Effect of MMX® mesalamine coadministration on the pharmacokinetics of amoxicillin, ciprofloxacin XR, metronidazole, and sulfamethoxazole: results from four randomized clinical trials

Background: MMX (R) mesalamine is a once daily oral 5-aminosalicylic acid formulation, effective in induction and maintenance of ulcerative colitis remission. Patients on long-term mesalamine maintenance may occasionally require concomitant antibiotic treatment for unrelated infections. Aim: To evaluate the potential for pharmacokinetic interactions between MMX mesalamine and amoxicillin, ciprofloxacin extended release (XR), metronidazole, or sulfamethoxazole in four open-label, randomized, placebo-controlled, two-period crossover studies. Methods: In all four studies, healthy adults received placebo once daily or MMX mesalamine 4.8 g once daily on days 1-4 in one of two treatment sequences. In studies 1 and 2, subjects also received a single dose of amoxicillin 500 mg (N=62) or ciprofloxacin XR 500 mg (N=30) on day 4. In studies 3 and 4, subjects received metronidazole 750 mg twice daily on days 1-3 and once on day 4 (N=30); or sulfamethoxazole 800 mg/trimethoprim 160 mg twice daily on days 1-3 and once on day 4 (N=44). Results: MMX mesalamine had no significant effects on systemic exposure to amoxicillin, ciprofloxacin, or metronidazole; the 90% confidence intervals (CIs) around the geometric mean ratios (antibiotic + MMX mesalamine: antibiotic + placebo) for maximum plasma concentration (C-max) and area under the plasma concentration-time curve (AUC) fell within the predefined equivalence range (0.80-1.25). Sulfamethoxazole exposure increased by a statistically significant amount when coadministered with MMX mesalamine; however, increased exposure (by 12% in C-max at steady state; by 15% in AUC at steady state) was not considered clinically significant, as the 90% CIs for each point estimate fell entirely within the predefined equivalence range. Adverse events in all studies were generally mild. Conclusion: MMX mesalamine may be coadministered with amoxicillin, ciprofloxacin, metronidazole, or sulfamethoxazole, without affecting pharmacokinetics or safety of these antibiotics.