Influence of activated charcoal on the pharmacokinetics and the clinical features of carbamazepine poisoning.

Carbamazepine (CBZ) poisoning has been associated with cases of severe toxicity and death. Multiple-dose activated charcoal was proposed to enhance the clearance of CBZ elimination, but there are no prospective controlled studies that demonstrated a change in clinical outcome after the use of multiple-dose activated charcoal. The aim of this study was to determine the CBZ elimination kinetics and the evolution of clinical features according to the dose of activated charcoal in acute poisoning patients. It is a prospective study for 6 months, from January to June 2004, including all pure acute CBZ-poisoned patients. Twelve patients were randomized to receive a multiple-dose activated charcoal (G1) or a simple dose of 1 g/kg (G2). Their mean age was 27.6+/-12.2 years; the Simplified Acute Physiology Score (SAPS II), 16.37+/-8.46; and the Acute Physiology and Chronic Health Evaluation (APACHE II), 8+/-3.96. They were 8 men and 4 women. The mean concentration of blood CBZ at hospital admission was of 29.42+/-6.68 mg/L. Each group includes 6 patients. The peak value of blood CBZ was comparable in the 2 groups: 33+/-3.46 mg/L (G1) vs 32.6+/-5.63 (G2) (P=.5); the requirement of mechanical ventilation was similar also (3 in each group). The duration of both coma and mechanical ventilation was significantly decreased in the first group compared with the second: 20.33+/-3.05 vs 29.33+/-4.11 hours for coma (P=.02) and 24.1+/-4.2 vs 36.4+/-3.6 hours for mechanical ventilation (P=.001). The length of stay was also significantly decreased in the first group: 30.3+/-3.4 vs 39.7+/-7.3 hours in the second group (P=.000006). Concurrently, we have noted a significant constant reduction of the half-life of CBZ from serum in the first group: 12.56+/-3.5 hours after multiple dose vs 27.88+/-7.36 hours after a simple dose (P=.0004). This decrease was correlated to the dose of charcoal. In summary, we can conclude that multiple-dose activated charcoal is more efficient than simple-dose; it permits a constant decrease of the half-life of blood CBZ without any rebound effect and could improve the prognosis by reducing the duration of coma and the length of stay.