Metoprolol Rifampicin

Swaisland HC, Ranson M, Smith RP, et al. Pharmacokinetic drug interactions of gefitinib with rifampicin, itraconazole and metoprolol. Clin Pharmacokinet 2005 44(10) 1067—1081. 

BETA-BLOCKERS RIFAMPICIN L plasma concentrations and efficacy of bisoprolol, carvedilol, celiprolol, metoprolol and propanolol Rifampicin induces hepatic enzymes (e.g. CYP2C19), which t metabolism of the beta-blockers in addition, it may also t P-gp expression Monitor PR and BP watch for poor response to beta-blockers... 

Beimett PN, John VA Whitmarsh VB. Effect of rifampicin on metoprolol and antipyrine kinetics. BrJ Clin Pharmacol ( 9S2) 13, 387-91. 

As parecoxib is rapidly metabolised to valdecoxib, the interactions are usually considered to be due to the effects of valdecoxib. The manufacturer of parecoxib cautions the concurrent use with carbamazepine, dexamethasone and rifampicin as their effects on parecoxib have not been studied. Valdecoxib increases the levels of dextromethorphan and omeprazole. Because of these interactions, caution is advised with drugs that are metabolised by the same isoenzymes, nameiy flecainide, metoprolol, propafenone, omeprazoie, diazepam, imipramine and phenytoin. No interaction appears to occur between parecoxib and midazolam. 

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