Incidence of Drug-Induced Delirium During Treatment With Antidepressants or Antipsychotics: A Drug Surveillance Report of German-Speaking Countries Between 1993 and 2016

Objectives Successful treatment of delirium depends on the detection of the reversible contributers. Drugs with delirogenic properties are the most prevalent reversible cause of delirium. Methods This observational study is based on data from AMSP (Arzneimittelsicherheit in der Psychiatrie), a multicenter drug surveillance program in German-speaking countries recording severe adverse drug reactions (ADRs) in psychiatric inpatients. The present study analyzes drug-induced delirium (DID) during treatment with antidepressants and antipsychotics. Results 436,565 psychiatric inpatients were treated with amtidepressants and/or antipsychotics during the observation period from 1993–2016 in the participating 110 hospitals. Overall, 254 cases (0.06 % of all patients treated with antidepressants and/or antipsychotics) of DID were detected. Implicated either in combination or alone (multiple drugs were implicated in 70.1% of DID), clomipramine (0.24%), amitriptyline (0.21%), and clozapine (0.18%) showed the highest incidence rates of DID. When implicated alone (98 cases overall), clozapine (0.11%), followed by amitriptyline (0.05%) were most likely causally associated with the occurrence of DID. Drugs with strong antimuscarinic properties generally exhibited higher risk of DID. Conclusions With an incidence rate of less than 0.1%, the use of antidepressants and antipsychotics was rarely associated with DID within the AMSP program. Tricyclic antidepressants and clozapine were the most commonly implicated psychotropic drugs. These data support the specific role of antimuscarinic properties in DID.