Massive gabapentin and presumptive quetiapine overdose.

Previous reports of gabapentin overdose have described mild symptoms of somnolence, ataxia and slurred speech. Quetiapine has produced a false positive for cyclic antidepressants on immunoassay drugscreens. Quetiapine overdose is associated with coma, QTc prolongation and hypotension. We report a case of massive gabapentin and presumptive quetiapine overdose with the highest recorded serum gabapentin concentration (104.5 u/ml) associated with coma, respiratory depression requiring mechanical ventilation, and hypotension.