NZ230828A

NZ230828A - Process for the micronisation of glubenclamide

Info

Publication number: NZ230828A
Application number: NZ230828A
Authority: NZ
Inventors: Ottmar Jaenicke
Original assignee: Hoechst Ag
Priority date: 1988-10-01
Filing date: 1989-09-29
Publication date: 1991-07-26
Also published as: GR3020754T3; PT91835A; ATE89268T1; ZA897421B; EP0362704B1; ES2057043T5; EP0362704A1; AU620448B2; DE3833439A1; EP0362704B2; FI894598A0; FI894598A; JPH02149516A; ES2057043T3; DE58904332D1; AU4230289A

Abstract

A process for preparing a micronised form of glibenclamide of the formula <IMAGE> with a BET surface area of the active compound particles of at least 3 m<2>/g is described. It entails a suspension of a sparingly soluble salt of glibenclamide in water being acidified with an acid. The result is a microfine precipitate of glibenclamide.

Description

New Zealand Paient Spedficaiion for Paient Number £30828 NO DRAWINGS 2308 28 Priority Date(s):. 1 • V=>* && ;Conpplete Specification ;Class: (5)...SW.. ;s°i. ;Publication Date: % 5 J01» JM a ;P.O. Journal, No: ... ;N.Z. No. ;NEW ZEALAND Patents Act 1953 COMPLETE SPECIFICATION PROCESS FOR THE MICRONIZATION OF GLIBENCLAHIDF ;HOECHST AKTIENGESELLSCHAFT, a corporation organized under the laws of the Federal Republic of Germany of D-6230 Frankfurt am Main 80, ;Federal Republic of Germany do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it Is to be performed, to be particularly described in and by the following statement:- ;- 1 - (Followed by 1A) ;t 4.,.. ,^r ;— ^ A ~" .'-. OAl' ' • Q ;- O nOECIIGT JgriEHQESETiTifiCIIMrtB Dx.D/gm DOE 00/r 274> ;Description ;Process for the ad.cronizati.on of glibenclamide ;Gllhenclamide, a sulfonylurea derivative of the formola ;0CH3 ;conhch2CH2-^ SO2NHCNH-0 ;0 ;5 is an oral antidiabetic which, is particularly suitable for the treatment of Diabetes melitus (c.f., for example, ;German Patent 1,301,812). ;It is known that, given the low solubility of glibenclamide in the digestive juices, the absorption rate depends 10 on the degree of distribution of the active compound ;(US Patents 3,979,520 and 4,060,634). very small particle sizes in the order of 2 fxm. with a surface area of at least 3 m2/g by the BET method offer the advantage of a high absorp-15 tion rate which results in a therapeutically desirable rapid drop in the blood sugar level. ;Various processes are known from the literature for the preparation of glibenclamid having large surface areas in the range from 3 to 10 mVg by the BET method. German 20 Patent 2,348,334 describes methods for the micro-precipitation of glibenclamide starting from glibenclamide or salts of glibenclamide. ;Microfine glibenclamid is obtained in accordance with the prior art indicated, for example by precipitating the 25 active compound from a water-miscible organic solvent. In this case, glibenclamide is dissolved, for example, in dimethylformamide, and the solution is run into water or water/acid mixtures with vigorous stirring.-- To:_achieve better mixing, it is proposed to run or pump the solutioi ;directly into the stirring head of an Ultra-Turrax turbine stirrer. ;Alternatively, the sodium salt of glibenclamide can be dissolved in a mixture of methanol and water. After filtration, the solution is metered into water to which the amount of acid necessary for neutralization of the sodium salt has been added. To ensure good mixing, an Ultra-Turrax turbine stirrer is likewise employed. ;As a further variant, the use of aqueous solutions of the alkali metal salt of glibenclamide is proposed. The low solubility of the alkali metal salts in water is disadvantageous, which means that the use of aqueous solutions for microprecipitation is not a useful industrial process. ;A further way of micronizing is fine grinding of glibenclamide. In order to achieve the high surface areas of up to 10 m2/g which, are desired, repeated grinding in jet mills is necessary, possibly also with addition of grinding auxiliaries. ;Chemical Abstracts 107, 28393g (1987) describes another variant for the preparation of micro fine glibenclamide having particles of 1-2 pm. Glibenclamide is dissolved in dimethylformamide, and the solution at 80-85°C is added to initially introduced water or the water is added to the hot solution. ;From various points of view, these methods representing the prior art have disadvantages in an economic respect, as far as quality is concerned, or regarding the technical complexity. ;In the case of microprecipitation in accordance with the prior art using organic solvents, side reactions of glibenclamide with the solvents cannot be avoided, permissible concentrations of byproducts in ;; , . . ...,. , -- ;230828 ;o o ;- 3 - ;cal active compounds such as glibenclamide are very low. In BP 80, the level of secondary compounds, such as the sulfonamide (4- [ 2- (5-chloro-2-methoxybenzamido) ethyl ] -phenylsulfonamide) or the urethane (methyl 4-[2-(5-5 chloro-2-methoxybenzamido) ethyl ] phenylsulf onylcarbamate) ;is limited