Inderal

Inderal (propranolol hydrochloride) is a non-selective beta-adrenergic blocking agent with a well-established clinical profile spanning over five decades. As a foundational therapy in the beta-blocker class, it exerts its primary therapeutic effects by competitively blocking catecholamine-induced stimulation of β1- and β2-adrenergic receptors. This mechanism underpins its efficacy in managing a spectrum of conditions, from hypertension and angina pectoris to essential tremor and migraine prophylaxis. Its utility extends to the management of certain cardiac arrhythmias, hypertrophic subaortic stenosis, and adjunctive therapy in pheochromocytoma. The drug is available in immediate-release and long-acting formulations, allowing for tailored therapeutic regimens based on individual patient needs and specific indications.

Features

• Active Ingredient: Propranolol Hydrochloride
• Drug Class: Non-selective Beta-Adrenergic Blocking Agent
• Available Formulations: Immediate-release tablets (10 mg, 20 mg, 40 mg, 60 mg, 80 mg) and Long-acting capsules (60 mg, 80 mg, 120 mg, 160 mg)
• Pharmacokinetics: High lipid solubility; extensive first-pass metabolism; approximately 90% protein binding
• Half-life: Immediate-release: 3–6 hours; Long-acting: 8–11 hours
• Bioavailability: Approximately 25% due to significant hepatic metabolism
• Excretion: Primarily renal (as metabolites)

Benefits

• Provides reliable reduction in blood pressure through decreased cardiac output and inhibition of renin release.
• Decreases myocardial oxygen demand, offering prophylactic management of angina pectoris.
• Effective in the prophylaxis of common migraine headaches, reducing frequency and severity.
• Management of essential tremor, significantly improving functional capacity and quality of life.
• Control of symptomatic tachycardia and certain supraventricular arrhythmias.
• Adjunctive management in thyrotoxicosis and pheochromocytoma to control catecholamine-mediated symptoms.

Common use

Inderal is indicated for the management of hypertension, either as monotherapy or in combination with other antihypertensive agents. It is widely used for the prophylaxis of angina pectoris, where it reduces the frequency of anginal attacks and improves exercise tolerance. In neurology, it is a first-line agent for the prophylaxis of migraine headaches and the management of essential tremor. Cardiologically, it is employed in the control of sinus tachycardia, atrial fibrillation, and flutter, as well as in the management of hypertrophic subaortic stenosis. Off-label uses include performance anxiety, portal hypertension, and certain anxiety-related disorders.

Dosage and direction

Dosage must be individualized based on the indication, patient response, and formulation used. For hypertension, initial dosing typically starts at 40 mg twice daily (immediate-release) or 80 mg once daily (long-acting), with gradual titration up to 640 mg daily in divided doses. For angina, initial dose is 80–320 mg daily in divided doses. Migraine prophylaxis usually begins at 80 mg daily in divided doses, with maintenance doses ranging from 160–240 mg daily. Essential tremor management starts at 40 mg twice daily, with effective doses often between 120–320 mg daily. Administration should be with food to enhance bioavailability and reduce variability. Abrupt discontinuation should be avoided; taper gradually over 1–2 weeks to prevent rebound hypertension or angina.

Precautions

Use with caution in patients with compensated heart failure; monitor for cardiac decompensation. May mask signs of hypoglycemia (tachycardia) in diabetic patients. Can precipitate bronchospasm in patients with reactive airway disease or COPD. May reduce coronary artery perfusion; use cautiously in patients with Prinzmetal’s angina. Can cause bradycardia; assess heart rate regularly. May exacerbate symptoms in patients with peripheral vascular disease or Raynaud’s phenomenon. Use with caution in hepatic impairment; dosage reduction may be necessary. Psychiatric reactions including depression, hallucinations, and sleep disturbances have been reported.

Contraindications

Bronchial asthma or history of bronchospasm. Severe sinus bradycardia (heart rate <50 bpm). Second- or third-degree heart block (in absence of functioning pacemaker). Cardiogenic shock. Decompensated cardiac failure. Hypersensitivity to propranolol or any component of the formulation. Severe peripheral arterial circulatory disorders. Untreated pheochromocytoma (must be used only with alpha-blockade).

Possible side effect

Common adverse reactions include fatigue (reported in up to 15% of patients), bradycardia (10%), cold extremities (8%), and nausea (5%). Less frequently observed are sleep disturbances, vivid dreams, depression, and impotence. Cardiovascular effects may include heart failure exacerbation, hypotension, and heart block. Respiratory side effects can include bronchospasm in susceptible individuals. Gastrointestinal disturbances such as diarrhea or constipation may occur. Rare but serious adverse effects include exacerbation of psoriasis, thrombocytopenic purpura, and agranulocytosis.

Drug interaction

Concurrent use with calcium channel blockers (verapamil, diltiazem) may potentiate bradycardia and AV block. Enhanced hypotensive effect with other antihypertensives. May potentiate insulin-induced hypoglycemia and mask its tachycardic symptoms. Cimetidine increases propranolol plasma levels. Rifampin decreases propranolol concentrations. May reduce clearance of lidocaine, requiring monitoring. Concomitant use with clonidine may produce paradoxical hypertension upon withdrawal. NSAIDs may attenuate antihypertensive effect. MAO inhibitors may exacerbate hypotension.

Missed dose

If a dose is missed, it should be taken as soon as remembered unless it is nearly time for the next scheduled dose. In that case, skip the missed dose and resume the regular dosing schedule. Do not double the dose to make up for a missed one. For once-daily formulations, if missed for more than 12 hours, wait until the next scheduled dose. Maintaining consistent dosing is important for stable beta-blockade; inconsistent dosing may lead to breakthrough symptoms or blood pressure variability.

Overdose

Symptoms of overdose include severe bradycardia, hypotension, heart failure, bronchospasm, hypoglycemia, and seizures. Cardiovascular manifestations may progress to cardiogenic shock and cardiac arrest. Management includes gastric lavage if presented early, activated charcoal, and close monitoring of vital signs. Specific antidotes include atropine for bradycardia, glucagon for myocardial depression, and vasopressors (norepinephrine, dopamine) for hypotension. Beta-agonist bronchodilators for bronchospasm. Cardiac pacing may be required for heart block. Hemodialysis is not effective due to high protein binding.

Storage

Store at controlled room temperature (20–25°C or 68–77°F). Protect from light and moisture. Keep in original container with lid tightly closed. Do not store in bathroom or near kitchen sink. Keep out of reach of children and pets. Do not use if tablets appear discolored or show signs of deterioration. For long-acting capsules, do not crush, chew, or open as this alters the release profile.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Inderal is a prescription medication and should only be used under the supervision of a qualified healthcare professional. Dosage and administration must be determined by a physician based on individual patient assessment. Patients should not alter their dosage or discontinue therapy without consulting their healthcare provider. The full prescribing information should be consulted before initiating therapy.

Reviews

Clinical studies consistently demonstrate Inderal’s efficacy in hypertension management, with meta-analyses showing average systolic blood pressure reduction of 10-15 mmHg and diastolic reduction of 8-10 mmHg. In migraine prophylaxis, randomized controlled trials show 50% or greater reduction in migraine frequency in approximately 60-80% of patients. For essential tremor, studies indicate significant improvement in tremor amplitude and functional capacity in 50-70% of patients. Long-term cardiovascular outcome studies demonstrate reduced mortality in post-MI patients. The drug’s safety profile is well-characterized, with most adverse effects being dose-dependent and reversible upon dosage adjustment or discontinuation.