CHOLESTEROL LEVEL-LOWERING AGENTS

Abstract: There is disclosed a cholesterol level-lowering agent which comprises as a main component a strongly basic anion exchange resin having imidazolium salts as a functional groups, said resin being a copolymer of (A) a high molecular quarternary salt and (B) a polyfunctional epoxy compound having two or more oxirane rings.

Description: This invention relates to a pharmaceutical composition which comprises a strongly basic anion exchange resin having imidazolium salts as a functional group. It further relates to the use of the said anion exchange resin for the making of a medicament effective in the lowering of the cholesterol level. It has already been known that an anion exchange resin is applicable as a so-called anticholesteremic agent for lowering the blood cholesterol level (U.S. Patent Nos. 3,499,960 and 3,780,171 and British Patent No. 929,391 and Japanese Patent Laid-Open Application No. 10386/1978). The mechanism that administration of an anion exchange resin could lower blood cholesterol may be considered as stated below. Namely, a basic anion exchange resin would adsorb and fix bile acids present in the intestine to prevent said bile acids from reabsorption and to promote conversion of cholesterol, which is equilibrated with bile acids in the liver, to bile acids, whereby blood cholesterol is lowered. The basic anion exchange resin, which has been hitherto applied as an anticholesteremic agent, is an ion exchange resin having aliphatic quarternary ammonium salts as functional groups (U.S. Patent Nos. 3,499,960 and 3,780,171). However, such an anion exchange resin has drawbacks of a large dosage (8 to 16 g/day) and difficulty in ingestion due to its low activity. Also, the anion exchange resin having aliphatic quarternary ammonium salts as functional groups can be prepared by reacting an aliphatic tertiary amine with a haloalkyl group introduced onto a cross-linked polymer, but the resultant anion exchange resin bears an offensive characteristic aliphatic amine odor and could not be put into practical use as such. Then, decrease in such offensive odor has been attempted practically by coating the surface of said anion exchange resin, but increase in dosage should be unavoidable due to a reduced ion exchange capacity caused by surface coating. In order to solve these drawbacks, the present inventors had already developed an anticholesteremic agent using as a main component an anion exchange resin prepared by using imidazoles for forming an anion exchangeable group, as filed in Japanese Patent Laid-Open Application No. 24310/1982. By said invention the prior difficulties are overcome, but there is still need for a far higher active product. The anion exchange resin of the prior invention is prepared by reacting a halomethyloxirane compound with an imidazole and then reacting the resultant modified imidazole with a polyfunctional epoxy compound. However, said modified imidazole is a mixture of imidazole, 1 : 1 or 1 : 2 adduct of imidazole and a halomethyloxirane compound, and an oligomer, and further is not separable so that the resultant anion exchange resin has a less content of the imidazolium salt capable of contributing to salt-splitting power among basic exchangeable groups upon imidazole and, though a higher activity can be seen as compared with the prior product, a far more highly active product has been desired. An object of this invention is to provide a pharmaceutical composition which comprises a strongly basic anion exchange resin having a higher adsorptivity of bile acids and no offensive odor, and the use of the said resin to make an improved medicament effective in the lowering of the cholesterol level. This object is accomplished by the provision of the aforementioned pharmaceutical composition which comprises a strongly basic anion exchange resin having imidazolium salts as a functional group, said resin being a copolymer of: (A) a high molecular quarternary salt having the following formula (I): wherein R₁ is a hydrogen atom, an alkyl group of 1 to 17 carbon atoms or an aryl group of 6 to 8 carbon atoms, R₂ and R₃ may be the same or different and each represents a hydrogen atom or an alkyl group of 1 to 3 carbon atoms, R₄ is a hydrogen atom or a methyl group, the counter ion Y ⊖ is a halide ion, a hydroxide ion or a 1/2 (sulfate) ion, and n is an integer of 5 to 50. Ar represents a residue represented by the formula: wherein R₁, R₂ and R₃ are as defined above, the formula: wherein R₁, R₂, R₃, R₄ and Y ⊖ are as defined above, the formula: wherein R₁, R₂, R₃, R₄ and Y ⊖ are as defined above