Determination of [³H]- and [¹⁴C]Hematoporphyrin Derivative Distribution in Malignant and Normal Tissue¹

The synthesis and tissue-localizing ability of [¹⁴C]- and [³H]hematoporphyrin derivative (HPD) in mice have been described. Tissue levels and distributions were the same for both radioactive compounds, indicating that in vivo tritium exchange did not occur with [³H]HPD. The amount of [¹⁴C]HPD or [³H]HPD which localized in the transplanted tumor tissue of mice at various times following i.p. injection (10 mg/kg) was higher than in skin or muscle tissue but was less than in liver, kidney, or spleen tissue. These results tend to disprove the generalization that HPD accumulates in malignant tissue to a higher degree than in all normal tissue. It is also reported that gross visualization of porphyrin fluorescence cannot be correlated with actual tissue concentrations of the dye.