For treatment of pulmonary arterial hypertension: For oral dosage forms suspension or tablets : Adults—20 milligrams mg 3 times a day. Children 1 year of age and older weighing 45 kilograms kg or more—20 mg 3 times a day. It’s available in 10 mg and 20 mg tablets. Proper Use Use sildenafil exactly as directed by your doctor. Stendra avanafil : This is an as-needed medication taken 30 minutes before sex and can last up to six hours. Ask your healthcare professional how you should dispose of any medicine you do not use.Sildenafil is a medication used in the management and treatment of erectile dysfunction and pulmonary arterial hypertension. It is in the phosphodiesterase-5 inhibitor (PDE5-I) class of medications. This activity describes the indications, actions, adverse effects, and contraindications of sildenafil as an agent in the clinical setting. Knowledge . Drug details Here are some details on sildenafil: Drug class: phosphodiesterase type 5 (PDE5) inhibitor Drug forms: oral tablet, liquid suspension, intravenous (IV) bolus injection Brand-name. Viagra comes as an oral tablet in different dosages. Discuss with your doctor what’s an appropriate dose for you. For daily use, Goldstein said, the generic form, sildenafil, comes in mg tablets.