Biliary MTX levels in one patient undergoing intermediate dose MTX therapy (500 mg/m2) were measured by HPLC. At the end of the 24 h infusion period they were found in the range of the corresponding serum levels. In one other patients undergoing high-dose MTX therapy (12 g/m2) MTX serum levels in the slow elimination phase were lowered by orally applicated cholestyramine. In one further patient who developed renal failure under high-dose MTX therapy total body clearance of MTX could be markedly improved by cholestyramine per os. The data presented, suggesting an appreciable biliary secretion of the drug in man, are discussed in view of the current concepts of enterohepatic circulation of MTX.
