|Title of Invention||
PROCESS FOR PREPARATION OF FORM- II OF 3-BENZYL-6-TRIFLUROMETHYL-7-SULFAMYL-3,4-DIHYDRO-1,2,4-BENZOTHIADIAZINE-1,1-DIOXIDE
|Abstract||Disclosed herein is a novel crystalline form of 3-Benzyl - 6-trifluromethyl - 7 - sulfamyl -3,4-dihydro - 1,2,4- benzothiadiazine - 1,1- dioxide, designated as 'Form II' and processes for preparation thereof. The invention further discloses a new process for preparation and isolation of crystalline Form I.|
THE PATENT ACT 1970
(39 of 1970)
The Patents Rules, 2003
(See section 10 and rulel3)
1. TITLE OF THE INVENTION:
"Novel crystalline form of 3-Benzyl - 6-trifluromethyl - 7 - sulfamyl - 3,4-dihydro -1,2,4- benzothiadiazine -1,1- dioxide"
(a) NAME: IPCA LABORATORIES LIMITED
(b)NATIONALITY: Indian Company incorporated under the Indian
Companies ACT, 1956
(c) ADDRESS: 48, Kandivli Industrial Estate, Mumbai - 400 067, Maharashtra, India
3.PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.
Field of Invention
The present invention relates to a novel crystalline form of 3-Benzyl - 6-trifluromethyl - 7 -sulfamyl - 3,4-dihydro - 1,2,4- benzothiadiazine - 1,1- dioxide hereinafter designated as 'Form II' and its solvates thereof. Consequently this invention relates to the preparation and isolation of the novel crystalline 'Form IP. The invention also relates to a new process for the preparation and isolation of 'Form P. The present invention further discloses pharmaceutical compositions containing the new polymorph and their use in medicine.
Background of the invention
3-Benzyl - 6-trifluromethyl - 7 - sulfamyl - 3,4-dihydro - 1,2,4- benzothiadiazine - 1,1-dioxide, which is most commonly known as Bendroflumethiazide, belongs to the medicinal class of thiazide diuretics. Diuretics are also find use as effective anti-hypertensive drugs. Thiazide diuretics are a family of drugs that effectively remove water from the body when required. Thiazide or thiazide diuretics are commonly used to treat high blood pressure. High blood pressure adds to the work load of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain , heart and kidneys, resulting in a stroke, heart failure or kidney failure. High blood pressure may also increase the risk of heart attacks. These problems may be less likely to occur if blood pressure is controlled. Thiazide diuretics have dual function, i.e., to help reduce the amount of water in the body by increasing the flow of urine and controlling the blood pressure. Thiazide diuretics are also combined with other drugs to treat various ailments.
The present invention relates to the solid state physical properties of bendroflumethiazide. These properties can be influenced by controlling the conditions under which bendroflumethiazide is obtained in solid form.
The synthesis of bendroflumethiazide was reported in patent GB 863474, however this patent does not disclose any solid state properties of bendroflumethiazide except melting point. Example 24 of the patent describes recrystllization of bendroflumethiazide from dioxane and the obtained solid has melting point 224.5-225.5 °c and Example 25 of the patent
describes isolation of it from n-butanol / Hexane mixture and, that has melting point about 222- 223 °c.
Also the bendroflumethiazide was described in GB 879592 that has got melting point in the range of 225.5-227.5°c
Another disclosure, GB 1049322, describes isolation of bendroflumethiazide solid from methanol / water mixture and the solid obtained had melting point at 226- 228°c. Other literature like German patent 1570023, AT253513, German patent 51,645, GB 946,864 and GB 89109 reports bendroflumethiazide with a melting point in the range 221- 228°C.
All above prior arts fails to describe characterization of solid state forms of Bendroflumethiazide. In, Analytical properties of drug substances vol. 5, Author: Klaus Florey and Frank M, the characterization and solid properties of bendroflumethiazide was described which shows melting point at 223.2°C - 226.2°C and has been described to have a melting range from 220°C - 228°C. The Powder diffraction pattern of Bendroflumethiazide was disclosed in this paper which is shown in Fig 1.
