What is the PDE inhibitor time window before nitroglycerin as per the guideline?

• A. Sildenafil or Vardenafil within 24 hours; Tadalafil within 48 hours
• B. Sildenafil within 48 hours; Vardenafil within 24 hours; Tadalafil within 72 hours
• C. Sildenafil within 12 hours; Vardenafil within 12 hours; Tadalafil within 24 hours
• D. No restrictions

Answer: (A)

Key idea: Nitrates and PDE5 inhibitors both lower blood pressure via the NO-cGMP pathway, so using them together can cause dangerous hypotension. Because of this interaction, guidelines set a waiting period after taking a PDE5 inhibitor before giving nitroglycerin.

Sildenafil and vardenafil have shorter durations of action, so waiting 24 hours after taking either of them before administering nitroglycerin is recommended. Tadalafil lasts longer, so a 48-hour window before nitroglycerin is advised. This difference aligns with how long each drug remains active in the body.

So the guideline calls for a 24-hour window after sildenafil or vardenafil and a 48-hour window after tadalafil before giving nitroglycerin.