Clinical response and total and unbound plasma concentrations after lidocaine overdose.

Plasma and unbound concentrations and hemodynamic and CNS effects were monitored in a patient after overdose of 2 g of lidocaine HCl infused during 1 h. Hypotension, decreased heart rate, tremors, and nonresponsiveness to stimuli were observed at plasma and unbound concentrations of 17.7 and 12.0 micrograms/ml. The half-lives of decline of plasma and unbound concentrations were 3.8 and 2.7 h; the difference in half-lives was due to nonlinear plasma protein binding.