Eperisone as a hypotensive agent

Abstract: 4′-ethyl-2-methyl-3-piperidinopropiophenone or a pharmacologically acceptable salt thereof is useful as a hypotensive agent.

Description: The present invention relates to a hypotensive agent for the treatment or prevention of hypertension. Various hypotensive agents are used for the purpose of treating hypertension. However, they have various side effects and, therefore, they pose problems when they are administered in large amounts or during repeated administration over a long period. For example, diuretic hypotensive agents such as sulfonamide preparations and thiazide preparations have a serious side effect of inducing hyperuricemia and hypokalemia; sympatholytic agents such as reserpine preparations and methyldopa preparations have a side effect of inducing thirst, disturbance of consciousness and orthostatic hypotension; and vasodilators such as Apresoline have a side effect of inducing headache, tachycardia and angina. The development of safer hypotensive agents free of these defects is thus demanded. J. Pharmacol. Exp. Ther., 1985, 235 (3), page 757 to 763 discloses the effect of eperisone, an antispasmodic, on the electrical and mechanical properties of smooth muscle cells of the guinea-pig basilar artery. It indicated that the eperisone possesses the properties of a calcium antagonist on smooth muscle tissue of the guinea-pig basilar artery. These studies were however made in vitro. J. Cardovasc. Pharmacol, 1985, 7, Supplement 1 page s21 to s27 describes the use of calcium antagonists in antihypertensive therapy. The Merck Manual, Fourteenth Edition, page 389 to 398 discloses the use of relaxants of vascular smooth muscle in the management of hypertension. It has now been found that 4'-ethyl-2-methyl-3-piperidinopropoiphenone of the following formula (I) and pharmacologically accetable salts thereof are useful as hypotensive agents in the treatment of hypertension. The invention relates to use of 4'-ethyl-2-methyl-3-piperidinopropiophenone or a pharmacologically acceptable salt thereof for the preparation of a medicament having an anti-hypertension action, without inducing increased heart rate. The compound of the above structural formula has the nonproprietary name of eperisone. Its hydrochloride has been used heretofore for relieving muscle tonus in low back pains and cervical syndrome or for treating spastic and paralysis induced by cerebral vascular lesions, etc. It has now been surprisingly found that compound (I) is effective as a hypotensive agent. It is surprising that this compound is effective for the treatment of hypertension, since the relieving of the muscle tonus is not related to the hypotensive effect from the viewpoint of the effects of medicines. The pharmacologically acceptable salts herein include inorganic acid salts such as hydrochloride, hydrobromide and sulfate; organic acid salts such as acetate, maleate, tartrate, methanesulfonate, benzenesulfonate and toluenesulfonate; and amino acid salts such as argininate, asparatate and glutamate, among which the hydrochloride is the most desirable. Eperisone hydrochloride of the following formula (II) can be prepared for example, by the process of Example 1 of GB 1452868 or the equivalent Japanese Patent Publication No. 27914/1980. The physico-chemical properties of this compound are as follows: molecular formula: C₁₇H₂₅NO.HC1 molecular weight: 295.85 structural formula: Eperisone hydrochloride is in the form of a white crystalline powder having a weak peculiar smell and a bitter taste. It is easily soluble in water, methanol, chloroform or glacial acetic acid, relatively easily soluble in ethanol, relatively difficultly soluble in acetic anhydride, difficultly soluble in acetone and scarcely soluble in ether. This compound is optically inactive. Melting point: ca. 167°C (dec.; after drying). In the accompanying drawings, Fig. 1 is a graph showing the effect of eperisone hydrochloride on the blood pressure of dogs suffering from Goldblatt hypertension. Fig. 2 is a graph showing the effect of eperisone hydrochloride on the heart rate of dogs suffering from Goldblatt hypertension. In the following animal tests, the hypotensive effect and toxicity of the compound of the present invention will be examined. Pharmacological Experimental Example 1. Agents used Eperisone hydrochloride used was a bitter, odorless, water-soluble compound in the form of white crystals having a molecular weight of 295.85. Nicardipine hydrochloride was used as a control. The dose was 5mℓ/kg. Commercially available tablets were given as they were by oral administration. 2. Experimental animals Female beagles suffering from Goldblatt hypertension of "one clip one kidney" type were used. They were prepared by removing the right kidney of each dog and narrowing the left renal artery to realize the hypertension. 3. Measurement of blood pressure and heart rate The blood pressure and heart rate were measured in the artery of the tail of each dog in a closed manner with a device for continuously measuring the systolic pressure (SCS-301; a product of Shimadzu Seisakusho Ltd.). Effects of eperisone hydrochloride given once by oral administration on the blood pressure and heart rate of dogs suffering from Goldblatt hypertension The Goldblatt hypertension model was prepared as follows: the right kidney of each beagle was removed and the left renal artery was narrowed to realize the renal hypertension model of the "one clip one kidney" type. The effects of eperisone hydrochloride given once by oral administration on the blood pressure and heart beat were compared with those of nicardipine hydrochloride. The nine beagles were divided into three groups, i.e. a control group, a group to which 10 mg/kg of eperisone hydrochloride was given and another group to which 10 mg/kg of nicardipine hydrochloride was given. Nine beagles were subjected to the tests of all of the three groups. Namely, the administration was discontinued at