Abstract: AIM: To investigate hypnotic and seda-lion interaction between midazolam, fentanyl and propofolin coinduction in general anesthesia.METHODS: Sixty patients', ASA class I orll, scheduled for elective celo Nc ope (peration were evenly distributed to 6 different com-pound dose groups according to weighted modificationmethodl Anesthesia was induced with midazolam which was administered over 15 s, and fentanyl which was administered over 15 s, and propofol which was administerel over 30 s. then monium 0.6 mg·kg^-1 was adwinisteredl to facilitate tracheal intubation. BIS, MAPHR were recorded at following times: before induction, Iand 2 tnin after induction, just at intubation, I and 3 and 5 and 7 min after intubation.RESULTS: The importantdegree of every drug was as follow: propofol > nltanylmidazolam. The optimal combinations was midazolam 0.02 mg·kg^-1, fentanyl 0.0025 mg·kg^-1 and propofol 0.8 mg·kg^-1. The optimal ratio was 1.0. 0.125: 40. Thenature of interaction was additive.CONCLUSION: Themidazolam, fentanyl and propofol combination possess ad-dtitive interaction in sedation and hypnosis. The optimcombinations was midazolam 0.02 mg·kg^-1, fentanyl 0.0025 mg·kg^-1 and propofol 0.8 mg·kg^-1.

Key words: midazolam, fentanyl, propofol, Coinduction drug interaction, weighted modification methol