Inderal (propranolol hydrochloride) is a non-selective beta-adrenergic blocking agent, representing a cornerstone in therapeutic regimens for a range of cardiovascular and neurological conditions. As a first-generation beta-blocker, its mechanism of action involves competitive antagonism of catecholamines at both β₁- and β₂-adrenergic receptor sites. This comprehensive blockade underpins its efficacy in managing hypertension, angina pectoris, cardiac arrhythmias, myocardial infarction prophylaxis, essential tremor, and migraine headache prophylaxis. Its established pharmacokinetic profile and extensive clinical history make it a trusted option for physicians seeking to modulate sympathetic nervous system overactivity. This product card provides a detailed, expert-level overview for healthcare professionals.

Features

• Active Pharmaceutical Ingredient: Propranolol Hydrochloride.
• Pharmacological Class: Non-selective Beta-Adrenergic Blocking Agent.
• Available Formulations: Immediate-release tablets (10 mg, 20 mg, 40 mg, 60 mg, 80 mg) and sustained-release capsules (60 mg, 80 mg, 120 mg, 160 mg).
• Mechanism of Action: Competitively blocks catecholamine effects at β-adrenoceptors, leading to decreased heart rate, reduced myocardial contractility, slowed AV conduction, and decreased blood pressure.
• Bioavailability: Approximately 25% for oral formulations due to significant first-pass metabolism.
• Protein Binding: Heavily bound to plasma proteins (90%).
• Half-Life: Elimination half-life is 3 to 6 hours for immediate-release; sustained-release extends the duration of action.
• Metabolism: Primarily hepatic via CYP2D6 and CYP1A2 isoenzymes.
• Excretion: Predominantly renal as metabolites.

Benefits

• Provides effective control of hypertension by reducing cardiac output and peripheral resistance.
• Decreases the frequency and severity of anginal attacks by lowering myocardial oxygen demand.
• Offers prophylactic management for migraine headaches, reducing their incidence and severity.
• Effectively manages symptomatic control of essential tremor, improving fine motor tasks and quality of life.
• Provides rate control in various tachyarrhythmias, including sinus tachycardia and atrial fibrillation.
• Improves long-term survival post-myocardial infarction by reducing cardiac workload and the risk of reinfarction.

Common use

Inderal is indicated for the management of hypertension, either as monotherapy or in combination with other antihypertensive agents. It is used for the prophylaxis of angina pectoris and for the long-term treatment of patients who have survived the acute phase of a myocardial infarction to reduce cardiovascular mortality. It is also indicated for the control of supraventricular, ventricular, and atrial tachyarrhythmias. Furthermore, it is approved for the prophylaxis of common migraine headaches and for the symptomatic treatment of essential tremor.

Dosage and direction

Dosage is highly individualized and must be titrated based on patient response and the condition being treated. It is typically administered in divided doses (BID or TID) for immediate-release tablets, or once daily for sustained-release capsules.

• Hypertension: Initial dose often starts at 40 mg IR twice daily, with a usual maintenance range of 120-240 mg per day in divided doses. Maximum dose may extend to 640 mg/day in some cases.
• Angina Pectoris: Starting dose is 80 mg IR daily in divided doses, with a usual effective dose ranging from 160-240 mg per day.
• Arrhythmias: 10-30 mg IR three or four times daily, before meals and at bedtime.
• MI Prophylaxis: 180-240 mg IR per day in divided doses (BID or TID).
• Migraine Prophylaxis: Initial dose of 80 mg IR per day in divided doses. The usual effective dose range is 160-240 mg per day.
• Essential Tremor: Starting dose is 40 mg IR twice daily, with a usual maintenance dose of 120-320 mg daily in divided doses.

Administration Note: Sustained-release capsules must be swallowed whole and not crushed or chewed. Abrupt withdrawal of therapy should be avoided; dosage should be tapered gradually over a period of 1-2 weeks under physician supervision.

Precautions

Inderal requires careful patient assessment and monitoring. It can mask the tachycardic signs of hypoglycemia in diabetic patients and may potentiate insulin-induced hypoglycemia. It can also mask clinical signs of hyperthyroidism, such as tachycardia. Caution is advised in patients with compensated heart failure, as it may further depress myocardial contractility. Hepatic or renal impairment may necessitate dosage adjustments. Patients should be advised that Inderal can cause fatigue, dizziness, and light-headedness, which can impair the ability to operate machinery or drive. Periodic monitoring of heart rate, blood pressure, and, when applicable, blood glucose is recommended.