at less than 0.4 %. Persons skilled in the art know that re-cleavage to form the sulfonamide occurs as a function of the temperature, in the order of some tenths of a percent even at 40° - 60°C, on dissolution of 10 glibenclamide in dimethylformamide. If glibenclamid is dissolved in methanol, a urethane is formed, as is known, and can reach concentrations of some tenths of a percent over a period of a few hours in the temperature range from 40° - 60°C. ;15 Since the temperatures before complete dissolution of glibenclamide inDMF, methanol or methanol/water mixtures are in the range from 40° - 60°C in the case of the concentrations which are necessary for industrial processes, a drop in the quality of glibenclamide in these 20 precipitation processes cannot be excluded, even if very careful procedures are followed. ;A further disadvantage of these precipitation processes is the additional costs incurred on disposal of the organic solvents, whether by recycling, combustion or 25 biodegradation in the treatment plant. ;The residual levels of solvents in the product is a further problem in the case of these processes for microprecipitation. Particularly high-boiling solvents such as dimethylformamide are bound adsorptively at the 30 large surface of the product. Substantial removal, as is necessary for pharmaceutical active compounds, is possible, but very complex. ;35 ;It is furthermore know to those skilled in the art that the surface areas of microprecipitated products can vary within broad limits since the crystal growth conditions ;a .4. 2308 28 ;are not adequately determined by the precipitation conditions. Thus, is frequently observed that the surface area of the active compound is not within the tolerances of the specification. In such cases, it is necessary to ^ 5 re-work the product with high additional costs. ;Microprecipitation from solution and also fine grinding are an additional process step which requires special technical equipment. ;For fine grinding, a grinding unit, usually comprising a 10 jet mill and a complex dust removal system, is necessary to completely remove the pharmacologically highly-ef fec-tive active compound. ;Production plants for microprecipitation require special equipment in order to be able to carry out the mixing, 15 which is preferably carried out, of the solutions in rotor-stator systems, such as the Ultra-Turrax turbine stirrer or in mixer pumps. ;Surprisingly, it has now been found that microprecipitation can be carried out in a technically very simple, 20 economically and ecologically very favorable manner. ;The invention therefore relates to a process for the preparation of a micronized form of glibenclamide in which the active compound particles have a surface area of at least 3 m2/g by the BET method, which comprises acidifying 25 a suspension of a sparingly-soluble salt of glibenclamide in water using an acid to give glibenclairide precipitated in micro fine form, and to the micronized glibenclamide obtainable by this process. ;Special technical equipment is not necessary for the 30 preparation. The process according to the invention can be carried out in a standard stirred kettle. ;A further advantage of the process according to the ;invention is that -the surface area of -the precipitated active compound can be determined in a reproducible manner by means of the precipitation temperature. ;For example, in the preparation of the sodium salt, the surface area is a .clear function of the temperature in the temperature range from 5° to 90°C, preferably from 2Qf to 60°C. Mean surface areas of 14-15 m2/g are achieved at 20°C, and a surface area of 2.5-3.0 m2/g is achieved at 60°C. The preferably desired surface area in the range from 5-10 mVg is achieved in the temperature range from 35-45°C. ;Suitable salts of glibenclamide are the salts of the alkali metals lithium, sodium or potassium and the ammonium salt, but preferably the sodium salt. ;The mineral acids nitric acid, sulfuric acid, hydrochloric acid or phosphoric acid and the organic acids acetic acid or citric acid are suitable for the precipitation. Nitric acid or hydrochloric acid is preferably employed. The pH of the suspension after precipitation is 1.0 to 6.0, preferably 2.0 to 4.5. ;By adding surf ace—active substances, the cristalline conversion of the glibenclamide salts into glibenclamide microfine can be influenced. Wetting agents which can be employed are physiologically acceptable ionogenic and non-ionogenic substances. Polyoxyethylene stearates, such as, for example, polyoxyethylene stearate having an average of 50 ethylene oxide units, are preferred. The concentration is, for example, 0.05-1.0 % by weight, preferably 0.1—0.2 % by weight, relative to the active compound. ;Addition of organic, water—miscible solvents, such as, ;for example, dimethylfbrmamide or lower alcohols (having from 1-4 carbon atoms), to the suspensions allows -the crystal size and thus fEe*su?¥aee— area of the glibenclamide to be controlled.

