Neuroprotective drug

Abstract: A neuroprotecting drug comprises as an essential active ingredient ethyl 2-[4,5-bis(4-methoxyphenyl)thiazol-2-yl]pyrrol-1-yl acetate, which is useful with high safety for the prophylaxis and treatment of brain dysfunction induced by hypoxia due to the distrubance of cerebral circulation such as cerebral hemorrhage or cerebral infarction in human being.

Description: This invention relates to a novel neuroprotective drug, more particularly to a neuroprotective drug containing as an essential active ingredient ethyl 2-[4,5-bis(4-methoxyphenyl)thiazol-2-yl]pyrrol-1-yl acetate [hereinafter, it is abbreviated as "KBT-3022"] which is represented by the following formula: Prior Art The brain is an organ which has an extremely high metabolic activity, but the brain loses significantly its function in the state of hypoxia induced by disturbance of cerebral circulation such as cerebral hemorrhage, cerebral infarction. Besides, even if the circulation of blood within the brain is recovered after such a cerebral circulation disturbance, the lipids within the cerebral cells are peroxidized by active oxygen, and hence, there is still a problem of cerebral cell disturbance due to the lipid peroxides. U. S. Patent 4,659,726 discloses some specific diphenylpyrrolylthiazole derivatives which include the specific compound KBT-3022 used in the present invention and processes for the preparation of said compounds, and the U. S. patent further discloses that these compounds are useful as a platelet aggregation inhibitor. However, the U. S. patent does not mention any neuroprotective activity of the KBT-3022 compound. Sem. Neurol., 1991, vol. 11(4), pages 353-364 indicates that various anti-platelet agents can be used in the therpay of patients who are threatened with a stroke. In particular, the antithrombotic use of the platelet aggregation inhibitors aspirin and ticlopidin in the treatment of ischemic cerebrovascular disease is mentioned. Object of the Invention The present inventors have extensively studied to develop a new neuroprotective drug having excellent protective activity against brain dysfunction induced by hypoxia due to the disturbance of cerebral circulation such as cerebral hemorrhage or cerebral infarction and having high safety with low toxicity suitable for the clinical use thereof, and have found that the specific compound KBT-3022 has potent neuroprotective activity satisfying the above requirements. Thus, an object of the invention is to provide a novel neuroprotective drug. Another object of the invention is to provide a pharmaceutical composition useful as a neuroprotective drug comprising as an essential active ingredient KBT-3022 in admixture with a conventional pharmaceutically acceptable carrier or diluent. A further object of the invention is to provide prophylaxis and treatment of brain dysfunction induced by hypoxia due to the disturbance of cerebral circulation such as cerebral hemorrhage or cerebral infarction by the oral administration of KBT-3022. Still further object of the invention is a use of KBT-3022 as a neuroprotecting drug. Detailed Description of the Invention The neuroprotective drug of the invention is usually in the form of a pharmaceutical composition comprising as an essential active ingredient the above-mentioned specific compound KBT-3022 in admixture with a conventional pharmaceutically acceptable carrier or diluent, which is prepared by a conventional method. The pharmaceutical composition of the invention is preferably formulated in the form of a preparation suitable for administration by oral route, for example, solid preparations such as tablets, granules, powders, capsules, etc., and liquid preparations such as syrups. The pharmaceutical composition can be prepared by a conventional method. For instance, the solid preparations are usually prepared by using a conventional pharmaceutically acceptable carrier, such as lactose, corn starch, crystalline cellulose, carboxymethylcellulose calcium, carboxymethylcellulose, talc, magnesium stearate, etc. The capsules can be prepared by encapsulating the granules, powders, etc. thus prepared into suitable capsules. The