1. β-Receptor-blocking drugs are rapidly and completely absorbed after oral administration. Systemic availability is nevertheless incomplete for propranolol, alprenolol and oxprenolol, owing to ‘first-pass’ extraction by the liver.
2. Plasma half-life is between 2 and 4 h, except for sotalol (10–12 h). Plasma elimination of propranolol is reduced with decreased liver blood flow, observed in congestive heart failure or during chronic propranolol therapy itself.
3. β-Receptor blockade is usually achieved in these concentration ranges: propranolol and alprenolol, 50–100 ng/ml; oxprenolol, 500–1000 ng/ml; pindolol, 10–30 ng/ml; sotalol, 2–6 μg/ml. Higher concentrations are often found with high doses administered to hypertensive patients.