IE66507B1 - Process for the production of aqueous mixed micelle solutions - Google Patents

Abstract

Described is a method of producing aqueous solutions containing mixed micelles formed from lipids and salts of gallic acids and in which active substances insoluble or only slightly soluble in water may, if required, be solubilized. The method is characterized in that mixtures of (a) solutions containing, in a water-soluble organic solvent, the lipids, the free gallic acids and, optionally, the active substances which are insoluble or only slightly soluble in water and (b) solutions containing 0.05-3 equivalents, relative to the gallic acids, of bases and, optionally, isotonizing additives and/or water-soluble active substances are prepared, the organic solvent removed by ultrafiltration, freeze-drying, vacuum distillation or reverse osmosis and the mixture thus obtained diluted, if required, with aqueous phase.

Description

The invention relates to a process for the manufacture of aqueous mixed micelle solutions containing mixed micelles formed from lipids and salts of bile acids, in which, if desired, active ingredients that are sparingly soluble or insoluble in water have been solubilised.

Processes for the manufacture of such mixed micelle solutions are known, for example, from German Patent Specification 27 30 570.

In the known processes, the mixed micelle solutions are manufactured by dissolving the lipoids, the salts of the bile acids, and, optionally, the active ingredients that are sparingly soluble or insoluble in water, in an organic solvent (for example ethanol), and concentrating the solutions so that a lipid film forms on the walls of the vessel, which film can be removed by means of aqueous solutions (Biochemistry X£, 1980, 602 ff and 615 ff; Naturforsch. 32c. 1977, 748 ff).

This process, however, is quite expensive and can be applied on an industrially useful scale only with considerable expenditure on apparatus.

In addition to that preferred process, there is also known, for example from Example 3 of Patent Specification 27 30 570 already mentioned, a process in which such mixed micelle solutions are manufactured by mixing the components and stirring the mixture.

That process, however, not only has the disadvantage that it takes several days but, when the procedure of that Example is followed - without active ingredient -, it is found that only very turbid solutions are obtained in that manner, which contain mixed micelles having an average diameter of approximately 340 nm.

Clear solutions containing mixed micelles having an average diameter of approximately 10 nm cannot be obtained in that manner.

It has now been found that it is possible to manufacture such clear aqueous solutions of mixed micelles in a simple manner and in a short time by means of a process that is characterised in that a) solutions that contain, in a water-soluble organic solvent, the lipids, the free bile acids and, option10 ally, the active ingredients that are sparingly soluble or insoluble in water and b) solutions that contain, based on the bile acids, from 0.05 to 3 equivalents of bases and, optionally, isotonising additives and/or water-soluble active 15 ingredients are prepared, the organic solvent is removed by ultrafiltration, lyophilisation, vacuum distillation or reverse osmosis, and, if desired, the resulting mixture is diluted with aqueous phase.

The process according to the invention can be carried out using the same bile acids as are used in the known processes. Suitable bile acids are 5B-cholane-24-acid derivatives of the general formula wherein Rj and R2and slso R3 and R4 together represent an oxo group, two hydrogen atoms or one hydrogen atom and one hydroxy group and X represents a hydroxy group or a grouping of the formula -NH"CH2~CO2H or -NH-(CH2)2-SO3H.

There may be mentioned as suitable bile acids, for example: cholic acid, glycocholic acid, taurocholic acid, deoxycholic acid, glycodeoxycholic acid, taurodeoxycholic acid, chenodeoxycholic acid, glycochenodeoxycholic acid and taurochenodeoxycholic acid.

Preferably from 1 to 30 g and especially from 2 g to 15 g of bile acid per 100 g of aqueous solution optionally containing isotonising additives and water-soluble active ingredients are used for the manufacture of the aqueous mixed micelle solution.

The same lipoids as those used in the known processes can be used in the process of the invention for the manufac-° ture of the aqueous mixed micelle solutions.

Suitable lipoids are, for example, monoglycerides, sulphatides and, especially, phospholipids, such as sphingomyelins, plasmalogens, phosphatidylcholines, phosphatidylathanolamines, phosphatidylserines, phosphatidyl inositols and cardiolipins or also mixtures of these lipoids (Dr. Otto-Albert Neumuller: Rompps ChemieLexikon," Franck'sche Verlagshandlung, Stuttgart (DE) 2665, 3X59, 3920 and 4045).

Preferably from 3 to 40 % and especially from 5 to 20 % lipoid per 100 g of aqueous solution optionally containing isotonising additives and/or water-soluble active ingredients are used for the manufacture of the aqueous mixed micelle solutions. The weight ratio of lipoid to bile acid is preferably from 0.1:1 to 2:1 and especially from 0.8:1 to 2:1.

