Structure
Sildenafil is a phosphodiesterase type 5 (PDE5) inhibitor with a complex heterocyclic structure, including a pyrazolopyrimidinone core.
Chemical Formula: C₂₁H₁₁N₄O₃S
Mode of Action
PDE5 Inhibition: Sildenafil selectively inhibits PDE5, an enzyme responsible for the degradation of cyclic guanosine monophosphate (cGMP).
cGMP Accumulation: Inhibition of PDE5 leads to increased levels of cGMP, resulting in smooth muscle relaxation and vasodilation in the corpus cavernosum.
Enhanced Blood Flow: Promotes increased blood flow to the penile tissues, facilitating erection in response to sexual stimulation.
Uses of Sildenafil
Erectile Dysfunction (ED): Treats the inability to achieve or maintain an erection sufficient for satisfactory sexual performance.
Pulmonary Arterial Hypertension (PAH): In its form as Revatio®, it is used to reduce pulmonary blood pressure.
Raynaud’s Phenomenon: Occasionally used off-label to manage severe cases by improving blood flow.