Isoprenaline

Mechanism :

Isoprenaline is a synthetic sympathomimetic amine that is structurally related to epinephrine but acts almost exclusively on beta receptors. Isoproterenol is a potent nonselective beta-adrenergic agonist with very low affinity for alpha-adrenergic receptors. Intravenous infusion lowers peripheral vascular resistance, primarily in skeletal muscle but also in renal and mesenteric vascular beds. Diastolic pressure falls. Renal blood flow is decreased in normotensive subjects but is increased markedly in shock. Systolic blood pressure may remain unchanged or rise, although mean arterial pressure typically falls.

Indication :

• Bradycardia in postoperative cardiac patients
• Cardiac Arrest
• Heart Block
• Adam-Stokes Attacks

Contraindications :

Use of isoproterenol hydrochloride injection is contraindicated in patients with tachyarrhythmias; tachycardia or heart block caused by digitalis intoxication; ventricular arrhythmias which require inotropic therapy; and angina pectoris. Use with caution in patients with hyperthyroidism or diabetes.

Dosing :

Adverse Effect :

Dyspnea, nervousness, dizziness, headache, angina, pulmonary edema, palpitations, hypotension, hypertension, tachyarrhythmia, ventricular arrhythmias, flushing of the skin, sweating, mild tremors, weakness.

Interaction :

Epinephrine: Isoproterenol and epinephrine should not be administered simultaneously because both drugs are direct cardiac stimulants and their combined effects may induce serious arrhythmias.
Halothane: Sensitize the myocardium to effects of sympathomimetic amines.

Hepatic Dose :