Abstract
INTRODUCTION: Quetiapine is available in both immediate-release (IR) and extended-release (XR) formulations. Quetiapine XR overdose is known to cause delayed increase in serum quetiapine concentrations. However, it is not certain whether quetiapine IR overdose would similarly cause a delayed increase in serum quetiapine concentrations. CASE REPORT: A 57-year-old woman with depression who was taking half a tablet of 25 mg quetiapine IR daily was transported to our emergency department with a complaint of disturbance of consciousness 12 h after a quetiapine IR overdose. On arrival, her initial vital signs were heart rate of 116 beats per minute, blood pressure of 77/43 mm Hg, and oxygen saturation of 91% under 10 L oxygen administration. Whole body plain computed tomography showed a large amount of gastric hyperdense content suggesting pharmacobezoar with a volume of 71.2 ml. After treatment with respiratory and circulatory support, gastric lavage was performed. Her disturbance of consciousness persisted until day 5, and she was extubated on day 7. The serum concentrations of quetiapine were 2690 ng/mL at 12 h after overdose, 5940 ng/mL at 40 h, and 350 ng/mL at 124 h after overdose. Serum concentrations of other co-ingestions were all below lethal levels. CONCLUSION: A massive quetiapine IR overdose with pharmacobezoars can cause a delayed increase in serum quetiapine concentrations.