Ointment base and ointment

Abstract: A gel ointment base having stable viscosity and resistant to a light which comprises an aqueous carboxyvinyl polymer solution and an amino acid in an amount effective for increasing the viscosity of the aqueous carboxyvinyl polymer solution, and a gel ointment comprises an active medical substance and the gel ointment base as set forth above, which has stable viscosity and resistant to a light at a pH range which does not give any irritation to viscous membranes and skins.

Description: This invention relates to the use of an amino acid to stabilize a gel ointment against irradiation of light and to increase the viscosity of the aqueous carboxyvinylpolymer solution of said gel ointment, said gel ointment comprising as a base an aqueous carboxyvinyl polymer solution and an active medical substance. Technical Background A gel base prepared by increasing the viscosity of an aqueous carboxyvinyl polymer solution with a basic viscosity-increasing agent such as sodium hydroxide, triethanolamine, diisopropanolamine, etc. has such excellent characteristics that (i) since the stock polymer has a high purity and uniform quality, it can give a topical preparation with a high reproducibility, (ii) it shows almost a constant viscosity in the range of a temperature of from 10° to 70°C, (iii) it is hardly decomposed with microorganisms such as bacteria, (iv) the gel is stable in a wide range of pH, and hence, it has been used for preparing various topical preparations such as medicines, cosmetics. However, the gel base has such defects that the viscosity thereof is decreased by irradiation with a light (ultraviolet light), and it shows low storage stability, and further that it is restricted in the utility. When the above-mentioned conventional basic viscosity-increasing agents are used, it must be adjusted to pH 10 or higher in order to eliminate the above defects. An ointment having pH 10 or higher shows high irritation to viscous membranes and skins which is not tolerable. FR-A-2 040 954 relates to a gel ointment base for cosmetics comprising a carboxyvinyl polymer solution and a certain amino acid. As amino acids histidine, arginine, lysine and ornithine are named. According to all examples the amino acid is used in a low concentration, for instance 1:0.275 in Example I and 1:0.35 in Example III. The amino acids listed in this document are all basic amino acids and are used for neutralizing the carboxyvinyl polymer. The viscosity of the gel ointment base for cosmetics as disclosed in FR-A-2 040 954 changes when irridiated with light, and the stability of the cosmetic preparation against ultraviolet light is not sufficient. EP-A-0 067 658 discloses on page 1 the use of alanine and glycine as a neutralizing agent for producing gels of Carbopol in addition to inorganic alkalies and organic amines, but there is no working example using such amino acids as a neutralizing agent. It should also be noted that glycine is not effective for stabilizing the gel against light. EP-A-0 162 007 describes stable gel compositions for the treatment of acne vulgaris comprising insulin. The composition also comprises a polyacrylic acid as gelling agent, which in all the examples is Carbopol and an inorganic or organic base as neutralising agent. The document gives, on page 6, a list of neutralising agents, which includes arginine and lysine. Carbopol Technical Bulletin, TDS 53, BFGoodrich, pages 1 to 5 (1973) describes the use of amino acids as neutralising agents for Carbopol resins. Basic amino acids such as glycine, beta-alanine, 4-amino butyric acid and 6-amino hexanoic acid are said to be the most effective, while amino acids lacking a terminal amino group yielded salts of Carbopol with lower thickening efficiency. The document discloses, under the heading "Clarity and Stability" on page 5, that "the ultraviolet radiation of strong sunlight may reduce the viscosity of clear gels by attacking the Carbopol resins and the amino acids". For this reason the addition of UV absorbing agents is recommended. More detailed information concerning these agents is given by way of reference to the previous Carbopol Bulletin GC-36, page 12. This document teaches that a combination of sodium salt of EDTA with a water-soluble UV adsorber, or thiourea alone, are effective stabilisers. An object of this invention is to provide a gel ointment having a stable viscosity and resistance to a light at a pH range which does