or the formula: wherein R₁, R₂, R₃, R₄ and Y ⊖ are as defined above and Haℓ is a halogen atom; and X represents a halogen atom or a residue represented by the formula: wherein R₁, R₂, R₃, R₄ and Y ⊖ are as defined above or the formula: wherein R₁, R₂, R₃, R₄ and Y ⊖ are as defined above. and (B) a polyfunctional epoxy compound having two or more oxirane rings which is selected from a bisphenol type epoxy resin, a polyglycol type epoxy resin, an alicyclic type epoxy resin, a carboxylic acid type epoxy resin, an amine type epoxy resin, a novolak type epoxy resin and a polyphenol type epoxy resin, and a pharmaceutically acceptable carrier. In the above formula (I), as the alkyl group of 1 to 17 carbon atoms, there may be mentioned straight, branched or cyclic alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, hexyl, cyclohexyl, undecyl and heptadecyl as the aryl group of 6 to 8 carbon atoms, there may be mentioned phenyl, tolyl and xylyl ; as the alkyl group of 1 to 3 carbon atoms, there may be mentioned methyl, ethyl, n-propyl, isopropyl and cyclopropyl as the halogen atom, there may be mentioned chlorine and bromine. Illustrative examples of the epoxy compound may include a bisphenol type epoxy resin, a polyglycol type epoxy resin, an alicyclic epoxy resin, a carboxylic acid type epoxy resin, an amine type epoxy resin and a novolak type epoxy resin As the halogen ion, there may be mentioned chloride bromide and iodide. The molecular weight of the polymeric substance, which may constitute the strongly basic anion exchange resins as specified with these substituents, is not particularly critical as far as said polymeric substance is insoluble in water. Preferable strongly basic anion exchange resins of this invention are illustratively exemplified as shown in Table 1. The particle diameter of the strongly basic anion exchange resin is one which can be passed through a 50 mesh sieve (Tyler) and, in general, preferably of 0,289 to 0.044 (50 to 325 mesh). The strongly basic anion exchange resin having imidazolium salts as functional groups according to this invention may be prepared according to the process as disclosed in the co-pending Japanese Patent Application No. 28055/1983 for an improved process for preparing an anion exchange resin. More specifically, a halomethyloxirane compound is subjected to reaction with an imidazole to form a high molecular quarternary salt (intermediate) having imidazolium salts on a main chain and the resultant salt is resinified with a polyfunctional epoxy compound to produce the desired resin. (1) Halomethyloxirane compounds They are represented by the following formula: wherein X₁ is a halogen atom, particularly a chlorine, bromine or iodine atom and R₄ is as defined above. Illustrative examples of these compounds which may be used in combination include epichlorohydrin, epibromohydrin and β-methylepichlorohydrin. (2) Imidazoles They are represented by the following formula: wherein R₁, R₂ and R₃ are as defined above. Illustrative examples of these imidazoles which may be used in combinaion are imidazole, 2-methylimidazole, 2-ethylimidazole, 2-n-propylimidazole, 2-isopropylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole and 2-phenyl-4-methylimidazole. (3) The preparation of a high molecular quaternary salt (I) The invention also refers to a pharmaceutical composition comprising a strongly basic anion exchange resin having imidazolium salts as functional groups, said resin being obtained by (a) polymerizing an imidazole represented by the formula (III): wherein R₁ is a hydrogen atom, an alkyl group of 1 to 17 carbon atoms or an aryl group of 6 to 8 carbon atoms, R₂ and R₃ may be the same or different and each represents a hydrogen atom or an alkyl group of 1 to 3 carbon atoms with a halomethyloxirane compound represented by the formula (II): wherein X₁ is a halogen atom and R₄ is a hydrogen atom or a methyl group to obtain a high molecular quarternary salt, (b) reacting the aforesaid high molecular quarternary salt with a predetermined amount of the aforesaid halomethyloxirane, and (c) effecting alkali treatment of the reaction product followed by heat curing; and pharmaceutically acceptable carriers. The reaction solvent may be any of those which would be inert to the above-mentioned reaction components and do not prevent resinification with the polyfunctional epoxy compound, and water is particularly preferred for the preparation of a high molecular quarternary salt with a large molecular weight. The molar ratio is preferably 0.9 to 1.5 moles of the halomethyloxirane compound to 1 mole of the imidazole, more