Review article: factors influencing antibiotic transfer across the gastric mucosa.

The delivery of antimicrobial drugs to Helicobacter pylori within the stomach is poorly understood. The gastric environment represents a unique pharmacokinetic compartment, into which drug can be delivered directly following oral administration, or indirectly following intestinal absorption and transfer from the blood into the stomach across the gastric mucosa. Several methods have been used to study drug disposition across the gastric mucosa, including endoscopic biopsy studies, nasogastric intubation studies and animal models. Direct, or topical, delivery is limited by luminal drug degradation, drug formulation and the permeability of the mucus layer. Indirect, or systemic, delivery is limited by factors affecting the concentration gradient across the gastric mucosa and the permeability of the mucosa. These factors include intragastric pH, plasma protein binding, drug lipophilicity, the presence of active transport mechanisms, drugs that damage the gastric mucosa and inflammation secondary to H. pylori infection. Little is known about the last of these, and further research in this area should help in the rational approach to development of treatments against H. pylori.