Detecting drug-drug interactions in medication profiles of psychiatric inpatients: a two-stage approach.

A two-stage evaluation methodology was developed to detect drug-drug interactions (D-DIs) of moderate and major severity in a psychiatric inpatient population. During a 3-month study period, the medication orders prescribed for 152 psychiatric inpatients in two psychiatric wards of a medical center were examined. A primary assessment of patients' reactions due to drug interactions was carried out by physicians who were provided with pertinent drug interaction monographs. A secondary assessment was performed by a three-member committee using explicit criteria to decide which reactions were actual D-DIs. Potential moderate or major severity D-DIs were identified in 79 (52.0%) of the 152 patients. A total of 130 potential interactions were detected in 339 (63.1%) of the 537 medication profiles. Actual D-DIs were seen in two patients (1.3%) who were prescribed trazodone with chlorpromazine and doxepin with paroxetine, respectively. The discrepancy between incidences of potential and actual D-DIs suggests that the method was sensitive in the detection and prudent in the assessment of D-DIs.