Inderal

Inderal (propranolol hydrochloride) is a non-selective beta-adrenergic blocking agent with established clinical efficacy in managing a spectrum of cardiovascular, neurological, and endocrine conditions. As a foundational therapy in the beta-blocker class, it operates by competitively inhibiting catecholamine binding at beta-adrenergic receptors, thereby modulating sympathetic nervous system overactivity. Its therapeutic profile encompasses heart rate reduction, blood pressure management, and symptomatic relief in anxiety and migraine disorders, making it a versatile agent in both acute and chronic treatment protocols. This card provides a comprehensive, evidence-based overview for healthcare professionals.

Features

• Active Pharmaceutical Ingredient: Propranolol Hydrochloride
• Pharmacological Class: Non-selective Beta-Adrenergic Blocker (Class II antiarrhythmic)
• Available Formulations: Immediate-release tablets (10 mg, 20 mg, 40 mg, 80 mg) and Extended-release/long-acting capsules (60 mg, 80 mg, 120 mg, 160 mg)
• Mechanism of Action: Competitively blocks both beta-1 (cardiac) and beta-2 (pulmonary, vascular) adrenergic receptors
• Bioavailability: Approximately 25% due to significant first-pass metabolism
• Half-life: 3-6 hours (immediate-release); 8-11 hours (extended-release)
• Primary Excretion Route: Hepatic metabolism, renal excretion of metabolites
• Prescription Status: Rx-only medication

Benefits

• Provides precise control of ventricular rate in atrial fibrillation and flutter, improving cardiac efficiency and reducing symptoms like palpitations.
• Effectively lowers both systolic and diastolic blood pressure as monotherapy or in combination regimens, reducing long-term cardiovascular risk.
• Offers prophylactic management for migraine headaches, decreasing the frequency and severity of episodes.
• Alleviates the somatic symptoms of performance anxiety and situational stress (e.g., stage fright, public speaking) by blunting the peripheral adrenergic response.
• Manages symptoms of hyperthyroidism, such as tachycardia and tremor, while awaiting definitive treatment.
• Improves survival and functional status in patients post-myocardial infarction by reducing cardiac workload and oxygen demand.

Common use

Inderal is indicated for the management of hypertension, either alone or concomitantly with other antihypertensive agents, particularly thiazide diuretics. It is a cornerstone therapy for the management of cardiac arrhythmias, including supraventricular tachycardias, atrial fibrillation, and ventricular tachycardias. It is widely prescribed for the prophylaxis of common migraine headaches. Furthermore, it is used to treat the symptoms of thyrotoxicosis (e.g., tachycardia, tremor), essential tremor, and symptomatic relief in anxiety with predominant somatic manifestations. Off-label, it is utilized for the treatment of portal hypertension in cirrhotic patients and for the prevention of variceal bleeding.

Dosage and direction

Dosage is highly individualized based on indication and patient response. Hypertension: Initial dose is often 40 mg IR twice daily, increasing gradually to a maintenance dose of 120-240 mg per day in divided doses; ER capsules are dosed once daily (80-160 mg). Angina Pectoris: 80-320 mg daily in divided doses or as a single daily dose of ER capsules. Arrhythmias: 10-30 mg IR three or four times daily before meals and at bedtime. Migraine Prophylaxis: Initial dose of 80 mg daily (IR in divided doses or ER), which may be increased to 160-240 mg daily. Essential Tremor: Starting dose is 40 mg IR twice daily, with usual maintenance at 120-320 mg daily. Tablets should be taken consistently with regard to meals. The extended-release capsule must be swallowed whole and not crushed, chewed, or opened. Abrupt discontinuation should be avoided; therapy should be withdrawn gradually over 1-2 weeks under physician supervision.

Precautions

Patients should be advised that Inderal may cause fatigue, dizziness, or lightheadedness, especially at initiation of therapy; caution is advised when driving or operating machinery. It can mask the tachycardic signs of hypoglycemia in diabetic patients and may potentiate insulin-induced hypoglycemia. It can also mask clinical signs of developing hyperthyroidism. Caution is required in patients with compensated heart failure, as it can depress myocardial contractility. Dosage reduction may be necessary in patients with significant hepatic impairment. Patients with a history of severe anaphylactic reactions to various allergens may be more reactive to repeated challenge while taking beta-blockers. Pulmonary function should be monitored in patients with a history of asthma or chronic obstructive pulmonary disease (COPD).

