- Isoproterenol (also known as Isoprenaline) is a synthetic non-selective beta-adrenergic agonist used primarily as a bronchodilator and cardiac stimulant.
- It mimics the effects of the sympathetic nervous system by stimulating β1 and β2 adrenergic receptors, leading to increased heart rate (positive chronotropic effect).
Chemical Structure & Formula
- Chemical Formula: C₁₁H₁₇NO₃
- Structure:
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Mechanism of Action (Detailed)
- Isoproterenol is a non-selective β-adrenergic agonist (stimulates both β1 and β2 receptors).
- β1 Activation: Increases heart rate & cardiac contractility → Increased cardiac output.
- β2 Activation: Causes vasodilation & bronchodilation → Decreased blood pressure & airway relaxation.
Physiological Effects
-
Cardiovascular:
- Increases heart rate (β1).
- Decreases peripheral vascular resistance (β2-mediated vasodilation).
- Decreases mean arterial pressure (due to vasodilation).
-
Respiratory:
- Relaxes bronchial smooth muscle (β2 effect → bronchodilation).
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Side Effects of Isoproterenol
- Tachycardia & Arrhythmias
- Hypotension (due to β2-mediated vasodilation)
- Palpitations & Tremors
- Flushing & Headache
Clinical Uses of Isoproterenol
- Bradycardia & Heart block (used in emergencies to increase HR).
- Bronchospasm (previously used for asthma but now replaced by selective β2 agonists like salbutamol).
- Cardiac arrest (temporary use) – Stimulates heart during asystole.
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