The Uptake of Porphyrin and Zinc‐metalloporphyrin by the Primate Prostate

The relative distribution of sensitizer drugs in the prostate and its contiguous organs is of importance in the treatment of localized prostatic cancer with photodynamic therapy. Using the primate model, whose prostate is both morphologically and physiologically homologous with its human counterpart, the distribution of hematoporphyrin derivative (HpD) amongst organs of urological interest was determined. Hematoporphyrin derivative levels were comparatively low in both caudal and cranial prostatic lobes (0.93-1.77 micrograms/g) and were similar to those in rectum, urethra and the skin. The reticuloendothelial organs, liver, spleen and also the kidney accumulated the highest quantities of porphyrin (4.76-9.8 micrograms/g, liver > spleen > kidney). Despite a high avidity of prostatic tissue for zinc, a zinc-metalloporphyrin (Zn-HpD) did not concentrate selectively in the prostate. The results are of clinical value in view of the homology between the primate and the human.