Plasma and tissue disposition of mitozolomide in mice

When mitozolomide was administered i.p. to mice, drug disposition appeared to fit a simple, one-compartment kinetic model with an elimination half-life of less than 1 h. The disposition of mitozolomide in mice bearing the ROS osteosarcoma, also followed a first-order process but in this case the elimination of the drug was significantly faster from plasma, liver, lung and kidney tissue compared to the elimination half-life of the drug from the same tissues of mice without tumour (P less than 0.05). Mitozolomide was rapidly and extensively distributed into tissues, including the tumour. Mitozolomide was not concentrated in any particular tissue although the brain contained the lowest drug concentration compared to any tissue studied. After 4 h following administration, mitozolomide could not be measured in plasma or tissues. AUC values calculated from mitozolomide concentration versus time profiles in plasma, liver and kidney homogenates were 27-29% lower in mice pretreated with phenobarbitone compared to those values obtained from mice administered saline only, (P less than 0.02). Since phenobarbitone is known to induce liver microsomal enzymes, it is possible that hepatic metabolism is involved in the degredation of mitozolomide.