Abstract: Aim To analyzed and evaluate the analgesic effect of acetaminophen (Ace),butabital(But)and caffeine (Caf)in combination.Methods According to the formula uniform design method,7 different doses at 7 different pro portions were administered (ig)to observe the analgesic effect in mice by the swirling tail method.The optimum doses and proportion in combination were obtained according to the experimental data,ma thematical analysis and the special field demand,which was demonstrated by another experiments (the swirling tail method and the light -electric vibrating box method).Acute toxicity of the combination was quantitatively analyzed by the parameter method.Results The combination of Ace 40.7,But 6.4 and Caf 5 mg/kg (proportion as 8.1∶1.25∶1)was appropriate and the acute toxicity didn't increased.Conclusion The formula uniform design method can be effectively applied to analyze the multidrug effects,but its result must take a special field demand into account,and the estimated optimum dose and proportion for combination be demonstrated by another further experiment.

Key words: acetaminophen, butabital, caffeine, uniform design, combination drug therapy, drug synergism