Isoprenaline Other names: N-Isopropylnorepinephrine N-Isopropylnoradrenaline L-Isopropylnoradrenaline Isoproterenol Isopropylnorepinephrine Isopropylnoradrenaline Isopropylarterenol Isopropyladrenaline Isopropydrin Isoprenaline Epinephrine Isopropyl Homolog

Concurrent use may increase the cardiovascular effects of either the other sympathomimetics or isoprenaline and phenylephrine and the potential for side effects.

Concurrent use may potentiate cardiovascular effects of isoprenaline and phenylephrine, possibly resulting in arrhythmias, tachycardia or severe hypertension or hyperpyrexia.

Concurrent use with isoprenaline and phenylephrine may increase the risk of cardiac arrhythmias; caution and electrocardiographic monitoring are very important if concurrent use is necessary.

Concurrent use with isoprenaline and phenylephrine may reduce the antianginal effects of these medications.

Concurrent use with isoprenaline may result in mutual inhibition of therapeutic effects; beta-blockade may antagonise beta-2-adrenergic bronchodilating effects of isoprenaline; use of a cardioselective beta-2-adrenergic blocker, such as acebutolol, atenolol, or metoprolol, at low doses may reduce antagonism of the bronchodilating effect.

Concurrent use may increase the effects of either these medications or isoprenaline and phenylephrine; thyroid hormones enhance risk of coronary insufficiency when sympathomimetic agents are administered to patients with coronary artery disease; dosage adjustment is recommended, although problem is reduced in euthyroid patients.

Isoprenaline should be used with caution, if at all, when potent inhalational anaesthetics such as halothane and cyclopropane are employed because of potential to sensitise the myocardium to effects of sympathomimetic amines.

Concurrent use with isoprenaline may result in additive CNS stimulation to excessive levels, which may cause unwanted effects such as nervousness, irritability, insomnia, or possibly convulsions or cardiac arrhythmias; close observation is recommended.

Caution should be maintained when using continuous intravenous isoprenaline infusions in conjunction with intravenous methyl xanthines (aminophylline, theophylline) and intravenous corticosteroids. The use of isoprenaline with aminophylline and corticosteroids may be additive in cardiotoxic properties and can lead to myocardial necrosis and death. Severe cardiac symptoms of sympathetic overactivation i.e. hypertension, tachycardia, arrhythmias, seizures, myocardial ischaemia, and fatal myocardial necrosis, have been reported.

Isoprenaline should not be used with chlorpromazine or monoamine oxidase inhibitors since the effects of isoprenaline may be magnified.

Isoprenaline and adrenaline should not be administered simultaneously because both medicines are direct cardiac stimulants and their combined effects may induce serious arrhythmias. The medicines may, however, be administered alternately provided a proper interval has elapsed between doses.

Concurrent use with isoprenaline and phenylephrine may increase the possibility of cardiac arrhythmias; dosage reduction of the sympathomimetic is recommended.

Particular caution is necessary in administering isoprenaline injection to the elderly and patients with coronary insufficient, ischaemic heart disease, hypertension, aneurysms, diabetes or hyperthyroidism, and in patients sensitive to sympathomimetic amines.

Care is required when sympathomimetic agents are given to patients with diabetes mellitus or closed angle glaucoma.

Category A.

Medicines which have been taken by a large number of pregnant women of childbearing age without any proven increase in the frequency of malformation or other direct or indirect harmful effects on the foetus having been observed.

There has been no clinical evidence of teratogenic effects attributable to Isuprel in more than 25 years use of the medicine. Isoprenaline may delay the second stage of labour by inhibiting contraction of the uterus. However, before administration of any medicine to pregnant or lactating women, or women of childbearing potential, the expected benefit of the medicine should be carefully weighed against the possible risk to the mother or child.

It is unknown whether isoprenaline hydrochloride is excreted into breast milk. Caution should be exercised in administering to a nursing mother.

Fertility

No data available.

No data available.

Serious effects to isoprenaline are infrequent. The following effects, however, have been reported:

CNS: Nervousness, headache, dizziness, restlessness, tension, fear of excitement, and rarely, nausea, vomiting, tinnitus, light headedness and asthenia.

Cardiovascular: Tachycardia, palpitations, angina, Adams-Stokes attacks, hypertension, hypotension, ventricular arrhythmias, tachyarrhythmias and pulmonary oedema. In a few patients, presumably with organic disease of the AV node and its branches, isoprenaline hydrochloride injection has been reported to precipitate Adams-Stokes seizures during normal sinus rhythm or transient heart block.

Other: Hot flashes, flushing of the skin, sweating, mild tremors, weakness.

These effects disappear quickly and usually do not require discontinuation of treatment with isoprenaline. No cumulative effects have been reported. Pulmonary oedema has been reported in a patient extremely intolerant to all sympathomimetic drugs.

The following effects to isoprenaline hydrochloride have been reported in healthy adult controls undergoing upright tilt testing:

^* P=0.03 (difference between patients vs. controls)