Disinfectant composition

Abstract: A disinfectant composition contains ethyl alcohol with a concentration of not lower than 50% by weight, chlorhexidine, and an organic acid. Even when the concentration of ethyl alcohol is not lower than 50% by weight, chlorhexidine can be compounded therein very stably.

Description: Field of the Invention The present invention relates to a disinfectant composition and, in particular, to stabilization of chlorhexidine in an ethyl alcohol base. Background of the Invention Chlorhexidine, i.e. 1,1-hexamethylenebis[5-(4-chlorophenyl)biguanide], has broad disinfecting action. For example, it has been compounded as a germicidal prophylactic agent for diseases, as an antiseptic, a deodorant, an anti-inflammatory agent in drugs for pyorrhea, and as a disinfectant. As infections within a hospital have often been reported recently, the demand for compounds such as chlorhexidine which can be used broadly for disinfection, is expected to increase. It has been reported that, within hospitals, an infection is transferred from one patient to another by doctors and nurses. Accordingly, it is necessary for them to disinfect their hands completely and rapidly after treating or taking care of one patient before treating or taking care of another. Therefore, various quick-drying disinfectants, mainly composed of ethyl alcohol, have recently been studied. Ethyl alcohol alone is insufficient to disinfect hands. Accordingly, chlorhexidine may be added to ethyl alcohol. However, while chlorhexidine is stable in aqueous solution, its stability is low in ethyl alcohol bases. In order to provide quick-drying and germicidal power, it is preferable for the ethanol content in such a mixture to be at the same level as that in disinfectant ethanol. Although there is a demand for disinfectants in which chlorhexidine is stably compounded while maintaining the germicidal property and quick-drying, no product has been found sufficiently satisfactory. US-A-5334388 discloses antimicrobial towels impregnated with compositions containing an antimicrobial agent such as a biguanide, a volatile liquid such as ethanol, an acidity regulator such as citric or lactic acid such that the pH is preferably about 5, and water. This formulation is intended for application to a towel from which the ethanol evaporates, leaving a dry towel. The pH of the compositions for application to the towels is preferably between 4.5 and 7.5, thus rather neutral than acidic. EP-A-0375827 discloses liquid compositions used in the disinfection of skin which contain chlorhexidine, over 50% of ethanol, and an emollient. Summary of the Invention It has now been found that chlorhexidine can stably be compounded in a highly concentrated ethyl alcohol solution when an organic acid is added thereto. According to the present invention, a liquid composition comprises an organic acid, chlorhexidine and at least 50% by weight ethyl alcohol, and has a pH from 3 to below 4.5. This can be used for disinfecting hands. Description of the Invention Preferably, the organic acid has 2 to 16 carbon atoms. Such organic acids include acetic acid, lactic acid, maleic acid, malic acid, citric acid, salicylic acid, myristic acid, and palmitic acid. Among them, lactic acid and citric acid are particularly preferred. Also, other ingredients may be compounded in the disinfectant composition in accordance with the present invention. For example, glycyrrhizinic acid and its derivatives, drugs such as vitamin E, vitamin E acetate, and vitamin B6, and watersoluble polymers such as xanthan gum, dextrin, hydroxyethyl cellulose, hydroxymethyl cellulose, methyl cellulose, carrageenan, and carboxymethyl cellulose, may be compounded. Further, nonionic surfactants and, in order to increase skin-protecting power, urea or the like may be compounded so as to impart a cleaning effect to the composition. The Drawing Figure 1 is a graph of the relationship between the amount of chlorhexidine remaining, against pH, in lactic acid (o) and citric acid (•) systems. Examples In the following, preferable examples of the present invention will be explained. However, the present invention is not restricted to these examples. Stability of Chlorhexidine vs. Ethyl Alcohol Concentration First, the inventors studied the relationship between ethyl alcohol concentration and stability of chlorhexidine. The aqueous solutions with the ethyl alcohol concentrations listed below and a chlorhexidine content of 0.2% W/V were prepared and then stored for one month each at 50°C and 0°C. Thereafter, chlorhexidine therein was quantitatively determined. The remaining ratio is calculated as the ratio of the amount of chlorhexidine remaining at 50°C with respect to that at 0°C which is taken as 100%. The results are shown in TABLE 1. Ethyl alcohol conc. 0 10 20 30 40 50 60 70 80 Remaining ratio 100 95 81 75 69 65 58 53 48 On the other hand, when quick- dryness and germicidal power are expected to be improved by ethyl alcohol, the concentration thereof should be not lower than 50% by weight or, more preferably, not lower than 70% by weight. Accordingly, the inventors studied how to improve the stability of chlorhexidine in highly concentrated ethyl alcohol. Stability vs. Various Additives In order to stabilize chlorhexidine in ethyl alcohol, the inventors added various materials, which hardly affected human bodies, to a mixture of chlorhexidine and ethyl alcohol. The concentration of ethyl alcohol in the mixture was 80% V/V, while each additive was added thereto so as to attain a content of 0.1% W/V. The stability of chlorhexidine in the resulting mixture was evaluated in the same manner as noted above. The results are shown in TABLE 2. Additive Remaining ratio Allantoin 92% Glycine 91% Citric acid 99% Lactic acid 99% Butyl hydroxy toluene 91% Tocopherol 94% As shown in TABLE 2, it was found that, among various additives, organic acids having a carbon number from 2 to 16 such as citric acid and lactic acid had a remarkably high stability- imparting action. Stability vs. System pH Changed by Addition of Organic Acid Next, in a system having an ethyl alcohol concentration of 80% by weight, the stability of chlorhexidine was evaluated while the pH of the system was changed by the amount of organic acids being added thereto. The stability was evaluated in the same manner as noted above. Since it was difficult to directly determine the pH in a highly concentrated alcohol system, purified water, which had once been boiled and cooled, was added to 5 g of the sample liquid to yield a solution having a whole amount of 50 g. While thus obtained solution was stirred at room temperature, the pH thereof was determined. The results are shown in Fig. 1. As clearly shown in this drawing, advantageous effects were recognized at the region where pH was from 3 to 5. In particular, the optimum region for stabilizing chlorhexidine existed near a pH of 4. As a result, it is understood that citric acid, lactic acid, and the like, as noted above, are preferable as compounds which can adjust, with a small amount thereof being added, the pH of the solution having an ethyl alcohol concentration of not lower than 50% by weight from 3 to 5. In the following, more specific compounding examples of disinfectant compositions in which chlorhexidine was stably compounded will be described. COMPOUNDING EXAMPLE 1 Hibitane gluconate liquid (with 20% chlorhexidine) 1.0 g Cationic surfactant 0.02 Glyceryl triisooctanate 0.4 Citric acid 0.1 Purified water 18.0 Ethanol q.s. to make 100 ml COMPOUNDING EXAMPLE 2 Hibitane gluconate liquid (with 20% chlorhexidine) 1.0 g Cationic surfactant 0.02 Glyceryl triisooctanate 0.4 Lactic acid 0.1 Purified water 18.0 Ethanol q.s. to make 100 ml Both disinfectant compositions in accordance with these compounding examples exhibited an excellent stability. As explained in the foregoing, in the disinfectant composition in accordance with the present invention, as an organic acid is added thereto, chlorhexidine can be compounded therein very stably even when the ethyl alcohol concentration therein is not lower than 50% by weight, thereby satisfying the germicidal property and quick- dryness of the disinfectant.

