CAS No: 171596-29-5
Appearance: white powder, odorless, tasteless, insoluble in water and alcohol.
Although sildenafil (Viagra), vardenafil (Levitra), and tadalafil (Cialis) all work by inhibiting PDE5, tadalafil’s pharmacologic distinction is its longer half-life (17.50 hours) – compared to sildenafil (4.0–5.0 hours) and vardenafil (4.0–5.0 hours) – resulting in longer duration of action, and so partly responsible for “The Weekend Pill” sobriquet. Furthermore, the longer half-life is the basis for current investigation of tadalafil’s daily therapeutic use in relieving pulmonary arterial hypertension. Sildenafil is approved in several world regions as a thrice-daily therapy for pulmonary arterial hypertension.