Classifications: antiarrhythmic, class iii; Therapeutic: antiarrhythmic, class iii
Pregnancy Category: C
2 mg/mL, 4 mg/mL, 50 mg/mL injection
Suppresses ventricular fibrillation by direct action on the myocardium and ventricular tachycardia by adrenergic blockade.
Shortly after administration, norepinephrine is released from adrenergic postganglionic nerve terminals, resulting in a moderate
increase in BP, heart rate, and ventricular irritability. Subsequently (12 h), drug-induced release and reuptake of
norepinephrine are blocked, leading to a state resembling surgical sympathectomy.
Suppresses arrhythmias with a reentry mechanism and decreases dispersion of ectopic foci. PR, QT, and QRS intervals are
unchanged. Because onset of desired action is delayed, bretylium is not a first-line antiarrhythmic agent.
Short-term prophylaxis and treatment of ventricular fibrillation; life-threatening arrhythmias such as ventricular fibrillation
not responsive to conventional therapy [e.g., lidocaine, procainamide, direct current (cardioversion)].
No contraindications for use in life-threatening refractory ventricular arrhythmias; digitalis toxicity; pregnancy (category
Digitalis-induced arrhythmias, patients with fixed cardiac output (e.g., severe aortic stenosis or severe pulmonary hypertension
because profound hypotension may result), sinus bradycardia, patients on digitalis maintenance, angina pectoris, impaired
renal function, renal disease; lactation.
Route & Dosage
Adult: IV 5 mg/kg rapid IV injection, may increase to 10 mg/kg and repeat q1530 min (max: 30 mg/kg/d); may also give by continuous
infusion at 12 mg/min IM 510 mg/kg, may repeat in 1 2 h if arrhythmia persists, then 510 mg/kg q68h for maintenance
Child: IV 5 mg/kg, may repeat 1530min (max: 30 mg/kg) IM 25 mg/kg as single dose
Limit use to patients in facilities adequately equipped and staffed for constant monitoring of ECG and BP and for cardiovascular/pulmonary
resuscitation and cardioversion.
- Administer no more than 5 mL in any one IM site.
- Keep a record of injection sites. Injection into same site can cause muscle atrophy, necrosis, and fibrosis.
- IV administration to infants and children: Verify correct IV concentration and rate of infusion/injection with physician.
PREPARE: Direct: Give undiluted. Intermittent: Give diluted in 50 mL or more of NS or D5W.
ADMINISTER: Direct: Give undiluted at a rate of 1 dose/15 seconds. Intermittent: Give diluted at a rate of 12 mg/min.
INCOMPATIBILITIES Solution/additive: Dobutamine, pantoprazole phenytoin, procainamide. Y-site: Amphotericin B, cholestryl, propofol, warfarin.
- Store at 15°30° C (59°86° F) unless otherwise directed.
Adverse Effects (≥1%)CV:
Both supine and postural hypotension
with dizziness, vertigo, lightheadedness, faintness, syncope, transitory hypertension, bradycardia, increased frequency
of PVCs, exacerbation of digitalis-induced arrhythmias. GI: Nausea, vomiting
(particularly with rapid IV
Diagnostic Test Interference
Urinary VMA, epinephrine, and norepinephrine levels may be decreased during bretylium therapy.
InteractionsDrug: Lidocaine, procainamide, quinidine, propranolol
may antagonize antiarrhythmic effects and compound hypotension; antihypertensive agents
will add to hypotensive effects; digitalis glycosides
may worsen arrhythmias through digitalis toxicity
increase the risk of arrhythmias.
Minutes after IV
; up to 6 h IM. Peak:
69 h. Duration:
624 h. Distribution:
Does not cross bloodbrain barrier; not known if crosses placenta or distributed into breast milk. Metabolism:
Not metabolized. Elimination:
7080% in urine in 24 h. Half-Life:
Assessment & Drug Effects
- Anticipate vomiting. IV administration is associated with a high incidence of nausea and vomiting. These side effects can
be minimized by slow administration of drug (≥10 min).
- Establish baseline readings and monitor BP and ECG when drug is administered. Observe for initial transient rise in BP,
increased heart rate, PVCs and other arrhythmias, or worsening of existing arrhythmias, which may occur within a few minutes
to 1 h after drug administration. Keep physician informed. Initial effect of hypertension is usually followed within 1 h
by a fall in supine BP and by orthostatic hypotension.
- Use supine position until patient develops tolerance to hypotensive effect of bretylium (generally in several days). Hypotension
can occur in the supine position, particularly in patients with severely compromised cardiac function. It may not readily
respond to therapy (e.g., vasopressors, fluids); early reporting is essential.
- Raise or lower head of bed slowly; advise patient to make position changes slowly in order to prevent orthostatic hypotension.
- Monitor I&O, particularly in patients with impaired renal function.
Patient & Family Education
- Make position changes slowly. If allowed to be out of bed, dangle legs for a few minutes before standing, but do not stand
still for prolonged periods. Men should sit on toilet to urinate.