METHOD OF SEPARATING VESICLE, PROCESS FOR PRODUCING MEDICINAL PREPARATION, AND METHOD OF EVALUATION

• US 20090232883A1
• Filed: 07/03/2007
• Published: 09/17/2009
• Est. Priority Date: 07/03/2006
• Status: Abandoned Application

• Current Assignee: Terumo Kabushiki Kaisha
• Original Assignee: Terumo Kabushiki Kaisha
• Inventors: Yoshino, Keisuke
• Application Number:
  US12/307,232
• Publication Number:
  US 20090232883A1
• Time in Patent Office: Days
• US Class Current: 424/450
• CPC Class Codes: A61K 31/704 attached to a condensed carbocyclic ring system, e.g. sennosides, thiocolchicosides, escin, daunorubicin digitoxin A61K31/7048
• CPC Class Codes: A61K 9/1271 Non-conventional liposomes, e.g. PEGylated liposomes, liposomes coated with polymers liposome as conjugate A61K47/6911
• CPC Class Codes: A61P 35/00 Antineoplastic agents
• CPC Class Codes: B01D 15/166 Fluid composition conditioning, e.g. gradient
• CPC Class Codes: B01D 15/363 Anion-exchange
• CPC Class Codes: Y10T 428/2984 Microcapsule with fluid core [includes liposome]

Abstract

A method of separating vesicles whose membrane has been modified with a hydrophilic polymer (polyethylene glycol, etc.). In the method, vesicles (liposome, etc.) differing in the degree of membrane modification are separated by ion-exchange chromatography using a concentration gradient in which the ionic intensity of an eluent is changed with time. Also provided are: a process for producing vesicles purified so as to have a desired degree of modification with a hydrophilic polymer which comprises utilizing the separation method in the step of purifying vesicles; a method of evaluating a medicinal vesicle preparation containing a drug therein, the method comprising using the separation method; and vesicles in which the membrane has been modified with a hydrophilic polymer and which include no vesicle having a degree of membrane modification less than 0.5 mol %.

Claims

1. A method for separating closed vesicles membrane-modified with a hydrophilic polymer, the method comprising separating closed vesicles differing in rate of membrane modification by use of ion-exchange chromatography applied with a concentration gradient wherein an ionic intensity of an eluent is changed with time.

2. The separation method according to claim 1, wherein said hydrophilic polymer is made of polyethylene glycol and the closed vesicle is made of a liposome.

3. The separation method according to claim 1, wherein the ionic intensity is an ionic intensity of NaCl.

4. The separation method according to claim 1, wherein the ion-exchange chromatography is a weak anion-exchange chromatography.

5. The separation method according to claim 4, wherein said eluent is an aqueous solvent containing a buffer agent and having a pH of 6 to 10.

6. The separation method according to claim 1, wherein said closed vesicle is a preparation containing a drug in the closed vesicle.

7. A method for preparing closed vesicles, the method comprising:

providing closed vesicles subjected to membrane modification with a hydrophilic polymer;

separating the closed vesicles depending on the rate of membrane modification with the hydrophilic polymer by the separation method of the closed vesicles defined in claim 1; and

collecting closed vesicles having a desired rate of modification with the hydrophilic polymer to obtain purified closed vesicles.

8. The preparation method according to claim 7, wherein the membrane-modified closed vesicle is a liposome whose membrane is modified with polyethylene glycol.

12. A method for evaluating a preparation of a closed vesicle membrane-modified with a hydrophilic polymer and containing a drug therein on the basis of a rate of modification with the hydrophilic polymer by use of the separation method defined in claim 1.

9. Closed vesicles modified with a hydrophilic polymer on an outer surface of a membrane thereof, which are free of closed vesicles wherein a rate of modification with the hydrophilic polymer is less than 0.5 mol % relative to a membrane lipid of the closed vesicle.

10. The closed vesicles according to claim 9, wherein the hydrophilic polymer is made of polyethylene glycol and the closed vesicle is made of a liposome.

11. The closed vesicles according to claim 9, wherein the closed vesicle is a preparation containing a drug therein.