The distribution of 10-hydroxy carbazepine in blood compartments

The distribution of 10-hydroxy carbazepine (MHD), the main metabolite of oxcarbazepine (OXC), was investigated in plasma and red cells. After the oral administration of 600mg of OXC to nine healthy volunteers, blood samples were withdrawn for the next 56h and packed red cells were separated from plasma by centrifugation. Also, in vitro studies of plasma binding of MHD were carried out by a dialysis technique. Results showed that the in vitro protein binding was low. The mean bound concentration ranged from 37 to 40%; however, an affinity of MHD to red corpuscles was found. These observations indicate that MHD red blood cell concentrations together with plasma measurements could be useful in cases of inefficacy or toxicity in order to make the appropriate drug adjustments.