A pharmaceutical composition for use in raised intracranial pressure

This invention relates to a pharmaceutical composition for use in reducing increased intracranial pressure in a warm-blooded animal.

Cerebral edema, which is a well-known complication of various cerebral diseases (e.g., cerebral hemorrhage, subarachnoid hemorrhage, cerebral thrombosis, cerebral embolism, head injury, cerebral tumor and encephalomyelitis), induces an increase in intracranial pressure due to compression of neighbouring brain tissues. Moreover, such increased intracranial pressure is known to adversely affect cerebral metabolism, result in disturbances of cerebral circulation and further aggravate cerebral edema. Therefore, the increase intracranial pressure exerts serious adverse effects on patients or is sometimes fatal to them. In this respect, a hypertonic solution (1000-1500 milliosmols!kg.H₂0) of glycerol or mannitol has been used for therapeutic treatment of patients suffering from increased intracranial pressure. The intravenous infusion of the hypertonic solution raises blood osmolality and creates an osmotic gradient between plasma and brain with resultant net removal of water from brain. Thus, the therapeutic effect of the hypertonic solution on the increased intracranial pressure is based on the hyperosmolar dehydrating effect and therefore, in order to obtain the desired therapeutic effect, as much as 500 to 1,500 mVman/day of the hypertonic solution must be administered to patients. Such hypertonic solution is also disadvantageous in that its intravenous infusion causes haematological abnormalities (e.g., disturbance of water-electrolyte equilibrium, haemolysis, decrease in haematocrit level) and is followed by a rebound increase in the intracranial pressure to levels higher than those that existed before therapy.

A composition for reducing cerebrospinal fluid pressure is described in GB-A-1 486 880. DE-A-2 508 474 describes infusion solutions and rinsing liquids for treating cerebral edema containing specific sugar derivatives.

The object of the present invention is to provide a novel pharmaceutical composition adapted for parenteral administration to a warm-blood animal which is useful in reducing or treating increased intracranial pressure in a warm-blooded animal, including human, in need of such reduction of intracranial pressure.

According to the invention this object is achieved by a pharmaceutical composition for use in reducing increased intracranial pressure which comprises an aqueous solution containing a propanol derivative of the formula: <chemistry id="chem0001" num="0001"><img file="EP0031925B1_D0001.tif" /></chemistry>wherein R is alkyl having one to 4 carbon atoms and Ring A is phenyl, halogenophenyl, methylphenyl or trifluoromethylphenyl, or a pharmaceutically acceptable acid addition salt thereof, and at least one member selected from mannitol, sorbitol, glycerol, xylitol, fructose, maltose and sodium chloride.

Said pharmaceutical composition of the invention is useful in reducing or treating increased intracranial pressure in a warm-blooded animal, including human, in need of such reduction of intracranial pressure and is especially suitable for parenteral administration to said warm-blooded animal. This pharmaceutical composition is also useful to reduce increased intracranial pressure without haematological abnormalities, rebound increase in said pressure and other untoward side effects as seen in the hypertonic solution of glycerol or mannitol. Moreover, said pharmaceutical composition may be used to treat a warm-blooded animal suffering from a disease or condition attributable to increased intracranial pressure.

The propanol derivative (I) of the present invention shows a significant decrease in intracranial pressure at a remarkably low dose such as 0.1-2 mg/kg of body weight/day. Representative examples of such compound include those of the formula (I) in which R is alkyl having one to 4 carbon atoms (e.g., methyl, ethyl, propyl, butyl), and Ring A is phenyl, methylphenyl (e.g., 2-methylphenyl), chlorophenyl (e.g., 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl), fluorophenyl (e.g., 2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl) or trifluoromethylphenyl (e.g., 3-trifluoromethylphenyl). Among those compounds, preferred group of compounds are those of the formula (I) in which R is methyl and Ring A is phenyl, chlorophenyl or fluorophenyl. More preferred group of compounds are those of the formula (I) in which R is methyl and Ring A is phenyl, 2-chlorophenyl, 2-fluorophenyl or 3 fluorophenyl. A specific preferred group of compounds includes 1 - (4 - acetamido - 2 - methoxyphenoxy) - 3 - (4 - phenylpiperazino) - 2 - propanol, 1 - (4 - acetamido - 2 - methoxyphenoxy) - 3 - [4 - (chlorophenyl)piperazino] - 2 - propanol and 1 - (4 - acetamido - 2 - methoxyphenoxy) - 3 - [4 - (fluorophenyt)piperazino] - 2 - propanol.