not give any irritation to viscous membranes and skins in living bodies, which is prepared by increasing the viscosity of an aqueous carboxyvinyl polymer solution with an amino acid and mixing that gel ointment base with an active ingredient. Brief Summary of the Invention The subject-matter of the invention is the use of an amino acid to stabilize a gel ointment against irradiation of light and to increase the viscosity of the aqueous carboxyvinyl polymer solution of said gel ointment, said gel ointment comprising as a base an aqueous carboxyvinyl polymer solution and an active medical substance selected from the group consisting of a hypnotic, a sedative, an antipyretic, an analgesic, an anti-inflammatory agent, a local anaesthetic, an agent for ophthalmic use, an agent for nasal use, a cardiotonic, an antiarrhythmic agent, a coronary vasodilator, an agent effective for digestic organs, a corticoid, an antiplasmin, a fungicide, an anti-tumor agent, an antibiotic and a physiologically active peptide, wherein said amino acid is one of the group consisting of valine, isoleucine, serine, cysteine, ornithine, lysine, arginine, histidine, proline, threonine and methionine and is used in an amount of 0.1 to 10.0% by weight based on the whole weight of the base. The present inventors have extensively studied as to various viscosity-increasing materials suitable for increasing the viscosity of a carboxyvinyl polymer solution which can give a gel having a stable viscosity and being resistant to a light (ultraviolet light) at a pH range which does not give any irritation to viscous membranes and skins. It has now been found that specific amino acids can increase the viscosity of a carboxyvinyl polymer to give a gel ointment base having excellent characteristics without decreasing the viscosity even by a light (ultraviolet light), and that a gel ointment prepared by admixing said base with an active ingredient is very excellent without decreasing the viscosity even by light (ultraviolet light). Brief Description of Drawing Figures show graphs of the comparison of lowering viscosity by irradiation with light under various test conditions as to the gel ointment base as defined in claim 1 and a reference base in Fig. 1 and Fig. 2, and as to the gel ointment as defined in claim 1 and a reference ointment in Fig. 3 and Fig.4, respectively. Detailed Description of the Invention The gel ointment base comprises an aqueous carboxyvinyl polymer solution and an amino acid of an amount effective for increasing the viscosity of the aqueous carboxyvinyl polymer solution, which can be prepared, for example, by adding an amino acid to an aqueous carboxyvinyl polymer solution with stirring and thereby mixing uniformly them, and optionally followed by adjusting to pH 4 to 9 with an appropriate pH adjustor. The carboxyvinyl polymer used in the gel ointment base is a hydrophilic polymer which is prepared by polymerizing predominantly acrylic acid, and is commercially available in the names of Carbopol 934®, ibid. 940® ibid. 941® which have been sold by Goodrich Chemical, U. S. A. The carboxyvinyl polymer is usually used in an amount of 0.05 to 5.0 % by weight based on the whole weight of the composition. The amino acid is valine, isoleucine, serine, cysteine, ornithine, lysine, arginine, histidine, proline, threonine and methionine. These amino acids are used in an amount of 0.1 to 10.0 % by weight based on the whole weight of the composition. Other amino acids such as phenylalanine, tyrosine, aspartic acid, glutamic acid, tryptophane, asparagine, glutamine, leucine, do not increase the viscosity of carboxyvinyl polymer. Although glycine shows increase of the viscosity of carboxyvinyl polymer, it is inferior to in the viscosity stability against the irradiation with light (ultraviolet light). Hence, these amino acids are not suitable for the present invention. The pH adjustor includes the conventional bases which are usually used as a viscosity-increasing agent, such as sodium hydroxide, potassium hydroxide, triethanolamine, diisopropanolamine, triisopropanolamine. These pH adjustors are added in a minimum amount which is necessary for adjusting the pH to the desired range under taking into consideration the stability and absorbability of the active ingredient. The gel ointment comprises an active medical substance and the gel ointment base as set forth above, which can be prepared by adding the active ingredient to the gel ointment base as