# US 6,296,870 B1 · Liposomes containing active agents

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- Number: US 6,296,870 B1
- Document ID: US6296870B1
- Status: Granted
- Kind: B1
- Application number: 09/017,984
- Filed: 1998-02-03
- Granted: 2001-10-02
- Earliest claimed: 1997-02-06
- Assignees: Duke University
- Inventors: David Needham; Ranjit S. Sarpal
- Web page: https://patentgrep.com/patent/US6296870B1

## CPC

- A61K 9/1271: Non-conventional liposomes, e.g. PEGylated liposomes or liposomes coated or grafted with polymers (liposomes as conjugates {A61K47/6911})
- A61K 9/1075: {Microemulsions or submicron emulsions; Preconcentrates or solids thereof; Micelles, e.g. made of phospholipids or block copolymers (A61K9/0026 takes precedence)}
- A61K: PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES (devices or methods specially adapted for bringing pharmaceutical products into particular physical or administering forms A61J3/00; chemical aspects of, or use of materials for deodorisation of air, for disinfection or sterilisation, or for bandages, dressings, absorbent pads or surgical articles A61L; soap compositions C11D)

## Abstract

Liposomes formulations are designed to maximize the amount of poorly water-soluble active agent that can be carried by the liposome. Liposomes containing active agent in the lipid bilayer of the liposome, and/or entrapped within the liposome interior space in a micellar preparation are described. Methods of making such liposomes are presented.

## Claims

### Claim 1

A liposome containing an active agent, wherein the lipid bilayer of the liposome comprises:
a) phospholipid;
b) an active agent associated with the lipid bilayer;
c) surfactant with a Critical Micelle Concentration (CMC) of about 1 millimolar or less, said surfactant contained in the lipid bilayer in an amount sufficient to increase the amount of active agent associated with the lipid bilayer, compared to that amount of active agent that would associate with the lipid bilayer in the absence of surfactant, wherein the active agent is aggregated with said surfactant to form micelles; and
d) from 3 mole percent to 60 mole percent of cholesterol present in the lipid bilayer in an amount sufficient to protect against the disruptive effects of the surfactant contained in the lipid bilayer,
wherein the lipid bilayer is unilaminar.

### Claim 2 (depends on 1)

A liposome according to claim 1, wherein said phospholipid is stearoyloleoylphosphatidylcholine(SOPC).

### Claim 3 (depends on 1)

A liposome according to claim 1, wherein said surfactant is a lysolipid.

### Claim 4 (depends on 1)

A liposome according to claim 1, wherein said surfactant is a lysophosphatidylcholine.

### Claim 5 (depends on 1)

A liposome according to claim 1, wherein said surfactant is monooleyolphosphatidylcholine(MOPC).

### Claim 6 (depends on 1)

A liposome according to claim 1, wherein said active agent is paclitaxel.

### Claim 7 (depends on 6)

A liposome according to claim 6, where paclitaxel is contained in the lipid bilayer in an amount of at least 10 mol % relative to SOPC.

### Claim 8 (depends on 1)

A liposome according to claim 1, said lipid bilayer further comprising polymer-derivatized lipids.

### Claim 9 (depends on 7)

A liposome according to claim 7, wherein said polymer is polyethylene glycol.

### Claim 10 (depends on 1)

A liposome according to claim 1, wherein said phospholipid is stearoyloleoylphosphatidylcholine(SOPC) and said surfactant is monooleyolphosphatidylcholine(MOPC), and MOPC is present in an amount at least sufficient to provide a mole ratio of 8:1 SOPC:MOPC.