Hypotension: Administration of bretylium tosylate regularly results in postural hypotension,
subjectively recognized by dizziness, light-headedness, vertigo or faintness. Some degree of hypotension is present
in about 50% of patients while they are supine. Hypotension may occur at doses lower than those needed to suppress
Patients should be kept in the supine position until tolerance to the hypotensive effect of bretylium develops.
Tolerance occurs unpredictably but may be present after several days.
Patients over 65 years may be at increased risk of developing orthostatic hypotension, especially when the
recommended rate of intravenous infusion is exceeded.
Hypotension with supine systolic pressure greater than 75 mm Hg need not be treated unless there are associated
symptoms. If supine systolic pressure falls below 75 mm Hg, an infusion of dopamine or norepinephrine may be used to
raise blood pressure. When catecholamines are administered, a dilute solution should be employed and blood pressure
monitored dosely because the pressor effects of the catecholamines are enhanced by bretylium. Volume expansion with
blood or plasma and correction of dehydration should be carried out where appropriate.
Transient hypertension and increased frequency of arrhythmias: Due to the initial release of
norepinephrine from adrenergic postganglionic nerve terminals by bretylium, transient hypertension or increased
frequency of premature ventricular contractions and other arrhythmias may occur in some patients.
Caution during use with digitalis glycosides: The initial release of norepinephrine caused by
bretylium may aggravate digitalis toxicity. When a life-threatening cardiac arrhythmia occurs in a digitalized
patient, bretylium should be used only if the etiology of the arrhythmia does not appear to be digitalis toxicity and
other antiarrhythmic drugs are not effective. Simultaneous initiation of therapy with digitalis glycosides and
bretylium should be avoided.
Patients with fixed cardiac output: In patients with fixed cardiac output (i.e., severe aortic
stenosis or severe pulmonary hypertension) bretylium should be avoided since severe hypotension may result from a
fall in peripheral resistance without a compensatory increase in cardiac output. If survival is threatened by the
arrhythmia, bretylium tosylate may be used but vasoconstrictive catecholamines should be given promptly if severe
Hyperthermia: In a small number of patients, hyperthermia, characterized by temperature in excess of
106°F, has been reported in association with bretylium tosylate administration. Temperature rise can begin within
one hour or later after administration of drug, and reach a peak within 1 to 3 days. If hyperthermia is suspected or
diagnosed, bretylium should be discontinued and appropriate treatment instituted immediately.