BNF for Children 2011-2012

BNFC 2011–2012 Appendix 1: Interactions 703Levodopa (continued)Clonidine: enhanced hypotensive effect when levodopagiven with clonidineDiazoxide: enhanced hypotensive effect when levodopagiven with diazoxideDiuretics: enhanced hypotensive effect when levodopagiven with diureticsDopaminergics: enhanced effects and increased toxicityof levodopa when given with selegiline (reducedose of levodopa)Iron: absorption of levodopa possibly reduced by oralironMemantine: effects of dopaminergics possiblyenhanced by memantineMethyldopa: enhanced hypotensive effect when levodopagiven with methyldopa; antiparkinsonian effectof dopaminergics antagonised by methyldopaMoxonidine: enhanced hypotensive effect when levodopagiven with moxonidineMuscle Relaxants: possible agitation, confusion andhallucinations when levodopa given with baclofenNitrates: enhanced hypotensive effect when levodopagiven with nitratesVasodilator Antihypertensives: enhanced hypotensiveeffect when levodopa given with hydralazine,minoxidil or sodium nitroprussideVitamins: effects of levodopa reduced by pyridoxinewhen given without dopa-decarboxylase inhibitorLevofloxacin see QuinolonesLevofolinic Acid see FolatesLevomepromazine see AntipsychoticsLevonorgestrel see ProgestogensLevothyroxine see Thyroid HormonesLidocaineNote Interactions less likely when lidocaine used topicallyAnaesthetics, Local: increased myocardial depressionwhen anti-arrhythmics given with bupivacaine, levobupivacaine,prilocaine or ropivacaine. Anti-arrhythmics: increased myocardial depressionwhen anti-arrhythmics given with other .antiarrhythmics. Antipsychotics: increased risk of ventricular arrhythmiaswhen anti-arrhythmics that prolong the QTinterval given with .antipsychotics that prolong theQT interval. Antivirals: plasma concentration of lidocaine possiblyincreased by .atazanavir and lopinavir; plasmaconcentration of lidocaine possibly increased bydarunavir and .fosamprenavir—avoid concomitantuse; increased risk of ventricular arrhythmias whenlidocaine given with .saquinavir—avoid concomitantuse. Beta-blockers: increased myocardial depression whenanti-arrhythmics given with .beta-blockers; increasedrisk of lidocaine toxicity when given with.propranolol. Diuretics: action of lidocaine antagonised by hypokalaemiacaused by .acetazolamide, .loop diuretics or.thiazides and related diureticsMuscle Relaxants: neuromuscular blockade enhancedand prolonged when lidocaine given with suxamethonium. Ulcer-healing Drugs: plasma concentration of lidocaineincreased by .cimetidine (increased risk oftoxicity)LinezolidNote Linezolid is a reversible, non-selective MAO inhibitor—seeinteractions of MAOIsAntibacterials: plasma concentration of linezolidreduced by rifampicin (possible therapeutic failure oflinezolid)Vaccines: antibacterials inactivate oral typhoidvaccine—see p. 620Liothyronine see Thyroid HormonesLipid-regulating Drugs see Colesevelam, Colestipol,Colestyramine, Ezetimibe, Fibrates, Nicotinic Acid,and StatinsLiraglutide see AntidiabeticsLisinopril see ACE InhibitorsLithium. ACE Inhibitors: excretion of lithium reduced by .ACEinhibitors (increased plasma concentration). Analgesics: excretion of lithium reduced by .NSAIDs(increased risk of toxicity); excretion of lithiumreduced by .ketorolac (increased risk of toxicity)—avoid concomitant use. Angiotensin-II Receptor Antagonists: excretion oflithium reduced by .angiotensin-II receptor antagonists(increased plasma concentration)Antacids: excretion of lithium increased by sodiumbicarbonate (reduced plasma concentration). Anti-arrhythmics: avoidance of lithium advised bymanufacturer of .amiodarone (risk of ventriculararrhythmias)Antibacterials: increased risk of lithium toxicity whengiven with metronidazole. Antidepressants: possible increased serotonergiceffects when lithium given with venlafaxine;increased risk of CNS effects when lithium given with.SSRIs (lithium toxicity reported); risk of toxicitywhen lithium given with tricyclicsAntiepileptics: neurotoxicity may occur when lithiumgiven with carbamazepine or phenytoin withoutincreased plasma concentration of lithium; plasmaconcentration of lithium possibly affected by topiramateAntipsychotics: increased risk of extrapyramidal sideeffectsand possibly neurotoxicity when lithium givenwith clozapine, flupentixol, haloperidol,phenothiazines or zuclopenthixol; possible risk oftoxicity when lithium given with olanzapine;increased risk of extrapyramidal side-effects whenlithium given with sulpirideAnxiolytics and Hypnotics: increased risk of neurotoxicitywhen lithium given with clonazepamCalcium-channel Blockers: neurotoxicity may occurwhen lithium given with diltiazem or verapamilwithout increased plasma concentration of lithium. Cytotoxics: increased risk of ventricular arrhythmiaswhen lithium given with .arsenic trioxide. Diuretics: excretion of lithium increased by.acetazolamide; excretion of lithium reduced by.loop diuretics and .thiazides and related diuretics(increased plasma concentration and risk of toxicity)—loopdiuretics safer than thiazides; excretion oflithium reduced by .potassium-sparing diuretics andaldosterone antagonists (increased plasma concentrationand risk of toxicity)5HT 1 Agonists: possible risk of toxicity when lithiumgiven with sumatriptan. Methyldopa: neurotoxicity may occur when lithiumgiven with .methyldopa without increased plasmaconcentration of lithiumMuscle Relaxants: lithium enhances effects of musclerelaxants; hyperkinesis caused by lithium possiblyaggravated by baclofenParasympathomimetics: lithium antagonises effects ofneostigmine and pyridostigmineTheophylline: excretion of lithium increased by theophylline(reduced plasma concentration)Lofepramine see Antidepressants, TricyclicLofexidineAlcohol: increased sedative effect when lofexidinegiven with alcoholAnxiolytics and Hypnotics: increased sedative effectwhen lofexidine given with anxiolytics and hypnoticsLomustine. Antipsychotics: avoid concomitant use of cytotoxicswith .clozapine (increased risk of agranulocytosis)Ulcer-healing Drugs: myelosuppressive effects oflomustine possibly enhanced by cimetidineLoperamideDesmopressin: loperamide increases plasma concentrationof oral desmopressinAppendix 1: Interactions