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
  • Preparations
  1. Short Acting Nitroglycerin
  2. Long Acting Nitroglycerin
  3. Intravenous Nitroglycerin
  • Indications
  1. Angina Pectoris
  2. Acute Myocardial Infarction
  3. Left Ventricular Failure (Congestive Heart Failure)
  • Contraindications
  1. Aortic Stenosis
  2. Pulmonary Hypertension
  3. Hypotension
  4. Phosphodiesterase Inhibitor (e.g. Viagra)
  5. Right sided Myocardial Infarction (seen with inferior Myocardial Infarction)
  • 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. Viagra or Sildenafil)
    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. Tissue Plasminogen Activator (Alteplase, tPA)
    1. IV Nitroglycerin may reduce plasma concentrations
  3. Heparin
    1. IV Nitroglycerin may reduce Anticoagulant response
  • Adverse Effects
  1. Headache
  2. Hypotension
    1. High risk with Aortic Stenosis, Pulmonary Hypertension, Hypotension, PDE5 Inhibitor, right-sided Myocardial Infarction
    2. Reduce Nitrate dose
    3. Administer Intravenous Fluid bolus
    4. Consider Atropine if Bradycardia present
  3. Methemoglobinemia
  4. Hypoxemia (Ventilation-perfusion mismatch)
  • References
  1. Orman and Mattu in Herbert (2017) EM:Rap 17(7): 6-7