Inderal

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Pharmacology and Indications

Propranolol (Inderal®) is a non-selective beta blocker (i.e. it blocks the action of epinephrine on both β₁- and β₂-adrenoreceptors). It is well and rapidly absorbed after oral dosing with maximal plasma levels observed 1 to 2 hours after application (to fasting patient). Propranolol has a low and variable bioavailability due to extensive first-pass-metabolism. Liver disease will therefore increase bioavailability and pharmacologic actions. The active metabolite 4-Hydroxypropranolol, having a somewhat shorter halflife than the mother-drug, also accounts for the actions of Propranolol. Propranolol is a highly lipophilic drug achieving high concentrations in the brain. The duration of action of an oral single dose is longer than the halflife indicates and may be up to 12 hours, if the single dose is high enough (e.g. 80mg). Effective plasma-concentrations are between 10 and 100 ng per ml.

It has various uses, such as treatment of high blood pressure, angina, and cardiac arrhythmias, prophylaxis of migraine attacks, controlling essential tremor, suppressing the symptoms of hyperthyroidism (tachycardia, tremor), lowering portal pressure in portal hypertension when this has led to esophageal varices, as well as in the management of anxiety and panic disorders. The treatment of pheochromocytoma together with an alpha-receptor blocking agent is another indication.

A new, and very interesting use, is the co-treatment of chronic heart failure with initially small and slowly increasing doses. Additionally, it can be tried to prevent arrhythmias and reinfarction in patients with recent myocardial infarction after hemodynamic stabilization. Longterm studies combining Propranolol and Aspirin showed a statistically significant reduction of reinfarction and cardiovascular mortality rates.

Propranolol is currently being investigated as a potential treatment for post-traumatic stress disorder.

Contraindications and Precautions

• Active Asthma Bronchiale (COLD), History of asthmatic disease
• Hypersensitivity to Propranolol
• Significant hypotension
• Hemodynamic instable acute myocardial infarction
• Acute decompensation of chronic heart failure
• Bradycardia, AV-Blockage of 2nd. and 3rd. degree
• Cardiogenic shock
• Prinzmetal-Angina (vasospastic angina)
• Severe peripheral arterial circulation disorder
• Untreated pheochromocytoma
• Metabolic acidosis
• Severe liver and renal disease
• Caution: unstable Diabetes mellitus (Hypoglycemia may be masked)
• Caution: pediatric patients
• Caution: preexisting psoriasis (worsening possible)
• Caution: preexisting myasthenia gravis (may be worsened)

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