Inderal Drug Interactions





Zuellig Pharma
Full Prescribing Info
Drug Interactions
Inderal modifies the tachycardia of hypoglycaemia. Caution must be exercised in the concurrent use of Inderal and hypoglycaemic therapy in diabetic patients. Inderal may prolong the hypoglycaemic response to insulin (see Contraindications and Precautions).
Simultaneous administration of rizatriptan and propranolol can cause an increased rizatriptan AUC and Cmax by approximately 70-80%. The increased rizatriptan exposure is presumed to be caused by inhibition of first-passage metabolism of rizatriptan through inhibition of monoamine oxidase-A. If both drugs are to be used, a rizatriptan dose of 5 mg has been recommended.
Class I anti-arrhythmic drugs (e.g. disopyramide) and amiodarone may have potentiating effect on atrial-conduction time and induce negative inotropic effect.
Digitalis glycosides in association with beta-blockers may increase atrioventricular conduction time.
Combined use of beta-blockers and calcium channel blockers with negative inotropic effects (e.g. verapamil, diltiazem) can lead to an exaggeration of these effects particularly in patients with impaired ventricular function and/or SA or AV conduction abnormalities. This may result in severe hypotension, bradycardia and cardiac failure. Neither the beta-blocker nor the calcium channel blocker should be administered intravenously within 48 hours of discontinuing the other.
Concomitant therapy with dihydropyridine calcium channel blockers e.g. nifedipine, may increase the risk of hypotension and cardiac failure may occur in patients with latent cardiac insufficiency.
Concomitant use of sympathomimetic agents, eg adrenalin, may counteract the effect of beta-blockers. Caution must be exercised in the parenteral administration of preparations containing adrenalin to patients taking beta-blockers as, in rare cases, vasoconstriction, hypertension and bradycardia may result.
Administration of Inderal during infusion of lignocaine may increase the plasma concentration of lignocaine by approximately 30%. Patients already receiving Inderal tend to have higher lignocaine levels than controls. The combination should be avoided.
Concomitant use of cimetidine or hydralazine increases, and concomitant use of alcohol may increase the plasma levels of propranolol.
Beta-blockers may exacerbate the rebound hypertension which can follow the withdrawal of clonidine. If the two drugs are co-administered, the beta-blocker should be withdrawn several days before discontinuing clonidine. If replacing clonidine by beta-blocker therapy, the introduction of beta-blockers should be delayed for several days after clonidine administration has stopped.
Caution must be exercised if ergotamine, dihydroergotamine or related compounds are given in combination with Inderal since vasospastic reactions have been reported in a few patients.
Concomitant use of prostaglandin synthetase inhibiting drugs e.g. ibuprofen and indomethacin, may decrease the hypotensive effects of Inderal.
Concomitant administration of Inderal and chlorpromazine may result in an increase in plasma levels of both drugs. This may lead to an enhanced antipsychotic effect for chlorpromazine and an increased antihypertensive effect for Inderal.
Caution must be exercised when using anaesthetic agents with Inderal. The anaesthetist should be informed and the choice of anaesthetic should be an agent with as little negative inotropic activity as possible. Use of beta-blockers with anaesthetic drugs may result in attenuation of the reflex tachycardia and increase the risk of hypotension. Anaesthetic agents causing myocardial depression are best avoided.
Pharmacokinetic studies have shown that the following agents may interact with propranolol due to effects on enzyme systems in the liver which metabolise propranolol and these agents: quinidine, propafenone, rifampicin, theophylline, warfarin, thioridazine and dihydropyridine calcium channel blockers such as nifedipine, nisoldipine, nicardipine, isradipine and lacidipine. Owing to the fact that blood concentrations of either agent may be affected dosage adjustments may be needed according to clinical judgement (see also the Interaction previously mentioned concerning the concomitant therapy with dihydropyridine calcium channel blockers).
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