The Individualized Management Approach for Acute Poisoning

Table 2

Carbamazepine and phenytoin PKs and the likeliness of dialysis efficacy.

Drug	Usual PKs	PKs in overdose	Efficacy of dialysis
Carbamazepine	(i) Molecular mass: 236 Da (small); (ii) Vd: 2 L/kg (high); lipophilic; (iii) Protein binding: 70–80% (high); (iv) Initial half-life is 25–65 h and then 10 h; (v) Active metabolites; (vi) Urine elimination (72%); (vii) Induces its own metabolism (chronic use); (viii) Time to peak = 4 hours	(i) Protein binding does not decrease significantly in overdose; (ii) No enzyme induction in CBZ naive individuals; (iii) Half-life much longer (ongoing absorption, impaired elimination, or both); (iv) High concentration exhibits anticholinergic proprieties, which delay GI motility, further prolonging absorption, with time to peak > 100 hours	High-efficiency hemodialysis is the best method; Then, venovenous CRRT and charcoal or resin hemoperfusion; May reduce the carbamazepine level by about 50%
Phenytoin	(i) Molecular mass: 252 Da (low); (ii) Vd: 0.7 L/kg (low); (iii) Protein binding: 90–95% (high); (iv) Half-life = 22 h; (v) Cl = 23 mL/min; (vi) Follows nonlinear PKs	(i) Clearance reduced; (ii) Half-life greatly prolonged (103 hours); (iii) Protein binding decreases (70–80%); (iv) Volume of distribution increases	High-efficiency hemodialysis is the best method, but hemoperfusion is an acceptable alternative.; However, because of the low incidence of irreversible tissue injury or death related to phenytoin poisoning and the relatively limited effect of dialysis on phenytoin removal, dialysis can be used only in very selected patients with severe phenytoin poisoning.