Tadalafil selectively inhibits phosphodiesterase type 5 (PDE5), the enzyme responsible for degrading cyclic GMP (cGMP) in vascular smooth muscle. Elevated cGMP activates protein kinase G, causing smooth muscle relaxation and vasodilation in penile corpora cavernosa, pulmonary vasculature, and other PDE5-expressing tissues. The longer half-life (~17.5h) vs sildenafil (~4h) allows once-daily dosing for sustained PDE5 inhibition research. FDA-approved for erectile dysfunction, benign prostatic hyperplasia, and pulmonary arterial hypertension (PAH). Research interest spans cardiovascular, metabolic, and neurological applications beyond its primary indication.
Also Known As
Cialis, IC351, Adcirca
Compound Class
PDE5 inhibitor / cGMP phosphodiesterase inhibitor
Molecular Formula
C₂₂H₁₉N₃O₄
Molecular Weight
389.40 Da
CAS Number
171596-29-5
Half-Life
~17.5 hours (longest PDE5i)
Research Applications
Erectile Function / Vascular Research
PDE5 inhibition in penile tissue: increased cGMP → smooth muscle relaxation → increased blood flow. Tadalafil once-daily vs on-demand dosing comparison well-characterised. Used in endothelial function research, vascular disease models.
Pulmonary Arterial Hypertension Research
FDA-approved (Adcirca) for PAH. PDE5 expressed abundantly in pulmonary vasculature. Tadalafil reduces mean pulmonary arterial pressure and pulmonary vascular resistance in PAH models. PHIRST trial: 6-min walk distance improvement.
Benign Prostatic Hyperplasia Research
Combined PDE5/BPH model: tadalafil reduces lower urinary tract symptoms via PDE5 inhibition in bladder smooth muscle and prostate stroma. FDA-approved indication at 5mg/day. Mechanistic overlap with alpha-blockers studied.
Cardioprotective / Ischaemia Research
Tadalafil pre-conditioning in myocardial ischaemia-reperfusion models: reduced infarct size via cGMP/PKG pathway. Also studied in heart failure, where PDE5 inhibition preserves RV function in right heart overload models.
Metabolic / Skeletal Muscle Research
Emerging: PDE5 inhibition increases cGMP in skeletal muscle, activating AMPK, improving insulin sensitivity in DIO mouse. Tadalafil studied in type 2 diabetes models and exercise capacity research.
Key Research Data
Study
Key Findings
PHIRST Trial 2009 NEJM
Tadalafil 40mg in PAH: 6-min walk distance +33m vs placebo, reduced clinical worsening
TADLUT 2011 J Urol
Once-daily tadalafil 5mg for BPH: IPSS score reduction, improved uroflowmetry
17.5h tadalafil vs 4h sildenafil — allows once-daily dosing
FAQ
What is Tadalafil (Cialis)?
Tadalafil (Cialis) is a PDE5 inhibitor / cGMP phosphodiesterase inhibitor. Tadalafil selectively inhibits phosphodiesterase type 5 (PDE5), the enzyme responsible for degrading cyclic GMP (cGMP) in vascular smooth muscle. Elevated cGMP activates protein kinase G, causing smooth muscle relaxation and vasodilation in penile corpora cave…
How does Tadalafil compare to other PDE5 inhibitors?
PDE5 inhibition in penile tissue: increased cGMP → smooth muscle relaxation → increased blood flow. Tadalafil once-daily vs on-demand dosing comparison well-characterised. Used in endothelial function research, vascular disease models….
What research applications does Tadalafil support?
FDA-approved (Adcirca) for PAH. PDE5 expressed abundantly in pulmonary vasculature. Tadalafil reduces mean pulmonary arterial pressure and pulmonary vascular resistance in PAH models. PHIRST trial: 6-min walk distance improvement….
Does QSC ship Tadalafil to the USA?
Yes. QSC ships Tadalafil 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.