preferably 1 to 1.1 moles. The reaction temperature is usually 30 to 150 o C, and preferably 50 to 120 o C. The reaction rate would be slow at less than 30 o C, while, undesirably, side-reaction may occur at more than 120 o C. Also, it is preferred to add dropwise the halomethyloxirane compound, to the imidazole at 50 to 80°C and, after completion of the dropwise addition, to raise the temperature to 80 to 120 o C. The reaction time is suitably 2 to 30 hours. According to the above reactions, there is obtained the high molecular quarternary salt (I) wherein Ar is and X is Haℓ. Further alkali treatment gives the salt (I) wherein Ar is As the alkali treatment agent, there may be mentioned for example, an alkali metal hydroxide such as NaOH and KOH and an alkaline earth metal hydroxide such as Ca(OH)₂. An amount of the alkali treatment agent to be used is preferably 0.001 to 0.5 mole per mole of the halomethyloxirane compound, more preferably 0.01 to 0.3 mole. The agent is usually and preferably employed in a form of an aqueous solution thereof. The reaction temperature is usually 0 to 50 o C and preferably 10 to 25 o C. The reaction time is suitably 1 to 5 hours. (4) Polyfunctional epoxy compounds The term "polyfunctional" is meant to indicate "having two or more oxirane rings". A group of the polyfunctional epoxy compounds which may be employed in this invention is an epoxy resin having an epoxide equivalent of approximately 100 to 3,000 and illustratively includes the following: Bisphenol type epoxy resins (e.g., bisphenol A diglycidyl ether), polyglycol type epoxy resins (e.g., ethylene glycol diglycidyl ether, glycerine triglycidyl ether, trimethylol propane triglycidyl ether), alicyclic type epoxy resins (e.g., vinylcyclohexene diepoxide), carboxylic acid type epoxy resins (e.g., diglycidyl phthalate), amine type epoxy resins (e.g., N,N'-4,4'-diphenylmethane tetraglycidylamine, diglycidylaniline, diglycidyl compounds having imidazolium bases represented by the formula (IV): wherein R₁, R₂, R₃, R₄ and Y ⊖ are as defined above and n₁ is an integer of 0 or more), novolak type epoxy resins (e.g., phenol novolak glycidyl ether), polyphenol type epoxy resins (e.g., tetrahydroxyphenylethane tetraglycidyl ether). They may be employed in combination therewith. Diglycidyl compounds having imidazolium bases represented by the above formula (IV) are synthesized according to the process in which the high molecular quarternary salt prepared in the above (3) is reacted with a predetermined amount of a halomethyloxirane compound, followed by alkali treatment. wherein R₁, R₂, R₃, R₄, X, X₁, Y ⊖ and n₁ are as defined above. (5) Resinification with polyfunctional epoxy compound Heat curing reaction of the high molecular quarternary salt with the polyfunctional epoxy compound thus prepared can be carried out by blending both of them homogeneously at a predetermined ratio and then heating the resulting mixture. Generally, the polyfunctional epoxy compound is used in an amount of 10 to 70 % by weight upon a total amount of the epoxy compound and the high molecular quarternary salt, preferably 20 to 60 % by weight and heating is effected at 60 to 190 o C, preferably 70 to 180 o C. The heating period is about 3 to 15 hours. Heat cure may be effected in the presence of a diluent. As illustrative examples of the diluent, there may be mentioned any of the above-recited solvents (e.g., water). Also, where the diglycidyl compound having imidazolium bases represented by the above formula (IV) is to be used as the polyfunctional epoxy compound, reaction of the high molecular quarternary salt prepared as above with a predetermined amount of the halomethyloxirane compound capable of reacting with a part of the former may be conducted, and then alkali treatment may be effected to accomplish synthesis of the aforesaid diglycidyl compound and admixture with the high molecular quarternary salt simultaneously. Then, resinification may be made by heating. (6) Granulation of resulting strongly basic anion exchange resin A resin mass of the strongly basic anion exchange resin prepared according to the above reactions is then granulated to a suitable particle size. One of grinding means is a ball mill. As an alternative grinding means, there may be mentioned one utilizing characteristics of the present strongly basic anion exchange resin, i.e., self-degradation caused by hydration of the resin mass in a large volume of an aqueous medium. As the aqueous medium, there my be mentioned methanol, ethanol and others, in addition to water, and the hydration temperature is about 20 to 100 o C. After