Pharmacokinetic interactions between ilaprazole and clarithromycin following ilaprazole, clarithromycin and amoxicillin triple therapy

Aim: To investigate the drug interactions between ilaprazole, a new proton pump inhibitor, and clarithromycin following ilaprazole, clarithromycin and amoxicillin combination therapy. Methods: Twelve healthy Chinese volunteers were recruited in a randomized, open-label, 3-period crossover study. All subjects were administered ilaprazole (5 mg), clarithromycin (500 mg) or a triple therapy, including ilaprazole (5 mg), clarithromycin (500 mg) and amoxicillin (1 g), twice daily for 6 consecutive days. On the 7th day, the drugs were given once, and blood samples were collected and analyzed using a well-validated HPLC/MS/MS method. Results: Following the triple therapy, the peak concentration ( C max ) and the area under the concentration-time curve from 0 h to 12 h (AUC 0→12 ) of ilaprazole were significantly decreased, as compared with the single medication group ( C max :1025.0±319.6 vs 1452.3±324.6 ng/mL; AUC 0→12 : 9777.7±3789.8 vs 11363.1±3442.0 ng·h/mL). Similar changes were found for ilaprazole sulfone ( C max : 5.9±0.5 vs 9.3±1.7 ng/mL; AUC 0→12 : 201.4±32.1 vs 277.1±66.2 ng·h/mL). The triple therapy significantly elevated the C max of clarithromycin (3161.5±702.2 vs 2541.9±476.2 ng/mL). Conclusion: The H pylori eradication therapy with clarithromycin, amoxicillin and ilaprazole may cause pharmacokinetic interactions that decrease the amount of ilaprazole and its metabolites and elevate that of clarithromycin.