prepared above and mixing them uniformly, or alternatively, depending on the active ingredient to be used, by dissolving or dispersing the active ingredient in an aqueous carboxyvinyl polymer solution, adding thereto an aqueous amino acid solution with stirring and mixing them uniformly, and optionally followed by adjusting to pH 5 to 9 with a pH adjustor. The medical substance used as the active ingredient in this invention may be either water-soluble or water-insoluble, and is preferably stable in the preparation, i.e. in an aqueous solvent used in the step of preparation thereof. Examples of the medical substance used for the gel ointment of this invention are hypnotics and sedatives such as glutethimide, choral hydrate, nitrazepam, amobarbital, phenobarbital, etc.; antipyretics, analgesics and anti-inflammatory agents such as aspirin, acetaminophene, ibuprofen, flurbiprofen, indomethacin, ketoprofen, diclofenac sodium, tiaramide hydrochloride, piroxicam, flufenamic acid, mefenamic acid, pentazocine; local anaesthetics such as ethyl aminobenzoate, lidocaine; agents for ophthalmic use such as pilocarpine, physostigmine sulfate, atropine sulfate, flavine adenine dinucleotide, cyanocobalamin, naphazoline nitrate, micronomicin sulfate, fluorometholone, sodium guaiazulenesulfonate, befunoiol hydrochloride, disodium cromoglicate; agents for nasal use such as tetryzoline hydrochloride, tramazoline hydrochloride, disodium cromoglicate; cardiotonics such as ubidecarenone; antiarrhythmic agents such as propranolol hydrochloride, pindolol, phenytoin, disopyramide; coronary vasodilators such as isosorbide nitrate, nifedipine, diltiazem hydrochloride, dipyridamole; agents effective for digestic organs such as domperidone; corticoids such as triamcinolone acetonide, dexamethasone, betamethasone phosphate sodium, prednisolone acetate, fluocinolide, beclomethasone propionate; antiplasmins such as tranexamic acid; fungicides such as clotrimazole, miconazole nitrate, ketoconazole; antitumor agents such as tegafur, fluorouracil, mercaptopurine; antibiotics such as amoxycillin, ampicillin, cephalexin, cephalothin sodium, ceftizoxime sodium, erythromycin, oxytetracycline hydrochloride, physiological active peptides such as insulin, elcatonin, urokinase, TPA, interferon. The dose of the active ingredients may vary depending on the kinds of the agents, but is usually in an amount sufficient for exhibiting the desired activity which will be apparent to those skilled in the art from the usual dosage of these available medicaments. In case of using an active ingredient which is insoluble in water, the obtained gel ointment becomes opaque white, but the active ingredient does not precipitate, and hence, it can effectively be used. However, when it is desirable that the active ingredient is dissolved because of easier absorption into the living bodies as in case of applying to the skin, it may be dissolved with a solubilizer or it may be previously dissolved in a water-soluble organic solvent, and then it is used for the preparation. The water-soluble organic solvent includes lower alcohols (e.g. ethanol, isopropanol), and glycols (e.g. propyene glycol, 1,3-butylene glycol, polyethylene glycol having a molecular weight of 300 to 500. Besides, the solubilizer includes, for example, various surfactants, crotamiton, glycol salicylate, peppermint oil, benzyl alcohol, which are selected depending on the solubility of the active ingredients. The gel ointment base and gel ointment have preferably a viscosity of 1,000 to 100,000 cP (centipoises). When the viscosity is lower than 1,000 cP, they have too high fluidity and hence are hardly applicable to the viscous membranes and the skins, and on the other hand, when the viscosity is higher than 100,000 cP, the preparations are too hard and hence are hardly administered. Besides, when the viscosity is lower, the active ingredient can rapidly be absorbed into the body and hence the preparation is a rapid release one, and on the other hand, when the viscosity is higher, the gel is slowly degraded and the active ingredient is slowly absorbed and hence the preparation is a sustained and delayed release one. The viscosity is somewhat affected depending on the kinds of the active ingredients to be added, but mainly depends on the concentration of carboxyvinyl polymer. In order to obtain the gel base or gel preparation having the desired viscosity, the carboxyvinyl polymer is used in an aqueous solution