Elimination Pathway of Hematoporphyrin from Normal and Tumor-Bearing Rats

Hematoporphyrin orally administered to rats largely precipitates in the stomach thus reaching the various tissues at a very slow rate. Whatever the administration pathway (oral, i.p., i.V.), hematoporphyrin is eliminated in the feces with no apparent chemical modification; the elimination is slower from rats affected by ascites hepatoma than from normal rats owing to the high affinity of tumor cells for the porphyrin.