Sildenafil

Category: pharmacological

Aliases: Viagra, Revatio

Pharmacological Mechanism

PDE5 inhibitor — raises cGMP in cavernosal smooth muscle → erectile vasodilation. CYP3A4 substrate (DDI with all azoles, ritonavir, grapefruit). Higher dose (Revatio) for pulmonary arterial hypertension.

Half-Life (t½)

PO: 4h

Dosing Guidelines

• PO: Typical 50 mg (Range: 25–100 mg)

Target Organ Systems

• cardiovascular
• respiratory
• digestive
• reproductive

Pathways It Modulates

• Nitric oxide synthesis (inhibitor) — PDE5 (downstream — blocks cGMP degradation, amplifying endogenous NO)
• PDE5 / NO-cGMP axis (inhibitor) — PDE5 (selective)
• PDE5 inhibitor PDE6 retinal cross-inhibition (inhibitor) — PDE5 (intended) + PDE6 (retinal, off-target)
• Pulmonary arterial hypertension (inhibitor) — PDE5 → ↑cGMP → pulmonary vasodilation

Chemical Identifiers

• PubChem CID: 135398744
• Formula: C22H30N6O4S
• Molecular weight: 474.58 g/mol
• InChIKey: BNRNXUUZRGQAQC-UHFFFAOYSA-N
• SMILES: CCCC1=NN(C2=C1N=C(NC2=O)C3=C(C=CC(=C3)S(=O)(=O)N4CCN(CC4)C)OCC)C

References

• PMID 9598563