ABSTRACT
<b>Objective: </b>In the previous study, the CYP database was constructed in order to relate drug-drug interactions to the CYP metabolic information of the package inserts. In this study, we evaluated the clinical usefulness of the CYP database by using the Pharmaceutical and Medical Devices Agency (PMDA) Drug Monitoring Information.<br><b>Methods: </b>We examined the drugs in CYP isoform responsible for drug metabolism. The age, sex, suspect drugs and co-administered drugs were extracted from 6,236 cases of the PMDA database of drug monitoring from January till November of 2008.<br><b>Results: </b>Twenty-three percent of all cases had co-administered drugs. Forty-five percent of these cases were metabolized both suspect and co-administered drugs by the same CYP isoform, and three fourths of these cases were able to be detected only by the CYP database. In addition, the administration of substrate medicines in combination with substrate medicines was the largest (57%), followed by cases of substrate medicines in combination with inhibitor medicines (28%). Seventy-seven percent of the suspect drugs that had a large number of reported cases of side effects were substrate medicines, and the frequency of co-administration with substrate medicines was very high.<br><b>Conclusion: </b>These data suggest that the CYP database, being used together with package inserts, might be a clinically useful tool to avoid adverse events caused by drug-drug interactions.