The reproduction of GB 879592 process to prepare Bendroflumethiazide in the laboratory have yielded bendroflumethiazide having a DSC endotherm at 225 °C and powder diffraction pattern identical to the one reported in Analytical properties of drug substances vol.5. This Form of bendroflumethiazide is now being designated as 'Form I'.
It is clear from above discussion that Bendroflumethiazide shows a melting range of 220 to 228°C depending upon the isolation conditions of Bendroflumethiazide. However powder diffraction pattern appears to be the same. By experimentation it has now been found that bendroflumethiazide can exist in different polymorphic forms, which differs in their solid sate properties.
It is therefore an object of this invention to obtain crystalline forms of bendroflumethiazide of improved handling properties and dissolution properties, which differ from each other in their
stability, their physical properties, their spectral characteristics and the process for their preparation.
Summary of the invention
It has now been found that Bendroflumethiazide can exist, in addition to known crystalline form, here in after designated as Form I, in other crystalline forms that is stable at room temperature, in particular, in a novel crystalline form which is designated as 'Form II'.
The present invention therefore relates to a novel polymorphic form, which is herein after designated as 'Form IF, and its solvates characterized by Fourrier Transform Infra-Red (FTIR) Spectroscopy and Powder X-Ray diffraction analyses. More particularly, the present invention relates to a novel crystalline form of bendroflumethiazide denoted as 'Form IF as characterized by a powder X-ray diffraction pattern with peaks at 21.02, 21.50, 24.34, 28.09, 29.06, 29.45, 10.73, 11.97, and 13.87 + 0.20 degrees 2 theta angles. The 'Form IF polymorphic bendroflumethiazide of the present invention is also characterized by a FT IR spectrum having absorptions at 3419, 3363, 3309, 3226, 888.7, 873 which are absent in Form I. The new crystalline form has a crystal content of at least 60 %, preferably 80% and more preferably over 90 % having characteristic peak at 21.02, 10.73, 11.97, and 13.87 ± 0.20 degrees 2 theta angle on a PXRD diagram.
In another aspect this invention relates to processes for obtaining the novel "Form IF crystals of bendroflumethiazide. These processes comprise dissolving amorphous or any other crystalline form/forms of bendroflumethiazide, in an organic solvent such as methanol or ethyl alcohol for sufficient period of time and distilling out the solvent or crystallizing it from such solution to give 'Form IF, or dissolving the starting bendroflumethiazide in a solution of 1 N NaOH aqueous solution for sufficient period of time and precipitating the 'Form IF crystals by neutralization of said solution with an acid such as 1 N hydrochloric acid aqueous solution.
In a further aspect, the present invention relates to pharmaceutical compositions comprising the novel Bendroflumethiazide 'Form IF or its mixture with 'Form F crystals in a sufficient
amount to effect anti-hypertensive or diuretic or cardiovascular effect. Bendroflumethiazide 'Form IF and its solvates thereof can be formulated into a variety of compositions for administration to humans and animals. Pharmaceutical compositions of the present invention contain Bendroflumethiazide 'Form II' or its solvates thereof, optionally as synergistic mixtures with other compatible pharmaceutically active ingredients, for e.g., antihypertensives. In addition to the active ingredient (s), the pharmaceutical compositions of the present invention can contain one or more commonly used inert pharmaceutical excipients. Excipients are added to the composition for a variety of purposes.
Brief Description of the figures
Figure 1 represents Powder X-Ray diffraction pattern (PXRD) of 'Form I' of Bendroflumethiazide obtained from standard methods (Florey K, Analyticlat profiles of drug substances vol. 5)
Figure 2 represents Powder X-Ray diffraction pattern (PXRD) of 'Form II' of Bendroflumethiazide prepared according to the present invention as in example 1.
Figure 3 represents Fourrier-transform Infra-Red, spectrum of 'Form II' of Bendroflumethiazide prepared as in example 1.
Figure 4 represents an overlay of Fourrier-transform Infra-Red spectrum of Form II over Form I of bendroflumethiazide.
