Distribution and metabolism of pentoxifylline in non-tumor-bearing mice.

Pentoxifylline increases tissue oxygen delivery in patients with atherosclerotic arterial disease by several mechanisms, including lowering blood viscosity and increasing erythrocyte flexibility. Since tumor neo-vessels are also abnormal and associated with intra-tumoral hypoxia and, thus, with radiation failure, pentoxifylline might also be useful as a radiation sensitizer. The mouse is frequently used to study such drugs, but the pharmacokinetics of pentoxifylline in the mouse have not been determined. We investigated this in three separate experiments by administering pentoxifylline intraperitoneally, subcutaneously, or orally. Plasma was assayed for the parent drug and its metabolites by capillary gas chromatography. High plasma levels of pentoxifylline and both major derivatives occurred within several minutes after intraperitoneal or subcutaneous injection, but plasma levels were low after oral administration.