having a concentration thereof in the range of 0.1 to 5.0 % by weight, as mentioned hereinbefore. When the viscosity is decreased by the addition of the active ingredient, an aqueous solution of carboxyvinyl polymer having a higher concentration thereof is used, and thereby, there can be obtained the desired gel having a suitable viscosity. The gel ointment base and gel ointment show less lowering of viscosity by the irradiation of a light and hence are superior in comparison with the conventional gel ointment bases or preparations which are prepared by using conventional basic substances as a viscosity-increasing agent, as is clear from the comparative experiments as disclosed hereinafter. The present invention is illustrated by the following Examples and Experiments, but should not be limited thereto. Hereinafter, "%" means % by weight. Besides, in this invention, the viscosity is measured by using C type viscometer (manufactured by Tokyo Keiki K.K., Japan) at 20° C. Example 1 Carboxyvinyl polymer (Carbopol 940) is dissolved in purified water to give a 4 % aqueous carboxyvinyl polymer solution. To the aqueous solution (12.5 g) is gradually added a 4 % aqueous L-arginine solution (25 g) with stirring, and thereto is added purified water so as to become totally 100 g, and the mixture is uniformly mixed to give a gel having pH 7.3 and a viscosity of 38,000 cP (the concentration of carboxyvinyl polymer: 0.5 %). In the same manner as described above except that the concentration of carboxyvinyl polymer is varied (the amount of L-arginine is double of that of carboxyvinyl polymer), there are prepared gels having the following viscosities. Concentration of carboxyvinyl polymer (%) Viscosity (cP) 4.0 120,000 3.0 87,000 2.0 72,000 1.0 50,000 0.50 38,000 0.25 29,000 0.10 10,000 Example 2 To the 4 % aqueous carboxyvinyl polymer solution (30.0 g) as prepared in Example 1 is gradually added a 4 % aqueous L-arginine solution (60 g) with stirring and thereto is further added purified water so as to become totally 100 g. The mixiture is uniformly stirred to give a gel having pH 6.7 and a viscosity of 56,000 cP (the concentration of carboxyvinyl polymer: 1.2 %). In the same manner as described above except that other amino acids are used instead of L-arginine (the amount of the amino acids is double of that of carboxyvinyl polymer) and the concentration of carboxyvinyl polymer is 1.2 %, there are prepared gels having the following viscosities. Amino acid (addition amount: 2.4 %) Viscosity (cP) L-arginine 56,000 L-serine 48,000 L-histidine 55,000 L-proline 49,000 L-valine 48,000 Example 3 To a 4 % aqueous carboxyvinyl polymer solution (12.5 g) is gradually added a 4 % aqueous L-lysine solution (12.5 g) with stirring to increase the viscosity and further is added a 2 % aqueous triethanolamine solution (17.5 g), and the mixture is stirred and thereto is further added purified water so as to become totally 100 g. The mixture is uniformly stirred to give a gel having pH 7.5 and a viscosity of 41,000 cP (the concentration of carboxyvinyl polymer: 0.5 %). Example 4 Eye drops of disodium cromoglicate (2.0 %): Materials Amount (%) disodium cromoglicate 2.0 1 % aqueous carboxyvinyl polymer solution 25.0 2 % aqueous L-arginine solution 25.0 purified water 48.0 To a 1 % aqueous carboxyvinyl polymer solution is gradually added a 2 % aqueous L-arginine solution and the mixture is stirred to increase the viscosity to give a gel. To the gel is added disodium cromoglicate, and the mixture is uniformly stirred to give a gel preparation (pH 7.3, viscosity 1,100 cP). Example 5 Nosal drops of disodium cromoglicate (2.0 %): Materials Amount (%) disodium cromoglicate 2.0 2 % aqueous carboxyvinyl polymer solution 25.0 2 % aqueous L-serine solution 25.0 2 % aqueous sodium hydroxide solution 10.0 purified water 38.0 To a 2 % aqueous carboxyvinyl polymer solution is gradually added a 2 % aqueous L-serine solution and the mixture is stirred to increase the viscosity to give a gel. The pH is adjusted with a 2 % aqueous sodium hydroxide solution, and thereto is added disodium cromoglicate, and the mixture is uniformly stirred to give a gel preparation (pH 7.4, viscosity 8,200 cP). Example 6 Rectal infusion preparation of insulin (10 U/g): Materials Amount (%) insulin 0.0377 4 % aqueous carboxyvinyl polymer solution 25.0 4 % aqueous L-lysine solution 50.0 purified water 24.9623 To a 4 % aqueous carboxyvinyl polymer solution is gradually added a 4 % aqueous