APPLICATION OF TC-99M LABELING FOR FAST COMPARATIVE SCREENING OF PREFORMED LIPOSOMES IN-VIVO

Labeling of preformed liposomes with Tc-99m is a simple, quick, and hi ghly versatile method, and its potential in the comparative screening of preformed liposomes with regard to their early biodistribution prop erties, such as the BLOOD/RES ratios at 2 and 30 min postadministratio n, was investigated. Liposomes differing in lipid composition and size were prepared and labeled under optimum conditions with Tc-99m using a slight modification of a previously described method (1). The amount of SnCl2 used to reduce pertechnetate affected liposome biodistributi on. The labeling method employed was capable of detecting anticipated changes in liposome biodistribution caused by alterations in liposome composition or size. It could also reveal the effect of a relative imm iscibility of monosialganglioside GM(1) with hatidyl-choline:di-myrist oyl-phosphatidyl-glycerol (DMPC:DMPG) on the biodistribution of DMPC:D MPG:GM(1) liposomes. It is proposed that Tc-99m labeling of liposomes provides a tool for fast comparative screening of preformed liposomal preparations according to their early bio-distribution.