Analysis of drug interactions in combined drug therapy by reflection method

AIM: To set up a new method to analyze multidrug interaction in combined dr ug therapy. METHODS: Based on a dose-effect curve of the combined drugs and the equieffective test, a new mathematical model was set as Q = (E-o-E-t)/ L(-1<Q<1 addition, Q less than or equal to 1 antagonism, Q greater than or equal to 1 synergism) where E-o = an observed value (or its fitted value) o f combined effect, E-t = an expected value Of combined effect, and L = an e quieffective cutoff between E-o and E-t decided by the equieffective criter ion of a special field, the number of data points, and the experimental err or. The different types of experimental data were analyzed by the new model . RESULTS:: This reflection method could deal with data in combined drug th erapy, unnecessary to distinguish between independent and similar action, o r exclusive acid non-exclusive case among drugs. The number of drugs for co mbination did not need to be Limited. But the experimental data should be e nough to fit a dose-effect curve of drugs in combination. if every dose-eff ect curve of drugs-for combination was made, a series of Q values was-obtai ned from all levels of dose-effect for a systematic analysis. To large anim al or human experiment, the points of dose-effect of each drug used alone c ould be reduced to even 1 point. The results of analysis took the criterion of a special field and laboratory error into account in-this method. CONCL USION: The reflection method is an effective method for analysis of multidr ug interaction in combined drug therapy.