CA2199004A1 — Preparation of multivesicular liposomes for controlled release of active agents

USPTO Abstract

Disclosed are multivesicular liposomes (MVL's) containing biologically active substances, the multivesicular liposomes having defined size distribution, adjustable average size, adjustable internal chamber size and number, and a controlled and variable release rate of the biologically active substance. The process involves encapsulating at least one biologically active substance and optionally an osmotic spacer in a first aqueous component encapsulated within the liposomes. The rate of release of the active substance into the surrounding environment in which the liposomes are introduced can be decreased by increasing the osmolarity of the first aqueous component or increased by decreasing the osmolarity.