syrups can be prepared by dissolving or suspending KBT-3022 in an aqueous solution containing white sugar, carboxymethylcellulose, etc. The pharmaceutical composition contains usually the KBT-3022 as an essential active ingredient in an amount of 1 mg to 20 mg in a dosage unit. The neuroprotective drug of the invention is usually administered orally for the purpose of the prophylaxis or treatment of brain dysfunction induced by hypoxia due to the disturbance of cerebral circulation such as cerebral hemorrhage or cerebral infarction. The dose of the neuroprotective drug of the invention may vary depending on the severity of the diseases, weight and age of the patients and the like, but is usually in the range of 2 to 100 mg per day in adult, which may be administered in single or 2 to 3 divided daily doses. The KBT-3022 has excellent protecting properties against brain dysfunction induced by various hypoxic insults as shown in Tests 1 to 3 with extremely low toxicity as shown in Test 4. Besides, KBT-3022 inhibited significantly the production of undesirable lipid peroxides induced by auto-oxidation of cerebral homogenate of guinea pig. Thus, the drug of the invention containing the KBT-3022 as an essential active ingredient is suitable for clinical use as a neuroprotecting drug in human being. Test 1 Effect on survival time of mice subjected to normobaric hypoxia: (1) Test compound: (i) KBT-3022 (ii) Pentobarbital sodium (as a reference compound) (2) Test method: To ddY male mice (weighing 18-24 g) fasted overnight was administered the test compound in the form of a solution or suspension in 0.5% polyoxyethylene sorbitan monooleate (= 0.5% Tween® 80) by oral route. A transparent plastic box (volume: 27 liters) with an exhaust vent was purged with nitrogen gas by passing through 100% nitrogen gas at a rate of 10 liter/minute to provide a low oxygen atmosphere (oxygen concentration within the box: <0.5%). The mice, one hour after the administration of the test compound as above, were put in the box, and the survival time (sec) of mice after being put in the box was measured. In the control group, the mice was administered only the solvent (0.5% Tween® 80), and the survival time of mice was measured likewise. (3) Test results: The test results are shown in Table 1. As is clear from the test results, KBT-3022 showed prolongation of the survival time of mice subjected to normobaric hypoxia. Test compound Dose (mg/kg) Number of mice Survival time (sec) average ± S.E. KBT-3022 1 5 23.9 ± 0.6 3 5 25.6 ± 1.0 10 5 26.2 ± 1.0 Pentobarbital sodium 10 5 22.1 ± 0.5 30 5 32.1 ± 1.5 Control group - 10 22.5 ± 0.2 Test 2 Protective effects on the KCN-induced hypoxia which caused death in mice: (1) Test compound: (i) KBT-3022 (ii) Pentobarbital sodium (as a reference compound) (2) Test method: To ddY male mice (weighing 18-24 g) fasted overnight was administered the test compound in the form of a solution or suspension in 0.5% polyoxyethylene sorbitan monooleate (= 0.5% Tween 80) by oral route. One hour after the administration of the test compound, the mice were further administered rapidly with a KCN-physiological saline solution (3 mg/kg) into the tail vein, and after 30 minutes the survival number of mice was measured. In the control group, the mice were administered only the solvent (0.5% Tween® 80), and the survival number of mice was measured likewise. (3) Test results: The test results (survival number of mice/number of test mice) are shown in Table 2. As is clear from the test results, KBT-3022 showed significant protective effects on the KCN-induced hypoxia which caused death in mice. Dose (mg/kg) Test compound KBT-3022 Pentobarbital Na 1 2/10 - 3 4/10 - 10 4/10 1/10 30 5/10 9/10 100 5/10 - Test 3 Effect on ischemia-induced brain edema: (1) Test compound: KBT-3022 (2) Test method: Gerbils (weighing 61-78 g) fasted overnight were administered with the test compound in the form of a suspension in 0.5% polyoxyethylene sorbitan monooleate (= 0.5% Tween® 80) by oral route. Three hours after the administration of the test compound, the gerbils were operated to expose the common carotid arteries of both sides, and the said common carotid