Lidocaine Beta blockers

LIDOCAINE BETA-BLOCKERS 1. Risk of bradycardia (occasionally severe), l BP and heart failure with intravenous lidocaine 2. Risk of lidocaine toxicity due to T plasma concentrations of lidocaine, particularly with propranolol and nadolol 3. t plasma concentrations of propranolol and possibly some other beta-blockers 1. Additive negative inotropic and chronotropic effects 2. Uncertain, but possibly a combination of beta-blocker-induced 1 hepatic blood flow (due to 1 cardiac output) and inhibition of metabolism of lidocaine 3. Attributed to inhibition of metabolism by lidocaine 1. Monitor PR, BP and ECG closely watch for development of heart failure when intravenous lidocaine is administered to patients on beta-blockers 2. Watch for lidocaine toxicity 3. Be aware. Regional anaesthetics should be used cautiously in patients with bradycardia. Beta-blockers could cause dangerous hypertension due to stimulation of alpha-receptors if adrenaline is used with local anaesthetic... 

Propranolol and some other beta blockers are known to reduce the metabolism of lidocaine—see Lidocaine + Beta blockers , p.263. 

Propranolol may increase procainamide plasma levels. Additive cholinergic effects may occur when procainamide is administered with other drugp with anticholinergic effects. There is the potential of additive cardiodepressant effects when procainamide is administered with lidocaine. When a beta blocker, such as Inderal, is administered with lidocaine, there is an increased risk of lidocaine toxicity. 

Codeine, dextromethorphan, haloperidol, thioridazine, perphenazine, nortriptyline, desipramine, fluoxetine, norfluoxetine, TCAs (hydroxylation), beta-blockers such as timolol and metoprolol, type 1C antiarrhythmics encainide, flecainide TCAs (desmethylation), triazolam, alprazolam, midazolam, carbamazepine, terfenadine, quinidine, lidocaine, erythromycin, cyclosporin... 

Drugs that may affect lidocaine include beta-blockers, cimetidine, procainamide, tocainide, and succinylcholine. 

Drugs that may affect amiodarone include hydantoins, cholestyramine, fluoroquinolones, rifamycins, ritonavir, and cimetidine. Drugs that may be affected by amiodarone include anticoagulants, beta-blockers, calcium channel blockers, cyclosporine, dextromethorphan, digoxin, disopyramide, fentanyl, flecainide, hydantoins, lidocaine, methotrexate, procainamide, quinidine, and theophylline. Drug/Lab test interactions Amiodarone alters the results of thyroid function tests, causing an increase in serum T4 and serum reverse T3 levels and a decline in... 

Drugs that may be affected by beta blockers include flecainide, gabapentin, haloperidol, hydralazine, phenothiazines, anticoagulants, benzodiazepines, clonidine, disopyramide, epinephrine, ergot alkaloids, lidocaine, nondepolarizing muscle relaxants, prazosin, sulfonylureas, and theophylline. 

Beta-blockers interact with a large number of other medications. The combination of beta-blockers with calcium antagonists should be avoided, given the risk for hypotension and cardiac arrhythmias. Cimetidine, hydralazine, and alcohol all increase blood levels of beta-blockers, whereas rifampicin decreases their concentrations. Beta-blockers may increase blood levels of phenothiazines and other neuroleptics, clonidine, phen-ytoin, anesthetics, lidocaine, epinephrine, monoamine oxidase inhibitors and other antidepressants, benzodiazepines, and thyroxine. Beta-blockers decrease the effects of insulin and oral hypoglycemic agents. Smoking, oral contraceptives, carbamazepine, and nonsteroidal anti-inflammatory analgesics decrease the effects of beta-blockers (Coffey, 1990). 

Patients should be advised to rest and to avoid extreme heat. They should be warned that symptoms may be aggravated by illness, stress, malnutrition, pain, or surgery. Various drugs have been shown to worsen symptoms of myasthenia gravis. These include the aminoglycoside antibiotics such as tobramycin, gentamicin, and neomycin tetracyclines such as doxycycline and minocycline class 1 antiarrhythmics such as lidocaine, quinidine, and procainamide magnesium in calcium and multivitamin supplements beta-blockers such as timolol and propranolol calcium channel blockers such as verapamil and penicillamine. 

