Pharm

Bretylium

search

Bretylium

  • Indications
  1. Refractory Ventricular Fibrillation
  2. Refractory Ventricular Tachycardia
  3. Not a first line drug, use only after failed use of:
    1. Electrical cardioversion
    2. Epinephrine
    3. Lidocaine
  4. New ACLS Guidelines (2000) do not refer to Bretylium
    1. Natural Bretylium sources exhausted
    2. Severe adverse effects (Hypotension)
  • Mechanism
  1. Background
    1. Adrenergic Neuronal blocking drug
    2. Originally used as an antihypertensive in 1950s
  2. Adrenergic Effects (Biphasic) in non-Cardiac Arrest
    1. Initial (Lasts first 20 minutes after dose)
      1. Stimulates Norepinephrine release
      2. Results in Hypertension and Tachycardia
    2. Subsequent (begins at 20 min and peaks at 60 min)
      1. Inhibits Norepinephrine release
      2. Results in Hypotension
  3. Effects on Fibrillation and Defibrillation
    1. Increases Ventricular Fibrillation threshold
      1. Lidocaine also increases fibrillation threshold
    2. Does not increase Defibrillation threshold
      1. Lidocaine does increase Defibrillation threshold
    3. Synergistic response when used with Lidocaine
  • Dose
  1. General
    1. Administer as rapid IV push
    2. Flush the IV line with saline immediately after bolus
  2. Pediatrics and Adult
    1. Initial: 5 mg/kg rapid IV push
    2. Subsequent: 10 mg/kg rapid IV push
      1. May be repeated every 5-20 min up to twice
      2. Max total dose of 35 mg/kg
  • Adverse Effects
  1. Postural Hypotension (non-Cardiac Arrest patient)
    1. Seen in 60% of patients
    2. Arterial Pressure usually falls less than 20 mmHg
    3. Treatment of symptomatic Hypotension
      1. Trendelenburg's position
      2. Vasopressors (e.g. Norepinephrine) rarely needed
  2. Initial transient effects
    1. Nausea or Vomiting
    2. Hypertension
    3. Tachycardia
  • Precautions
  1. May exacerbate Digitalis Toxicity!
    1. Occurs with Bretylium mediated Catecholamine release
  • References
  1. (2000) Circulation 102(suppl I): 86-89
  2. Katzung (1989) Pharmacology, Lange, p. 179