granulation, the resultant product is washed with any of the above aqueous medium to remove soluble unreacted materials and then dried to afford the present strongly basic anion exchange resin in the form of granules. The so-produced strongly basic anion exchange resin has the following characteristics; salt-splitting capacity: 2.5 to 5.5 meq/g of dry resin, particle diameter: 0,289 to 0,044mm (50 to 325 mesh). These various characteristics were measured according to the methods as described in the Preparation Example 1. The present strongly basic anion exchange resin having imidazolium salts as functional groups has a higher content of the imidazolium base contributing to salt-splitting power, since the high molecular quarternary salt employed as a constituent component holds an extremely less contamination of a low molecular weight material as compared with the prior art product. Consequently, the resin shows a higher adsorption activity on bile acids, i.e., a stronger anti-cholesteremic activity. Also, the resin is less colored and odorless so that it is a very useful medicine. The acute toxicity of the present strongly basic anion exchange resin will be explained below. A suspension of the resin in a 1% tragacanth gum solution as a dispersion medium was orally administered to ICR-JCL strain mice and the LD₅₀ value was determined upon mortality after 1 week to show an LD₅₀ value of above 5 g/kg. The dosage of the present pharmaceutical composition may be 0.5 to 10 g daily for adults, preferably 1 to 4 g, because of the higher activity as compared with the prior art product, and the pharmaceutical composition may usually be administered in 1 to 3 divided forms daily. Administration of the present pharmaceutical composition to humans, is normally in oral form. For oral administration, one may ingest it before meals in the form of preparations such as tablet, fine granule, granule and others or may take it in a suspended form in water or other solutions. Preparation Examples and Experiment Examples will be given below for illustrating this invention in greater detail and explaining effects of this invention. Preparation Example 1 i) In a four-necked flask equipped with a reflux condenser, a thermometer and a stirrer were placed 72.4 g of 2-methylimidazole and a homogeneous solution was formed with 100 ml of water. While the reaction temperature was kept at 55 to 60 o C, 81.6 g of epichlorohydrin were added dropwise with stirring over about 1 hour. The reaction temperature was raised to 90 o C and stirring was continued at that temperature over 14 hours to give a preparation solution of the high molecular quarternary salt (hereinafter referred to as "Intermediate A"). ii) 63 parts of Intermediate A were homogeneously blended with 37 parts of a trifunctional epoxy compound "Epolite® 100 MF" (manufactured by Kyoeisha Yushikagaku Kogyo Co., Ltd.) and then the heat cure was effected at 80 o C for 3 hours and then at 170 o C for further 5 hours in the same manner as done in a conventional curing process of epoxy resins. The cured product was easily hydrated and decomposed by allowing it to be cooled and then left in water, thereby yielding a resinous and granular product. The resulting granular product was washed with ethanol and water to remove unreacted materials. Thereafter, heat drying was done and the resultant resin was ground by a ball mill. The resulting strongly basic anion exchange resin (hereinafter referred to briefly as "CR-1") had the following characteristics: salt-splitting capacity: 3.9 meq/g, particle diameter: 0,149 to 0,044mm (100 to 325 mesh). The above characteristics were determined according to the following methods. Salt-splitting capacity : About 3 g of the resin are immersed in 100 ml of a 1.0 N-NaOH solution for 5 hours and then washed with water up to neutral. After drying under reduced pressure, 2 to 3 g of the dried resin are precisely weighed (its weight is defined as A g), 100 ml of a 0.5N-NaCl solution are added thereto and the mixture is stirred for 4 hours and then left standing overnight. After suction-filtering, the filtrate is titrated with a 0.1N-HCl solution (a volume of the 0.1N-HCl solution required for titration in this instance is defined as B ml). Salt-splitting capacity is determined according to the following equation: salt-splitting capacity (meq/g) = B x (titer of HCl solution)/10A Particle diameter : The dried resin was ground with a ball mill made by Alfred-Frisch Co., Ltd. over 1 to 2 hours. The ground resin was sieved to a given particle size by means of a magnetic laboratory sieve shaker. The characteristics