JUNI99; »l'j 2308 28 The glibenclamide obtainable by the process according to the invention is suitable for the preparation of medicaments .

The preparation according to the invention of micronized 5 glibenclamide having a surface area of at least 3 m2/g, preferably 5-10 m2/g, by the BET method is explained with reference to the examples below: Q Example 1 2480 1 of demineralized water are introduced into the 10 kettle, and 62 kg of the Na salt of glibenclamide are introduced with stirring. The temperature of the suspension is adjusted to 40°C. 65.4 1 of 2N nitric acid are allowed to run in over the course of 30 minutes with vigorous stirring. The glibenclairi.de precipitates as a 15 finally divided suspension, which is removed by centri-fugation and washed with plenty of water. After drying, the yield is 55.3 kg = 96.5 % of theory. The product has a surface area of 6.9 m2/g by the BET method. The melting point is 170°C.

Example 2 1500 ml of water are introduced into the kettle. First 0.35 g of polyoxyethylene stearate 50 (®Macrogol) are dissolved therein and subsequently 37.7 g of the Na salt of glibenclamide are suspended therein. The temperature of 25 the suspension is adjusted to 30°C. 40 ml of 2N nitric acid are run in over the course of 30 minutes with vigorous stirring. The pH of the suspension is then pH 2.2. The suspension of microfine glibenclamide is filtered off with suction and carefully washed with water. After 30 drying in vacuo at 60°C, the yield is 33.97 = 97.4% of theory. The surface area by the BET method is 8.7 m2/g.

Example 3 75.5 g of the Na salt of glibenclandde are suspended in 2700 ml of demineralized water and 300 ml of methanol. 35 80 ml of 2N nitric acid are allowed to run in over the 230828 course of 40 minutes at 30°C with stirring. The mixture is stirred for a further 1 hour, and the product is filtered off with suction and washed with plenty of water. After drying in vacuo at 60°C, a yield of 67.8 g - 96.8 % of theory of microfine glibenclamide having a surface area of 4.8 m2/g is obtained. ' rs •- • "> r. 9 Q _ O U O o

Claims

WHAT WE CLAIM IS: 1 - A process for the preparation of a micronized form of glibenclamide of the formula 0CH3
CONHCHgCHg-SO2NHCNH-0 0 in which, the glibenclamide particles have a 5 surface area of at least 3 m2/g by the bft method, which comprises acidifing a suspension of a sparingly—soluble salt of glibenclamide in .water using an acid to give gl -? Tvan ami at* precipitated in microfine form. 10 2. The process as claimed in claim 1, wherein the temperature during formation of the microprecipi-tated glibenclamide is in range •Frrun 5® — 90°C.
3. The process as claimed in claim 2, wherein the temperature doting formation of the microprecipitated glibenclamide is in the range from 35°C - 45°C.
4. The process as claimed in claim 1, wherein the salt of glibenclamide employed is the lithhim, potassium, ammonium or sodium salt
5. The process as claimed in claim 4, wherein the salt of glibenclamide employed is the sodium salt
6. The process as claimed in claim 1, wherein the add employed is a mineral acid, or a weak organic acid.
7. The process as claimed in claim 6, wherein the add employed is nitric acid, hydrochloric add or sulfuric add.
8. The process as claimed in claim 6, wherein the aad^employai is-ac^ic acid or citric acid. •ZT5-« -9- 10 ;>G828
9. The process as claimed in claim 7, wherein the acid employed is nitric acid or hydrochloric acid.
10. The process as claimed in claim 1, wherein the pH value of the suspension of the micronized glibenclamide after precipitation is pH 1.0-6.0.
11. The process as claimed in claim 10, wherein the pH value of the suspension of the micronized glibenclamide after precipitation is pH 2.0-4.5.
12. Hie process as claimed in claim 1, wherein a pharmacologically acceptable wetting agent is added to the water in a concentration of from 0.05 to 1.0 % by weight, relative to glibenclamide. 15
13. The process as claimed in claim 12, wherein a polyoxyethylene stearale is added.
14. The process as claimed in claim 13, wherein polyoxyethylene stearate containing an average of 50 ethylene oxide units is added. 20 15. The process as claimed in Haim 13 or 14, wherein the polyoxyethylene stearate is in a concentration of from 0.1 to 0.2 % by weight relative to glibenclamide.
C o 25 30
16. The process as claimed in claim 1, wherein an organic, water-miscible solvent, is added to the water.
17. The process as riaim«i in Halm 16, wherein dimethylformamide or a lower alcohol is added to the water.
18. Glibenclamide in micronized form when prepared by the process as claimed in any one of claims 1 to 17. 35
19. A process according to as herein described or exemplified. BJ&CHSt AKTIENGESELLSCHAFT \ By Tfr in Attorneys HUGHES LTD