BNF for Children 2011-2012

BNFC 2011–2012 Appendix 1: Interactions 679Calcium-channel Blockers. Antivirals (continued)diltiazem); plasma concentration of diltiazemreduced by efavirenz; plasma concentration ofcalcium-channel blockers possibly increased by.ritonavir; manufacturer of lercanidipine advisesavoid concomitant use with ritonavirAnxiolytics and Hypnotics: enhanced hypotensiveeffect when calcium-channel blockers given withanxiolytics and hypnotics; diltiazem and verapamilinhibit metabolism of midazolam (increased plasmaconcentration with increased sedation); absorption oflercanidipine increased by midazolam; diltiazem andverapamil increase plasma concentration of buspirone(reduce dose of buspirone)Aprepitant: plasma concentration of both drugs mayincrease when diltiazem given with aprepitant. Beta-blockers: enhanced hypotensive effect whencalcium-channel blockers given with beta-blockers;increased risk of AV block and bradycardia whendiltiazem given with .beta-blockers; asystole, severehypotension and heart failure when verapamil givenwith .beta-blockers (see p. 109); possible severehypotension and heart failure when nifedipine givenwith .beta-blockersCalcium-channel Blockers: plasma concentration ofboth drugs may increase when diltiazem given withnifedipine. Cardiac Glycosides: nifedipine possibly increasesplasma concentration of .digoxin; diltiazem,lercanidipine and nicardipine increase plasma concentrationof .digoxin; verapamil increases plasmaconcentration of .digoxin, also increased risk of AVblock and bradycardia. Ciclosporin: diltiazem, nicardipine and verapamilincrease plasma concentration of .ciclosporin; combinationof lercanidipine with .ciclosporin mayincrease plasma concentration of either drug (orboth)—avoid concomitant use; plasma concentrationof nifedipine possibly increased by ciclosporin(increased risk of toxicity including gingival hyperplasia)Cilostazol: diltiazem increases plasma concentration ofcilostazol (consider reducing dose of cilostazol)Clonidine: enhanced hypotensive effect when calciumchannelblockers given with clonidine. Colchicine: diltiazem and verapamil possibly increaserisk of .colchicine toxicity—suspend or reduce doseof colchicine (avoid concomitant use in hepatic orrenal impairment)Corticosteroids: hypotensive effect of calcium-channelblockers antagonised by corticosteroids; diltiazemincreases plasma concentration of methylprednisolone. Cytotoxics: verapamil possibly increases plasma concentrationof doxorubicin; plasma concentration ofboth drugs may increase when verapamil given with.everolimus; nifedipine possibly inhibits metabolismof vincristineDiazoxide: enhanced hypotensive effect when calciumchannelblockers given with diazoxideDiuretics: enhanced hypotensive effect when calciumchannelblockers given with diuretics; diltiazem andverapamil increase plasma concentration of eplerenone(reduce dose of eplerenone)Dopaminergics: enhanced hypotensive effect whencalcium-channel blockers given with levodopaGrapefruit Juice: plasma concentration of felodipine,isradipine, lacidipine, lercanidipine, nicardipine, nifedipine,nimodipine and verapamil increased bygrapefruit juice; plasma concentration of amlodipinepossibly increased by grapefruit juiceHormone Antagonists: diltiazem and verapamilincrease plasma concentration of dutasteride. Ivabradine: diltiazem and verapamil increase plasmaconcentration of .ivabradine—avoid concomitantuseCalcium-channel Blockers (continued). Lipid-regulating Drugs: diltiazem increases plasmaconcentration of atorvastatin and simvastatin—possibleincreased risk of myopathy; increased risk ofmyopathy when verapamil given with .simvastatin;possible increased risk of myopathy when amlodipinegiven with simvastatinLithium: neurotoxicity may occur when diltiazem orverapamil given with lithium without increasedplasma concentration of lithium. Magnesium (parenteral): profound hypotensionreported with concomitant use of nifedipine and.parenteral magnesium in pre-eclampsiaMethyldopa: enhanced hypotensive effect whencalcium-channel blockers given with methyldopaMoxisylyte: enhanced hypotensive effect whencalcium-channel blockers given with moxisylyteMoxonidine: enhanced hypotensive effect whencalcium-channel blockers given with moxonidineMuscle Relaxants: verapamil enhances effects of nondepolarisingmuscle relaxants and suxamethonium;enhanced hypotensive effect when calcium-channelblockers given with baclofen or tizanidine; manufacturerof verapamil advises avoid concomitant use ofintravenous dantrolene; possible increased risk ofventricular arrhythmias when diltiazem given withintravenous dantrolene—manufacturer of diltiazemadvises avoid concomitant use; calcium-channelblockers possibly enhance effects of non-depolarisingmuscle relaxantsNitrates: enhanced hypotensive effect when calciumchannelblockers given with nitratesOestrogens: hypotensive effect of calcium-channelblockers antagonised by oestrogensProstaglandins: enhanced hypotensive effect whencalcium-channel blockers given with alprostadilRanolazine: diltiazem and verapamil increase plasmaconcentration of ranolazine (consider reducing doseof ranolazine)Sildenafil: enhanced hypotensive effect when amlodipinegiven with sildenafil. Sirolimus: diltiazem increases plasma concentration of.sirolimus; plasma concentration of both drugsincreased when verapamil given with .sirolimusSulfinpyrazone: plasma concentration of verapamilreduced by sulfinpyrazone. Tacrolimus: diltiazem and nifedipine increase plasmaconcentration of .tacrolimus; felodipine,nicardipine and verapamil possibly increase plasmaconcentration of tacrolimus. Theophylline: calcium-channel blockers possiblyincrease plasma concentration of .theophylline(enhanced effect); diltiazem increases plasma concentrationof theophylline; verapamil increasesplasma concentration of .theophylline (enhancedeffect)Ulcer-healing Drugs: metabolism of calcium-channelblockers possibly inhibited by cimetidine (increasedplasma concentration); plasma concentration ofisradipine increased by cimetidine (halve dose ofisradipine)Vardenafil: enhanced hypotensive effect when nifedipinegiven with vardenafilVasodilator Antihypertensives: enhanced hypotensiveeffect when calcium-channel blockers given withhydralazine, minoxidil or sodium nitroprussideCalcium-channel Blockers (dihydropyridines) seeCalcium-channel BlockersCandesartan see Angiotensin-II Receptor AntagonistsCannabis ExtractAntidepressants: possible increased risk of hypertensionand tachycardia when cannabis extract givenwith tricyclicsCapecitabine see FluorouracilCapreomycinAntibacterials: increased risk of nephrotoxicity whencapreomycin given with colistimethate sodium orpolymyxins; increased risk of nephrotoxicity andAppendix 1: Interactions