BRAIN EDEMA INHIBITOR

Abstract: The present invention relates to a composition for treating or preventing brain edemas which comprises an endothelin antagonist as an active ingredient, for example, the compound of the following formula (I): or pharmaceutically acceptable salts or hydrates thereof, bosentan, cyclo[D-aspartyl-L-[3-(4-phenylpiperazin-1-ylcarbonyl)]-alanyl-L-aspartyl-D-[2-(2thienyl)]glycyl-L-leucyl-D-tryptophyl]disodium or cyclo [D-Asp-L-Pro-D-Val-L-Leu-D-Trp]. Furthermore, the present invention provides a method for treating or preventing brain edemas, which comprises administering an effective amount of an endothelin antagonist and use of an endothelin antagonist in the manufacture of a medicament for treating or preventing brain edemas. An endothelin antagonist exhibits an inhibitory effect on all brain edemas regardless of the mechanism of onset and thus is highly useful in the treatment or prevention of brain edemas.

Description: The present invention relates to the use of an endothelin antagonist in the manifacture of a medicament for treating or preventing brain edemas. BACKGROUND OF THE INVENTION Brain edema means a state of the brain such that water in a living body has unusually accumulated inside the brain parenchyma so as to increase the volume of the brain tissue. As for the factors inducing brain edemas, for example, cerebrovascular diseases such as stroke, head injury, brain tumor, hypertension, respiratory insufficiency, CO poisoning, hyponatremia, acute nephropathy, disequilibrium syndrome caused by hemodialysis, hyperglycemia, hypoglycemia, adrenal insufficiency, collagen diseases, and tin, lead or arsenical poisoning are examples. Particularly, a treatment of brain edemas which are caused in an acute phase of stroke or by head injury is a very important problem to be solved. Furthermore, brain edemas are likely to cause, for example, a cerebral hernia, a headache, nausea, vomiting, restlessness, convulsions or clouding of consciousness. Particularly, a deterioration of a cerebral hernia sometimes causes patients to die. Brain edemas are classified, for example, into cytotoxic edemas and vasogenic edemas according to the mechanisms of occurrence, but these types of edemas often appear together, and so the etiology of brain edemas has not been sufficiently clear. It is desirable to make the etiology clearer and to establish a treatment. Currently, treatments such as by hyperosmotic medicaments or adrenocortical steroids have been used for treating brain edemas. As hyperosmotic medicaments, 10% glycerol, 5% fructose-added physiological saline and 15% or 20% mannitol may be exemplified. Intravenous administration of these hypertonic medicaments raises the blood osmotic pressure so as to produce a difference in pressure between the brain parenchyma tissues and the blood; as a result, water accumulated in the brain tissues moves into the bloodstream so as to improve brain edemas. Furthermore, these medicaments are characterized by slight side effects since they scarcely pass through the blood brain barrier to reach the brain parenchyma tissues. But even for these medicaments, their accumulation in the brain in some degree cannot entirely be avoided, when the blood concentration reaches a high level by large quantity administration. In the case where the blood brain barrier is injured, the medicaments move easily into the brain; if the blood concentration of the medicaments decreases after stopping administration of the medicaments and the osmotic pressure in the brain tissue becomes greater than that in the blood, water in the blood could move back to the brain parenchyma tissue and brain edemas may appear again. These medicaments also have side effects such as electrolytic aberration and nephropathy. As for adrenocortical steroids, dexamethasone and hydrocortisone are examples. These adrenocortical steroids exhibit ameliorative effects on brain edemas around brain tumors, but these have little effect on ischemic and traumatic brain edemas and exhibit side effects such as digestive tract hemorrhage, infectious disease exacerbation, and diabetes exacerbation. Recently, calcium antagonists such as Nimodipine, Nicardipine and NC1100 have attracted attention as alternative medicaments for treating brain edemas. It is reported that pretreatment with these calcium antagonists delays the progress of cellular brain edemas. MK-801, a glutamate antagonist, is also known to exhibit an inhibitory effect on brain edemas. These calcium antagonists and glutamate antagonists which have inhibitory effects on brain edemas, however, have not yet been used clinically . DISCLOSURE OF THE INVENTION In the above situations, the present inventors have studied intensively to develop medicaments which have superior