This study aimed to describe the effects of the
antipsychotic amisulpride in overdose, including the frequency of QT prolongation and
torsades de pointes. Cases of
amisulpride overdose (>1 g) were recruited from 2 state
poison centers and a tertiary toxicology unit over 5 years. A 1-page clinical research form was used to collect clinical information. Copies of all electrocardiograms were obtained. Electrocardiogram parameters (QRS and QT intervals) were manually measured as previously described, and plots of QT-heart rate (HR) pairs were compared with the QT nomogram. There were 83 patients with
amisulpride overdoses with a median age of 29 years (interquartile range [IQR], 23-40 years), and 42 (51%) were female. The median dose ingested was 6 g (IQR, 3-13 g, range, 1.2-120 g). The median HR was 66 beats/min (IQR, 60-81 beats/min).
Bradycardia occurred in 20 cases (24%), and
hypotension in 19 (23%). From 440 electrocardiograms (average of 5 per case; range, 1-15), an abnormal QT-HR pair occurred in 61 cases (73%).
Torsades de pointes developed in 6 cases (7%), with doses of 4, 4.6, 18, 24, 32, and 80 g. The patient taking 32 g died after a
cardiac arrest. Widened QRS did not occur except transient rate-dependent
bundle-branch block in 3 cases. There were significant associations of
bradycardia,
hypokalemia, and hypocalcaemia, with QT prolongation and
torsades de pointes. Central nervous system effects were uncommon with
coma in 7 cases,
seizures in 2, and dystonic reactions in 2.
Amisulpride overdose commonly causes QT prolongation,
bradycardia, and
hypotension.
Torsades de pointes occurred commonly enough to suggest that
amisulpride is highly cardiotoxic in overdose.