Secretion of intravenously administered antibiotics in gastric juice: implications for management of Helicobacter pylori.

AIMS: To study whether differences in eradication rates of antibiotics may be explained by differences in secretion of antibiotics in gastric juice. METHODS: A single intravenous dose of either ampicillin 500 mg, erythromycin 500 mg, or metronidazole 500 mg was administered to four healthy Helicobacter pylori negative volunteers on different days. Antibiotic concentrations were measured in gastric juice before and every 10 minutes after administration of the drug for two hours and after one hour in serum. RESULTS: No ampicillin was detected in gastric juice. Erythromycin concentrations in gastric juice showed considerable individual variation and reached maximum concentrations of 2.2-4.8 mcg/ml between 30 and 80 minutes after dosing. Metronidazole concentrations in gastric juice showed much less individual variation and maximum concentrations of 5-6 mcg/ml were reached within 30 minutes and remained high during the study period. CONCLUSION: Metronidazole and erythromycin are secreted across the gastric mucosa, but ampicillin is not.