arteries were ligated with an aneurysm clip. Fifteen minutes after the ligation, the clip was removed to allow reperfusion. At four hours after the reperfusion, the head of each gerbil was cut and the brain was taken out. The weight (in wet) of the brain thus taken out was measured, and thereafter, the brain was dried at 90°C overnight and the weight (in dry) of the brain was measured. The water content of the brain were calculated by the following equation: Water content (% by weight) = (Weight in wet) - (Weight in dry) Weight in wet x 100 In the control group, the gerbils were administered only the solvent (0.5% Tween® 80), and the water content was measured likewise. In the non-treated group, the gerbils were administered only the solvent (0.5% Tween® 80), and after the operation, the brain was taken out without subjecting to the ligation treatment, and then the water content of the brain was measured likewise. (3) Test results: The test results are shown in Table 3. As is clear from the test results, KBT-3022 inhibited significantly the brain edema (increase of water content in the brain) induced by transient forebrain ischemia in gerbils. Test compound Dose (mg/kg) Number of mice Water content (%) average ± S.E. KBT-3022 1 6 79.5 ± 0.1 3 6 79.3 ± 0.1 10 6 79.2 ± 0.1 * Control group - 6 79.7 ± 0.1 Non-treated group - 6 78.9 ± 0.1 * Test 4 Acute toxicity: (1) Test compound: KBT-3022 (2) Test method: To ddY male mice (weighing 18-23 g, 5 mice per group) fasted overnight was administered the test compound in the form of a suspension in 1% gum arabic solution by oral route, and it was observed whether the mice would be died or not for 10 days. (3) Test results: No mice was died by administration of KBT-3022 even at a dose of 5000 mg/kg. Thus, KBT-3022 has a LD₅₀ of >5000 mg/kg by oral administration. When the same acute toxicity test was also done in rats and dogs, the same results as the above were obtained. Besides, KBT-3022 showed also a very low toxicity in the sub-acute toxicity test in mice, rats and dogs and further in the chronic toxicity test in mice and dogs. The pharmaceutical composition of this invention is illustrated by the following Examples. Example 1 Preparation of tablets: [Formulation] Components Amount (g) KBT-3022 40 Lactose 1600 Crystalline cellulose 1580 Carboxymethylcellulose calcium 100 Carboxymethylcellulose 60 Magnesium stearate 20 Totally 3400 [Procedure] The above components are uniformly mixed, and the mixture is tabletted by a conventional method to give tablets (170 mg per tablet). Example 2 Preparation of tablets: [Formulation] Components Amount (g) KBT-3022 100 Lactose 1560 Crystalline cellulose 1560 Carboxymethylcellulose calcium 120 Talc 40 Magnesium stearate 20 Totally 3400 [Procedure] The above components are uniformly mixed, and the mixture is tabletted by a conventional method to give tablets (170 mg per tablet). Example 3 Preparation of powders: [Formulation] Components Amount (g) KBT-3022 5 Lactose 585 Corn starch 410 Totally 1000 [Procedure] The above components are uniformly mixed, and the mixed powder is packed to give packed powders (1 g per pack).

Claims: Use of ethyl 2-[4,5-bis(4-methoxyphenyl)thiazol-2-yl]pyrrol-1-yl acetate in a prophylactically or therapeutically effective amount for the preparation of a neuroprotecting drug together with a pharmaceutically acceptable carrier or diluent. Use of ethyl 2-[4,5-bis(4-methoxyphenyl)thiazol-2-yl]pyrrol-1-yl acetate in a prophylactically or therapeutically effective amount for the preparation of a pharmaceutical agent which is effective in the prophylaxis and treatment of brain dysfunction. Use according to claim 2 wherein the brain dysfunction is induced by hypoxia due to the disturbance of cerebral circulation, cerebral hemorrhage or cerebral infarction. Use according to any one of the preceding claims, wherein the pharmaceutical agent is suitable for oral administration.

Inventors: ITO KEIZO, YAMAMOTO NORIKO, YAMASHITA AKIRA, YOKOTA KOICHI, ITO, KEIZO, YAMAMOTO, NORIKO, YAMASHITA, AKIRA, YOKOTA, KOICHI
Applicants: KANEBO LTD, KANEBO, LTD.
Application year: 1993
Main classification: A61K31
IPC codes: A61K31, C07D417, A61P25