Effects of food and formulation on the relative bioavailability of bismuth biskalcitrate, metronidazole, and tetracycline given for Helicobacter pylori eradication

Abstract

Aims: To evaluate the effects of food and formulation on the pharmacokinetics of bismuth biskalcitrate, metronidazole and tetracycline when combined in a new 3-in-1 single capsule (BMT) for eradication of Helicobacter pylori.

Methods: In a randomized, 3 x 3 cross-over design, 23 healthy males received one dose of BMT in the fed and fasting states and equivalent doses of the three drugs given together but as separate capsules while fasting. Bioequivalence was evaluated according to 90% confidence intervals (CIs) of ratios of geometric least square means for C(max), AUC(t), and AUC(infinity).

Results: With respect to food, none of the three drugs met bioequivalence guidelines. Bismuth had lower limit CIs ranging from 12% for C(max) to 25% for AUC(infinity). The corresponding values for tetracycline were 59% and 51%. Metronidazole had a lower limit CI of 74% for C(max). With respect to formulation, bismuth had lower limits of CIs ranging from 39% for C(max) to 50% for AUC(t) and higher limits of 146% for AUC(t), metronidazole met bioequivalence guidelines, and tetracycline had lower limits of CIs between 72% for AUC(t) and 74% for AUC(infinity).

Conclusions: Food significantly decreased the relative bioavailability of each drug but formulation was without effect. This decrease may be beneficial when a local gastric action is needed, as confirmed by a near 90% eradication rate when this combined capsule is administered with food to treat gastro-duodenal local infection by H. pylori.

Figure 1

Mean plasma bismuth concentrations vs. time following the administration of the combined BMT capsule in the fasting state (⋄), after food (▵), and when the drugs were given as separate capsules in the fasting state (□)

Figure 2

Mean plasma metronidazole concentrations vs. time following the administration of the combined BMT capsule in the fasting state (⋄), after food (▵), and when the drugs were given as separate capsules in the fasting state (□)

Figure 3

Mean plasma tetracycline concentrations vs. time following the administration of the combined BMT capsule in the fasting state (⋄), after food (▵), and when the drugs were given as separate capsules in the fasting state (□)