Description

Zenegra (sildenafil)

Zenegra is a generic sildenafil citrate available in 25 mg, 50 mg, and 100 mg tablets. Clinical reporting for sildenafil at the commonly prescribed doses puts significant side effects in the range of one in ten men or fewer — mainly headache, facial flushing, indigestion, back pain, and myalgia. For most men these are transient and dose-dependent; they diminish at lower doses or stop when the drug is discontinued.

Dosing

The standard starting dose for men without specific health conditions is 50 mg, taken 60 minutes before sexual activity, swallowed whole with water. Heavy, fatty meals delay absorption — a light meal or empty stomach gives the most predictable onset. One dose per 24 hours. Duration of effect: 4 to 6 hours.

25 mg is appropriate for older men, those with significant hepatic or renal impairment, and patients on CYP3A4 inhibitors (certain antifungals, HIV antivirals, erythromycin). These situations raise sildenafil blood levels and increase side effect exposure. 100 mg is the maximum for men where 50 mg shows insufficient response and the lower-dose side effect profile was manageable. Sexual stimulation is required; sildenafil doesn’t produce erections without it.

Nitrates

Sildenafil combined with nitrates — nitroglycerin, isosorbide dinitrate, isosorbide mononitrate, amyl nitrate — causes severe blood pressure drops that can be fatal. This is an absolute contraindication with no safe dose or timing interval.

Contraindications

All nitrates. Severe hypertension or hypotension. Heart failure, unstable angina, or recent stroke or heart attack (within 6 months). Severe liver disease. Peptic ulcers. Blood disorders predisposing to priapism — leukemia, sickle cell anemia, thrombosis. Retinitis pigmentosa. Penile structural abnormalities. Hypersensitivity to sildenafil.

Side effects

Headache, facial redness, burning stomach, myalgia, and back pain are the most commonly reported. Visual effects — blue tint, increased brightness sensitivity — are dose-related and reflect PDE6 involvement in the retina. Sudden vision loss or sudden hearing loss are rare but require immediate evaluation and should prompt stopping the drug.

Alcohol significantly potentiates the blood-pressure-lowering effect of sildenafil. The additive vasodilation increases risk of dizziness and postural hypotension.

Priapism — erection lasting more than 4 hours — is a medical emergency. Delay results in permanent damage to erectile tissue.