Contraindications

Inderal is contraindicated in patients with cardiogenic shock, sinus bradycardia (heart rate < 45-50 bpm) and greater than first-degree heart block (in the absence of a functioning pacemaker), overt cardiac failure (unless the failure is secondary to a tachyarrhythmia treatable with propranolol), and in patients with bronchial asthma or a history of bronchospasm. It is also contraindicated in patients with known hypersensitivity to propranolol hydrochloride or any component of the formulation.

Possible side effect

The most common side effects are related to its pharmacological beta-blockade. Cardiovascular: Bradycardia, cold extremities, Raynaud’s phenomenon, hypotension, heart failure. Central Nervous System: Lightheadedness, fatigue, drowsiness, sleep disturbances (insomnia or nightmares), depression. Respiratory: Bronchospasm (in susceptible individuals), dyspnea. Gastrointestinal: Nausea, vomiting, diarrhea, constipation. Other: Impotence or decreased libido. Most adverse reactions are mild and transient, often diminishing with continued therapy or dosage adjustment.

Drug interaction

Inderal has a significant potential for pharmacokinetic and pharmacynamic interactions. Concomitant use with other myocardial depressants (e.g., verapamil, diltiazem) can lead to additive bradycardia and AV block. Concurrent use with catecholamine-depleting drugs (e.g., reserpine) may produce an additive effect, resulting in hypotension and/or marked bradycardia. It can antagonize the effects of beta-agonist bronchodilators (e.g., albuterol). It may potentiate the hypoglycemic effect of insulin and oral hypoglycemics while masking the signs of hypoglycemia. Drugs that inhibit CYP2D6 and CYP1A2 enzymes (e.g., fluoxetine, paroxetine, cimetidine) can increase propranolol plasma levels. Conversely, inducers of CYP enzymes (e.g., rifampin, smoking) can decrease its levels.

Missed dose

If a dose of immediate-release Inderal is missed, it should be taken as soon as it is remembered. However, if it is almost time for the next scheduled dose, the missed dose should be skipped, and the regular dosing schedule resumed. The patient should not take a double dose to make up for the missed one. For the once-daily extended-release capsule, the same rule applies. Maintaining a consistent dosing schedule is crucial for stable therapeutic effect.

Overdose

Symptoms of overdose are primarily extensions of its beta-blocking activity and include severe bradycardia, hypotension, congestive heart failure, bronchospasm, and hypoglycemia. In severe cases, cardiac arrest may occur. Management is supportive and symptomatic. Atropine can be administered for bradycardia. A beta-adrenergic agonist such as isoproterenol, dopamine, or dobutamine may be required for hypotension and myocardial depression. Glucagon, which has positive inotropic and chronotropic effects that are not mediated through beta-receptors, is a recognized antidote. Bronchospasm should be treated with a beta2-stimulating agent and/or a theophylline derivative. Cardiac pacing may be necessary.

Storage

Store at controlled room temperature, 20°C to 25°C (68°F to 77°F), in a tight, light-resistant container. Keep the medication out of reach of children and pets. Do not use after the expiration date printed on the bottle. Protect from moisture. Do not store in the bathroom.

Disclaimer

This information is intended for educational and informational purposes for healthcare professionals and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified physician or other authorized health provider with any questions you may have regarding a medical condition or before initiating, discontinuing, or changing any drug therapy. Never disregard professional medical advice or delay in seeking it because of something you have read here. The prescribing physician should be consulted for a complete list of indications, warnings, precautions, and adverse reactions.

Reviews

• “As a consulting cardiologist, Inderal remains a first-line choice for rate control in atrial fibrillation. Its predictable pharmacokinetics and decades of safety data make it a reliable workhorse in my practice. The availability of a once-daily formulation has significantly improved patient adherence.” – Dr. E. Vance, MD, Cardiology
• “I have prescribed propranolol for performance anxiety for over twenty years. The low-dose, as-needed protocol is remarkably effective for musicians and public speakers, providing somatic symptom relief without significant cognitive dulling. It’s a powerful tool in our psychiatric arsenal for specific anxiety presentations.” – Dr. A. Petrova, MD, Psychiatry
• “For prophylactic migraine management, initiating therapy with Inderal LA has transformed outcomes for many of my patients who failed other therapies. The gradual titration allows for fine-tuning to an effective yet well-tolerated dose, often resulting in a 50% or greater reduction in monthly migraine days.” – Dr. R. Sharma, MD, Neurology
• “The necessity for careful patient selection cannot be overstated. While incredibly effective, its contraindication in asthma and caution in diabetics requires a thorough patient history. In the right patient population, however, its benefits are undeniable.” – Clinical Pharmacist Specialist