inhibitory effects on brain edemas, and have found that endothelin antagonists inhibit brain edemas. According to the present invention, there is provided the use of an effective amount of an endothelin antagonist in the manifacture of a medicament for treating or preventing brain edemas. Thus, the present invention relates to a composition for treating or preventing brain edemas which comprises an endothelin antagonist as an active ingredient. Currently, endothelin antagonists have been reported only to have the possibility to be medicaments for treating or preventing diseases caused by endothelin, for example, cerebral vasoconstriction after subarachnoid hemorrhage, hypertension, ischemic disorders, cerebral circular disorders, renal insufficiency and asthma (see for example EP-A-0 628 569; Neurological Research 1995, 17(4), 259-264; Drugs 1996, 51(1), 12-27; Journal of Pharmacology and Experimental Therapeutics 1994, 268(3), 1122-1128; Peptides 1994, 15(3), 467-469; Br. J. Pharmacol 1994, 112(3), 963-971; Journal of Cardiovascular Pharmacology 1995, 26 (n° Suppl. 3), S404-S407). In the present specification, the term "endothelin antagonist" includes all compounds which have endothelin antagonist activity, and any compounds which have endothelin antagonist activity can preferably be used for the present invention. Typical examples of such compounds, for example include compounds of the following formula (I): wherein R 1 is hydrogen or a metabolizable ester residue; R 2 is hydrogen or -R 3 -R 4 , wherein R 3 is -SO 3 -, -CH 2 COO-, -COCOO-, or -COR 5 COO-, wherein R 5 is alkylene having 1 to 6 carbon atoms or alkenylene having 2 to 6 carbon atoms, and R 4 is hydrogen or alkyl having 1 to 6 carbon atoms (hereinafter referred to as Compound (I)), pharmaceutically acceptable salts (WO92/12991, JP-A 753484) or hydrates thereof, bosentan (p-tert-butyl-N-[6-(2-hydroxyethoxy)-5-(o-methoxyphenoxy)-2-(2-pyrimidinyl)-4-pyrimidinyl]-benzenesulfonamide; (British Journal of Pharmacology, 1994. Nov., 113(3) 845-852)), cyclo[D-aspartyl-L-[3-(4-phenylpiperazin-1-ylcarbonyl)]-alanyl -L-aspartyl-D-[2-(2-thienyl)]glycyl-L-leucyl-D-tryptophyl]disodium (hereinafter referred to as TAK-044; Life Science 1994, 55(4), 301-310), cyclo[D-Asp-L-Pro-D-Val-L-Leu-D-Trp] (hereinafter referred to as BQ-123; Life Sciences, 1992, 50, 247-255),2(R)-[2(R)-[2(S)[[1-(hexahydro-1H-azepinyl]carbonyl]amino-4-methylpentanoyl]amino-3-[3-(1-methyl-1H-indolyl)]propionyl]amino-3-(2-pyridyl)propionic acid (FR139317; Pharmacology 1994, 49(5), 319-324), (1S,2R,3S)-3-(2-carboxymethoxy-4-methoxyphenyl)-1-(3,4-methylenedioxyphenyl)-5-(prop-1-yloxy)-indan-2-carboxylic acid (SB-209670; Biochemistry, 1994, Dec., 33(48), 14543-14549), 3-benzo-[1, 3]-dioxol-5-yl-5-hydroxy-5-(4-methoxyphenyl)-4 -(2,3,4-trimethoxybenzyl)-5H-furan-2-one (PD-156123; International Publication No. W095/05376), and (-)-N-(4-isopropylbenzenesulfonyl)-α-(4-carboxy-2-n-propylphenoxy)-3, 4-methylenedioxyphenylacetamide (L-754142; The Journal of Pharmacology and Experimental Therapeutics 1995, 275(3), 1518-1526). BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows the effect of Compound (I-Na) on brain edemas . The ordinate represents the brain water content (%) and the abscissa represents the parts of brain. "ACA", "MCA" and "Caudate putamen" means a cerebral cortex supplied by an anterior cerebral artery and a cerebral cortex supplied by middle cerebral artery and a striatum, respectively. The bars from the left, respectively represent a sham-operation group (N=5), a vehicle administered group (N=13), a pre-ischemic administered group (N=6), and a post-ischemic administered group (N=7). Data are represented by means of standard error. The significant difference with a P value <0.05 from the vehicle -administered group is represented by an asterisk. Figure 2 shows the dose-dependent effects of Compound (I-Na) on brain edemas. The ordinate represents the brain water content (%) and the abscissa represents the parts of the brain. "ACA", "MCA" and "Caudate putamen" have the same meanings as described above. The bars from the left, respectively represent a sham-operation group (N=5), a vehicle-administered group (N=13), a group (N=6) to which Compound (I-Na) was administered at a 0.03 mg/kg/hr dose, a group (N=7) to which Compound (I-Na) was administered at a 0.1 mg/kg/hr dose, a group (N=6) to which Compound (I-Na) was administered at a 0.3 mg/kg/hr dose, and a group (N=6) to which Compound (I-Na) was administered at a 1.0 mg/kg/hr dose. Data are represented by means of standard error. The significant differences with P values <0.05 and <0.01 from the vehicle administered group are represented by a single asterisk and double asterisks. Figure 3 shows the effect of bosentan on brain edemas. The ordinate