L-lysine solution with stirring and the mixture is continuously stirred to give a gel. To the gel is added a suspension of insulin in purified water, and the mixture is uniformly stirred to give a gel preparation (pH 6.8, viscosity 26,100 cP). Example 7 Rectal infusion preparation of diltiazem hydrochloride (1.0 %): Materials Amount (%) diltiazem hydrochloride 1.0 4 % aqueous carboxyvinyl polymer solution 12.5 4 % aqueous L-valine solution 25.0 2 % aqueous sodium hydroxide solution 10.0 purified water 51.5 To a 4 % aqueous carboxyvinyl polymer solution is added purified water and thereto is gradually added diltiazem hydrochloride with stirring. To the mixture is gradually added a 4 % aqueous L-valine solution and the mixture is uniformly stirred to increase the viscosity and thereto is gradually added a 2 % aqueous sodium hydroxide solution. The mixture is stirred to give a gel preparation (pH 6.9, viscosity 10,000 cP). Example 8 Rectal infusion preparation of diclofenac sodium (2.5 %): Materials Amount (%) diclofenac sodium 2.5 4 % aqueous carboxyvinyl polymer solution 12.5 4 % aqueous L-arginine solution 50.0 purified water 35.0 To a 4 % aqueous carboxyvinyl polymer solution is gradually added a 4 % aqueous L-arginine solution with stirring and the mixture is continuously stirred to give a gel. To the gel is added a solution of diclofenac sodium in purified water and the mixture is uniformly stirred to give a gel preparation (pH 7.2, viscosity 8,000 cP). Example 9 Eye drops of ketoprofen (0.1 %): Materials Amount (%) ketoprofen 0.1 1 % aqueous carboxyvinyl polymer solution 20.0 1 % aqueous L-proline solution 40.0 2 % aqueous sodium hydroxide solution 16.0 purified water 23.9 To a 1 % aqueous carboxyvinyl polymer solution is gradually added a 1 % aqueous L-proline solution with stirring and the mixture is continuously stirred to give a gel. To the gel are added a 2 % aqueous sodium hydroxide solution and a solution of ketoprofen in purified water, and the mixture is uniformly stirred to give a gel preparation (pH 7.8, viscosity 1,000 cP). Experiment 1 As to the gel ointment bases and gel ointments of this invention and reference bases and reference preparations which were prepared in the same manner as described above except that a conventional viscosity-increasing agents (sodium hydroxide, triethanolamine) is used, there were compared the lowering of viscosity by irradiation with a light in a transparent glass vessel. The test conditions (i to v) are shown in the following table. The results are shown in Tables 1 to 5 and Fig. 1 to Fig. 4. In the tables, the carboxyvinyl polymer is represented by "CVP", and the results are shown by the found viscosity at a time after being elapsed for a certain period of time from the initiation of test, and the viscosity retension rate compared with the initial viscosity is also shown within a parenthesis. Test conditions No. Samples Active ingredient Light-irradiation Concentration of CVP (%) Results i Base - Room diffused light 0.5 Table 1 & Fig. 1 ii Base - Direct sun light 0.25 Table 2 & Fig. 2 iii Base - Direct sun light 1.0 Table, 3 iv Ointment Tranexamic acid Direct sun light 1.0 Table 4 & Fig. 3 v Ointment Ketoprofen Direct sun light 1.0 Table 5 & Fig. 4

Claims: Use of an amino acid to stabilize a gel ointment against irradiation of light and to increase the viscosity of the aqueous carboxyvinyl polymer solution of said gel ointment, said gel ointment comprising as a base an aqueous carboxyvinyl polymer solution and an active medical substance selected from the group consisting of a hypnotic, a sedative, an antipyretic, an analgesic, an anti-inflammatory agent, a local anaesthetic, an agent for ophthalmic use, an agent for nasal use, a cardiotonic, an antiarrhythmic agent, a coronary vasodilator, an agent effective for digestic organs, a corticoid, an antiplasmin, a fungicide, an antitumor agent, an antibiotic and a physiologically active peptide, wherein said amino acid is one of the group consisting of valine, isoleucine, serine, cysteine, ornithine, lysine, arginine, histidine, proline, threonine and methionine and is used in an amount of 0.1 to 10.0 % by weight based on the whole weight of the base.

Inventors: KAMISHITA TAKUZO, MIYAZAKI TAKASHI, OKUNO YOSHIHIDE, KAMISHITA, TAKUZO, MIYAZAKI, TAKASHI, OKUNO, YOSHIHIDE
Applicants: TOKO YAKUHIN KOGYO KK, TOKO YAKUHIN KOGYO KABUSHIKI KAISHA
Application year: 1988
Main classification: A61K9
IPC codes: A61K47, A61K9