Research Article Changes in the Amounts of Amoxicillin and Metronidazole Used for Helicobacter pylori Eradication Therapy in the Stomach after Their Oral Administration to Rats

In the eradication therapy of Helicobacter pylori, the changes of the amounts and concentrations of antibiotics in the stomach after oral administration were unclear. Amoxicillin (AMX) and metronidazole (MTZ), which are used for such therapy, were selected for this study. The levels of these drugs in homogenate of the stomach after their oral administration to rats were determined by HPLC. The doses of AMX and MTZ to the rats were 15 mg/kg and 5 mg/kg, respectively. The proportions of these drugs remaining in the stomach decreased according to first-order kinetics. The rate constants for AMX and MTZ were 0.512 and 0.436 h -1 , respectively. The decrease of the stomach volume was also expressed as first-order kinetics, with a rate constant of 0.184 h -1 . These data are useful for the design of intragastric