Effect of green tea on the gastrointestinal absorption of amoxicillin in rats

BACKGROUND: The investigation of food-drug and plant-drug interactions has become increasingly important. In case of antibiotics, it is essential to achieve and maintain a plasma concentration sufficient for the antimicrobial action. Although, on theoretical basis, the interaction of polyphenols and antibiotics may be hypothesized, experimental data are lacking to assess its clinical relevance. The aim of our study was to assess the interaction between one of the most widely used antibiotics, amoxicillin, and green tea, the most frequently consumed drink with high polyphenol content. METHODS: The effects of green tea on the plasma level of amoxicillin was studied in an in vivo experiment in rats. The plasma level of amoxicillin was monitored by LC-MS/MS for 240 min after oral administration. The polyphenol content of green tea was determined by the Folin-Ciocalteu method. RESULTS: The peak plasma concentration of amoxicillin significantly decreased upon its co-administration with green tea, although the AUC(0–240) of the antibiotic did not decrease significantly in the group treated with amoxicillin suspended in green tea. CONCLUSIONS: Our results suggest a potentially relevant interaction between green tea and amoxicillin, worth being further studied in humans.