Avanafil Stendra. The body takes longer to absorb it after a high-fat meal or alcohol. This medicine also works best when you take it an hour before sex on an empty stomach. Recent heart or blood vessel problems. These medicines are called PDE5 inhibitors. These are commonly prescribed for an enlarged prostate or male pattern baldness. By controlling the enzyme, sildenafil helps to maintain an erection after the penis is stroked.Sildenafil oral tablet is available as a brand-name drug and as a generic drug. Brand names: Viagra, Revatio. Sildenafil comes in three forms: an oral tablet, an oral . Generic version. Viagra is available in generic form called sildenafil. A generic drug is an exact copy of the active drug in a brand-name medication. generic Revatio and Viagra Used for Pulmonary Hypertension and Erectile Dysfunction MORE expand_more Check your prescription Prescription 20mg sildenafil (30 tablets) .