bretylium (Bretylol, Ornido)
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Introduction
Tradename: Bretylol. Class III antiarrhythmic agent.
Indications
- formerly used as second line agent for treatment of life-threatening ventricular arrhythmias NOT responding to lidocaine (no longer used in ACLS protocols)
Contraindications
- digitalis-induced arrhythmias
Dosage
- initial dose 5 mg/kg IV.
- repeat dose 10 mg/kg, max 35 mg.
- infusion 500 mg in 50 mL D5W (10 mg/mL) at 1-3 mg/min (7-21 mL/hr)
Dosage adjustment in renal failure
Table
| creatinine clearance | dosage |
|---|---|
| 10-50 mL/min | 25-50% of dose |
| < 10 mL | avoid use |
Pharmacokinetics
- onset of action is 5-10 minutes
- may be delayed up to 20-60 minutes
- duration of action: 6-12 hours
elimination via kidney 80 %
elimination via liver 20 %
protein binding = 0-8 %
elimination by hemodialysis = +
Adverse effects
- common (> 10%)
- less common (1-10%)
- uncommon (< 1%)
- transient hypertension, PVCs, bradycardia, flushing, nasal congestion, vertigo, syncope, confusion, rash, diarrhea, abdominal pain, muscle atrophy & necrosis with repeated IM injections at the same site, conjunctivitis, renal impairment, hyperthermia, hiccups, respiratory depression, angina
- other
- parotid pain & swelling
- emotional liability
- proarrhythmic affects resulting from initial elaboration of catecholamines
Drug interactions
- enhances pressor effects of catecholamines
- may aggravate digoxin-induced tachyarrhythmias
- tricyclic antidepressants (TCA) may inhibit bretylium uptake by the myocardium
Laboratory
Mechanism of action
- inhibits catecholamine release resulting in catecholamine depletion
- results in initial increase in blood pressure, heart rate & myocardial contractility, followed by hypotension
- blocks K+ channels
- prolongs action potential duration
- increases refractory period in Purkinje fibers & ventricular muscle
More general terms
References
- ↑ The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
- ↑ Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (ed), Companion Handbook, McGraw Hill, NY, 1994
- ↑ Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 161
- ↑ Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998 - not on National VA formulary
- ↑ Kaiser Permanente Northern California Regional Drug Formulary, 1998
- ↑ Clinical Guide to Laboratory Tests, 3rd ed. Teitz ed., W.B. Saunders, 1995