intervals of one week according to Latin square. The blood pressure and heart rate were measured before the administration and then at specified intervals from one hour to five hours after the administration. The effects of eperisone hydrochloride on the blood pressure and heart rate of the beagles suffering from Goldblatt hypertension are shown in Figs. 1 and 2. In the control group, the initial blood pressure was 201 ± 3 mmHg, which was unchanged after 5h. In the group of 10 mg/kg of epersone hydrochloride, the blood pressure was 202 ± 4 mmHg before the administration and 172 ± 3 mmHg after 3 h. Thus, a significant reduction in the blood pressure was observed. In the group of 10 mg/kg of nicardipine hydrochloride, it was 200 ± 4 mmHg before the administration and 164 ± 4 mmHg after 3 h. Thus, a significant reduction in the blood pressure was also observed (see Fig. 1). As for the heart rates shown in Fig. 2, no increase in the heart rate was observed with eperisone hydrochloride, while a significant increase (p<0.01) was observed as the blood pressure was lowered with nicardipine hydrochloride. Namely, in the group of 10 mg/kg of nicardipine hydrochloride, the heart rate which was 106 ± 7 beats/min before the administration was increased to 184 ± 15 beats/min after 1 h and to a maximum of 189 ± 6 beats/min after 2 h, which was gradually recovered to 154 ± 30 beats/min. On the contrary, in the group of 10 mg/kg of eperisone hydrochloride, the heart rate before the administration was 97 ± 5 beats/min and that after one hour was 97 ± 7 beats/min. Substantially no increase in the heart rate was observed in the latter case. Preparation of the statistics The analysis of variance was conducted by the time series analysis. The test groups were compared with the control group by Dunnet's method. It is apparent from the results of the above pharmacological experiments that the compounds of the present invention have an excellent hypotensive effect. Though the hypotensive effect of the compounds of the present invention was equivalent to that of nicardipine hydrochloride used in the comparison experiment, no tachycardia was induced at all by eperisone hydrochloride of the present invention, while the heart rate was considerably increased due to a sharp reduction in blood pressure when nicardipine hydrochloride was used. The acute toxicity (LD₅₀) of eperisone hydrochloride is shown in Table 1. The medicament of the present invention can be administered as a hypotensive agent parenterally in the form of injections, suppositories, external preparations or intravenous drip infusion or orally in the form of powder, granule, capsule or syrup. The dose varies depending on the symptoms, age and manner of the administration (either oral or parenteral administration). Usually the dose for adults is about 10 to 800 mg, preferably about 50 to 500 mg and still preferably 50 to 200 mg a day. It is given in several portions a day. A desired preparation may be prepared using ordinary carriers by ordinary methods. The medicament of the present invention can be formulated into a preparation to be administered by any of the conventional formulation methods. The medicament containing any necessary pharmaceutical carrier or excipient is used by ordinary methods. The composition is provided preferably in a form suitable for absorption through the digestive tracts. In the preparation of formulations for injection, additives such as a pH adjustor, buffering agent, suspending agent, solubilizer, stabilizer, isotonizer and preservative are added, if necessary, to the active ingredient. Formulations for use in subcutaneous, intramuscular or intravenous injections may be prepared by ordinary methods. The suspending agents include, for example, methycellulose, Polysorbate 80, hydroxyethylcellulose, acacia, powdered tragacanth, sodium carboxymethylcellulose and polyoxyethylene sorbitan monolaruate. The solubilizers include, for example, propylene glycol, polyoxtethylene-hardened castor oil, Polysorbate 80, nicotinamide, polyoxyethylene sorbitan monolaruate, macrogol, ethyl ester of castor oil fatty acid, and glucose. The stabilizers include, for example, sodium sulfite, sodium metasulfate and ether. The preservatives include, for example, methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, sorbic acid, phenol, cresol and chlorocresol. An oral solid preparation may be prepared by adding an excipient and, if necessary, a binder disintegrator, lubricant, colorant, corrigent, etc. to the active ingredient and shaping the mixture into tablets, coated tablets, granules, powders or capsules by an ordinary method. The excipients include, for example, lactose, corn starch, white sugar, glucose, sorbitol, crystalline cellulose and silicon dioxide. The binders include, for example, polyvinyl alcohol, polyvinyl ether, ethylcellulose, methylcellulose, acacia, tragacanth, gelatin, shellac, hydroxypropylcellulose, hydroxypropylstarch and polyvinylpyrrolidone. The disintegrators include, for example, starch, agar, gelatine powder, crystalline cellulose, calcium carbonate, sodium hydrogencarbonate, calcium citrate, dextrin and pectin. The lubricants include, for example, magnesium stearate, talc, polyethylene glycol, silica and hardened vegetable oils. The colorants include those accepted as colorants for medicines. The corrigents include, for example, cocoa powder, menthol, aromatic powder, peppermint oil, borneol and cinnamon powder. These tablets and granules can be suitably coated with sugar, gelatin, etc.

Claims: Use of 4'-ethyl-2-methyl-3-piperidinopropiophenone or a pharmacologically acceptable salt thereof, for the preparation of a medicament with an anti-hypertension action without inducing increased heart rate.

Inventors: NAKAJIMA YOSHIKAGE, TAJIMA TETSUYA, TANAKA MAMORU, NAKAJIMA, YOSHIKAGE, TAJIMA, TETSUYA, TANAKA, MAMORU
Applicants: EISAI CO LTD, EISAI CO., LTD.
Application year: 1988
Main classification: A61K31
IPC codes: A61P9, A61K31