Clinical features in 28 consecutive cases of laboratory confirmed massive poisoning with carbamazepine alone

A retrospective study of consecutive cases of massive carbamazepine poisoning treated in an intensive care unit during the period 1981-1991 was performed, mainly to determine whether serum carbamazepine levels were predictive of toxicity. Out of a total of 51 admissions with a diagnosis of carbamazepine self-poisoning, 28 (25 patients) were included. The reasons for exclusion were coingestion of other drugs (11 cases), incorrect diagnosis or inadequate information (6 cases), a peak observed serum concentration of carbamazepine below 76 mumol/L [18 mg/L] (4 cases), and lack of any documented serum carbamazepine assay (2 cases). The peak serum concentrations ranged from 78 to 285 mumol/L [18.4 to 67.4 mg/L]. It was found that serum levels equal to or above 170 mumol/L [40 mg/L] were significantly associated with an increased risk of serious complications such as coma, seizures, respiratory failure and cardiac conduction defects. In 60% of the 10 patients with a serum level > or = 170 mumol/L at least two of these symptoms occurred, in 50% at least three, and in 40% all four. There were two fatalities. Among the 16 patients (18 admissions) with a serum carbamazepine concentration below 170 mumol/L, only one was comatose and none had any of the other severe symptoms. It is concluded that serum carbamazepine levels accurately predict the severity of toxicity in massive carbamazepine poisoning in adults.