# US 8,569,322 B2 · Lamivudine oxalate and preparation method thereof

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- Number: US 8,569,322 B2
- Document ID: US8569322B2
- Status: Granted
- Kind: B2
- Application number: 13/581,268
- Filed: 2010-12-23
- Published: 2013-02-28
- Granted: 2013-10-29
- Earliest claimed: 2010-02-25
- Assignees: Chia Tai Tianqing Pharmaceutical Group Co., Ltd.
- Applicants: Yanlong Liu; Fei Liu; Xiquan Zhang
- Inventors: Yanlong Liu; Fei Liu; Xiquan Zhang
- Web page: https://patentgrep.com/patent/US8569322B2

## CPC

- C07D 411/04: directly linked by a ring-member-to-ring-member bond
- A61P 31/12: Antivirals
- A61P 31/14: for RNA viruses
- A61P 31/18: for HIV
- C07D: HETEROCYCLIC COMPOUNDS (macromolecular compounds C08)
- A61P: SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS

## Abstract

Lamivudine oxalate, preparation method and crystalline forms thereof are disclosed. A preparation method of Lamivudine is also disclosed.

## Claims

### Claim 1

A Lamivudine oxalate, characterized in that the Lamivudine oxalate has the following structural formula:

### Claim 2 (depends on 1)

The Lamivudine oxalate of claim 1, wherein the Lamivudine oxalate is a crystalline Lamivudine oxalate.

### Claim 3 (depends on 2)

The Lamivudine oxalate of claim 2, wherein X-ray powder diffraction peak spectrum of the crystalline Lamivudine oxalate using Cu—Kα radiation is expressed in degree 2θ at 21.04, 22.44, 23.46, 23.78, and 25.26.

### Claim 4 (depends on 3)

The Lamivudine oxalate of claim 3, wherein X-ray powder diffraction peak spectrum of the crystalline Lamivudine oxalate is expressed in degree 2θ at 13.94, 14.86, 21.04, 21.30, 22.44, 23.46, 23.78, 25.26, and 33.36.

### Claim 5 (depends on 3)

The Lamivudine oxalate of claim 3, wherein endothermic transition peak of the crystalline Lamivudine oxalate measured by DSC is at about 201.9° C. and a starting transition temperature thereof is about 199° C.

### Claim 6 (depends on 4)

The crystalline Lamivudine oxalate of claim 4, characterized in that endothermic transition peak measured by DSC is at about 201.9° C. and a starting transition temperature is about 199° C.

### Claim 7 (depends on 1)

A method for producing Lamivudine, comprising the steps of:
(a) adding ethanol to the Lamivudine oxalate of claim 1 to produce a first mixture;
(b) adding triethylamine to the first mixture from step (a) to produce a second mixture;
(c) stirring the second mixture;
(d) centrifuging the second mixture; and
(e) vacuum-drying the product from step (d) to produce Lamivudine crystal.

### Claim 8 (depends on 7)

The method of claim 7, wherein step (b) is performed at 40-45° C. for 0.5 hour.

### Claim 9 (depends on 7)

The method of claim 7, wherein step (c) is performed at 40-45° C. for about 4 hours.

### Claim 10 (depends on 7)

The method of claim 7, wherein step (d) is performed at room temperature.

### Claim 11 (depends on 7)

The method of claim 7, wherein step (e) is performed at 40-45° C.