Claims: A liquid composition comprising an organic acid, chlorhexidine and at least 50% by weight ethyl alcohol, and having a pH from 3 to below 4.5. A composition according to claim 1, wherein the organic acid has 2 to 16 carbon atoms. A composition according to claim 2, wherein the organic acid is lactic acid or citric acid. Use of a composition according to any of claims 1 to 3, for disinfecting hands.

Inventors: FUKUHARA RINA, IGARASHI YASUO, KIMURA TOMOKO, MOTOYAMA AKIRA, SUZUKI TAKASHI, TORII ATSUKO, FUKUHARA, RINA, IGARASHI, YASUO, KIMURA, TOMOKO, MOTOYAMA, AKIRA, SUZUKI, TAKASHI, TORII, ATSUKO, Fukuhara, Rina, c/o Shiseido Research Center (2), Igarashi, Yasuo, c/o Shiseido Research Center (2), Kimura, Tomoko, c/o Shiseido Research Center (2), Motoyama, Akira, c/o Shiseido Research Center (2), Suzuki, Takashi, c/o Shiseido Research Center (2), Torii, Atsuko, c/o Shiseido Research Center (2)
Applicants: SHISEIDO CO LTD, SHISEIDO COMPANY LIMITED
Application year: 1995
Main classification: A01N47
IPC codes: A01N37, A01N47, A01N31, A01N25