Time course of the interaction between tadalafil and nitrates

J Am Coll Cardiol. 2003 Nov 19;42(10):1855-60. doi: 10.1016/j.jacc.2003.09.023.


Objectives: This study was designed to determine the time course of nitrate interaction with tadalafil, a phosphodiesterase 5 (PDE5) inhibitor with a half-life (t(1/2)) of 17.5 h.

Background: The PDE5 inhibitors augment the blood pressure (BP)-lowering effects of nitrates, yet the time course of this interaction is unclear. Recent guidelines from the American College of Cardiology/American Heart Association recommend that nitrates be withheld for 24 h after taking sildenafil (t(1/2) = 4 h).

Methods: Male subjects (n = 150) received seven consecutive daily doses of placebo or tadalafil (20 mg). On day 7 and beyond, subjects received repeated doses of sublingual nitroglycerin (0.4 mg) after the last dose of placebo or tadalafil. After a 10- to 21-day washout period, subjects crossed over to either placebo or tadalafil, and nitrate dosing was repeated.

Results: In response to nitroglycerin at 4, 8, and 24 h, standing systolic BP fell below 85 mm Hg in more subjects on tadalafil compared with placebo (p < 0.05), with no difference in the response to nitroglycerin at 48, 72, and 96 h (p > 0.2). Similar observations were made for standing diastolic BP <45 mm Hg, decrease in systolic BP >30 mm Hg, and decrease in diastolic BP >20 mm Hg. Nitroglycerin also evoked greater mean maximal decreases in standing systolic BP at 8 and 24 h after taking tadalafil versus placebo (p < 0.02), with no significant difference at 48, 72, or 96 h (p > 0.49).

Conclusions: The hemodynamic interaction between tadalafil and sublingual nitroglycerin lasted 24 h, but was not seen at 48 h and beyond. Similar to other PDE5 inhibitors, tadalafil should not be administered in combination with organic nitrates.

Publication types

  • Clinical Trial
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Angina Pectoris / drug therapy
  • Carbolines / therapeutic use*
  • Contraindications
  • Cross-Over Studies
  • Double-Blind Method
  • Drug Synergism
  • Erectile Dysfunction / drug therapy
  • Humans
  • Hypotension / chemically induced*
  • Male
  • Middle Aged
  • Nitrates* / therapeutic use
  • Phosphodiesterase Inhibitors / therapeutic use*
  • Tadalafil
  • Time Factors


  • Carbolines
  • Nitrates
  • Phosphodiesterase Inhibitors
  • Tadalafil