Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-01-27
2002-04-16
Coleman, Brenda (Department: 1624)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Heterocyclic carbon compounds containing a hetero ring...
C540S551000
Reexamination Certificate
active
06372734
ABSTRACT:
The present invention relates to a process for the preparation of thiazepine derivatives and, in particular, to the preparation of 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine and salts thereof.
The compound, 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine (Formula I)
exhibits useful antidopaminergic activity and may be used, for example, as an antipsychotic agent with a substantial reduction in the potential to cause side effects such as acute dystonia, acute dyskinesia, pseudo-Parkinsonism and tardive dyskinesia.
The compound of formula I is described in granted European Patent EP 240,228. This patent describes the properties of the compound of formula I and its synthesis from dibenzo[b,f][1,4]thiazepine-11(10-H)-one. In this synthetic route it is necessary to prepare and purify the compound 2-(2-hydroxyethoxy)ethyl-1-piperazine (HEEP).
Granted European Patent EP 282,236 describes an improved process for the preparation of the compound of formula I which obviates the need to prepare and purify the compound 2-(2-hydroxyethoxy)ethyl)-1-piperazine since this improved process does not use 2-(2-hydroxyethoxy)ethyl-1-piperazine. It also obviates the need to use carboxyethyl piperazine which is used to prepare 2-(2-hydroxyethoxy)ethyl-1-piperazine.
Many Pharmaceuticals are developed as salts of pharmacologically acceptable acids or bases. This is usually done if the biologically active substance itself has a physical form which makes it unsuitable to handle in manufacturing processes. Most manufacturing processes involve materials handling in mixing and formulation which is facilitated by the active materials being either a liquid or free-flowing high melting solids. Although salts can be made with suitable acids or bases these often add nothing to the therapeutic benefit of the pharmaceutical and are therefore redundant biologically. It would be better if the pharmaceutical could be manufactured as the pure active substance.
The reported synthesis of 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine provides 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine as a fumarate salt since it has been necessary to prepare the salt to efficiently obtain a sufficiently pure product. Moreover, to prepare the fumarate salt it has been necessary to first prepare the hydrogen fumarate salt and subsequently convert it to the fumarate.
The present invention is based, at least in part, on an improved method of purifying the compound of formula I, and in particular on a method of purifying the compound of formula I such that the compound of formula I is obtained in a crystalline form.
According to the present invention there is provided crystalline 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine. The crystalline 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine may be converted into one of its pharmaceutically acceptable salts and so the present invention also provides crystalline 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine or a pharmaceutically acceptable salt prepared therefrom.
The crystalline 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine is generally provided in a substantially pure form. It is generally preferred that the crystalline 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine is greater than 90% pure more preferably 99% or greater than 99% pure.
According to the present invention there is also provided a process for preparing crystalline 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine or a pharmaceutically acceptable salt thereof which comprises crystallising 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine from a non-aromatic solvent;
and whereafter, when a pharmaceutically acceptable salt is required, reacting 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine with an acid which affords a pharmaceutically acceptable anion.
According to the present invention there is also provided a process for preparing crystalline 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine or a pharmaceutically acceptable salt thereof which comprises crystallising 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine from a non-aromatic solvent substantially in the absence of water;
and whereafter, when a pharmaceutically acceptable salt is required, reacting 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine with an acid which affords a pharmaceutically acceptable anion.
The crystallisation may be initiated with the aid of a seed crystal.
The salts of 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine will generally comprise acid-addition salts. Convenient salts may be selected from those pharmaceutically acceptable salts known in the art. These may be obtained by any conventional salt preparation method known in the art. For example, salts may be obtained by reacting 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine with a convenient acid, such as, hydrochloric acid maleic acid, fumaric acid, citric acid, phosphonic acid, methanesulphonic acid and sulphuric acid.
Preferred salts include fumarate salts and in particular the hemi-fumarate salt. It is generally preferred that the fumarate salt of 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine is bis-[11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine]fumarate.
It is generally preferred, for example, that the solvent is dry. It is further preferred that the 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine is also dry so that the solution formed on dissolving 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine in the solvent is substantially free from water. More especially, the solution formed in the crystallisation process should be free from water.
Thus, in a preferred embodiment there is provided a process for preparing 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine, or a pharmaceutically-acceptable salt thereof, which comprises crystallising 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine from a solution of 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine in a non-aromatic solvent which is free from water. The crystalline 11-(4-[2-(2-hydroxyethoxy)ethyl]-1-piperazinyl)-dibenzo[b,f][1,4]thiazepine may, if desired, be converted to a pharmaceutically-acceptable salt, as mentioned above.
Examples of suitable solvents include, for example, esters such as those of formula R
1
CO
2
R
2
wherein R
1
and R
2
are alkyl groups; ethers of formula R
3
OR
4
wherein R
3
and R
4
are alkyl groups; and ketones of formula R
5
COR
6
wherein R
5
and R
6
are alkyl groups.
Particular values of R
1
, R
2
, R
3
, R
4
, R
5
and R
6
include, for example, (1-6C)alkyl such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, pentyl and hexyl. Conveniently, R
1
, R
2
, R
3
and R
4
are selected from (1-4C)alkyl.
Specific examples of suitable solve
Coleman Brenda
Pillsbury & Winthrop LLP
Zeneca Limited
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