of those strongly basic anion exchange resins as obtained in the following Preparation Examples were determined according to the above-mentioned measuring methods. Preparation Example 2 i) 75 parts of Intermediate A prepared in Preparation Example 1 i) were blended homogeneously with 25 parts of a bifunctional epoxy compound, "Epolite® 40 E" (manufactured by Kyoeisha Yushikagaku Kogyo Co., Ltd.) and then heat cure and post-treatment were carried out in the same manner as in Preparation Example 1 ii). The resulting strongly basic anion exchange resin (hereinafter referred to briefly as "CR-2") had the following characteristics: salt-splitting capacity: 4.1 meq/g , particle diameter: 0,149 to 0,044 (100 to 325 mesh). Preparation Example 3 i) Following the same procedures as in Preparation Example 1 i) except that 63.5 g of 2-phenylimidazole and 40.8 g of epichlorohydrin were employed, there was obtained a preparation solution of a high molecular quarternary salt (hereinafter referred to as "Intermediate B"). ii) 71 parts of Intermediate B were blended homogeneously with 29 parts of a bifunctional epoxy compound, "Epikote® 828" (manufactured by Shell Chemical Co., Ltd.) and then heat cure and post-treatment were carried out in the same manner as in Preparation Example 1 ii). The resulting strongly basic anion exchange resin (hereinafter referred to briefly as "CR-3") had the following characteristics: salt-splitting capacity: 2.7 meq/g , particle diameter: 0,149 to 0,044mm (100 to 325 mesh). Preparation Example 4 i) Following the same procedures as in Preparation Example 1 i) except that 48.6 g of 2-ethyl-4-methylimidazole, 60 ml of water and 40.8 g of epichlorohydrin were employed, there was obtained a preparation solution of a high molecular quarternary salt (hereinafter referred to as "Intermediate C"). ii) 70 parts of Intermediate C were blended homogeneously with 30 parts of a bifunctional epoxy conpound, "Epolite® 40 E" and then heat cure and post-treatment were carried out in the same manner as in Preparation Example 1 ii). The resulting strongly basic anion exchange resin (hereinafter referred to briefly as "CR-4") had the following characteristics: salt-splitting capacity: 3.1 meq/g , particle diameter: 0,149 to 0,044mm (100 to 325 mesh). Preparaion Example 5 i) Following the same procedures as in Preparation Example 1 i) except that 30 g of imidazole, 30 ml of water and 40.8 g of epichlorohydrin were employed, there was obtained a preparation solution of a high molecular quarternary salt (hereinafter referred to as "Intermediate D"). ii) 71 parts of Intermediate D were blended homogeneously with 29 parts of a bifunctional epoxy compound, "Epolite® 40 E" and then heat cure and post-treatment were carried out in the same manner as in Preparation Example 1 ii). The resulting strongly basic anion exchange resin (hereinafter referred to briefly as "CR-5") had the following characteristics: salt-splitting capacity: 4.1 meq/g , particle diameter: 0,149 to 0,044mm (100 to 325 mesh). Preparation Example 6 85 parts of Intermediate A prepared in Preparation Example 1 i) were blended homogeneously with 15 parts of a tetrafunctional epoxy compound, "Epomate® YH-434" (manufactured by Toto Kasei Co., Ltd.) and then heat cure and post-treatment were carried out in the same manner as in Preparation Example 1 ii). The resulting strongly basic anion exchange resin (hereinafter referred to briefly as "CR-6") had the following characteristics: salt-splitting capacity: 4.6 meq/g , particle diameter: 0,149 to 0,044mm (100 to 325 mesh). Preparation Example 7 80 parts of Intermediate A obtained in Preparation Example 1 i) were blended homogeneously with 20 parts of a bifunctional epoxy compound represented by the following formula (V): and then heat cure and post-treatment were carried out in the same manner as in Preparation Example 1 ii). The resulting strongly basic anion exchange resin (hereinafter referred to briefly as "CR-7") had the following characteristics: salt-splitting capacity: 4.9 meq/g , particle diameter: 0,149 to 0,044mm (100 to 325 mesh). The bifunctional epoxy compound represented by the above-mentioned formula (V) was synthesized as follows: (a) In a four-necked flask equipped with a reflux condenser, a thermometer and a stirrer were placed 24.6 g (0.3 mole) of 2-methylimidazole, and then 60 ml of water were added to form a homogeneous solution. (b) While the reaction temperature was kept at 25 to 30 o C, 55.5 g (0.6 mole) of epichlorohydrin were added dropwise over 1 hour and stirring was continued for further 3 hours. (c) After the reaction