PharmaceuticalSympathomimeticBeta agonist (non-selective)Catecholamine

Isoproterenol (Isoprenaline)

Also known as Isoprenaline · Isuprel

Written by enwyReviewed 15 Jul 20261 sources0 comments

Isoproterenol is a non-selective beta-adrenergic agonist (beta-1 and beta-2) used clinically as an intravenous drug for bradycardia, heart block and certain diagnostic tests. Its strong beta-1 cardiac stimulation makes it potent but hazardous, and it has essentially no role as a physique or fat-loss drug because its cardiovascular effects dominate and it is not orally bioavailable in a useful way.

01 Overview

Isoproterenol (isoprenaline) is a synthetic catecholamine that stimulates both beta-1 and beta-2 receptors with little alpha activity. Beta-1 stimulation increases heart rate, contractility and conduction; beta-2 stimulation causes bronchodilation and vasodilation. It is given intravenously in hospital settings to raise heart rate in bradyarrhythmias, to support certain types of heart block, and in electrophysiology and tilt-table testing.

Because it is non-selective and strongly chronotropic, isoproterenol markedly raises myocardial oxygen demand and can provoke arrhythmias and ischaemia. It has no meaningful use as a thermogenic or cutting agent: the beta-1 cardiac effects that would accompany any systemic dose make it dangerous, and it is administered under monitoring by infusion, not taken recreationally.

02 Mechanism

Non-selective beta-adrenergic agonist stimulating beta-1 (cardiac chronotropy, inotropy, conduction) and beta-2 (bronchodilation, vasodilation) receptors, raising cyclic AMP. Strong beta-1 activity dominates its clinical and toxic profile.

03 Dosing

Tier	Dose	Route	Notes
Bradycardia infusion	2–10 mcg	IV	2-10 mcg/min titrated infusion for symptomatic bradycardia or heart block, under continuous monitoring.

04 Effects

Effect	Magnitude	Evidence
Increased heart rate and conductionRaises heart rate and improves conduction in bradyarrhythmias and heart block.	strong chronotropy	Clinical
Bronchodilation and vasodilationRelaxes bronchial and vascular smooth muscle; peripheral vasodilation can lower diastolic pressure.	beta-2 mediated	Clinical

05 Side effects

Effect	Severity	Frequency	Evidence	Countermeasures
Arrhythmia and myocardial ischaemiaStrong beta-1 stimulation raises myocardial oxygen demand, provoking tachyarrhythmias and ischaemia, especially in coronary disease.	Severe	Dose-dependent	Clinical
Palpitations and tremorPalpitations, tremor, flushing and anxiety from combined beta-1 and beta-2 stimulation.	Moderate	Very common	Clinical

06 Legal status

United States

Prescription drug (hospital use)

FDA-approved parenteral drug (Isuprel) for bradyarrhythmias; not available for outpatient or physique use. · as of Jan 2026

07 References

Isoproterenol — clinical pharmacologyStatPearls / NCBI Bookshelf

08 Discussion0 comments

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This page is reference information, not medical advice. Doses and protocols are documented as they appear in the clinical literature and in practice — describing them is not a recommendation to use them. Countermeasures listed here are not a substitute for a physician. Legal status varies by jurisdiction and changes.