Source: Medicines & Healthcare Products Regulatory Agency (GB) Revision Year: 2020 Publisher: Tillomed Laboratories Ltd, 220 Butterfield, Great Marlings, Luton, LU2 8DL
Pharmacotherapeutic Group: Beta Blocking Agents, Non-Selective and other Hypertensives
ATC Code: C07AA05
Propranolol is a competitive antagonist at both beta1 and beta2-adrenoceptors. It has no agonist activity at the beta-adrenoceptor, but has membrane stabilising activity at concentrations exceeding 1 to 3mg/litre, though such concentrations are rarely achieved during oral therapy. Competitive beta-adrenoceptor 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 other beta-adrenoceptor blocking drugs, has 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 will give rise to different therapeutic effects.
Propranolol is effective and well tolerated in most ethnic populations, although the response may be less in black patients.
The sustained release preparation of propranolol maintains a higher degree of beta1-blockade 24 hours after dosing compared with conventional propranolol.
Propranolol reduces the myocardial oxygen requirement and protects the heart against ischaemia. It also helps to divert blood from the sub-epicardiac zones to the less well irrigated sub-endocardiac zones.
Sustained release form. The coating of the multiple microgranules provides a sustained release of the active principle, propranolol, and allows a 24 hours sustained action.
Propranolol is completely absorbed after oral administration. Following oral dosing with the sustained release preparation of propranolol, the blood profile is flatter than after conventional Propranolol. Peak blood level is reached after 5 hours for the controlled-release form. The apparent half-life of elimination is 3-6 hours. The liver removes up to 90% of an oral dose. Propranolol is widely and rapidly distributed throughout the body with highest levels occurring in the lungs, liver, kidney, brain and heart. Propranolol is highly protein bound (80 to 95%).
Propranolol crosses the placental barrier and is found in the blood of the umbilical cord (concentration: about 1.5 times that of the concentration in the maternal blood). The concentration in the mother’s milk is about half the concentration in the blood.
Propranolol is a drug on which extensive clinical experience has been obtained. Relevant information for the prescriber is provided elsewhere in this Summary of Product Characteristics.
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