temperature was brought to 0 to 5 o C, 60 g of a 20 % aqueous solution of sodium hydroxide (0.3 mole) were added dropwise over 1 hour. Stirring was continued at this temperature for 3 hours to give a preparation solution of the present epoxy compound. Preparation Example 8 i) Following the same procedures as in Preparation Example 1 i) except that 41 g (0.5 mole) of 2-methylimidazole, 46.3 g (0.5 mole) of epichlorohydrin and 60 ml of water were employed, there was obtained a preparation solution of a high molecular quarternary salt (Intermediate A). ii) To a reaction mixture containing the high molecular quarternary salt as prepared hereinabove were added dropwise, while keeping temperature at 45 to 50 o C under stirring, 8.7 g (0.394 mole) of epichlorohydrin over 1 hour and reaction was continued at this temperature for further 2 hours. iii) After cooling to room temperature, 18.9 g (0.094 mole) of a 20 % aqueous solution of sodium hydroxide were added dropwise over 15 minutes. After stirring at this temperature for further 2 hours, heat cure and post-treatment were carried out in the same manner as in Preparation Example 1 ii). The resulting strongly basic anion exchange resin (hereinafter referred to briefly as "CR-8") had the following characteristics: salt-splitting capacity: 5.0 meq/g, particle diameter: 0,149 to 0,044mm (100 to 325 mesh). Experiment Example 1: Test in vitro 1) Adsorption test of sodium cholate with various strongly basic anion exchange resin, in vitro Into an Erlenmeyer flask were placed 30 ml of an aqueous solution of sodium cholate at a concentration of 2.58 mg/ml and each 30 mg of CR-1, CR-2, CR-3, CR-4, CR-5, CR-6, CR-7, CR-8 and cholestyramine was added thereto, respectively. After incubation at 37 o C for 6 hours, a supernatant was collected by centrifugation and the residual sodium cholate was quantitatively assayed according to an enzymatic reaction method [using a reagent for determining a concentration of bile acid, manufactured by Daiichi Kagaku Co., Ltd. (Sterognost-3α-kit)]. The results are shown in Table 2. Proportion of combined sodium cholate (%) Cholestyramine 47 CR-1 65 CR-2 64 CR-3 51 CR-4 53 CR-5 67 CR-6 70 CR-7 78 CR-8 78 From the results shown in Table 2, it is apparent that the present strongly basic anion exchange resins, CR-1 to CR-8, can adsorb a large amount of sodium cholate. 2) Adsorption test of various bile acid sodium salts, in vitro In an Erlenmeyer flask were placed each 30 ml of an aqueous solution of bile acid sodium salts (sodium glycocholate, sodium taurocholate, sodium deoxycholate) at a concentration of 2.58 mg/ml and then each 30 mg of CR-1, CR-8 or cholestyramine were added thereto. Adsorption test was carried out according to the same method as in Experiment Example 1 - 1), to quantitatively assay residual bile acid sodium salts, respectively. The results are shown in Table 3. Bile acid sodium salt Proportion of combined bile acid sodium salts(%) Cholestyramine CR-1 CR-8 Sodium glycocholate 54 71 80 Sodium taurocholate 60 76 85 Sodium deoxycholate 60 84 91 From the results shown in Table 3, it is apparent that the present strongly basic anion exchange resin can also show a high adsorption activity on not only sodium cholate but also on the corresponding deoxy form (sodium deoxycholate), conjugated form with glycine (sodium glycocholate), conjugated form with taurine (sodium taurocholate) which are present in a large amount in vivo (in intestine). Experiment Example 2: Test for rats in vivo Groups each consisting of 7 animals selected from Sprague-Dawley strain male rats weighing 175 to 180 g (6 weeks of age, Shizuoka Laboratory Animal Cooperative Union), were used for experiment. After pre-feeding for 1 week, the first group of rats was fed with only a high lipid diet [a powdery feed for rats containing 1 % cholesterol and 0.5 % bile powder (manufactured by Nippon Kurea Co., Ltd.)], while the 2nd to 4th, 5th to 7th and 8th to 10th groups of rats were orally administered forcibly once a day with, in addition to the above high lipid diet, suspensions in distilled water of cholestyramine (doses: 125, 250 and 500 mg/kg), CR-1 (doses: 125, 250 and 500 mg/kg) and CR-8 (doses: 125, 250 and 500 mg/kg), respectively. After 7 days from administration of the high lipid diet and the drug, blood samples were obtained from the tail vein of the rat and then a total cholesterol level in the centrifuged blood plasma was quantitatively determined by means of Cholesterol Test Wako Kit manufactured by Wako Pure Chemical Ind. Co., Ltd. The results are shown in Table 4. From the results shown in Table 4, it is