Pharmacokinetics of carbamazepine in monkeys following intravenous and oral administration.

The pharmacokinetics of carbamazepine were evaluated in four male rhesus monkeys. A 20-mg/kg dose was administered by intravenous (5-min) infusion and orally (nasal-gastric intubation) in a propylene glycol-ethanol-water solvent. Plasma and urine determinations were performed by GLC. All semilogarithmic intravenous curves exhibited an irregular decay behavior in the first 3-hr period, followed by a linear disappearance phase (T 1/2 equals 1.0-2.4 hr). Urinary excretion measurements confirmed the short elimination half-life and showed that less than 1% of the dose was excreted unchanged. Oral studies also yielded a short elimination half-life (1.0-1.60 hr), which was confirmed by urinary excretion measurements. The oral curves were analyzed pharmacokinetically. The fraction of the dose reaching the systemic circulation ranged between 58 and 87%. Measurable (but insignificant) amounts of drug were found in the feces after intravenous and oral administrations.