represents the brain water content (%) and the abscissa represents the parts of the brain. "ACA", "MCA" and "Caudate putamen" have the same meanings as described above. The bars from the left, respectively represent a vehicle administered group (N=5) and a post-ischemic-administered group (N=5). Data are represented by means of a standard error. The significant difference with a P value <0.05 from the vehicle-administered group is represented by an asterisk. Figure 4 shows the effect of TAK-044 on brain edemas . The ordinate represents the brain water content (%) and the abscissa represents the parts of the brain. "ACA", "MCA" and "Caudate putamen" have the same meaning as described above. The bars from the left, respectively represent a vehicle administered group (N=7) and a post-ischemic-administered group (N=7). Data are represented by means of a standard error. The significant difference with a P value <0.05 from the vehicle-administered group is represented by an asterisk. Figure 5 shows an effect of BQ-123 on brain edemas. The ordinate represents the brain water content (%) and the abscissa represents the parts of brain. "ACA", "MCA" and "Caudate putamen" have the same meaning as described above. The bars from the left, respectively represent a vehicle administered group(N=8) and a post-ischemic-administered group (N=7). Data are represented by means of standard error. The significant difference with a P value <0.05 from the vehicle-administered group is represented by an asterisk. THE PREFERRED EMBODIMENTS OF THE INVENTION In the present invention, any compounds which have endothelin antagonist activity can preferably be used as an endothelin antagonist. Specifically exemplified are Compound (I), pharmaceutically acceptable salts and hydrates thereof and bosentan, TAK-044, and BQ-123. Compound (I) and pharmaceutically acceptable salts and hydrates thereof are preferred and compound (I) wherein R 1 is hydrogen and R 2 is -COCH=CHCOOH, and pharmaceutically acceptable salts and hydrates thereof are particularly preferable. In the present specification, "metabolizable ester residue" means an ester residue which is hydrolyzed in the living body to produce a biologically active carboxylic acid group. Examples of the above metabolizable ester residue include alkyl having 1 to 6 carbon atoms such as methyl, ethyl and tert-butyl; aryl such as phenyl; (1-acyloxy)alkyl such as pivaloyloxymethyl, acetoxymethyl and 1-acetoxyethyl; 1-(alkyloxycarbonyloxy)alkyl such as 1-(ethoxycarbonyloxy)ethyl, 1-(isopropoxycarbonyloxy)ethyl; and (5-methyl-1,3-dioxolen-4-yl)methyl. The term "alkyl having 1 to 6 carbon atoms" means straight or branched alkyl, and methyl, ethyl, propyl and tert-butyl are exemplified. The term "alkyl" means the same as above. As for the "alkenylene having 2 to 6 carbon atoms", these are preferably groups defined by the formula -(CH=CH) m - (m represents an integer of 1-3). The compound (I) may form pharmaceutically acceptable salts, for example, with mineral acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid and hydrobromic acid; with organic acids such as formic acid, acetic acid, tartaric acid, lactic acid, citric acid, fumaric acid, maleic acid, succinic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, naphthalenesulfonic acid and camphorsulfonic acid; with organic bases such as ammonium, trimethyl ammonium and triethyl ammonium; with alkali metals such as sodium and potassium; or with alkaline earth metals such as calcium and magnesium. The compound (I) may form hydrates and may coordinate to one or more molecules of water per molecule of the compound (I). The composition for treating or preventing brain edemas of the present invention has the effect of decreasing intracranial pressure and exhibits an inhibitory effect on all types of brain edemas regardless of the mechanism of onset and is highly useful for treating ischemic and traumatic brain edemas. Moreover, it has an ameliorative effect on infarction. The composition for brain edemas of the present invention is effective for treating or preventing brain edemas when it is administered in the situation where brain edemas have been caused or may be caused in, for example, cerebrovascular disease such as stroke, head injury or brain tumor. Moreover, the composition for brain edemas of the present invention is also effective for treating or preventing cerebral hernia and clouding of consciousness caused by brain edemas. It is also effective for the treatment of brain edemas caused in the acute phase of stroke and by head injury. When the composition for brain edemas of the present invention is applied as a pharmaceutical composition, it can safely be administered either orally or parenterally. In case of an oral administration, it may be in any