Alpinia officinarum Hance of the Chinese traditional herb for the treatment of emesis,abdominal pain and diarrhea has been used to counteract gastric disease induced by indomethacin in rats without obvious side effects.However,the role of herb-drug interaction between indomethacin and A.officinarum based on pharmacokinetic,tissue distribution and excretion still remains unknown.In this study,an ultra-fast liquid-tandem mass spectrometry(UFLC-MS/MS)method was developed for simultaneous determina-tion of indomethacin and its three metabolites,O-desmethylindomethacin(ODI),deschlor-obenzoylindomethacin(NDI)and indomethacin acyl-β-D-glucuronide(IDAβG)by oral administration of indomethacin solution with and without the ethanolic extract of A.officinarum and applied to comparative pharmacokinetic,tissue distribution and excretion studies.Our results clarified that oral administration of A.officinarum produced significant alterations in the pharmacokinetic parameters of indomethacin.And the pharmacokinetic interaction between indomethacin and A.officinarum reduced the systemic exposure of indomethacin and increased its elimination.Tissue distribution results demonstrated that co-administration of A.Officinarum could not reduce the accumulation of indo-methacin in the target tissue of the stomach,but could accelerate the excretions of indomethacin and its three metabolites including ODI,NDI and IDAβG in the bile and feces of rats in the excretion study.Therefore,A.Officinarum might have a gastrointestinal protective effect through the interaction role with indomethacin based on the pharmacokinetics and excretion in rats.