The most preferred compound is 1 - (4 - acetamido - 2 - methoxyphenoxy) - 3 - [4 - (3 - fluorophenyl)piperazino] - 2 - propanol. All of these propanol derivatives (I) and the synthetic process thereof have already been disclosed in Japanese Patent Publication (unexamined) No. 21127/1978.

The propanol derivative (I) may be employed for pharmaceutical use either as the free base or in the form of a pharmaceutically acceptable acid addition salt thereof. Pharmaceutically acceptable acid addition salt of the propanol derivative (1) include, for example, inorganic acid addition salts such as hydrochloride, phosphate, nitrate and sulfate; and organic acid addition salts such as acetate, lactate, citrate, fumarate, maleate, glycinate, aspartate, methanesulfonate and benzoate. The therapeutic dose of the propanol derivative (1) or its salt depends on route of administration; the age, weight and condition of patients; and the particular diseases to be treated. In general, it may be used at a dose of 0.1 to 5 mg (in terms of free base) per kilogram of body weight per day. Likewise, suitable amount of the propanol derivative (I) or its salt to be contained in the pharmaceutical composition may vary over a wide range depending on route of administration; conditions of patients; or the particular form of pharmaceutical compositions to be used. In general, however, suitable concentration of the propanol derivative (I) or its salt in the aqueous solution is 0.0004 to 1.5 w/v %, especially 0.005 to 0.8 w/v %.

On the other hand, it is preferred that said aqueous solution of the present invention for parenteral administration has an osmotic pressure approximately not lower than that of blood plasma. Therefore, mannitol, sorbitol, glycerol, xylitol, fructose, maltose or sodium chloride should be used in an amount sufficient to adjust the osmotic pressure of the aqueous solution to a level not lower than 250 milliosmols/kg.H₂0, especially 270 to 850 milliosmols/kg.H₂0, and more especially 270 to 550 milliosmols/kg.H₂0. For this purpose, mannitol, sorbitol, xylitol or fructose must be used in an amount of at least 4.6 w/v %, glycerol in an amount of at least 2.3 w/v %, maltose in an amount of at least 9.3 w/v % or sodium chloride in an amount of at least 0.8 w/v %. 5 to 15 w/v % of mannnitol, sorbitol, xylitol or fructose, 2.5 to 7.5 w/v % of glycerol, 10 to 30 w/v % of maltose and 0.9 to 2.7 w/v % of sodium chloride may be used to adjust the osmotic pressure of said aqueous solution to a level of 270 to 850 milliosmols/kg.H₂0. On the other hand, 5 to 10 w/v % of mannitol, sorbitol, xylitol or fructose, 2.5 to 5 w/v % of glycerol, 10 to 20 w/v % of maltose and 0.9 to 1.8 w/v % of sodium chloride may be used to adjust the osmotic pressure of said aqueous solution to a level of 270 to 550 milliosmols/kg.H₂0.

Such aqueous solution of the invention for parenteral administration can be formulated by dissolving the propanol derivative (I) or a salt thereof in an aqueous solution containing at least one member selected from mannitol, sorbitol, glycerol, xylitol, fructose, maltose and sodium chloride. It is preferred to adjust a pH of said aqueous solution to 4 to 7.5, and conventional alkali agents such as sodium hydroxide may be preferably employed to adjust the pH of the aqueous solution. Further, said aqueous solution may be sterilized and/or filtered in a conventional manner. If desired, to said aqueous solution may be added other drugs or carriers suitable for use in injections.