apparent that the present strongly basic anion exchange resins, CR-1 and CR-8 can exert an anticholesteremic activity or a cholesterol level-lowering activity in vivo. Experiment Example 3: Test for rabbits in vivo 1) Groups each consisting of 7 animals selected from female New Zealand-White strain rabbits weighing 2.0 - 2.2 kg (4 months of age), were used for experiment. After pre-feeding, the rabbits were fed with a high lipid diet [a rabbit feed containing 0.67 % cholesterol (manufactured by Oriental Yeast Co., Ltd.)] for 8 days, thereby providing hyperlipidemic rabbits. The rabbits having approximately similar levels of hyperlipidemia were selected and divided into groups. The first group of rabbits was fed continuously with a high lipid diet solely, while the 2nd and 3rd groups and the 4th to 6th groups of rabbits were orally administered forcibly once a day with, in addition to the above high lipid diet, suspensions in distilled water of cholestyramine (doses: 125 and 500 mg/kg) and CR-8 (doses: 31.25, 125 and 500 mg/kg), respectively. After 1, 2 and 3 weeks from administration of the high lipid diet and the drug, blood samples were obtained from the auris vein of the rabbit and a total cholesterol level in the centrifuged blood plasma was quantitatively determined by means of Cholesterol Test Wako Kit (manufactured by Wako Pure Chemical Ind. Co., Ltd.). The results are shown in Table 5a. 2) An anion exchange resin prepared according to the method described in Preparation Example 1 of Japanese Patent Laid-Open Application No. 24310/1982 (hereinafter referred to as "CR-9") was tested in the same manner as in the above Experiment Example 1-1) and the results are shown in Table 5b. 3) Inhibition ratios were determined upon Tables 5a and 5b and the results are shown in Table 5c. Dose (mg/kg) Inhibition ratio (%) 2 weeks 3 weeks Cholestyramine 125 10.4 8.2 500 39.3 49.1 CR-8 31.25 20.7 11.2 125 62.2 55.2 500 95.1 118.0 CR-9 250 18.9 14.3 500 54.2 72.4 From the results shown in Table 5c, it is apparent that the present strongly basic anion exchange resin (CR-8) shows a higher cholesterol level lowering activity, as compared with the prior art product (cholestyramine) and the resin disclosed in Japanese Patent Laid-Open Application No. 24310/1982 (CR-9), and also exerts a sufficient activity even at a lower dosage. Therefore, a lowered dosage may be applicable with the present cholesterol level lowering agent, as compared with the prior art product.

Claims: A pharmaceutical composition which comprises a strongly basic anion exchange resin having imidazolium salts as a functional group, said resin being a copolymer of: (A) a high molecular quarternary salt having the following formula (I): wherein R₁ is a hydrogen atom, an alkyl group of 1 to 17 carbon atoms or an aryl group of 6 to 8 carbon atoms, R₂ and R₃ may be the same or different and each represents a hydrogen atom or an alkyl group of 1 to 3 carbon atoms, R₄ is a hydrogen atom or a methyl group, the counter ion Y ⊖ is a halide ion, a hydroxide ion or a 1/2 (sulfate) ion, and n is an integer of 5 to 50, Ar represents a residue represented by the formula: wherein R₁, R₂ and R₃ are as defined above, the formula: wherein R₁, R₂, R₃, R₄ and Y ⊖ are as defined above, the formula: wherein R₁, R₂, R₃, R₄ and Y ⊖ are as defined above or the formula: wherein R₁, R₂, R₃, R₄ and Y ⊖ are as defined above and Haℓ is a halogen atom; and X represents a halogen atom or a residue represented by the formula: wherein R₁, R₂, R₃, R₄ and Y ⊖ are as defined above or the formula: wherein R₁, R₂, R₃, R₄ and Y ⊖ are as defined above, and (B) a polyfunctional epoxy compound having two or more oxirane rings which is selected from a bisphenol type epoxy resin, a polyglycol type epoxy resin, an alicyclic type epoxy resin, a carboxylic acid type epoxy resin, an amine type epoxy resin, a novolak type epoxy resin and a polyphenol type epoxy resin, and a pharmaceutically acceptable carrier. The pharmaceutical composition according to Claim 1, wherein R₁ is a hydrogen atom, a methyl group or a phenyl group, R₂ is a hydrogen atom or a methyl group, and R₃ and R₄ are each a hydrogen atom in formula (I). The pharmaceutical composition according to Claim 2, wherein R₁ is a methyl group, R₂, R₃ and R₄ are each a hydrogen atom in formula (I). The pharmaceutical composition according to Claim 2, wherein R₁ is a phenyl group, and R₂, R₃ and R₄ are each a hydrogen atom in formula (I). The pharmaceutical composition according to Claim 2, wherein R₁, R₂, R₃ and R₄ are each a hydrogen atom in formula (I). The pharmaceutical composition according