Mediastinal node and diaphragmatic targeting after intracavitary injection of avidin/^99mTc-blue-biotin-liposome system

A method for delivering drugs to sites of disease extension in mediastinal nodes is described. Mediastinal node and lymphatic distributions were determined after intracavitary injection of the avidin/biotin-liposome system in normal rats. The effect of the injected dose on lymphatic targeting of liposomes after intraperitoneal injection of ^99mTc-blue-biotin-liposomes and intrapleural injection of avidin, and vice versa, is presented. Scintigraphic imaging was used to follow the movement of ^99mTc-blue-biotin- liposomes to determine the pharmacokinetics and organ uptake. Tissue biodistribution studies were performed 22 h after injection of the ^99mTc-blue-biotin-liposomes. Results indicated that independent of the cavity in which each agent was injected, a dose of 5.0 mg of each agent results in higher mediastinal node targeting (8%-10% ID/Organ) as compared with the injection of a 0.5 mg dose (2%-5% ID/Organ, p < 0.05). Targeting of diaphragm and associated lymphatics was observed when ^99mTc-blue- biotin-liposomes were injected in peritoneum and avidin in pleural space. In contrast, pleural, and pericardial lymphatic targeting was observed when ^99mTc-blue-biotin-liposomes were injected in pleural space and avidin in peritoneum. Intracavitary injection of the avidin/biotin-liposome system could potentially be used for the delivery of prophylactic drugs that could reduce tumor metastasis and infection spread to mediastinal nodes.