The pharmaceutical composition of the present invention can be administered to a warm-blooded animal either intravenously, intramuscularly or subcutaneously. If desired, said pharmaceutical composition of the invention may be used in the form of an injection for intravenous drip infusion. Moreover, the pharmaceutical composition of the present invention can be used for therapeutic treatment or prognosis of a warm-blooded animal, including human, suffering from increased intracranial pressure due to various cerebral diseases such as cerebral infarction, cerebral thrombosis, cerebral embolism, cerebral hemorrhage, subarachnoid hemorrhage, head injury, cerebral tumor, cerebral edema, encephalomyelitis and the like. The propanol derivative (1) may be also used to ameliorate such various cerebral diseases as mentioned above. Further, since the propanol derivative (I) has a potent cerebral blood flow-increasing activity in addition to its effect on the intracranial pressure, it can also be used to improve the cerebral circulation, especially in ischemic areas in brain.

The propanol derivative (I) shows significant decrease in intracranial pressure even when administered at such a remarkably low dose as 0.5 mg/kg of body weight; said therapeutic effect lasts for a long period of time such as for more than 5-6 hours; and its use is not associated with rebound increase in intracranial pressure. Unlike those of the hypertonic solutions of glycerol or mannitol, the therapeutic effect of the propanol derivative (I) of the present invention is not ascribable to the cerebral dehydrating effect. The propanol derivative (I) may be used for the treatment or prophylaxis of increased intracranial pressure during and after brain surgical operation. Moreover, the propanol derivative (I) may be used for improving impaired consciousness, nervous disturbance and subjective symptoms (e.g., headache, nausea, vomiting) which are attributed to the cerebral diseases such as those mentioned hereinbefore. Further, whereas it is known that cerebral edema induces an increase in intracranial pressure and increased intracranial pressure serves to cause a build-up of edema which in turn impairs cerebral circulation, the propanol derivative (I) can interrupt such vicious cycle of cerebral diseases because of its potent intracranial pressure-lowering effect and ameliorate the cerebral circulatory impairment. The toxicity of the propanol derivative (I) of the present invention is low. For example, when 1 - (4 - acetamido - 2 - methoxyphenoxy) - 3 - [4 - (3 - fluorophenyl)piperazino] - 2 - propanol hydrochloride was administered intravenously to male ddY-strain mice weighing 21 to 25 g (each group consisting of 10 mice), the 50% lethal dose (LD_so) of said compound which was calculated according to the Weil's method from the number of mice dead a week after the administration was 280 mg/kg. On the other hand, even when 1 - (4 - acetamido - 2 - methoxyphenoxy) - 3 - [4 - (3 - fluorophenyl)piperazino] - 2 - propanol hydrochloride was administered intraperitoneally to male and female Wistar-KBL-strain rats weighing 180 to 200 g (each group consisting of 10 male rats and 10 female rats) at a dose of 10, 30 or 100 mg/kg once a day for 30 consecutive days, all rats survived at least for 30 days after the administration of the test compound was commenced.

Further, when a therapeutic index is estimated in terms of the ratio of the 50% lethal dose to the minimum effective dose (i.e., a minimum dose at which a test compound shows intracranial pressure-lowering activity), 1 - (4 - acetamido - 2 - methoxyphenoxy) - 3 - [4 - (3 - fluorophenyl)-piperazino] - 2 - propanol of the invention when administered intravenously shows the therapeutic index of not less than about 400.

Concomitantly, the propanol derivative (I) of the present invention is prepared in accordance with the method described in Japanese Patent Publication (unexamined) No. 21127/1978, i.e., by reacting a 3 - (4 - acylamino - 2 - methoxyphenoxy) - 1,2 - epoxypropane with a piperazine derivative of the formula: <chemistry id="chem0002" num="0002"><img file="EP0031925B1_D0002.tif" /></chemistry>wherein Ring A is the same as defined above.