Suitable bases for the manufacture of the aqueous mixed micelle solutions according to the process of the invention are, on the one hand, alkali metal hydroxides, such as lithium hydroxide, potassium hydroxide and, especially, sodium hydroxide and, on the other hand, organic nitrogen bases, provided that they form physiologically tolerable salts. Such nitrogen bases are, for example, ammonia, primary, secondary or tertiary amines, ethanolamine, diethanolamine, piperazine, morpholine, lysine, ornithine, arginine, N,N-dimethylglucamin@, choline and, especially, N-methylglucamine and trishydroxymethyl ami noraethane. These bases are used according to the invention in an amount such that the solutions contain, based on the bile acids, from 0.05 to 3 equivalents of base and, especially, from 0.5 to 2 equivalents of base.

Suitable water-soluble organic solvents are, for example, lower alcohols, such as methanol, ethanol, propanol or isopropanol, or acetone. These solvents are preferably used in an amount such that the resulting mixtures also are solutions. The solvents mentioned can be removed both by vacuum distillation and by reverse osmosis (T.H. Meltzer, Advances in Parenteral Science 13, Filtration in the Pharmaceutical Industry, Marcel, Dekker Verlag New York etc., 1st edition, 72-74, 483-488 and 838-854; Chem.-Ing. Tech, 61. 1989, 535-544).

If the solvent is removed by lyophilisation, it is advantageous to add to the solution beforehand from 20 to 300 mg of a mono- or di-saccharide, such as glucose or galactose, or of a sugar alcohol, such as sorbitol or mannitol.

If the solvent is removed by ultrafiltration, filters having a maximum exclusion size of 300,000 Daltons are advantageously used.

In the case of reverse osmosis, which is already used industrially for water treatment, as is known the liquid to be removed is removed via an asymmetric membrane that has no pores. Suitable membranes are, for example, those consisting of polydimethylsiloxane or polyvinyl alcohol of approximately from 0.1 to 2 gm thickness, applied to a sponge-like or textile-like supporting layer. Suitable membrane modules are likewise capillary or tube modules or also plate modules or helical coil modules. With regard to the development of solvent-selective membranes and their mode of operation reference is made to the above-mentioned publication in the journal Chem. Ing. Tech. SO, 1988, 590 ff.

Reverse osmosis not only can be used for the removal from aqueous dispersions of solvents that have a higher vapour pressure than water but also is suitable for the removal of solvents having a lower vapour pressure than water, such as, for example, dimethylformamide, dimethyl sulphoxide or acetonitrile.

When the solvent has been removed, the resulting mixture may, if desired, be diluted with aqueous phase. It may be advantageous here to use an aqueous phase that contains not more than 10 ml of a neutralised bile acid 5 and, if desired, in. addition, isotonising additives.

Suitable active ingredients that are sparingly soluble or insoluble in water are preferably those whose solubility in water at room temperature does not exceed 2 %. Such active ingredients are, for example, plant-protecting 10 agents, such as sparingly soluble insecticides or herbicides, and, especially, sparingly soluble pharmaceutical active ingredients.

