Sildenafil was the first selective PDE5 inhibitor discovered (Pfizer, 1989). Inhibits PDE5 with IC50 ~3.5 nM, >10-fold selectivity over PDE6 (retina) and >700-fold over other PDE isoforms. Mechanism: smooth muscle relaxation via elevated cGMP in PDE5-expressing tissues. Shorter half-life (~4h) than tadalafil makes it preferred for acute, on-demand dosing research designs. Also FDA-approved as Revatio for pulmonary arterial hypertension. The reference PDE5 inhibitor for pharmacological studies due to its extensive characterisation since the 1990s.
Also Known As
Viagra, UK-92480, Revatio
Compound Class
PDE5 inhibitor / cGMP phosphodiesterase inhibitor
Molecular Formula
C₂₂H₃₀N₆O₄S
Molecular Weight
474.58 Da
CAS Number
139755-83-2
Half-Life
~3–5 hours
Research Applications
PDE5 Inhibition Reference Compound
Sildenafil is the original, most-characterised PDE5i. Used as reference compound in PDE isoform selectivity assays, cGMP accumulation studies, and in vitro smooth muscle relaxation models. Extensive pharmacokinetic data across species.
Pulmonary Arterial Hypertension
FDA-approved (Revatio) for PAH. SUPER-1 trial: sildenafil improved 6-min walk, mPAP, and WHO functional class in PAH. Reference for comparing new vasodilatory agents in pulmonary hypertension models.
Erectile Dysfunction / Sexual Function Research
cGMP-mediated corporal smooth muscle relaxation: extensively characterised across dose-response, species, and vascular disease models. Compared vs tadalafil and vardenafil for onset, duration, and PDE5 selectivity.
Cardioprotection / Preconditioning
Sildenafil preconditioning in myocardial I/R models: reduced infarct size via PKG pathway. Studied in heart failure models — acute haemodynamic effects in HFrEF. Cognitive effects (PDE5 in CNS) also under investigation.
Key Research Data
Study
Key Findings
SUPER-1 Trial 2005 NEJM
Sildenafil 20/40/80mg in PAH: 6-min walk distance improved all doses, dose-dependent mPAP reduction
Original Pfizer Phase 3 RCTs 1998
N=3,000 across trials: sildenafil vs placebo in ED — IIEF-15 score improvement, dose-response 25-100mg characterised
Shorter half-life (4h) — suited for acute/on-demand research designs
FAQ
What is Sildenafil (Viagra)?
Sildenafil (Viagra) is a PDE5 inhibitor / cGMP phosphodiesterase inhibitor. Sildenafil was the first selective PDE5 inhibitor discovered (Pfizer, 1989). Inhibits PDE5 with IC50 ~3.5 nM, >10-fold selectivity over PDE6 (retina) and >700-fold over other PDE isoforms. Mechanism: smooth muscle relaxation via elevated cGMP in PDE5-expressin…
How does Sildenafil compare to other PDE5 inhibitors?
Sildenafil is the original, most-characterised PDE5i. Used as reference compound in PDE isoform selectivity assays, cGMP accumulation studies, and in vitro smooth muscle relaxation models. Extensive pharmacokinetic data across species….
What research applications does Sildenafil support?
FDA-approved (Revatio) for PAH. SUPER-1 trial: sildenafil improved 6-min walk, mPAP, and WHO functional class in PAH. Reference for comparing new vasodilatory agents in pulmonary hypertension models….
Does QSC ship Sildenafil to the USA?
Yes. QSC ships Sildenafil domestically across the USA and to EU, UK, Canada, and Australia. Every batch carries a Janoshik third-party COA confirming ≥99% HPLC purity and MS identity.
