Hemangiol

ATC code: C07AA05 Propranolol is a competitive antagonist at both the beta 1 and beta 2 -adrenoceptors, has no agonist activity at the beta adrenoceptor, but has membrane stabilising activity at concentrations exceeding 1 to 3 mg/litre, though such concentrations are rarely achieved during oral therapy. Competitive beta blockade has been demonstrated in man by a parallel shift to the right in the dose-heart rate response curve to beta agonists such as isoprenaline. Propranolol as with all other beta-blockers, has a negative inotropic effects and is therefore, contra-indicated in uncontrolled heart failure. Propranolol is a racemic mixture and the active form is the S (-) isomer. With the exception of inhibition of the conversion of thyroxine to triiodothyronine it is unlikely that any additional ancillary properties possessed by R (+) propranolol, in comparison with the racemic mixture this will give rise to different therapeutic effects. Propranolol is effective and well tolerated in most ethnic populations although the response may be a bit less in black patients. The sustained release preparations of propranolol maintains a higher degree of beta 1 -blockade 24 hours after dosing compared with conventional propranolol.