title: Photodynamic therapy using rhodamine-123 as a new laser dye: biodistribution, metabolism and histology in New Zealand rabbits.
abstract: Rhodamine-123 (Rh-123) has been tested recently as a new laser dye for photodynamic therapy of human tumors in vitro and in vivo. Prior to initiation of clinical studies of this technique, we evaluated the biodistribution, metabolism, and pathological changes of Rh-123 in rabbits after systemic, repetitive injections of the dye in escalating doses. At doses between 0.1 to 1 mg/kg of Rh-123 injected intramuscularly (IM) daily for 5 days, no local or systemic toxicity was observed during the 4 weeks of follow-up. The peak concentrations of Rh-123 in micrograms/g of tissue was distributed as follows: kidney (3.24) greater than heart (2.24) greater than spleen (1.77) greater than lung (0.61) greater than liver (0.38) greater than skin (0.30) greater than skeletal muscle (0.17) greater than genitals (0.13) greater than brain (0.04). The elimination of Rh-123 was very rapid, with the dye falling to 2.7% of peak concentration at 72 hours in the kidneys, and to undetectable levels at 240 hours postinjection in all organs, except the skin, which retained 3% of the peak level at 240 hours. The low toxicity and rapid metabolism of Rh-123 in this preclinical model suggests that the dye and Argon laser may represent an effective combination for treatment of superficial malignancies.
authors.affiliation: Division of Head and Neck Surgery, UCLA School of Medicine 90024-1624.
authors.forename: D J
authors.initials: DJ
authors.lastname: Castro
authors.forename: A
authors.initials: A
authors.lastname: Gaskin
authors.forename: R E
authors.initials: RE
authors.lastname: Saxton
authors.forename: E
authors.initials: E
authors.lastname: Reisler
authors.forename: E
authors.initials: E
authors.lastname: Nishimura
authors.forename: S Y
authors.initials: SY
authors.lastname: To
authors.forename: D O
authors.initials: DO
authors.lastname: Rodgerson
authors.forename: L J
authors.initials: LJ
authors.lastname: Layfield
authors.forename: P B
authors.initials: PB
authors.lastname: Tartell
authors.forename: D J
authors.initials: DJ
authors.lastname: Castro
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004396:Coloring Agents / Q000493:pharmacokinetics / Q000627:therapeutic use*; D004353:Drug Evaluation, Preclinical; D005260:Female; D006321:Heart / Q000187:drug effects; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000378:metabolism; D010778:Photochemotherapy / Q000379:methods*; D011817:Rabbits; D020112:Rhodamine 123; D012235:Rhodamines / Q000493:pharmacokinetics / Q000627:therapeutic use*; D013154:Spleen / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D004396:Coloring Agents; D012235:Rhodamines; D020112:Rhodamine 123