Pharmaceutical active ingredients that are sparingly soluble or insoluble in water, belonging to the following 15 groups of active ingredient, are suitable for the manufacture of the medicaments according to the invention : gestagenically active steroid hormones, such as, for example, 13-ethyl-l7.8~hydroxy-18,19-dinor-X/ffi"pregn-4-en20 20"Vl-3-one (= levonorgestrel), 13"ethyl-l7S-hydroxy~ 18,19~dinor"17G-pregna-4,15~dien-20-yn-3~one (= gestoden.e) or 13-ethyT-l7B-hydroxy-ll-methylene-18,19-dinor17c"pregn-4"en-20"yne (desogestrel), oestrogenical ly active steroid hormones, such as 3-hydroxy-l,3,5(10)25 oestratrien-17-one (= oestrone) or I,9-nor-I7c-pregna1,3,5 (10)-trien-20-yne-3,I73-diol (ethiny.1 oestradiol); androgenically active steroid hormones, such as 173" hydroxy"4-androsten"3"one (= testosterone) and esters thereof or 17B-hydroxy-lC"methyl"5a-androsten"3-one (= mesterolone); antiandrogenically active steroid hormones, such as 17cacetoxy-6-chloro-lB, 2B-dihydro~3H-cyclopropa[ 1,2]-pregna1,4,S~triene-3,20-dione (cyproterone acetate); corticoids, such as 11B, 17c, 21-trihydroxy"4-pregnene3,20-dione (= hydrocortisone), 11B, 17c,21-trihydroxy-l,4pragnadiene~3,20-dione (= prednisolone), 118,X7c,21trihydroxy-Sa-methyl-i, 4-pregnatriene-3,20-dione (= mefchvlprednisolone) and 6C"fluoro-llB,21-dihydroxy15c-raethyl-l,4-pregnadiene-3,20-dione (= difluorocortolone); ergolines, such as 3-(9,10-dihydro-5-methyl-8a-ergol~ inyl)-1,1-diethylurea (= ergoline), 3-(2-bromo-9,10dihydro-S-methyl-8c-ergolinyl)~l, 1-diethylurea (= broraergoline) or 3-(S-methyl-8c-ergolinyl)-1,1-diethylurea (= terguride); antihypertonics, such as 7c-acetvlthio-17c-hydroxy-3oxo-4-pregnene-21-carboxyl.ic acid-!f~lactone (= spironolactone) or 7c-acetylthio~15B, loS-methylene-S-oxo-lVcpregna-I,4-diene-21,17-carbolactone (= raespirenone); anticoagulants, such as 5-[hexahydro-5~hvdroxy-4-(3hydroxy-4-raethyl-l-octen"S-ynyl)-2(lH)-pentalenylidene) ]pentanoic acid (= iloprost); psycho-active drugs, such as 4-(3-cyclopentyloxy~4methoxy-phenyl-2-pyrrolidone (= rolipram) and 7-chloro1,3-dihydro-X-methyl~5-phenyl-2H-l, 4-benzodiazepin-2-one (diazepam); carotenoids, such as c-carotene and B-carotene; fat-soluble vitamins, such as vitamins of the vitamin A, vitamin D, vitamin E and vitamin K groups.

An especially preferred group consists of β-carbolines, described, for example, in European Patent Applications 234,173 and 239,667. Examples of B-carbolines that may be mentioned are 6--benzoyloxy-4-methoxymethyl-S-carboline~3"carboxylic acid isopropyl ester (= becarnil) and 5—(4-chlorophenoxy)-d-methoxymethyl-S-carboline-Gcarboxylie acid isopropyl ester (= Cl-phocip).

The aqueous mixed micelle solutions manufactured by the process according to the invention may, if desired, contain isotonic additives in order to increase their osmotic pressure. Suitable additives are, for example, inorganic or organic salts or buffer substances, such as sodium chloride, phosphate buffer, citrate buffer, glycine buffer, citrate phosphate buffer, TRis-KCT buffer, maleate buffer, etc., mono- or di-saccharides, such as glucose, lactose, saccharose, sugar alcohols, such as mannitol, sorbitol, xylite or glycerin, or watersoluble polymers, such as dextran or polyethylene glycol.

These isotonising substances are usually used in such concentrations that the resulting aqueous mixed micelle solution has an osmotic pressure of from 5 to 1000 mosm and, in the case of injection solutions, optimally 300 mosm.

The aqueous mixed micelle solutions may furthermore contain additional water-soluble active ingredients in order to produce combination preparations. Examples of such combination preparations are mixtures of watersoluble and fat-soluble vitamins or preparations containing water-soluble antibiotics in addition to corticoids.

Apart from the conditions specified in patent claim 1, the manufacture is carried out by means of conventional methods by heating the mixtures to the temperatures specified in patent claim 1 while stirring vigorously.

Since the lipoids and also a number of active ingredients are sensitive to oxidation the process is advantageously carried out under an inert gas atmosphere, such as nitrogen or argon, and the resulting aqueous mixed micelle solutions are stabilised by the addition of antioxidants, such as sodium ascorbate, tocopherol or sodium hydrogen sulphite.

The process according to the invention has the advantage that it is significantly easier to carry out on an industrial scale than are the known processes.

The steps required to carry it out, dissolving, mixing and vacuum distillation or reverse osmosis, can be carried out continuously on an industrial scale and involve little expenditure. In addition, the process according to the invention has the advantage that the thermal stressing of the components is lower than in the known processes, especially when the process of reverse osmosis is applied to remove the solvents. Once manufactured, the resulting aqueous mixed micelle solution can be sterile-filtered and/or heat-sterilised at from 100’C to 140C= The following Examples of procedure serve to explain the process of the invention in more detail.

Example.. 1 400 ml of an aqueous solution containing 2,13 g of sodium hydroxide are placed in a 2 litre round-bottomed flask» 100 ml of an ethanolic solution containing 45 g of phospholipid (Phospholipon 100 L, produced by A. Nattermann & Cie.tf DE-5000 Cologne) and 27„1 g of glycocholic acid are then added thereto. A clear mixture with a slightly yellow colour and a pH value of 6.5 is obtained» The ethanol is removed by reverse osmosis by concentrating the solution from 500 ml to 250 ml in an apparatus for reverse osmosis (Membra-Fil P-28, Messrs Buchi, Goppingen, Membran DRC-1000). The pressure is 35 bar.