Detailed Description of invention
As used herein , the phrase "Bendroflumethiazide 'Form I'" or "bendroflumethiazide 'Form II'", where T , 'IF are Roman numerals or letters refers to a crystalline form of Bendroflumethiazide that one of skill in the art can identify as a distinct entity distinguishable from other crystalline forms of Bendroflumethiazide based on the characterization provided herein. As used herein, the phrase "having at least one characteristics of 'Form I' or 'Form IP" refers to a crystalline form of Bendroflumethiazide that possesses one of the PXRD peaks
or absorption in a Fourier-Transform Infra-Red spectrum provided herein which is not found in another crystalline form. For example, a single or a combination of PXRD peaks which is not found in another crystalline form of bendroflumethiazide is enough to show at least one of the characteristics of Form ' IP.
In one aspect, this invention provides novel bendroflumethiazide in a specific and distinguishable crystalline form that is denoted as "bendroflumethiazide 'Form IP". The character of this new form is identified and confirmed by PXRD (Powder X-Ray diffraction) patterns and Fourier-transform Infra-Red spectroscopy (also referred as FTIR) obtained from a sample thereof which are provided in FIGS. 2 and 3 respectively. The PXRD pattern shows at least one characteristic peak at 21.02, 21.50, 24.34, 28.09, 29.06, 29.45, 10.73, 11.97, and 13.87 + 0.20 degrees 2 theta angles.
The new 'Form IP was also characterized by infrared spectroscopy. The various characterization techniques used in the identification of 'Form IP are further described in detail below:
The new crystalline bendroflumethiazide 'Form IP is identified and characterized using Fourier-Transform Infra -red spectroscopy (FTIR). The samples of form IP as obtained in EXAMPLE 2 were analyzed in the form of 0.3% KBr disks. The FTIR spectra obtained shows characteristic absorptions at 3419, 3363, 3309, 322,6, 888.7, and 873 which are absent in Form I.
The PXRD pattern was measured on a SIEMAN D500 40KV/30mA powder X-Ray Diffract meter with a solid state detector. Copper radiation of 1.5406 A0 wavelength was used. The crystalline 'Form IP of Bendroflumethiazide has X-ray powder diffraction pattern substantially as shown in the Figure 1 and the characteristic peaks with their 2 theta value and corresponding d spacing and their relative intensity in percentage are listed in the table given below.
2-theta values in degrees D spacing Percentage relative intensity
In another aspect, the present invention provides suitable processes for preparing Bendroflumethiazide in a crystalline form that denoted as 'Form II' having at least one characteristic as listed above.
In one embodiment, the process includes the steps of dissolving or suspending amorphous or any other crystalline form/forms of Bendroflumethiazide (obtained as per the process described in GB879592) in an alcohol solvent such as methanol or ethanol, maintaining such mixture for sufficient period of time and removing the solvent partially or completely by distillation till the product falls out ('Form IP) and isolating the crystals of 'Form II'. Heat may be supplied to effect dissolution of the bendroflumethiazide (solute) in the organic solvent. Further, the distillation of the solvent from the bendroflumethiazide solution is effected at atmospheric pressure or at reduced pressure.
The amount of methanol used in the process is in about 5 to 30 volumes relative to the weight of Bendroflumethiazide used and preferably the volume; of solvent is 7 to 10 times that of bendroflumethiazide. The 'Form II' crystals of bendroflumethiazide formed is stable to the experimental conditions.
In another embodiment of the present invention, the 'Form IF bendroflumethiazide is prepared by a process which comprises making a solution of bendroflumethiazide in sodium hydroxide aqueous solution; and precipitating the new 'Form IF crystals by neutralization of said solution of bendroflumethiazide using an aqueous hydrochloric acid solution. In the process, the dissolution of bendroflumethiazide in HCl is effected at room temperature or by way of heating the mixture. The strength of the alkali aqueous solution used is preferably 1 N NaOH solution and the acid used is preferably 1 N hydrochloric acid aqueous solution.
Further, the process optionally includes the steps of reducing the temperature of the Bendroflumethiazide suspension so obtained after neutralization and maintaining the suspension at reduced temperature for a holding time. The 'Form IF crystals can then be separated from the mixture by conventional means such as filtration, centrifugation etc. and can be optionally dried at ambient or elevated temperatures.
