BNF for Children 2011-2012

BNFC 2011–2012 Appendix 1: Interactions 669Antifungals, Triazole. Tacrolimus (continued)concentration of .tacrolimus (consider reducingdose of tacrolimus)Tadalafil: itraconazole possibly increases plasma concentrationof tadalafil. Theophylline: fluconazole possibly increases plasmaconcentration of .theophylline. Ulcer-healing Drugs: plasma concentration of posaconazolereduced by .cimetidine; voriconazole possiblyincreases plasma concentration of esomeprazole;voriconazole increases plasma concentration ofomeprazole (consider reducing dose of omeprazole);absorption of itraconazole reduced by histamine H 2 -antagonists and proton pump inhibitors; manufacturerof posaconazole advises avoid concomitant usewith histamine H 2 -antagonists and proton pumpinhibitors (plasma concentration of posaconazolepossibly reduced). Vardenafil: itraconazole possibly increases plasmaconcentration of .vardenafil—avoid concomitant useAntihistaminesNote Sedative interactions apply to a lesser extent to thenon-sedating antihistamines. Interactions do not generallyapply to antihistamines used for topical action (includinginhalation)Alcohol: increased sedative effect when antihistaminesgiven with alcohol (possibly less effect with nonsedatingantihistamines). Analgesics: sedative effects possibly increased whensedating antihistamines given with .opioid analgesicsAntacids: absorption of fexofenadine reduced byantacids. Anti-arrhythmics: increased risk of ventricular arrhythmiaswhen mizolastine given with .amiodarone,.disopyramide, .flecainide or .propafenone—avoidconcomitant use. Antibacterials: plasma concentration of rupatadineincreased by erythromycin; manufacturer of loratadineadvises plasma concentration possiblyincreased by erythromycin; metabolism of mizolastineinhibited by .erythromycin—avoid concomitantuse; increased risk of ventricular arrhythmias whenmizolastine given with .moxifloxacin—avoid concomitantuse; effects of fexofenadine possibly reducedby rifampicin; metabolism of mizolastine possiblyinhibited by .macrolides (avoid concomitant use)Antidepressants: increased antimuscarinic and sedativeeffects when antihistamines given with MAOIs ortricyclics; manufacturer of promethazine advisesavoid for 2 weeks after stopping MAOIs; cyproheptadinepossibly antagonises antidepressant effectof SSRIs; possible increased antimuscarinic andsedative effects when antihistamines given withtricyclic-related antidepressantsAntidiabetics: thrombocyte count depressed whenketotifen given with metformin (manufacturer ofketotifen advises avoid concomitant use). Antifungals: plasma concentration of rupatadineincreased by ketoconazole; manufacturer of loratadineadvises plasma concentration possiblyincreased by ketoconazole; metabolism of mizolastineinhibited by .itraconazole or .ketoconazole—avoid concomitant use; metabolism of mizolastinepossibly inhibited by .imidazoles (avoid concomitantuse)Antimuscarinics: increased risk of antimuscarinic sideeffectswhen antihistamines given with antimuscarinics. Antivirals: plasma concentration of chlorphenaminepossibly increased by lopinavir; plasma concentrationof non-sedating antihistamines possibly increased byritonavir; increased risk of ventricular arrhythmiaswhen mizolastine given with .saquinavir—avoidconcomitant useAnxiolytics and Hypnotics: increased sedative effectwhen antihistamines given with anxiolytics andhypnoticsAntihistamines (continued). Beta-blockers: increased risk of ventricular arrhythmiaswhen mizolastine given with .sotalol—avoidconcomitant useBetahistine: antihistamines theoretically antagoniseeffect of betahistine. Grapefruit Juice: plasma concentration of rupatadineincreased by .grapefruit juice—avoid concomitantuseHistamine: antihistamines theoretically antagoniseeffects of histamine—manufacturer of histamineadvises avoid concomitant useUlcer-healing Drugs: manufacturer of loratadineadvises plasma concentration possibly increased bycimetidineAntihistamines, Non-sedating see AntihistaminesAntihistamines, Sedating see AntihistaminesAntimalarials see Artemether with Lumefantrine,Chloroquine and Hydroxychloroquine, Mefloquine,Primaquine, Proguanil, Pyrimethamine, and QuinineAntimetabolites see Cytarabine, Fludarabine, Fluorouracil,Gemcitabine, Mercaptopurine, Methotrexate,Pemetrexed, Raltitrexed, and TioguanineAntimuscarinicsNote Many drugs have antimuscarinic effects; concomitantuse of two or more such drugs can increase side-effects suchas dry mouth, urine retention, and constipation; concomitantuse can also lead to confusion in the elderly. Interactions donot generally apply to antimuscarinics used by inhalationAlcohol: increased sedative effect when hyoscine givenwith alcoholAnalgesics: possible increased risk of antimuscarinicside-effects when antimuscarinics given withcodeine; increased risk of antimuscarinic side-effectswhen antimuscarinics given with nefopam. Anti-arrhythmics: increased risk of ventricular arrhythmiaswhen tolterodine given with .amiodarone,.disopyramide or .flecainide; increased risk of antimuscarinicside-effects when antimuscarinics givenwith disopyramideAntibacterials: manufacturer of fesoterodine advisesdose reduction when fesoterodine given withclarithromycin and telithromycin—consult fesoterodineproduct literature; manufacturer of tolterodineadvises avoid concomitant use withclarithromycin and erythromycin; plasma concentrationof darifenacin possibly increased by erythromycin;plasma concentration of active metabolite offesoterodine reduced by rifampicinAntidepressants: plasma concentration ofdarifenacin and procyclidine increased by paroxetine;increased risk of antimuscarinic side-effects whenantimuscarinics given with MAOIs or tricyclics;possible increased antimuscarinic side-effects whenantimuscarinics given with tricyclic-related antidepressantsAntifungals: antimuscarinics reduce absorption ofketoconazole; manufacturer of fesoterodine advisesdose reduction when fesoterodine given withitraconazole and ketoconazole—consult fesoterodineproduct literature; plasma concentration of darifenacinincreased by ketoconazole—avoid concomitantuse; plasma concentration of solifenacin increased byitraconazole and ketoconazole; manufacturer oftolterodine advises avoid concomitant use withitraconazole and ketoconazole; manufacturer ofdarifenacin advises avoid concomitant use withitraconazoleAntihistamines: increased risk of antimuscarinic sideeffectswhen antimuscarinics given with antihistaminesAntipsychotics: antimuscarinics possibly reduceeffects of haloperidol; increased risk of antimuscarinicside-effects when antimuscarinics givenwith clozapine; antimuscarinics reduce plasma concentrationof phenothiazines, but risk of antimuscarinicside-effects increasedAntivirals: manufacturer of darifenacin advises avoidconcomitant use with atazanavir, fosamprenavir,Appendix 1: Interactions