Contraindications

Inderal is contraindicated in patients with:

• Cardiogenic shock.
• Sinus bradycardia and greater than first-degree heart block.
• Bronchial asthma or a history of bronchospasm.
• Overt cardiac failure (unless the failure is secondary to a tachyarrhythmia treatable with propranolol).
• Hypersensitivity to propranolol hydrochloride or any component of the formulation.
• Severe peripheral arterial circulatory disorders.

Possible side effect

Adverse reactions are generally dose-dependent and often related to the pharmacological effects of beta-blockade.

• Cardiovascular: Bradycardia, congestive heart failure, intensification of AV block, hypotension, peripheral ischemia, cold extremities, Raynaud’s phenomenon.
• Central Nervous System: Lightheadedness, mental depression, insomnia, fatigue, lethargy, vivid dreams, hallucinations.
• Respiratory: Bronchospasm, dyspnea, wheezing (especially in predisposed patients).
• Gastrointestinal: Nausea, vomiting, epigastric distress, abdominal cramping, diarrhea, constipation.
• Dermatological: Alopecia, psoriasis-like eruptions, skin rashes.
• Other: Impotence or decreased libido, agranulocytosis, thrombocytopenic purpura, elevated blood urea levels.

Drug interaction

Inderal has a significant potential for pharmacokinetic and pharmacynamic interactions.

• CYP2D6/CYP1A2 Inhibitors (e.g., Fluoxetine, Paroxetine, Cimetidine, Fluvoxamine): Can increase propranolol plasma concentrations, potentiating its effects.
• Other Antihypertensives (e.g., Diuretics, ACE inhibitors, Alpha-blockers): May have an additive hypotensive effect.
• Calcium Channel Blockers (e.g., Verapamil, Diltiazem): Concomitant use can lead to additive negative effects on heart rate, AV conduction, and contractility; risk of severe bradycardia and heart failure.
• Digoxin: Additive effects on AV conduction can lead to bradycardia.
• Sympathomimetics (e.g., Epinephrine, Isoproterenol): Propranolol may blunt the positive inotropic and bronchodilator effects while potentiating the vasoconstrictor effects, leading to severe hypertension and bradycardia.
• Insulin/Oral Hypoglycemics: Can enhance hypoglycemic effect and mask warning signs (tachycardia).
• Warfarin: May increase warfarin concentrations and prolong prothrombin time.
• Theophylline: Propranolol may antagonize the bronchodilator effect of theophylline.

Missed dose

If a dose is missed, it should be taken as soon as remembered. However, if it is almost time for the next scheduled dose, the missed dose should be skipped. The patient should not double the dose to make up for the missed one. Maintaining a consistent dosing schedule is crucial for stable therapeutic effect.

Overdose

Symptoms of overdose are primarily extensions of its beta-blocking activity and can be severe and life-threatening. They include:

• Severe bradycardia
• Congestive heart failure
• Hypotension (often profound)
• Bronchospasm
• Hypoglycemia
• Seizures (especially in patients with epilepsy)
• Coma

Management: Treatment is primarily supportive and symptomatic. Gastric lavage may be considered if ingestion was recent. Atropine can be administered for bradycardia. Beta-adrenergic agonists like isoproterenol, dobutamine, or levarterenol may be used to reverse cardiovascular depression. In refractory cases, glucagon has been shown to be effective. Cardiac pacing may be required. Hemodialysis is not effective due to high protein binding.

Storage

Store at controlled room temperature, 20°C to 25°C (68°F to 77°F). Protect from light, moisture, and excessive heat. Keep the container tightly closed. Keep out of reach of children and pets. Do not use after the expiration date printed on the packaging.

Disclaimer

This information is intended for educational and informational purposes only for healthcare professionals and is not a substitute for professional medical advice, diagnosis, or treatment. The prescribing physician remains solely responsible for determining the appropriate diagnosis and treatment for their patient, including drug selection, dosage, and monitoring. Always consult official prescribing information and other authoritative sources before administering any medication.

Reviews

“Inderal remains a fundamental tool in our therapeutic arsenal. Its versatility across cardiovascular and neurological indications is unmatched by many newer agents. While its non-selectivity requires vigilance, particularly in patients with reactive airways, its efficacy in managing tremor and migraine prophylaxis is exceptional.” – Cardiologist, 15 years experience.

“As a neurologist, I frequently prescribe Inderal for essential tremor. The improvement in patients’ quality of life and functional ability is often dramatic. The key is careful dose titration to maximize benefit while minimizing side effects like fatigue.” – Neurologist, 10 years experience.

“For long-term secondary prevention post-MI, propranolol’s mortality benefit is well-documented in clinical trials. It’s a classic for a reason, providing robust cardioprotection through its hemodynamic effects.” – Clinical Pharmacologist.