# US 4,397,846 A · Storage-stable lipid vesicles and method of preparation

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- Number: US 4,397,846 A
- Document ID: US4397846A
- Status: Granted
- Kind: A
- Application number: 06/263,942
- Filed: 1981-05-15
- Granted: 1983-08-09
- Earliest claimed: 1981-05-15
- Inventors: Murray Weiner; Klaus Gersonde
- Web page: https://patentgrep.com/patent/US4397846A

## CPC

- A61K 9/1277: Preparation processes; Proliposomes
- 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

Lipid vesicles, such as those containing inositol hexaphosphate useful for improving the oxygen-release of intact erythrocytes, may be rendered stable to long term storage at temperatures below the freezing point of the encapsulated solution, by rapid freezing at a temperature of from about -196.degree. C. to about -30.degree. C.

## Claims

### Claim 1

The process for preparing an aqueous lipid vesicle suspension, wherein a biologically active agent is encapsulated within a unilamellar phopholipid membrane, stable to long term storage at temperatures of -20.degree. C. and below, which comprises rapidly freezing the lipid vesicle suspension at a temperature of from about -196.degree. C. to about -30.degree. C., wherein the lipid vesicle suspension is frozen in a liquid propane bath at a temperature of from -190.degree. C. to -141.degree. C.

### Claim 2 (depends on 1)

The process according to claim 1 wherein the encapsulated biologically active agent is inositol hexaphosphate.

### Claim 3 (depends on 1)

The process according to claim 1 wherein the phospholipid membrane comprises phosphatidylcholine, phosphatidylserine and cholesterol in a molar ratio of from 10 to 5:from 4 to 1:from 10 to 3.

### Claim 4 (depends on 3)

The process of claim 3 wherein the membrane comprises phosphatidylcholine, phosphatidylserine and cholesterol in a ratio of 8:2:7.

### Claim 5 (depends on 1)

A storage stable lipid vesicle suspension prepared according to claim 1 wherein the encapsulated biologically active agent is inositol hexaphosphate in an aqueous, buffered solution.

### Claim 6 (depends on 5)

The storage stable lipid vesicle suspension of claim 5 wherein the phospholipid membrane comprises phosphatidylcholine, phosphatidylserine and cholesterol in a molar ratio of from 10 to 5:from 4 to 1:from 10 to 3.

### Claim 7 (depends on 6)

The storage stable lipid vesicle suspension of claim 6 wherein the phospholipid membrane comprises phosphatidylcholine, phosphatidylserine and cholesterol in a ratio of 8:2:7.

### Claim 8

In a process for preparing an aqueous lipid vesicle suspension, a biologically active agent being encapsulated in an aqueous buffered solution within a unilamellar phospholipid membrane in said suspension, and wherein said suspension has a predetermined freezing point,
the steps comprising
rapidly freezing the lipid vesicle suspension at a temperature of from about -196.degree. C. to about -30.degree. C. following preparation of said lipid vesicle suspension,
subsequently storing said lipid vesicle suspension at a temperature below said freezing point so as to be stable for long term storage, and
thereafter thawing said lipid vesicle suspension to a temperature suitable for said lipid vesicle suspension to be carried into living cells.

### Claim 9 (depends on 8)

The process as claimed in claim 8 further comprising the step of ensonifying said liquid vesicle suspension at an energy of about 100 watts per square centimeter.

### Claim 10 (depends on 8)

The process as claimed in claim 8, wherein said liquid vesicle suspension is stored at a temperature range from about -20.degree. C. to about -30.degree. C.

### Claim 11 (depends on 9)

A storage stable lipid vesicle suspension prepared according to the process of claim 9, and wherein the biologically active agent includes inositol hexaphosphate.

### Claim 12 (depends on 1, 9)

A storage stable lipid vesicle suspension prepared according to the procedure of claim 1 or claim 9.