Process for preparation of crystalline form-1 of pantoprazole sodium sesquihydrate

An improved process for making crystalline Form-I of Pantoprazole sodium sesquihydrate is provided.

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We claim:

1. A process for preparing crystalline Form-I of Pantoprazole sodium sesquihydrate, comprising: dissolving Pantoprazole free base in a solvent containing a stoichiometric amount ofaqueous sodium hydroxide; b) adding an anti-solvent; c) cooling the mixture of (a) and (b) until a precipitate is formed; and d) isolating crystalline Form-I of Pantoprazole sodium sesquihydrate.

2. The process of claim 1, further comprising drying the isolated Pantoprazole sodium sesquihydrate.

3. The process of claim 1, wherein said solvent is a C.sub.1 -C.sub.4 straight or branched alcohol, tetrahydrofuran, acetonitrile, or ethyl acetate.

4. The process of claim 1, wherein said solvent is tetrahydrofuran, acetonitrile or ethyl acetate.

5. The process of claim 1, wherein said anti-solvent is an aliphatic or alicyclic hydrocarbon solvent a chlorinated solvent, or an ether of groups having 1-4 carbon atoms in a straight or branched chain.

6. The process of claim 1, wherein said anti-solvent is dichloromethane or diisopropylether or methyl-tertiary butyl ether.

7. The process of claim 1, wherein said dissolving step comprises heating a mixture of the starting Pantoprazole free base and the solvent to a temperature of from about 25.degree. C. to about 50.degree. C. until the solution is formed.

8. The process of claim 7, wherein the mixture is heated to from about 40.degree. C. to about 50.degree. C.

9. The process of claim 1, further comprising filtering said provided solution of Pantoprazole prior to said cooling step.

10. The process of claim 1, wherein the solution of Pantoprazole is cooled to from about -10.degree. C. to about 20.degree. C.