Dose-Dependent Effects of Benzodiazepines and Other Psychotropic Drugs on Seizure Duration in Electroconvulsive Therapy

OBJECTIVE: To examine the effects of psychotropic drugs on the seizure duration in patients receiving electroconvulsive therapy (ECT). MATERIALS AND METHODS: Medical records of patients receiving ECT at a university hospital in Bangkok from March 2014 to February 2017 were retrospectively reviewed. Demographics, psychotropic drug use, ECT parameters, and motor seizure duration were recorded. Daily doses of drugs with antipsychotic properties and benzodiazepines were converted to risperidone and diazepam equivalent doses, respectively. Besides descriptive statistics, logistic regression analyses were performed using the linear quantile mixed model analysis to examine the association between seizure duration and the use and daily dose of psychotropic drugs. RESULTS: Data from 249 inpatients were analyzed. Seizure duration was inversely associated with benzodiazepine dosage (β=-0.070, P=0.026), especially at diazepam-equivalent dose ≥20 mg (β=-5.303, P=0.031). After adjustment for thiopental dose, charges, age, and sex, this association remained significant (β=-5.321, P=0.033). Antipsychotic use (P=0.672) and risperidone-equivalent daily dose (P=0.996), as well as clozapine use (P=0.395) and dose (P=0.733), were not associated with seizure duration. The use of anticonvulsants (P=0.989), including valproate (P=0.500), and antidepressants (P=0.649), including SSRIs (P=0.666), SNRIs (P=0.713), and trazodone (P=0.249), also showed no significant associations. After adjusting for thiopental dose, charge, age, sex, and BZD dose, other psychotropic medications showed no significant association with seizure duration. CONCLUSIONS: Benzodiazepine doses at diazepam equivalents of ≥20 mg were associated with shorter seizure duration. If patients benefit from benzodiazepine use during ECT, clinicians may consider prescribing it at a diazepam-equivalent dose of <20 mg/d if necessary.