Penbutolol is a non-selective beta-blocking
drug with 'moderate' intrinsic
sympathomimetic (partial agonist) properties, and a relatively narrow dose-response range. In many other aspects its pharmacological profile resembles that of
propranolol. Significant beta-blockade, as demonstrated by reduction in heart rate during exercise in healthy subjects, persists for at least 24 hours after
penbutolol administration, and thus the recommended dosage schedule in both
hypertension and angina involves single daily doses (20 or 40mg daily) in most patients, with a divided dose (40mg twice daily) if a higher dose is needed. However, most angina prophylaxis studies to date have not been designed to clearly demonstrate that the beneficial effects of beta-blockade with a single dose of
penbutolol extend throughout a 24-hour dosing interval. Further studies are needed to provide such evidence. As might be expected,
penbutolol appears to be about as effective as usual doses of
propranolol in both mild to moderate
hypertension and in angina, but much of the clinical experience with the
drug is in unpublished form and is thus somewhat difficult to evaluate in detail. The choice of a beta-blocking
drug should be based on a knowledge of the characteristic pharmacodynamic and pharmacokinetic properties of the individual drugs within this group, and on careful consideration of how these properties might be used to benefit the individual patient. As is the case with most other beta-blocking drugs,
penbutolol has some specific properties (e.g. relatively narrow dose-response range minimising the difficulty of dose titration, moderate intrinsic
sympathomimetic activity) which may be used to advantage in certain patients.