Pharm

Nitroglycerin

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Nitroglycerin, Antianginal

  • History
  1. Albert Nobel stabilized Nitroglycerin for dynamite
    1. Some postulate that he died of Nitroglycerin toxicity
  • Medications
  1. Short Acting Nitroglycerin (Sublingual Nitroglycerin)
    1. Peak Levels: 1-2 minutes
    2. Duration: 30 to 60 minutes
  2. Long Acting Nitroglycerin (Isosorbide Dinitrate)
    1. Onset: 5 minutes for sublingual (30 minutes oral)
    2. Duration: 1 to 4 hours for sublingual (4-6 hours for oral, 8 hours for sustained release)
  3. Intravenous Nitroglycerin
    1. Onset in 2 minutes
    2. Duration 3 to 5 minutes
  4. Transdermal Nitroglycerin
    1. Peak levels: 30 to 60 minutes
    2. Duration: 12-14 hours per day (until patch removed)
  5. Nitroglycerin Paste (Ointment)
    1. Onset: 1 hour
    2. Duration: 2 to 12 hours
  • Contraindications
  1. Aortic Stenosis
  2. Pulmonary Hypertension
  3. Hypotension
    1. Avoid when systolic Blood Pressure <90 to 100 mmHg or more than 30 mmHg below baseline\
  4. Phosphodiesterase Inhibitor (e.g. Sildenafil, Tadalafil, Vardenafil)
  5. Guanylate Cyclase Simulator (Riociguat)
  6. Right sided Myocardial Infarction (seen with inferior Myocardial Infarction)
  7. Restrictive Cardiomyopathy (or Pericardial Tamponade, constrictive Pericarditis)
  • Mechanism
  1. Relaxes vascular Smooth Muscle
  2. Venous Dilation (more than Nitroprusside)
    1. Inhibits venous return (Preload)
      1. Decreases intra-myocardial wall tension
      2. Decreases intraventricular work
    2. Reduces left ventricular filling pressure
      1. Decreases myocardial oxygen demand
      2. Reduces Myocardial Ischemia
    3. Cardiac Output
      1. Increased in Congestive Heart Failure
      2. Decreased or normal if no Heart Failure
  3. Arterial Dilation (less than Nitroprusside)
    1. Relieves Angina
    2. Dilates large coronary arteries
    3. Antagonizes vasospasm
    4. Increases coronary collateral Blood Flow
      1. Increases perfusion to ischemic Myocardium
    5. Decreases Systemic Vascular Resistance
  4. Esophageal Spasm also responds to nitrates
    1. Pain relief with Nitroglycerin is not always Angina
  • Drug Interactions
  1. Phosphodiesterase Inhibitors (e.g. Sildenafil, Tadalafil, Vardenafil)
    1. Profound hypotensive reaction
    2. Do not use with Nitroglycerin!
    3. Nitrates may be used >24 hours after Sildenafil or vardenafil or >48 hours after Tadalafil
  2. Guanylate Cyclase Simulator (Riociguat)
  3. Tissue Plasminogen Activator (Alteplase, tPA)
    1. IV Nitroglycerin may reduce plasma concentrations
  4. Heparin
    1. IV Nitroglycerin may reduce Anticoagulant response
  • Adverse Effects
  1. Headache
  2. Methemoglobinemia
  3. Hypoxemia (Ventilation-perfusion mismatch)
  4. Hypotension
    1. Risk Factors
      1. Aortic Stenosis
      2. Pulmonary Hypertension
      3. Hypovolemia
      4. PDE5 Inhibitor (e.g. Sildenafil)
      5. Right-sided Myocardial Infarction
    2. Prevention
      1. Administer Intravenous Fluid bolus
      2. Reduce Nitrate dose
      3. Consider Atropine if Bradycardia present
  5. Rebound Tachycardia
  6. Peripheral Edema
  • Safety
  1. Pregnancy Category C
  2. Unknown safety in Lactation
  • References
  1. Orman and Mattu in Herbert (2017) EM:Rap 17(7): 6-7
  2. Olson (2020) Clinical Pharmacology, Medmaster Miami, p. 70-1