Targeted and Sustained Delivery of Aclarubicin to Lymphatics by Lactic Acid-Oligomer Microsphere in Rat

We examined targeted delivery of an anticancer drug, aclarubicin (ACR), to the lymphatic system in rats by encapsulation of the drug in microsphere (MS) prepared from nontoxic and biodegradable L-lactic acid oligomer with an average molecular weight (M^-w) of 3600. ACR was released at an almost constant rate from two kinds of ACR-MSs having different size (1-5μm and less than 1μm) over 20d in phosphate-buffered saline at 37°C. The intraperitoneal administration of both ACR-MSs (dose of ACR; 5mg/kg) to rats sustained an almost constant ACR level (300-400 and 400-600ng/ml) in the lymph of the thoracic duct during over 10d, and the ACR level in the blood was extremely low, although intraperitoneal injection of ACR alone gave lower level of ACR in the lymph than in the blood level within 12h.