usual form such as tablets, granules, powders, capsules, pills, solutions, suspensions, syrups, buccal tablets, and sublingual tablets for administration. When the composition is parenterally administered, any usual form is preferred, for example, injections such as intravenous injections or intramuscular injections, suppositories, endermic agents and inhalations and intravenous injection is particularly preferred. A pharmaceutical composition of the present invention may be manufactured by, if necessary, mixing an effective amount of the active ingredient with various pharmaceutical ingredients suitable for the final administration form, such as excipients, binders, moistening agents, disintegrators, lubricants, and diluents. When the composition is for injection, the active ingredient can be sterilized with a suitable carrier to give a pharmaceutical composition. Specifically, examples of excipients include lactose, saccharose, glucose, starch, calcium carbonate and crystalline cellulose, examples of the binders include methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, gelatin and polyvinylpyrrolidone, examples of disintegrators include carboxymethylcellulose, sodium carboxymethylcellulose, starch, sodium alginate, agar and sodium lauryl sulfate, and examples of lubricants include talc, magnesium stearate and macrogol. Cacao oil, macrogol and methyl cellulose may be used as base materials of suppositories. When the composition is manufactured as a solution, emulsified injection or suspended injection, dissolving accelerators, suspending agents, emulsifiers, stabilizers, preservatives and isotonic agents may be added, and when it is manufactured for oral administration, sweetening agents and flavors may be added. Although the dosage of the compound as a brain edema inhibitor should be established taking account of the patient's age, body weight, administration route, type and extent of disease, the compound may usually be administered orally in single or divided doses of 1 µg - 200 mg/kg/day for an adult. When it is parenterally administered, although the dosage depends largely on the administration route, the compound may be administered in single or divided doses of 0.1 µg - 20 mg/kg/day. EXAMPLE The present invention is further explained by the following Examples and Experiments, which are not intended to limit the scope of the present invention. Experimental method ( 1 ) Animals for experiment Male Wistar rats of 12 weeks old (270g to 320g, Japan SLC, Inc.) were subjected to pre-feeding for at least a week, and used for the experiment. ( 2 ) Preparation of focal cerebral ischemia-reperfusion model Focal cerebral ischemia-reperfusion models were prepared by modifying the method of Longa et al (Stroke, 1989, vol.20 pp.84-91). Rats were anesthetized with 2% halothane and the right common carotid artery was exposed and the right external carotid artery (ECA) was carefully ablated, ligated and cut. The right external carotid artery was turned over and a 4-0 nylon thread coated with silicon (18 mm) was inserted from the right external carotid artery to the right internal carotid artery to occlude the origin of the right middle cerebral artery. The end of the thread was ligated to the external carotid artery to prevent the blood flowing backward and the anesthesia was discontinued. After the discontinuation of the anesthesia, the rat body temperature was maintained at 37 °C and rats showing hemiparesis in the left-side fore-leg within 15 minutes were used in the following experiments as ischemia load models. After 60 minutes of the middle cerebral artery occlusion, the rats were anesthetized again and the threads were removed to allow reperfusion of the ischemic area via the right common carotid artery. (3) Method of measurement of brain edemas (brain water content) After 24 hours of the ischemia-reperfusion, the rats were decapitated under anesthesia with pentbarbital and the brains were taken out. The brains were separated with tweezers in a humidifier into 3 parts: (a) cerebral cortex supplied by anterior cerebral artery (ischemia-contiguous cortex; ACA), (b) cerebral cortex supplied by middle cerebral artery (ischemic cortex; MCA) and (c) caudate putamen (ischemic core). After the wet weight of each sample was measured, the samples were dried at 105 °C for 24 hours to measure the dry weight. The water content was calculated according to the following formula and used as an index of the brain edema. Brain water content (%) = (wet weight - dry weight) / wet weight x 100 Experiment 1 Inhibitory effect of compound (I-Na) on brain edemas in preischemic administration and post-ischemic administration A compound represented by the formula (I) in which R 1 is Na and R 2 is -COCH=CHCOONa (hereinafter referred to as compound (I-Na)) was dissolved in physiological saline and used as an endothelin antagonist. In the pre-ischemic administration group, an osmotic pressure pump filled with the compound (I-Na) was subcutaneously buried in the back of a rat 24 hours before the middle cerebral artery occlusion (ischemic burden) and the compound (I-Na) was administered by a continuous hypodermic administration (12 mg/kg/day) from 24 hours before the ischemic load to 24 hours after the reperfusion. In the post-ischemic administration group, the compound (I-Na) was administered by an intravenous injection(12mg/kg) immediately after the reperfusion from the tail vein (bolus administration) and further administered by a continuous hypodermic administration (12 mg/kg/day) from 10 minutes to 24 hours after the reperfusion. Twenty four hours after the reperfusion, the brain water content in the ischemic area increased significantly in the vehicle-administered group compared with that of the sham operation group. This meant the formation of the brain edemas in the former group. The pre-ischemic administration of the compound (I-Na) suppressed the formation of brain edemas significantly in the ACA and MCA areas but not in the caudate putamen (Fig.1). The post-ischemic administration of the compound (I-Na) significantly suppressed the formation of the brain edemas not only in the ACA and the MCA areas but also in the caudate putamen (Fig.1). This result means that even in the post-ischemic administration of the compound (I-Na) the formation of the brain edemas is remarkably suppressed. Experiment 2 The influence of the dose of the compound (I-Na) on the inhibitory effect in brain edemas The compound (I-Na) dissolved in physiological saline was put into an osmotic pressure pump buried in the back of a rat, and then administered through a polyethylene tube from the femoral vein from 10 minutes to 24 hours after the ischemia reperfusion (0.03 -1.0 mg/kg/hour). As a result, the compound (I-Na) suppressed the formation of the brain edemas dose-dependently and significantly at a dose of 0.1 - 1.0 mg/kg/hour (Fig. 2). This effect was observed in all of the ACA area, the MCA area, and the caudate putamen. Experiment 3 Inhibitory effect of other endothelin antagonists on brain edemas Each of Bosentan, TAK-044 and BQ-123 dissolved in physiological saline was put into an osmotic pump buried in the back of a rat and administered through a polyethylene tube from the crotch vein from 10 minutes to 24 hours after ischemia reperfusion (0.3/mg/kg/hour). As a result, the brain edema formation was significantly suppressed in the ACA and MCA areas and moderately in the caudate putamen (Figs.3, 4 and 5). Formulation 1 Compound (I-Na) 50 mg Lactose 46 mg Corn starch 20 mg Low-substituted hydroxypropylcellulose 8 mg Hydroxypropylmethylcellulose 5 mg Magnesium stearate 1 mg Total 130 mg After all of the above ingredients except for hydroxypropylmethylcellulose and magnesium stearate were mixed uniformly, an 8% (w/w) aqueous solution of hydroxypropylmethylcellulose was added to the mixture as a binder to give granules for tablet formation by a convenient wet granulation method. These granules were mixed with magnesium stearate and then formed into oral tablets (7 mm diameter and 130 mg per tablet) by a tablet press. Formulation 2 TAK-044 50 mg Physiological saline 200 ml TAK-044 was dissolved in physiological saline to give drip infusions. EFFECT OF THE INVENTION The composition for brain edemas of the present invention can be administered to treat or prevent brain edemas when brain edemas have been or may be induced.

Claims: Use of an endothelin antagonist in the manufacture of a medicament for treating or preventing brain edemas. Use as claimed in claim 1 wherein the endothelin antagonist is a compound of the following formula (I): wherein R 1 is hydrogen or a metabolizable ester residue; R 2 is hydrogen or R 3 -R 4 , wherein R 3 is -SO 3 -, -CH 2 COO-, -COCOO-, or -COR 5 COO-, wherein R 5 is alkylene having 1 to 6 carbon atoms or alkenylene having 2 to 6 carbon atoms, and R 4 is hydrogen or alkyl having 1 to 6 carbon atoms, pharmaceutically acceptable salts or hydrates thereof, bosentan, cyclo[D-aspartyl-L-[3-(4-phenylpiperazin-1-ylcarbonyl)]-alanyl-L-aspartyl-D-[2-(2-thienyl)]glycyl-L-leucyl-D-tryptophyl]disodium or cyclo[D-Asp-L-Pro-D-Val-L-Leu-D-Trp]. Use as claimed in claim 2, wherein the endothelin antagonist is the compound represented by the formula (I), wherein R 1 is hydrogen and R 2 is -COCH=CHCOOH, or pharmaceutically acceptable salts or hydrates thereof.

Inventors: MATSUO YOSHIYUKI, NINOMIYA MITSUYOSHI, MATSUO, YOSHIYUKI, NINOMIYA, MITSUYOSHI
Applicants: SHIONOGI & CO, SHIONOGI & CO., LTD.
Application year: 1996
Main classification: A61K45
IPC codes: A61K31, A61K38