Chapter 4.2 - Designing therapeutically optimized liposomal anticancer delivery systems: Lessons from conventional liposomes

Abstract

This chapter describes liposomal anticancer drugs, and the dilemma faced when designing optimized liposomal anticancer drugs. Recent technological advances in the production, stability, and biological properties of liposomes have greatly increased the degree of sophistication that can be designed into liposomes to improve their therapeutic/toxic activity profile. Investigators designing liposomal anticancer drug carrier technology must contend with a dilemma of opposing goals in the different biological compartments that the formulations experience. Because the uptake of liposomes in tumors appears to be passive, extended circulation times appear necessary to facilitate liposome accumulation. It follows that drug leakage from the liposomes must be minimized to avoid toxicities associated with free drug. The inability to differentially control drug release rates in the plasma compartment and disease site is perhaps the most significant limitation of presently available liposomes. The processes that dictate the fate of liposomes after intravenous injection has increased and help to design formulations that will optimize the selectivity of action for encapsulated agents. Inclusion of additional components into conventional liposomes can now be done on the basis of extensive data describing the in vivo behavior of various liposome types.