Hepatic pharmacokinetics of glutaraldehyde-treated methotrexate-loaded carrier erythrocytes in dogs

Methotrexate-loaded glutaraldehyde-treated canine carrier erythrocytes were used to deliver a 1.6-mg/kg dosage of drug. About 90% of the drug-loaded cells disappeared from circulation within 1 h. Approximately 11 mg of drug reached the liver, and a substantial portion of the methotrexate entered the enterohepatic bile salt circulation. Biochemical tests of liver function, such as alkaline phosphatase and serum glutamine pyruvate transaminase, indicated mild hepatocellular necrosis which was attributed to the action of methotrexate on the hepatocytes. Bilirubin levels were unchanged during and following drug treatment. The plasma half-life of the drug was extended 2.4-fold in the first 24 h following injection.