Biodistribution characteristics of all-trans retinoic acid incorporated in liposomes and polymeric micelles following intravenous administration

The aim of this study was to investigate the biodistribution characteristics of all-trans retinoic acid (ATRA) incorporated in liposomes and polymeric micelles following intravenous administration. [3H] ATRA were incorporated in distearoylphosphatidylcholine (DSPC)/cholesterol (6:4) liposomes. Two types of block copolymers, poly (ethylene glycol)-b-poly-(aspartic acid) derivatives with benzyl (Bz-75) groups, were synthesized to prepare the polymeric micelles for [3H]ATRA incorporation. ATRA were dissolved in mouse serum to analyze their inherent distribution. After intravenous administration, the blood concentration of [3H] ATRA in liposomes and polymeric micelles (Bz-75) was higher than that of inherent [3H]ATRA, suggesting that liposomes and polymeric micelles (Bz-75) control the distribution of ATRA. Pharmacokinetic analysis demonstrated that [3H]ATRA incorporated in polymeric micelles (Bz-75) exhibit the largest AUCblood and lowest hepatic clearance of ATRA, suggesting that polymeric micelles (Bz-75) are an effective ATRA carrier system for acute promyelocytic leukemia (APL) therapy. These results have potential implications for the design of ATRA carriers for APL patients. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association.