Lack of Pharmacokinetic Interaction between Lansoprazole and Intravenously Administered Phenytoin

• Published in: Journal of clinical pharmacology 1999-12, Vol.39 (12), p.1283-1289
• Main Authors: Karol, Michael D, Locke, Charles S, Cavanaugh, John H
• Format: Article
• Language: English
• ISSN: 0091-2700
• DOI: 10.1177/009127009903901211

The objective of this randomized, double-blind, two-period crossover study was to investigate whether concomitant steady-state lansoprazole influences the pharmacokinetics of CYP2C9 substrates using single intravenously dosed phenytoin as a mlodel substrate. In addition, the safety of concomitant administration of these two drugs was evaluated. Twelve healthy, nonsmoking, adult male subjects received 60 mg lansoprazole orplacebo once dailyfor 9 days during each study period. On the morning of day 7, each subjectreceived a single 250 mg intravenous phenytoin dose. There were no statistically significant differences between the two regimens for mean phenytoin C sub(max) or t sub(max*) There was a minor (< 3%) but statistically significant difference between the two regimens forphenytoin AUC resultingfrom a very low intrasubject coefficient of variation (2.3%). The treatment and control mean plasnma concentration phenytoin profiles were virtually super-imposable. In conclusion, concomitant multidose lansoprazole administration is unlikely to have any clinically significant effect on the pharnacokinetics of CYP2C9 substrates in general or intravenous phenytoin specifically.