In a third embodiment of the present invention, there is provided a new process for
preparation of 'Form I' bendroflumethiazide, which comprises dissolving
bendroflumethiazide in a ketone solvent like methyl isobutyl ketone and precipitating the
new crystalline form by addition of an anti-solvent. Anti-solvent herein means a solvent in
which the solute is insoluble or sparingly soluble so that addition of such solvent to a solution
precipitates out the solute from the solution. J
The preferred anti-solvent for this purpose is hydrocarbon solvents such as hexane, cyclohexane or the like. The bendroflumethiazide may be dissolved in these solvents by means of supplying heat preferably to a temperature range of 35 to 80 °C. Further, the process optionally includes the steps of reducing the temperature of the Bendroflumethiazide solution in the first solvent prior to the addition of anti-solvent and maintaining the suspension at reduced temperature for a holding time. The 'Form IF crystals can then be separated from the mixture of solvents by conventional means such as filtration, centrifugation etc. and can be optionally dried at ambient or elevated temperatures.
In an alternate embodiment of the present invention the amorphous, 'Form I' or partially crystalline or any crystalline form of Bendroflumethiazide can be converted to crystalline 'Form IP by way of the present process.
The novel Bendroflumethiazide 'Form II' or its solvates thereof of the present invention are useful for treating patients with hypertension and for producing an anti-hypertensive/cardiovascular/diuretic effect in mammals, including human patients. Bendroflumethiazide 'Form IF can be formulated into a variety of pharmaceutical compositions for administration to humans and mammals for treatment of above ailments.
Pharmaceutical compositions of the present invention contain Bendroflumethiazide 'Form IF or its solvates, optionally as mixture with other crystalline forms and/or other active pharmaceutical drugs which forms such synergistic compositions useful in the treatment of above ailments such as other anti-hypertensive drugs. In addition to the active ingredient(s), the pharmaceutical compositions of the present invention can contain one or more commonly used inert pharmaceutical excipients. Excipients are added to the composition for a variety of purposes.
Bendroflumethiazide 'Form IF can be administered for treatment of hypertension or cardiovascular/diuretic effect by any means that delivers the active pharmaceutical ingredient (s) to the site of the body where the active component exerts a therapeutic effect on the patient. For example, administration can be oral, buccal, parenteral (including subcutaneous, intramuscular, and intravenous) rectal, inhalant and ophthalmic. Although the most suitable route in any given case will depend on the nature and severity of the condition being treated, the most preferred route of the present invention is oral. Bendroflumethiazide 'Form IF can be conveniently administered to a patient in oral unit dosage form and prepared by any of the methods well-known in the pharmaceutical arts.
Dosage forms include solid dosage forms like tablets, powders, capsules, sachets, troches and lozenges as well as liquid syrups, suspensions and elixirs. The active ingredient (s) and excipients can be formulated into compositions and dosage forms according to methods known in the art.
Accordingly, Bendroflumethiazide 'Form II' can be milled into a powder and be used in a pharmaceutical product/composition or physically modified such as by granulation to produce larger granules. Bendroflumethiazide 'Form II' can also be used to prepare a liquid pharmaceutical composition by dissolving or dispersing or suspending/emulsifying it in a pharmaceutically acceptable liquid medium such as water, glycerin, vegetable oil.
Selection of particular excipients and the amounts to use can be readily determined by the formulation scientist based upon experience and consideration of standard procedures and reference works in the field. The solid compositions of the present invention include powders, granulates, aggregates and compacted compositions.
The following non-limiting examples are provided to further illustrate the invention with specific embodiments stipulated in the present invention. ,
EXAMPLES Example 1
Bendroflumethiazide 'Form IP
In a reaction flask 10 gm bendroflumethiazide (prepared according to the process in GB879592, purity 99.7 as per USP HPLC procedure) was taken and mixed with IN NaOH solution till a clear solution was obtained. 1 N HC1 solution was added into the flask till a pH of 7 was obtained and maintained for 30 minutes. The precipitated crystals were collected by filtration, washed with water and dried at 50 °C under vacuum for 5 hours. The IR and PXRD pattern is shown in Fig 3, and figure 2, respectively and is designated as 'Form IF.
