Isoprenaline Macure (Isoprenaline Hydrochloride)

Isoprenaline acts on the cardiovascular and respiratory systems to correct rhythm and airway problems.

• Bradycardia: raises heart rate to maintain adequate cardiac output.
• Heart block: improves atrioventricular conduction and stabilises rhythm.
• Hypotension: enhances cardiac contractility and peripheral resistance to raise blood pressure.
• Asthma: relaxes bronchial smooth muscle to relieve airway obstruction.
• COPD: provides bronchodilation for acute exacerbations.

• Isoprenaline binds to both beta‑1 and beta‑2 adrenergic receptors, activating adenylate cyclase and increasing intracellular cyclic AMP. The rise in cAMP enhances calcium influx in cardiac myocytes, producing positive chronotropic and inotropic effects, while in bronchial smooth muscle it promotes relaxation, resulting in bronchodilation.

Isoprenaline may cause a range of adverse reactions that vary with dose and patient condition.

Common Side Effects

• Tachycardia: rapid heart rate exceeding therapeutic goals.
• Palpitations: awareness of heart beating fast or irregularly.
• Tremor: fine muscle shaking, especially in the hands.
• Headache: mild to moderate pain often related to vascular changes.
• Nausea: upset stomach that may accompany rapid heart activity.

Serious or Rare Side Effects

• Arrhythmias: potentially life‑threatening irregular heart rhythms.
• Myocardial ischemia: reduced blood flow to heart muscle due to increased demand.
• Severe hypotension: sudden drop in blood pressure leading to dizziness or shock.
• Pulmonary edema: fluid accumulation in lungs causing breathlessness.
• Anaphylactic reaction: rare severe allergy with airway compromise.
• Severe bronchospasm: paradoxical narrowing of airways despite beta‑2 stimulation.

Careful monitoring and patient assessment are essential when using Isoprenaline.

• Cardiac monitoring: observe heart rate and rhythm continuously during infusion.
• Blood pressure monitoring: watch for hypertension or excessive hypotension.
• Use with caution in ischemic heart disease: increased myocardial oxygen demand may precipitate angina.
• Avoid in severe arrhythmias: drug may exacerbate existing rhythm disturbances.
• Review concomitant medications: beta‑blockers can blunt therapeutic effect.
• Store at ambient temperature: keep in original container, protect from light and moisture.

Isoprenaline can interact with several drug classes, requiring attention to avoid reduced efficacy or heightened risk.

Major Interactions (Avoid)

• Beta‑blockers: antagonize beta‑adrenergic stimulation, diminishing therapeutic response.
• Calcium channel blockers (verapamil, diltiazem): may cause profound bradycardia or AV block when combined.
• Monoamine oxidase inhibitors: increase risk of hypertensive episodes.

Moderate Interactions (Monitor Closely)

• Diuretics: can amplify hypotensive effects, requiring blood pressure checks.
• Digitalis glycosides: raise the likelihood of arrhythmias due to combined cardiac effects.
• Theophylline: may enhance bronchodilator action, leading to excessive tachycardia.