DRUG-INTERACTIONS AMONG COMMONLY USED MEDICATIONS - CHART SIMPLIFIES DATA FROM CRITICAL LITERATURE-REVIEW

OBJECTIVE To simplify risk assessment, we have developed a way to pres ent critically appraised drug interaction information through a chart. DATA SOURCES Fifty drugs most frequently prescribed by Canadian famil y physicians and 16 drugs and substances that frequently interact with these drugs were the basis for a literature review. Drug interaction textbooks and MEDLINE (from 1966 to 1994) were searched for documented interactions. Reports of additive effects and animal or in vitro stud ies were excluded. STUDY SELECTION All reports of interactions were ev aluated for clinical effect, clinical significance, and quality of evi dence. SYNTHESIS Of the 464 drug-drug or drug-substance pairs evaluate d, 387 (83.4%) demonstrated an interaction, 59 (12.7%) documented no e ffect, and 18 (3.9%) pairs had conflicting evidence. Five percent of i nteractions were of major clinical significance; only 1.3% were of maj or clinical significance and supported by good-quality evidence. By us ing symbols, colours, and legends in a ''grid-map'' format, a large am ount of drug interaction information was reduced to a single-page char t suitable for a desk reference or wall mounting. CONCLUSIONS Our char t organizes a large amount of drug interaction information in a format that allows for rapid appreciation of outcome, clinical significance, and quality of evidence.