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Effect of High‐Dose Metronidazole on Pharmacokinetics of Oral Budesonide and Vice Versa: A Double Drug Interaction Study
Author(s) -
Dilger Karin,
Fux Richard,
Röck Daniel,
Mörike Klaus,
Gleiter Christop H.
Publication year - 2007
Publication title -
the journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 116
eISSN - 1552-4604
pISSN - 0091-2700
DOI - 10.1177/0091270007308617
Subject(s) - budesonide , metronidazole , pharmacokinetics , medicine , pharmacology , drug interaction , cyp3a , ketoconazole , concomitant , gastroenterology , corticosteroid , antibiotics , chemistry , cytochrome p450 , antifungal , biochemistry , metabolism , dermatology
Recent case reports suggest that addition of high‐dose metronidazole might be associated with elevated plasma concentrations of substrates of cytochrome P450 (CYP) 3A. Because patients with fistulizing Crohn's disease benefit by using high doses of metronidazole for prolonged periods, this study's primary aim was to evaluate the effect of high‐dose metronidazole on the pharmacokinetics of oral budesonide, a sensitive substrate of CYP3A commonly prescribed in acute inflammatory bowel disease. Twelve healthy adults received 1.5 g metronidazole per day over 1 week. The CYP3A‐dependent metabolic profile of an oral dose of budesonide (3 mg) and that of endogenous cortisol were compared intraindividually before and after administration of metronidazole. There was neither a significant effect of high‐dose metronidazole on the area under the plasma concentration‐time curve (AUC) of budesonide (90% confidence interval, 79%–115%) nor on the AUC ratios of 6β‐hydroxybudesonide/budesonide and 16α‐hydroxyprednisolone/budesonide. In parallel, metronidazole did not significantly alter formation of 6β‐hydroxycortisol. Vice versa, budesonide did not affect the AUC of metronidazole (90% confidence interval, 91%–100%). The authors conclude that in contrast to concomitant intake of other imidazoles such as ketoconazole, concomitant intake of metronidazole may not lead to serious safety concerns due to elevated systemic concentrations of the glucocorticoid budesonide.