Knowra Sildenafil Sildenafil Sildenafil is a phosphodiesterase type 5 inhibitor sold as Viagra for erectile dysfunction and as Revatio for pulmonary arterial hypertension. It prolongs nitric oxide–mediated cyclic GMP signaling, relaxing smooth muscle.
Phosphodiesterase type 5 : Phosphodiesterase type 5 is an enzyme that breaks down cyclic GMP in smooth muscle and other tissues. Sildenafil inhibits this enzyme, slowing cyclic GMP breakdown.
Erectile dysfunction : Erectile dysfunction is the persistent inability to achieve or maintain an erection sufficient for satisfactory sexual activity. This is sildenafil’s best-known indication.
Tadalafil : Tadalafil is a long-acting phosphodiesterase type 5 inhibitor used for erectile dysfunction and related conditions. Its longer duration distinguishes it from sildenafil.
Sildenafil adverse effects : Sildenafil adverse effects include headache, flushing, indigestion, nasal congestion, and temporary visual changes. These effects follow from its vascular action and activity against related phosphodiesterases.
Cyclic GMP : Cyclic guanosine monophosphate is a signaling molecule that regulates processes including smooth-muscle relaxation. Its persistence after PDE5 inhibition mediates sildenafil’s effects.
Pulmonary arterial hypertension : Pulmonary arterial hypertension is a progressive disease marked by elevated pressure in the arteries supplying the lungs. Sildenafil lowers pulmonary vascular resistance in this condition.
Vardenafil : Vardenafil is a phosphodiesterase type 5 inhibitor prescribed for erectile dysfunction. It treats the same condition through the same enzyme target, with different pharmacological properties.
Priapism : Priapism is a prolonged erection, often painful, that requires urgent medical attention. It is a rare but serious event reported with erectile dysfunction treatments, including sildenafil.
Nitric oxide signaling : Nitric oxide signaling uses the gaseous molecule nitric oxide to regulate cellular processes, including smooth-muscle relaxation. Sildenafil amplifies this pathway but does not initiate it.
Viagra : Viagra is the brand name for sildenafil tablets approved to treat erectile dysfunction. It is the best-known commercial formulation of sildenafil.
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