Example 1

(Effect of an i.v. injection of test compounds on intracranial pressure in rats)

Method:

Male SD-strain rats weighing 500 to 800 g (each group consisting of 5 rats) were anesthetized with urethane. A solution of a test compound in an aqueous 5 w/v % mannitol solution was infused via the femoral vein at a rate of 0.2 ml/kg/minute for 40 minutes (when the test compound was used in the form of free base, said solution was prepared by dissolving it in an aqueous 5 w/v % mannitol solution with the aid of 0.5 N hydrochloric acid). Intracranial pressure (i.e., cerebrospinal fluid pressure in the cisterna magna) was continuously monitored via a cannula inserted in the cisterna magna. The cannula. was connected to a transducer, and recordings were made on graph paper. The effect of the test compound on the intracranial pressure was estimated in terms of the increase or decrease in intracranial pressure, which was calculated in accordance with the following formula:<maths id="math0001" num=""><img file="EP0031925B1_D0003.tif" /></maths>Test compounds: <ul id="ul0001" list-style="none"><li>1. 1-(4-acetamido-2-methoxyphenoxy)-3-l4-phenylpiperazino)-2-propanol</li><li>2. 1-(4-acetamido-2-methoxyphenoxy)-3-[4-(2-methylphenyl)piperazino]-2-propanol</li><li>3. 1-(4-acetamido-2-methoxyphenoxy)-3-[4-(2-chlorophenyl)piperazino]-2-propanol</li><li>4. 1-(4-acetamido-2-methoxyphenoxy)-3-(4-(3-fluorophenyl)piperazino]-2-propanal hydrochloride</li><li>5. 1-(4-acetamido-2-methoxyphenoxy)-3-(4-(2-fluorophenyl)piperazino]-2-propanol</li><li>6. 1 -(4-acetam ido-2-methoxyphenoxy)-3-[4-13-triffuoromethylphenyl)piperazino]-2-propanol</li></ul>

Results:

The results are shown in the following Table 1. <tables id="tabl0001" num="0001"><img file="EP0031925B1_D0004.tif" /></tables>

Example 2

(Effect of i.v. injection of test compounds on intracranial pressure in rats)

Method:

Male SD-strain rats weighing 500 to 800 g (each group consisting of 5 rats) were anesthetized with urethane. 0.03 ml of autologous blood were injected into the brain of the rats to induce an increase in intracranial pressure. The level of increased intracranial pressure in the rats was about twice as high as its initial level 120 to 180 minutes after injection of autologous blood and said in eased intracranial pressure was maintained at an approximately same level thereafter. 180 minutes after injection of autologous blood, a solution of a test compound in an aqueous 5 w/v % mannitol solution was infused via the femoral vein of the rats at a rate of 0.2 ml/kg/minute for 40 minutes. Then, the effect of the test compound on the intracranial pressure was calculated according to the following formula:<maths id="math0002" num=""><img file="EP0031925B1_D0005.tif" /></maths><ul id="ul0002" list-style="none"><li>Note: ^*: The initial intracranial pressure, i.e., the normal intracranial pressure measured before injection of autologous blood, was 71.5 + 3.9 mm H₂0.</li><li>^**: The intracranial pressure measured before administration of test compound was 143 ± 21 mm H₂0.</li></ul>

Test compound:

Compound No. 4 listed in Example 1 was used in this experiment.

Results:

The resutts are shown in the following Table 2. <tables id="tabl0002" num="0002"><img file="EP0031925B1_D0006.tif" /></tables>

Example 3

(Effect of i.v. injection of test compounds on intracranial pressure in beagle dogs)

Method:

Male beagle dogs weighing 10 to 15 kg (each group consisting of 4 beagle dogs) were anesthetized with barbital. A solution of a test compound in an aqueous 5 w/v % mannitol solution was infused via the saphenous vein of the beagle dogs at a rate of 0.1 ml/kg/minute for 40 minutes. Then, the effect of the test compound on the intracranial pressure was estimated in the same manner as described in Example 1.

Test compound:

Compound No. 4 listed in Example 1 was used in this experiment.

