FORM 2
THE PATENT ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION:
PROCESS FOR PREPARATION OF OCTREOTIDE OR SALT OR DERIVATIVE THEREOF
2. APPLICANT (S)
(a) NAME: WOCKHARDT LTD.
(b) NATIONALITY: INDIAN
(c) ADDRESS: Wockhardt Towers, Bandra-Kurla Complex, Bandra (East),
Mumbai-400 051.
3. PREAMBLE TO THE DESCRIPTION
The present invention relates to an efficient process for the preparation of octreotide or salt or derivative thereof.
The following specification particularly describes the invention and the manner
in which it is to be performed.
4. DESCRIPTION
The present invention relates to an efficient process for the preparation of octreotide or salt or derivative thereof.
Octreotide is a octapeptide. It is a long-acting octapeptide with pharmacologic properties mimicking those of the natural hormone somatostatin. Octreotide is indicated to reduce blood levels of growth hormone and IGF-I in acromegaly patients. It is also indicated for the symptomatic treatment of patients with metastatic carcinoid tumors and Vasoactive Intestinal Peptide Tumors (VIPomas)
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FORMULA 1
US Patent No 4,395,403 (the '403 Patent) and European Patent No EP029, 579 (the '579 Patent) discloses solution synthesis for the preparation of octreotide.
Several solid phase synthesis procedures have been subsequently described viz. European Patent No EP 953,577 and U.S. Pat. No 5,889,146 and in various research publications. Mergler et al (Proceedings of the 12.sup.th American Peptide Symposium) have used aminomethyl resin and Fmoc-butyl protection scheme for synthesis of octreotide. Alsina et al. Tetrahedron Letters, 38, 883, 1997) have used an active carbonate resin and Boc-Bzl protection scheme, necessitating the use of hydrogen fluoride/anisole for final deprotection. Edwards et al (J. Med. Chem., 37, 3749, 1994)) have described another synthesis using Fmoc-butyl protection and HMP resin, and Berta et al (EP 0 953 577) described a synthesis using 2-chlorotrityl-type resin and Fmoc-butyl protection scheme.
Ail the solid phase synthesis procedures described are not suitable for commercial manufacture of octreotide because they use costly resins and costly Fmoc-butyl protected amino acids in 2 to 4 times excess at every step. Some synthesis procedures use destructive and hazardous reagents for final deprotection.
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The present inventors now found out an efficient process for the preparation of octreotide or salt or derivative thereof which is optimized at every step and has the advantages of simple technique, reduced process time, low ratio of reactants, lowered cost, enhanced yield and purity, easy purification and applicability for large-scale production.
In one of the aspects of the invention there is provided a process for preparation of trifluoroacetate salt of 8P-OL, wherein the said process comprises of
a) coupling of t-BOC-6P-OH and Cys(Acm)-Thr-OL in a suitable organic solvent,
b) removing the t-BOC protection from the product t-BOC-8P-OL using trifluoroacetic acid,
c) extracting the trifluoroacetate salt of 8P-OL in water,
d) removing undissolved DCC-Urea complex from the solution thereof,
e) isolating trifluoroacetate salt of 8P-OL from the aqueous solution by lyophilization.
The present inventors have observed that when trifluoroacetate salt of 8P-OL remains in contact with urea, complete degradation of product occurs in two to three days. However, removal of DCC-Urea complex from the crude trifluoroacetate salt of 8P-OL provides excellent stability to the product and the product remains stable for 55 days. Yield and quality of the product was also improved. It was also noticed that if DCC-Urea complex is not removed at this stage, it continues in the next stages of the octreotide preparation till final purification of the product on preparative chromatography leading to damage of the costly separation columns.
The starting materials t-BOC-6P-OH and Cys(Acm)-Thr-OL can be prepared by processes known in the art. The two starting materials were coupled in presence of DCC and HOBt in presence of polar aprotic solvent such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulphoxide, N-
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mythylpyrrolidone, tetrahydrofuran, acetonitrile and the like. After completion the reaction, the mass is concentrated and the residue is treated with non-polar solvent such as ether, hexane etc. The separated solids were filtered and extracted in ethyl acetate and the suspension is warmed, cooled and filtered to get the desired t-BOC-8P-OL
For removal of t-BOC protection, the product is treated with trifluoroacetic acid in dichloromethane in presence of thioanisole, anisole and mercaptoethanol as scavengers. After completion of reaction the mixture is concentrated and the residue is treated with ether. The separated product is filtered and suspended in water. The insoluble particles of DCC-Urea are filtered and the resultant aqueous solution is lyophilized to get the desired product.
