Propranolol interactions with other drugs

Propranolol 13- Adrenoceptor blockade Direct membrane effects (sodium channel block) and prolongation of action potential duration slows SA node automaticity and AV nodal conduction velocity Atrial arrhythmias and prevention of recurrent infarction and sudden death Oral, parenteral duration 4-6 h Toxicity Asthma, AV blockade, acute heart failure Interactions With other cardiac depressants and hypotensive drugs... 

The P-blockers propranolol and timolol are FDA-approved for migraine prophylaxis, but other drugs in the class are also as effective.46 Cautious dosage titration is advised for those patients who do not have other indications for P-blocker use. Rizatriptan interacts with propranolol and thus dosages must be titrated downward, or another triptan chosen for abortive therapy.36 Comorbid reactive airway disease is a relative contraindication to P-blocker prophylaxis, and patients with cardiac conduction disturbances should be closely monitored. Calcium channel antagonists are often used when patients cannot tolerate P-blockers. They are purported to beneficially... 

Because of their mechanism of action, bile acid sequestrants can potentially bind with and decrease the oral absorption of almost any other drug. Because these anion-exchange resins contain numerous positive charges, they are much more likely to bind to acidic compounds than to basic compounds or nonelectrolytes. This is not an absolute, however, because cholestyramine and colestipol have been reported to decrease the oral absorption of propranolol (a base) and the lipid-soluble vitamins. A, D, E, and K (nonelectrolytes). As a result, the current recommendation is that all other oral medication should be administered at least 1 hour before or 4 hours after cholestyramine and colestipol. Interestingly, this drug interaction has been used in a beneficial manner to treat digitalis overdose and toxicity. 

Interactions with the following drugs may increase the risk of hypoglycemia other hypoglycemics, sulfonamides, propranolol, salicylates, clofibrate, probenecid, pentamidine, valproic acid, dicumarol, cimetidine, MAO inhibitors, and alcohol. In addition, co-ingestion of alcohol may occasionally produce a disulfiram-like interaction (see p 186). 

The two enantiomers of a racemic drug may interact with each other at different pharmacokinetic or pharmacodynamic levels. This type of interaction has been studied for atenolol [2] and propranolol [51 53]. For atenolol, there was no pharmacokinetic or pharmacodynamic interaction between the two enantiomers the half-dosed S(—)-atenolol produced the same effect as did the racemic atenolol [2]. Additionally, the plasma concentration-time profiles of S(—)-atenolol were identical after the administration of the racemate and the half-dosed pure enantiomer. On the other hand, both single [51] and multiple [52] dose studies have shown that there is a significant interaction between the enantiomers of propranolol. When administered as pure enantiomer, as opposed to the racemate, R(- -)-propranolol tends to show lower plasma concentrations [52]. However, the kinetics of the more active S(—)-enantiomer appear to be the same whether it is administered as a pure enantiomer or racemate [51-53]. 

Hypotension, bradycardia, ventricular fibrillation and asystole have been seen in a few patients given amiodarone with propranolol, metoprolol or sotalol (for sotalol, see also Drugs that prolong the QT interval + Other drugs that prolong the QT interval , p.2S7). However, analysis of clinical trials su ests that the combination can be beneficial. Amiodarone may inhibit the metabolism of beta blockers metabolised by CYP2D6, such as metoprolol, which might be a factor in the interaction. 

A study in 6 healthy subjects receiving 30-hour infusions of lidocaine at a rate of 2 mg/minute found that pretreatment with propranolol 80 mg every 8 hours for 3 days raised the steady-state plasma lidocaine levels by 19% (from 2.1 to 2.5 micrograms/mL) and reduced the plasma clearance by 16%. Other similar studies have found a 22.5 to 30% increase in steady-state serum lidocaine levels and a 14.7 to 46% fall in plasma clearance due to the concurrent use of propranolol. Two cases of lidocaine toxicity attributed to a lidocaine-propranolol interaction were revealed by a search of the FDA adverse drug reaction file in 1981. A further case of lidocaine toxicity (seizures) has been described in a man on propranolol after accidental oral ingestion of lidocaine for oesophageal anaesthesia. High serum levels of lidocaine were detected. ... 

The manufacturers warn of the possible risks of giving ziprasidone with drugs that prolong the QT interval, and of the possible antagonism that may occur with ievodopa and other dopamine agonists. Ziprasidone appears not to interact to a clinically relevant extent with an aiuminium/magnesium hydroxide antacid, benzatropine, cimetidine, iorazepam, propranolol or tobacco smoking. 

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