Quantification of the selective retention of palladium octabutoxynaphthalocyanine, a potential photothermal drug, in mouse tissues

Palladium octabutoxynaphthalocyanine (PdNc(OBu)(8)) is a potential photothe rmal therapy (PTT) agent, absorbing strongly in the near-infrared region wi th no ability to induce photodynamic-type sensitisation (unlike many relate d napthalocyanines). We report here on the application of high pressure liq uid chromatography (HPLC) with near-infrared absorption detection for the d etermination of the tissue accumulation and clearance of PdNc(OBu)(8) in a tumour-bearing mouse model (Balb/c mice with EMT6 carcinoma tumour). Due to its insolubility in aqueous-based solvents, the drug was delivered intrape ritoneally in a Cremophor-containing vehicle. Good selective accumulation o f the drug into the tumour versus muscle or skin is observed, with the best combination of selectivity and tumour concentration occurring at 24-72 h a fter drug administration. Clearance times are quite long. Comparison with o ther similar drugs as reported in the Literature indicates that the Cremoph or-containing vehicle is likely in large part responsible for the observed pharmacokinetic behaviour. This drug shows potential for PTT and will be in vestigated further for therapy in this animal model. (C) 2000 Elsevier Scie nce B.V. All rights reserved.