While the present invention has been described in terms of its specific embodiments, certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the present invention.
EXAMPLE 1
Preparation of t-BOC- 8P-OL (BOC- (D)- Phe-Cys(Acm)- Phe- (D)-Trp-Lys (BOC)-Thr-Cys (Acm)-Thr-OL)
A solution of protected t-BOC-6P-OH (100 g) and HOBt (15.4 g) in tetrahydrofuran (600 ml) and N.N-dimethylacetamide (60 ml) was added to a solution of trifluoroacetate salt of Cys(Acm)-Thr-OL (71.4g) and triethylamine (32.72 ml) in tetrahydrofuran (100 ml) and N.N-dimethylacetamide (100 ml) and stirred at 5°C. DCC (20.73g) and triethylamine (7.1 ml) in tetrahydrofuran (104 ml) was added at 4°C and the resultant mass was stirred at ambient temperature for 12 hours, followed by concentration under vacuum. To the residue was added ether (1600 ml) and the separated product is filtered and the solid was washed
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with ether (470 ml). Solid was suspended into ethyl acetate (1600 ml), warmed to 60°C for half an hour and brought to room temperature under stirring followed by filtration of the separated product. The ethyl acetate washing was repeated twice. The product obtained is dried under vacuum to get the title compound. Yield = 116 g Calculated mass = 1362, Mass obtained = 1363.8.
Example 2 Preparation of trifluoroacetate salt of 8P-OL (H-(D) - Phe -Cys (Acm)-Phe-(D)- Trp-Lys- Thr-Cys (Acm)-Thr-OL2TFA)
A mixture of t-BOC-8P-OL (100 g) and mercaptoethanol (20.66 ml), Anisole (32 ml) and thioanisole (34.53 ml) in DCM (200 ml) was cooled to 5°C and trifluoroacetic acid (400 ml) was added followed by stirring for one hour. The resultant mass was concentrated under vacuum at 30°C and to the residue was added ether (1500 ml). The separated solids were filtered and dried under high vacuum to get the title product having DCC-Urea in it. Yield = 96 g
Solid product obtained above was suspended into water (1000 ml) and stirred for one hour. The undissolved product (DCC-Urea) was filtered and discarded. The filtrate was charged for lyophilization and dried for 16 hrs. Yield= 67.3 g Calculated mass = 1390, Obtrained mass = 1163.4
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WE CLAIM:
1. A process for preparation of trifluoroacetate salt of 8P-OL, wherein the said
process comprises of
a) coupling of t-BOC-6P-OH and Cys(Acm)-Thr-OL in a suitable organic solvent,
b) removing the t-BOC protection from the product t-BOC-8P-OL using trifluoroacetic acid,
c) extracting the trifluoroacetate salt of 8P-OL in water,
d) removing undissolved DCC-Urea complex from the solution thereof,
e) isolating trifluoroacetate salt of 8P-OL from the aqueous solution by lyophilization.
2. A process according to claim 3, wherein suitable organic solvent comprises of
polar aprotic solvent.
3. A process as claimed in claim 2 wherein polar aprotic solvent is N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulphoxide, N-methyl pyrrolidone, tetrahydrofuran or acetonitrile.
4. A process of claim 1 wherein a catalyst or coupling reagent is used in step a) coupling reaction.
5. A process of claim 4 wherein the catalyst is HOBt.
6. A process of claim 4 wherein the coupling reagent is DCC.
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7. A process of claim 1 wherein DCC-Urea is removed by filtering aqueous solution of salt of 8P-OL
8. Trifluoroacetate salt of 8P-OL having less than 1% of DCC-Urea.
9. A process for preparation of octreotide comprising use of trifluoroacetate salt of 8P-OL having less than 1% of DCC-Urea.
10. A process for preparation of octreotide or salt thereof wherein the said
process comprises of process of claim 1.

Dated this 28th day of February, 2006

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