Psychiatric admissions due to adverse drug reactions

This is a report of the findings of a 6-year study of hospitalizations caused by adverse psychiatric reactions to prescribed medications. Of 15,800 consecutive psychiatric admissions to two university hospitals, 112 (0.7%) were caused by adverse reactions to medications. In 67% of cases these admissions were due to extrapyramidal symptoms such as parkinsonism and/or akathisia, and coexisting neuroleptic-related depression. In 25% the admitting diagnosis was drug-induced delirium or psychosis; one third of these patients suffered from Parkinson's disease and had been treated with a combination of two or more antiparkinsonian agents. Older age, polydrug therapy, and the parenteral administration of neuroleptics at high dosages were important risk factors for severe adverse drug reactions leading to hospitalization.