Drug-related problems of antipsychotics in treating delirium among elderly patients: A real-world observational study

Delirium is more common and life-threatening among the elderly. Currently, no other medications, including antipsychotics, have been approved for delirium. The number of practice guidelines recommends antipsychotics to be the first option among selected patients. This study aimed to identify the type of drug-related problems (DRPs) concerning antipsychotics use among elderly patients with delirium.

A retrospective observational study was conducted by collecting data from 2013 to 2016 in Maharaj Nakorn Chiang Mai Hospital, Thailand. Inpatients who were 60 years and over, diagnosed with delirium by ICD-10 diseases coding F05.X and treated with antipsychotics for delirium were included. A modified version of the American Society of Hospital Pharmacists classification criteria (mASHP-delirium) was used.

A total of 379 patients were enrolled. Mean daily dose of haloperidol (oral) was 1.06 ± 1.33 mg, haloperidol (intramuscular) 2.71 ± 1.88 mg, haloperidol (intravenous; IV) 3.42 ± 1.97 mg, risperidone was 0.71 ± 0.52 mg, and quetiapine was 19.26 ± 15.63 mg. Among all, 427 events were classified as DRPs. The most common DRPs included inappropriate duration, dose, route of administration or dosage form accounting for the 416 events (97.4%), followed by actual adverse drug reactions (extrapyramidal symptoms; EPS), 6 events (1.4%) and potential drug-drug interactions for 5 events (1.2%). Of those 416 events, 200 events (48.1%) antipsychotics were continued after discharge and continued for more than 10 days. Dosage exceeding initial dose or maximum daily dose accounted for 179 events (43.0%). Other DRPs such as inappropriate route haloperidol IV and receiving the extended-release dosage form of quetiapine involve 26 (6.3%) and 11 (2.6%) events, respectively.

To the best of our knowledge, this is the first study using mASHP-delirium to identify DRPs of antipsychotics in treating delirium among elderly patients. Several DRPs were found that might lead to severe adverse drug reactions, particularly EPS and QTc interval prolongation. However, all DRPs could be prevented by developing antipsychotic setting protocols and specialty consulting systems to communicate among healthcare providers caring for vulnerable groups of patients. In addition, a prospective pharmacist intervention is required.