Results:

The results are shown in the following Table 3. <tables id="tabl0003" num="0003"><img file="EP0031925B1_D0007.tif" /></tables>

Example 4

(Effect of i.v. injection of test compounds on intracranial pressure in rabbits)

Method:

Male rabbits weighing 2.8 to 3.2 kg (each group consisting of 6 rabbits) were anethetized with urethane. 0.1 to 0.2 ml of autologous blood were injected into the lateral ventricle of the rabbits to induce a rise in intracranial pressure. The level of intracranial pressure was about 2.3 times as high as its initial level 150 to 180 minutes after injection of autologous blood. 180 minutes after injection of autologous blood, a solution of a test compound in an aqueous 10 w/v % maltose solution was administered intravenously to the rabbits at a rate of 0.1 ml/kg/minute for 20 minutes. Then, the effect of the test compound on the intracranial pressure was calculated in the same manner as described in Example 2. (The initial intracranial pressure (i.e., the normal intracranial pressure measured before injection of autologous blood) was 75 ± 2.6 mm H₂0, and the intracranial pressure measured before administration of test compound was 176 ± 16 mm H₂0).

Test compound:

Compound 4 listed in Example 1 was used in this experiment.

Results:

The results are shown in the following Table 4. <tables id="tabl0004" num="0004"><img file="EP0031925B1_D0008.tif" /></tables>

Example 5

(Effect of test compounds on common carotid blood flow in cats)

Method:

Cats weighing 2.5 to 3.5 kg (each group consisting of 5 cats) were anethetized with urethane and chloralose. A solution of a test compound in an aqueous 10 w/v % maltose solution was injected into the right thyroid artery of the cats. The common carotid artery blood flow was continuously monitored via the flow probe set at the common carotid artery. The flow probe was connected to an electromagnetic flow meter, and recordings were made on graph paper. The effect of the test compound on the common carotid blood flow was estimated 30 seconds after administration of the test compound.

Test compound:

Compound No. 4 listed in Example 1 was used in this experiment.

Results:

The results are shown in the following Table 5. <tables id="tabl0005" num="0005"><img file="EP0031925B1_D0009.tif" /></tables>

Example 6

(Intramuscular injection)

4 g of 1 - (4 - acetamido - 2 - methoxyphenoxy) - 3 - [4 - (3 - fluorophenyl)piperazino] - 2 - propanol hydrochloride and 50 g of sorbitol were dissolved in about 900 ml of distilled water, and the solution was adjusted to a total volume of one liter with distilled water. The solution was filtered through a membrane filter (pore size: 0.22 lim), and the filtrate was filled into ampoules (1.1 ml per ampoule). The ampoules were sealed and then sterilized for 60 minutes with steam (100°C).

Example 7

(Intravenous injection)

Citric acid was dissolved in distilled water to give an aqueous 0.003 N citric acid solution. 0.4 g of 1 - (4 - acetamido - 2 - methoxyphenoxy) - 3 - [4 - (3 - fluorophenyl)piperazino] - 2 - propanol and 9 g of sodium chloride were dissolved in about 900 ml of the aqueous citric acid solution. The solution thus obtained was adjusted to a pH of 6 to 6.5 with an aqueous 0.1 N sodium hydroxide solution, and then adjusted to a total volume of one liter with distilled water. Then, the solution was filtered by a membrane filter (pore size: 0.22 µm), and the filtrate was filled into ampoules (5.3 ml per ampoule). The ampoules were sealed and then sterilized for 60 minutes with steam (100°C).

Example 8

(Intravenous drip infusion solution)

0.1 g of 1 - (4 - acetamido - 2 - methoxyphenoxy) - 3 - [4 - (3 - fluorophenyl)piperazino) - 2 - propanol hydrochloride and 50 g of mannitol were dissolved in about 900 ml of distilled water. The solution was adjusted to a pH of 6.5 to 7.0 with an aqueous 0.1 N sodium hydroxide solution, and then adjusted to a total volume of one liter with distilled water. The solution thus obtained was filtered , through a membrane filter (pore size: 0.22 µm), and the filtrate was filled into vials (206 ml per vial). The vials were sealed and then sterilized at 115°C for 30 minutes in an autoclave.