to Claim 1, wherein the bisphenol type epoxy resin is bisphenol A diglycidyl ether, the polyglycol type epoxy resin is ethylene glycol diglycidyl ether, glycerine triglycidyl ether or trimethylol propane triglycidyl ether, the alicyclic type epoxy resin is vinylcyclohexene diepoxide, the carboxylic type epoxy resin is diglycidyl phthalate, the amine type epoxy resin is N,N'-4,4'-diphenylmethane tetraglycidylamine, diglycidylaniline or a diglycidyl compound having imidazolium bases represented by the formula (IV): R₁, R₂ R₃, R₄ and Y ⊖ are as defined in claim 1 and n₁ is an integer of 0 or more; the novolak type epoxy resin is phenol novolak glycidyl ether, and the polyphenol type epoxy resin is tetrahydroxyphenylethane tetraglycidyl ether. The pharmaceutical composition according to Claim 1, wherein said resin has a salt-splitting capacity of 2.5 to 5.5 meq/g and a particle diameter of 50 to 325 mesh (0,289 to 0,044mm). The pharmaceutical composition according to Claim 1, wherein R₁ is a methyl group and R₂, R₃ and R₄ are each a hydrogen atom, the counter ion Y ⊖ is Cl ⊖ in formula (I); the polyfunctional epoxy compound is a trifunctional epoxy compound; and the resin has a salt-splitting capacity of 2.5 to 5.5 meq/g and a particle diameter of 50 to 325 mesh (0,289 to 0,044mm). The pharmaceutical composition according to Claim 1, wherein R₁ is a methyl group and R₂, R₃ and R₄ are each a hydrogen atom, and the counter ion Y ⊖ is Cl ⊖ ; the polyfunctional epoxy compound is a diglycidyl compound having imidazolium bases represented by the formula (IV): wherein R₁, R₂, R₃, R₄ and Y ⊖ are as defined in Claim 1 and n₁ is an integer of 0 or more. The pharmaceutical composition according to claim 9, wherein the resin has a salt-splitting capacity of 2.5 to 5.5 meq/g and a particle diameter of 50 to 325 mesh, (0,289 to 0,044 mm). A pharmaceutical composition comprising a strongly basic anion exchange resin having imidazolium salts as functional groups, said resin being obtained by (a) polymerizing an imidazole represented by the formula (III): wherein R₁ is a hydrogen atom, an alkyl group of 1 to 17 carbon atoms or an aryl group of 6 to 8 carbon atoms, R₂ and R₃ may be the same or different and each represents a hydrogen atom or an alkyl group of 1 to 3 carbon atoms with a halomethyloxirane compound represented by the formula (II): wherein X₁ is a halogen atom and R₄ is a hydrogen atom or a methyl group to obtain a high molecular quarternary salt, (b) reacting the aforesaid high molecular quarternary salt with a predetermined amount of the aforesaid halomethyloxirane, and (c) effecting alkali treatment of the reaction product followed by heat curing; and pharmaceutically acceptable carriers. A pharmaceutical composition according to claim 11 wherein the imidazole is 2-methylimidazole and the halomethyloxirane is epichlorohydrin. A pharmaceutical composition according to claim 11 or 12, wherein the polymerization in step (a) is effected at about 90°C. A pharmaceutical composition according to one or more of claims 11 - 13, wherein the reaction of the high molecular quarternary salt with the halomethyloxirane in step (b) is effected at about 45 to 50°C. A pharmaceutical composition according to one or more of claims 11 - 14, wherein the alkali treatment in step (c) is effected at room temperature. A pharmaceutical composition according to one or more of claims 11 - 15, wherein the heating in step (c) is effected in the range of 80°C-170°C. A pharmaceutical composition according to one or more of claims 11 - 16, wherein in step (a) the imidazole compound and the halomethyloxirane compound are polymerized with substantially equimolar amounts, whereby the halomethyloxirane compound is added dropwise to the imidazole and whereby water is used as the solvent. A pharmaceutical composition according to one or more of claims 11 - 17, wherein about 0.188 mole halomethyloxirane per 1 mole imidazole is added in the step (b), and wherein the alkali is added in the step (c) in an amount of about 0.188 mole per 1 mole imidazole. The use of a strongly basic anion exchange resin as given in one or more of the claims 1 to 18 for making a medicament effective in the lowering of the cholesterol level.

Inventors: HASHIMOTO, MUNEHIRO RES. LAB. MITSUBISHI YUKA, KIHARA, KUNIO C/O CENTRAL RESEARCH LABORATORIES, MIZOGAMI, SUSUMU RES. LAB. MITSUBISHI YUKA, TODA, HIDEO C/O CENTRAL RESEARCH LABORATORIES
Applicants: MITSUBISHI KASEI CORPORATION, MITSUBISHI PETROCHEMICAL CO., LTD.
Application year: 1985
Main classification: A61K31
IPC codes: A61K31, C08G59, B01J41, A61P3, C07D405, C07D233