Claims for Patent: 6,171,613

Summary for Patent: 6,171,613

Title:	Method for producing liposomes with increased percent of compound encapsulated
Abstract:	The efficiency of encapsulating a drug into a liposomal formulation is increased by use of a lipid having a carbon chain containing from about 13 to about 28 carbons during preparation of the liposomes. Preferably the liposomes are multivesicular liposomes.
Inventor(s):	Ye; Qiang (San Diego, CA), Sankaram; Mantripragada Bhima (San Diego, CA)
Assignee:	SkyePharma Inc. (San Diego, CA)
Application Number:	09/431,525
Patent Claims:	1. A method for encapsulating at least one biologically active compound in a liposome comprising a) obtaining a liposome, by any conventional means, having the substance encapsulated therein and having at least one first amphipathic lipid having a carbon chain from about 1 to about 12 carbons in the lipid component of the formulation; b) determining the percent amount of the encapsulated compound; and c) substituting said at least one first amphipathic lipid having a carbon chain from about 1 to about 12 carbons in the lipid component of the formulation with at least one second amphipathic lipid with a substantially similar chemical structure having from one to 16 more carbons in a fatty acyl chain of the second lipid; wherein the resulting percent of the compound encapsulated is from about 0.2 to about 85 percent. 2. The method of claim 1 wherein the liposome is multilamellar. 3. The method of claims 1 wherein the liposome is multivesicular. 4. The method of claim 1 wherein the number of carbons in the amphipathic lipid is in the range from about 14 to 22. 5. The method of claim 2 wherein the amphipathic lipid is selected from the group consisting of 1,2-dioleoyl-sn-glycero-3-phosphocholine, 1,2-dilauroyl-sn-glycero-3-phosphocholine, 1,2-dimyristoyl-sn-glycero-3-phosphocholine, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, 1,2-distearoyl-sn-glycero-3-phosphocholine, 1,2-dibehenoyl-sn-glycero-3-phosphocholine, 1,2-dipalmitoleoyl-sn-glycero-3-phosphocholine, 1,2-dieicosenoyl-sn-glycero-3-phosphocholine, 1,2-dierucoyl-sn-glycero-3-phosphocholine, 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol and 1,2-dioleoyl-sn-glycero-3-phosphoglycerol. 6. The method of claim 2 wherein the amphipathic lipid is saturated. 7. The method of claim 2 wherein the amphipathic lipid is unsaturated. 8. The method of claim 1 wherein subsequent batches of liposome formulations are made by repeating step c).