CAS Number: 139755-83-2 Chemical Formula: C22H19N3O4 Molecular Weight: 389.4 Content: 99.5% Sildenafil citrate, Viagra Solubility: Slightly soluble in water, methanol; very slightly soluble in ethanol, chloroform Appearance: White crystalline powder Storage: shading, confined preservation. Usage: Viagra (Sildenafil citrate) is a drug used to treat erectile dysfunction (impotence) in males and pulmonary arterial hypertension (PAH).