ABSTRACT
Liposomes have been proposed as carriers to introduce biologically active agents into cells, and their various applications have been extensively reviewed, One approach to improve liposomes as a drug-delivery system is to increase their specific distribution in target tissues and organs. Only very large liposomes are removed by the lungs; positively charged liposomes are retained in the lungs better than negatively charged ones while the spleen and bone marrow have preferences for negative liposomes. Many attempts have been made in vitro targeting of liposomes with varying degrees of success. The stability of liposomes in vivo and in vitro is affected by the amount of Choi incorporated in liposomes. The tissue distribution of liposomes in rats was found to vary with different glycolipids; however, no clear and useful direction of liposomes to target organs and tissues was observed. In addition to natural glycolipids and glycoproteins, small-molecular-weight synthetic glycolipids are effective for the introduction of saccharide determinants onto the surface of liposomes.
