Evaluation of the influence of antacids and H2 antagonists on the absorption of moxifloxacin after oral administration of a 400mg dose to healthy volunteers

Clin Pharmacokinet. 2001:40 Suppl 1:39-48. doi: 10.2165/00003088-200140001-00006.

Abstract

Objective: To determine the effect of concomitant administration of the antacid Maalox 70 or the histamine H2 receptor antagonist ranitidine on the bioavailability of moxifloxacin.

Design: These were nonblinded, randomised, crossover studies performed in healthy volunteers.

Participants: 24 healthy males aged 22 to 39 years (study 1; n = 12) and 24 to 43 years (study 2; n = 12) were included in these studies.

Methods: In study 1, 12 participants received ranitidine 150mg twice daily during a 3-day pretreatment phase and 1 tablet of ranitidine together with a single 400mg dose of moxifloxacin on the profile day. In study 2, 12 participants received a single 400mg dose of moxifloxacin alone (treatment A), simultaneously with Maalox 70 10ml (treatment B), or with Maalox 70 10ml given 4 hours before (treatment C) or 2 hours after (treatment D) the fluoroquinolone. In treatments B, C and D, administration of the antacid (10ml, 1 hour after each meal) was continued for 2 days. Plasma and urine samples were obtained for determination of the pharmacokinetic parameters of moxifloxacin.

Results: Coadministration of moxifloxacin with ranitidine showed lack of interaction for area under the plasma concentration-time curve extrapolated to infinity (AUCinfinity) [35.5 versus 34.3 mg/L x h with versus without ranitidine; relative bioavailability 103%, 90% confidence interval (CI) 97.7 to 109.3%] and maximum plasma concentration (Cmax) [2.98 versus 2.76 mg/L with versus without ranitidine; ratio 107.9%, 90% CI 90.5 to 128.6%]. When moxifloxacin was given simultaneously with Maalox 70, AUCinfinity ( 14.7 mg/L x h) and Cmax (1.00 mg/L) were reduced by approximately 60%. When the antacid was given 4 hours before or 2 hours after the fluoroquinolone, AUCinfinity values (28.0 and 26.7 versus 34.3 mg/L x h) were moderately reduced (by <27%), terminal elimination half-life values declined by approximately 24% (9.4 and 9.3 versus 12.3 hours) compared with moxifloxacin alone and Cmax values were almost unchanged (2.55 and 2.38 versus 2.57 mg/L). The mean bioavailabilities corrected for the elimination rate constants (lambdaz) were 101% (antacid given 4 hours before moxifloxacin) and 98% (antacid given 2 hours after moxifloxacin), indicating that Maalox 70 may interfere with the gastrointestinal recirculation of moxifloxacin.

Conclusions: The bioavailability of moxifloxacin is not affected by concurrent administration of ranitidine. Absorption of moxifloxacin is impaired by concomitant administration of aluminium- and magnesium-containing antacids and administration of these agents should be staggered. An interval of 2 hours before or 4 hours after taking the antacid ensures that the effect of the interaction is not clinically relevant.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Administration, Oral
  • Adult
  • Aluminum Hydroxide / pharmacology*
  • Antacids / pharmacology*
  • Anti-Infective Agents / administration & dosage
  • Anti-Infective Agents / blood
  • Anti-Infective Agents / pharmacokinetics*
  • Anti-Infective Agents / urine
  • Area Under Curve
  • Aza Compounds*
  • Biological Availability
  • Chromatography, High Pressure Liquid
  • Cross-Over Studies
  • Drug Combinations
  • Drug Interactions
  • Fluoroquinolones*
  • Half-Life
  • Histamine H2 Antagonists / pharmacology*
  • Humans
  • Hydrogen-Ion Concentration
  • Intestinal Absorption
  • Magnesium Hydroxide / pharmacology*
  • Male
  • Metabolic Clearance Rate
  • Moxifloxacin
  • Quinolines*
  • Ranitidine / pharmacology*

Substances

  • Antacids
  • Anti-Infective Agents
  • Aza Compounds
  • Drug Combinations
  • Fluoroquinolones
  • Histamine H2 Antagonists
  • Quinolines
  • aluminum hydroxide, magnesium hydroxide, drug combination
  • Aluminum Hydroxide
  • Ranitidine
  • Magnesium Hydroxide
  • Moxifloxacin