Example 9

(Intravenous drip infusion solution)

An intravenous drip infusion solution was prepared in the same manner as described in Example 10 except that 50 g of xylitol were used instead of 50 g of mannitol.

Example 10

(Intravenous drip infusion solution)

An intravenous drip infusion solution was prepared in the same manner as described in Example 10 except that 50 g of fructose were used instead of 50 g of mannitol.

Example 11

(Intravenous drip infusion solution)

An intravenous drip infusion solution was prepared in the same manner as described in Example 10 except that 25 g of glycerol and 50 g of sorbitol were used instead of 50 g of mannitol.

Preparation of the propanol derivative (I)

<ul id="ul0003" list-style="none"><li>(1) 1.0 g of 3 - (4 - acetamido - 2 - methoxyphenoxy) - 1,2 - epoxypropane is dissolved in 40 ml of ethanol, and 750 mg of 4-phenylpiperazine are added thereto. The mixture is stirred at room temperature for 18 hours. Then, the mixture is concentrated under reduced pressure to remove ethanol. The residue is recrystallized from a mixture of ethyl acetate and methanol, whereby 1.55 g of 1 - (4 - acetamido - 2 - methoxyphenoxy) - 3 - (4 - phenylpiperazino) - 2 - propanol are obtained as colorless needles. M.p. 154°-156°C <ul id="ul0004" list-style="none"><li>Hydrochloride: M.p. 242°-244°C (decomp.)</li><li>Methanesulfonate: M.p. 191°―193°C</li></ul></li><li>(2) 800 mg of 3 - (4 - acetamido - 2 - methoxyphenoxy) - 1,2 - epoxypropane are dissolved in 4 ml of ethanol, and 670 mg of 4-(2-fluorophenyl)piperazine are added thereto. The mixture is refluxed for 4 hours. Then, the mixture is concentrated under reduced pressure to remove ethanol. The residue is recrystallized from a mixture of isopropyl alcohol and isopropyl ether, whereby 770 mg of 1 - (4 - acetamido - 2 - methoxyphenoxy) - 3 - [4 - (2 - fluorophenyl)piperazino] - 2 - propanol are obtained as colorless granules.</li></ul>

The mother liquor obtained after recrystallization is concentrated to dryness. The residue is purified by silica gel chromatography (Solvent: 2% ethanol-chloroform), and then recrystallized from a mixture of isopropyl alcohol and isopropyl ether. 460 mg of 1 - (4 - acetamido - 2 - methoxyphenoxy) - 3 - [4 - (2 - fluorophenyl)piperazino] - 2 - propanol are further obtained. M.p. 143.5°-144.5°C.

The following compounds are obtained in the same manner as described in paragraph (1) or (2). <ul id="ul0005" list-style="none"><li>1-(4-acetamido-2-methoxyphenoxy)-3-[4-(2-methylphenyl)piperazino]-2-propanol, M.p. 126.5^0-128⁰C</li><li>1-(4-acetamido-2-methoxyphenoxy)-3-[4-(4-chlorophenyl)piperazino]-2-propanol, M.p. 177^0-178.5⁰C.</li><li>1-(4-acetamido-2-methoxyphenoxy)-3-[4-13-chlorophenyl)piperazino]-2-propanol, M.p. 141-143.5°C</li><li>1 - (4 - acetamido - 2 - methoxyphenoxy) - 3 - [4 - (2 - chlorophenyl)piperazino] - 2 - propanol, M.p. 137.5°-140°C</li><li>1-(4-acetamido-2-methoxyphenoxy)-3-[4-(4-fluorophenyl)piperazino]-2-propanol, M.p. 175.5-176.5°C</li><li>1-(4-acetamido-2-methoxyphenoxy)-3-[4-(3-fluorophenyl)piperazino]-2-propanol, M.p. 14.4.5°―146°C Hydrochloride: M.p. 224°-226°C</li><li>1-(4-acetamido-2-methoxyphenoxy)-3-[4-(3-trifluoromethylphenyl)piperazino]-2-propanol, M.p. 125°-127°C</li></ul>