Background Patients with bipolar disorder frequently experience
polypharmacy, putting them at risk for clinically significant drug-drug
interactions (DDI). Online drug interaction database programs are used to alert
physicians, but there are no internationally recognized standards to define DDI.
This study compared the category of potential DDI returned by 6 commercial drug
interaction database programs for drug interaction pairs involving drugs
commonly prescribed for bipolar disorder.
Methods The category of potential DDI provided by 6 drug interaction
database programs (3 subscription, 3 open access) was obtained for 125 drug
interaction pairs. The pairs involved 103 drugs (38 psychiatric, 65
nonpsychiatric); 88 pairs included a psychiatric and nonpsychiatric drug; 37
pairs included 2 psychiatric drugs. Every pair contained at least 1 mood
stabilizer or antidepressant. The category provided by 6 drug interaction
database programs was compared using percent agreement and Fleiss kappa
statistic of interrater reliability.
Results For the 125 drug pairs, the overall percent agreement among the 6
drug interaction database programs was 60%; the Fleiss kappa agreement
was slight. For drug interaction pairs with any category rating of severe
(contraindicated), the kappa agreement was moderate. For drug interaction pairs
with any category rating of major, the kappa agreement was slight.
Conclusion There is poor agreement among drug interaction database
programs for the category of potential DDI involving psychiatric drugs. Drug
interaction database programs provide valuable information, but the lack of
consistency should be recognized as a limitation. When assistance is needed,
physicians should check more than 1 drug interaction database program.