In a second step, the concentrate is diluted to the starting volume with a 3.5 mM solution of neutralised glycocholic acid. Thereafter, the resulting mixed micelle formulation contains less than 0.01 mg/ml ethanol.

The composition is as follows: Phospholipon; produced by Nattermann AG, DE-5000 Cologne glycocholic acid: sodium hydroxide: water: pH value: ad 0 mg 52.1 mg 4.3 mg 1.0 ml 6.6 Example„2 120 ml of an ethanolic solution containing 45 g of Phospholipon and 27 g of glycocholic acid are added to 800 ml of an aqueous solution containing 2.8 g of potassium hydroxide, a clear solution is produced, the pH value of which is adjusted to 6.5 with 0.1H potassium hydroxide solution. 18 g of sorbitol are added to this solution and stirred until completely dissolved.

The ethanol-containing mixed micelle solution is transferred to an ultrafiltration system (Amicon GmbH, DE 8510 Witten; type DC 2, membrane: HIP 30-20). ultrafiltration is carried out at a membrane differential pressure of not more than 1 bar. The volume of the ultrafiltrate removed is continuously replaced by a 10 mM neutralised glycocholic acid solution. When the ultrafiltrate volume reaches 2.5 litres, the continuous supply is interrupted and the mixed micelle solution is concentrated from 1 litre to 500 ml.

The formulation has the following composition: Phospholipon: 88.9 mg glycocholic acid: 58.0 mg potassium hydroxide: 6.4 mg water: ad 1.0 ml pH value: 6.8 Example 3 Under the conditions described in Example 2, a mixed micelle solution is manufactured, but with the difference that the aqueous solution additionally contains 50 mg of sodium EDTA and the ethanol ic solution additionally contains 580 mg of active ingredient (Cl-phocip)„ The resulting mixed micelle formulation has the following composition: Phospholipon: 89.2 mg glycocholic acid: 52.3 mg potassium hydroxide: 6.1 mg Cl-phocip: 1.01 mg water: ad 1.0 ml pH value: 6.7

Claims (5)

Patent Claims

1. Process for the manufacture of mixed micelle solutions containing mixed micelles formed from lipids and salts of bile acids, in which, if desired, active ingredients that are sparingly soluble or insoluble in water have been solubilised, characterised in that a) solutions that contain, in a water-soluble organic solvent, the lipids, the free bile acids and, optionally, the active ingredients that are sparingly soluble or insoluble in water and b) solutions that contain, based on the bile acids, from 0.05 to 3 equivalents of bases and, optionally, isotonising additives and/or water-soluble active ingredients are prepared, the organic solvent is removed by ultrafiltration, lyophilisation, vacuum distillation or reverse osmosis, and, if desired, the resulting mixture is diluted with aqueous phase.

2. Process for the manufacture of mixed micelle solutions according to patent claim 1, characterised in that the solutions a) are used in such a dilute form that the resulting mixtures are also solutions.

3. Process for the manufacture of aqueous mixed micelle solutions according to patent claims 1 and 2, characterised in that there is used as bile acid a 56-cholane24-acid derivative of the general formula wherein Ri and R 2 anc3 SJ- S ° R3 and R4 together represent an oxo group, two hydrogen atoms or one hydrogen atom and one 5 hydroxy group and X represents a hydroxy group or a grouping of the formula -NH-CH 2 -CO 2 H or -NH-(CH 2 ) 2 -SO 3 H.

4. Process for the xaanufacture of aqueous mixed micelle solutions according to patent claims 1 to 3, charac10 terised in that phospholipids are used as lipids. 5. Process for the manufacture of aqueous mixed micelle solutions according to patent claims 1 to 4, characterised in that sodium hydroxide or potassium hydroxide is used as base. 15 6. Process for the manufacture of aqueous mixed micelle solutions according to patent claims 1 to 5, characterised in that pharmaceutical active ingredients that are sparingly soluble or insoluble in water are used as active ingredients that are sparingly soluble or insol20 uble in water. 7. Use of aqueous mixed micelle solutions manufactured according to patent claim 6 for the xnanufacture of injection solutions. 8. A process substantially as hereinbefore described with reference to the Examples 9. A use substantially as hereinbefore described with reference to the Examples.

5. 10. A solution of aqueous mixed micelles whenever prepared by a process as claimed in any of claims 1 to 6 or 8.