Some beta-blockers reduce hepatic blood flow and inhibit microsomal enzymes, reducing the clearance of lidocaine there is a clinically significant increase in the plasma concentration of lidocaine during concomitant propranolol therapy (75). 

Wyse DG, Kellen J, Tam Y, Rademaker AW. Increased efficacy and toxicity of lidocaine in patients on beta-blockers. Int J Cardiol 1988 21(l) 59-70. 

Clinically important, potentially hazardous interactions with alcohol, amiodarone, beta-blockers, cimetidine, donidine, digoxin, diltiazem, disopyramide, ephedrine, epinephrine, ergot alkaloids, guanethidine, halothane, isoprenaline, lidocaine, noradrenaline, NSAIDs, phenylephrine, quinidine, reserpine, verapamil... 

Adrenaline is contraindicated in cases of diabetes, hyperthyroidism, serious heart arrhythmias and coronary insufficiency or in combination with beta-blockers or monoamine oxidase (MAO) inhibitors. Lidocaine with adrenaline has a very rapid onset of action. Its duration of action is longer than that of lidocaine without adrenaline. However, inadvertent injection of a lidocaine-adrenaline solution into the vessels located near the nerve trunks increases the heart rate (immediate sinus tachycardia at over 130 beats per minute, spontaneously reversible in around 15 minutes) and increases ventricular excitability (risk of fibrillation). It can trigger angina attacks that may lead to a heart attack. It is therefore preferable not to use adrenaline before a full-face phenol peel. 

Class IB drugs act primarily on ventricular muscle and, in the case of lidocaine, concen- j trate in ischemic tissues. Adenosine is indicated for SVTs and nodal tachycardias. The primary actions of both beta blockers (esmolol) and CCBs (diltiazem) are at the AV node— they are not particularly effective in ventricular arrhythmias. Flecainide, a class IC drug, has been implicated in sudden deaths post-MI. 

Class IB drugs such as lidocaine and mexiletine typically block sodium channels and decrease the action potential duration. Mexiletine, but not lidocaine, is orally active. The answer is (G). Verapamil is the calcium channel blocker in this list. (Adenosine and beta-blockers also slow AV conduction but do not act primarily on calcium channels.) The answer is (J). 

A matched study in 51 cardiac patients taking a variety of beta blockers (including propranolol, metoprolol, timolol, pindolol) found no significant differences in either total or free concentrations of lidocaine during a lidocaine infusion, but there was a trend towards an increase in the adverse effects of lidocaine (bradycardias) with concurrent beta blocker treatment. ... 

Not fully agreed. There is some debate about whether the increased serum lidocaine levels largely occur because of the decreased cardiac output caused by the beta blockers, which decreases the flow of blood through the liver thereby reducing the metabolism of the lidocaine, or because of direct liver enzyme inhibition. There may also be a pharmacodynamic interaction, with an increased risk of myocardial depression. ... 

Note that local anaesthetic preparations of lidocaine often contain adrenaline (epinephrine), which may interact with beta blockers, see Beta blockers -I- Inotropes and Vasopressors , p.848. 

If polymorphic QRS complexes and normal QT interval, administer beta blockers, lidocaine, amiodarone, procainamide, or sotalol (follow ACLS protocol) if drug is unsuccessful, cardioversion. 

Smoking cessation, with or without nicotine substitutes, may alter response to concomitant medication in ex-smokers. Smoking may affect alcohol, benzodiazepines, beta-adrenergic blockers, caffeine, clozapine, fluvoxamine, olanzapine, tacrine, theophylline, clorazepate, lidocaine (oral), estradiol, flecanide, imipramine, heparin, insulin, mexiletine, opioids, propranolol, catecholamines, and cortisol. 

---