administration, onset of action within 30 minutes, duration of effect ≤ 36 hours, not affected by food intake.

2. Erectile dysfunction with benign prostatic hyperplasia (BPH): Once-daily administration to improve urinary tract symptoms and erectile function.

3. Pulmonary arterial hypertension (PAH): Approved by the FDA for use in adults with PAH to improve exercise tolerance.

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