IMMUNODEPRESSANT ACTIVITY AND 6-MERCAPTOPURINE LEVELS AFTER ADMINISTRATION OF 6-MERCAPTOPURINE AND AZATHIOPRINE

Abstract

A comparative study of the immunosuppressive activities of 6-mercaptopurine and its derivative azathioprine has been performed. It has been shown that in mice and rats, 6-mercaptopurine is markedly superior to azathioprine in reducing the number of spleen hemolytic plaque-forming cells when injected by parenteral routes, whereas azathioprine is more effective by the oral route. Determinations of the levels of 6-mercaptopurine in serum and spleen after injection of both agents did not reveal substantial differences in the concentration of this compound. The possible role of the imidazole moiety released from the in vivo splitting of azathioprine in the reduced activity of the latter drug given parenterally is advanced.