Bendroflumethiazide 'Form IF
In a reaction flask 10 gm bendroflumethiazide (prepared according to the process in
GB879592, purity 99.7 as per USP HPLC procedure) was taken dissolved in 70 ml methanol
till a clear solution was obtained. Methanol was distilled ,under vacuum from the solution till
dryness. The solid obtained was collected and dried at 50 °C under vacuum for 5 hours. The
IR and PXRD pattern is substantially as shown in Fig 3 and figure 2, respectively.
Bendroflumethiazide 'Form I'
In a reaction flask 10 gm bendroflumethiazide (prepared according to the process in GB879592, purity 99.7 as per USP HPLC procedure) was dissolved in 25 ml methyl isobutyl ketone at 75 °C till a clear solution was obtained. The solution was cooled to 40 °C and to it 120 ml hexane was added slowly and further the slurry obtained was maintained at 30 to 35 °C for 30 minutes. The mass was further cooled to 0 °C in 20 minutes and the precipitated crystals were collected by filtration, washed with hexane and dried at 65 °C under vacuum for 8 hours. The PXRD pattern is as substantially shown in Fig 1 and matches with 'Form I'.
1. A novel crystalline form of Bendroflumethiazide of Formula I, designated as "Form II", characterized by a powder X-Ray diffraction pattern showing peaks at 21.02, 21.50, 24.34, 28.09, 29.06, 29.45, 10.73, 11.97, and 13.87 ± 0.20 degrees 2 theta angles.
2. The novel crystalline Form II" of claim 1 is further characterized a FT IR spectrum having absorptions at 3419, 3363, 3309, 3226, 888.7, 873 which are absent in known crystalline "Form I" of bendroflumethiazide.
3. Bendroflumethiazide having a crystal content of at least 60% of Form II crystals according to claim 1 or 2.
4. Bendroflumethiazide having a crystal content of at least 90% of Form II crystals according to claim 1 or 2.
5. A process for preparation of crystalline "Form II" according to claim 1, comprises:
a. dissolving amorphous or any other crystalline form/forms of
bendroflumethiazide in an organic solvent selected from methanol or ethyl
b. recovering said Form II crystal form of Bendroflumethiazide either by
distilling out the solvent or crystallizing from said solution.
6. The process as claimed in claim 5, wherein the quantity of alcohol ranges from 5 to 30 volume relative the quantity of bendroflumethiazide.
7. A process for preparation of crystalline "Form II" according to claim 1, comprises:
a. dissolving bendroflumethiazide in NaOH aqueous solution for sufficient
period of time; and
b. recovering said Form II by neutralization of said solution with an acid such as
hydrochloric acid aqueous solution.
8. A process for preparation of crystalline "Form II" according to claim 7, wherein the sodium hydroxide aqueous solution is IN NaOH solution in water.
9. A process for preparation of crystalline "Form II" according to claim 7, wherein the hydrochloric acid solution is IN HC1 solution in water.
10. A process for preparation of crystalline "Form I" comprising the steps of:
a) dissolving bendroflumethiazide in a ketonic solvent such as methyl isobutyl ketone; and
b) precipitating the Form I by addition of an anti-solvent selected from hexane or cyclohexane.
11. A novel crystalline form of Bendroflumethiazide designated as "Form II" and processes for preparation thereof as substantially described herein with reference to the foregoing examples 1 to 2.
12. A process for preparation of crystalline "Form I" of Bendroflumethiazide as substantially described herein with reference to the forgoing example 3.
Dr. Gopakumar G.Nair Agent for the Applicant
Dated this 21st day of September 2006
Disclosed herein is a novel crystalline form of 3-Benzyl - 6-trifluromethyl - 7 - sulfamyl -3,4-dihydro - 1,2,4- benzothiadiazine - 1,1- dioxide, designated as 'Form II' and processes for preparation thereof. The invention further discloses a new process for preparation and isolation of crystalline Form I.
|Indian Patent Application Number||1179/MUM/2005|
|PG Journal Number||25/2011|
|Date of Filing||23-Sep-2005|
|Name of Patentee||IPCA LABORATORIES LTD|
|Applicant Address||48,Kandivli Indusrial Etate, Mumbai-400 067|
|PCT International Classification Number||C07C7/00|
|PCT International Application Number||N/A|
|PCT International Filing date|