• CAS: 171599-83-0 | MW (citrate salt): 666.70 g/mol | BCS Class II
• Mechanism: Selective competitive PDE5 inhibitor (>1000-fold selectivity) — sustains cGMP-mediated smooth muscle relaxation
• ADME: Rapid oral absorption (Tmax ~1h), t½ ~4h, 96% protein bound, CYP3A4/2C9 metabolism, active N-desmethyl metabolite, predominantly faecal excretion (73–88%)
• Critical drug interaction: Absolute contraindication with organic nitrates — risk of severe/fatal hypotension
• Stability: Stable under ICH conditions; proposed retest period 36 months at 15–30°C
• Regulatory: FDA-approved 1998 (ED) and 2005 (PAH); compliant with ICH Q1A, Q3A/B/C/D, Q6A, Q7, Q11, M7

Disclaimer: This DMF is compiled for reference and study purposes from published pharmacology textbooks and regulatory frameworks. An actual regulatory submission DMF must include original analytical data, batch records, validated method reports, and site master file details generated by the manufacturing facility. It must be authored and signed by qualified pharmaceutical scientists.