Isoproterenol hydrochloride injection should generally be
started at the lowest recommended dose. This may be gradually increased if
necessary while carefully monitoring the patient. Doses sufficient to increase
the heart rate to more than 130 beats per minute may increase the likelihood of
inducing ventricular arrhythmias. Such increases in heart rate will also tend
to increase cardiac work and oxygen requirements which may adversely affect the
failing heart or the heart with a significant degree of arteriosclerosis.
Adequate filling of the intravascular compartment by
suitable volume expanders is of primary importance in most cases of shock and
should precede the administration of vasoactive drugs. In patients with normal cardiac
function, determination of central venous pressure is a reliable guide during
volume replacement. If evidence of hypoperfusion persists after adequate volume
replacement, isoproterenol hydrochloride injection may be given.
In addition to the routine monitoring of systemic blood
pressure, heart rate, urine flow, and the electrocardiograph, monitor the
response to therapy by frequent determination of the central venous pressure
and blood gases. Closely observe patients in shock during isoproterenol
hydrochloride injection administration. If the heart rate exceeds 110 beats per
minute, it may be advisable to decrease the infusion rate or temporarily
discontinue the infusion. Determinations of cardiac output and circulation time
may also be helpful. Take appropriate measures to ensure adequate ventilation.
Pay attention to acid-base balance and to the correction of electrolyte
Carcinogenesis, Mutagenesis, Impairment of Fertility
Long-term studies in animals to evaluate the carcinogenic
potential of isoproterenol hydrochloride have not been done. Mutagenic
potential and effect on fertility have not been determined. There is no
evidence from human experience that isoproterenol hydrochloride injection may
be carcinogenic or mutagenic or that it impairs fertility.
Pregnancy Category C
Animal reproduction studies have not been conducted with
isoproterenol hydrochloride. It is also not known whether isoproterenol
hydrochloride can cause fetal harm when administered to a pregnant woman or can
affect reproduction capacity. Isoproterenol hydrochloride should be given to a
pregnant woman only if clearly needed.
It is not known whether this drug is excreted in human
milk. Because many drugs are excreted in human milk, caution should be
exercised when isoproterenol hydrochloride injection is administered to a
Safety and efficacy of isoproterenol in pediatric
patients have not been established.
Intravenous infusions of isoproterenol in refractory
asthmatic children at rates of 0.05-2.7 mcg/kg/min have caused clinical
deterioration, myocardial necrosis, congestive heart failure and death. The
risks of cardiac toxicity appear to be increased by some factors [acidosis,
hypoxemia, coadministration of corticosteroids, coadministration of
methylxanthines (theophylline, theobromine) or aminophylline] that are
especially likely to be present in these patients. If I.V. isoproterenol is
used in children with refractory asthma, patient monitoring must include
continuous assessment of vital signs, frequent electrocardiography, and daily
measurements of cardiac enzymes, including CPK-MB.
Clinical studies of Isuprel did not include sufficient
numbers of subjects aged 65 and over to determine whether they respond
differently from younger subjects in clinical circumstances. There are,
however, some data that suggest that elderly healthy or hypertensive patients
are less responsive to beta-adrenergic stimulation than are younger subjects.
In general, dose selection for elderly patients should usually start at the low
end of the dosing range, reflecting the greater frequency of decreased hepatic,
renal or cardiac function and of concomitant diseases or other drug therapy.