JPS6130567A - Method of stabilizing urea - Google Patents

Abstract

PURPOSE:To suppress a decomposition reaction of urea and to keep its stability for a long period, by blending an aqueous solution of urea with a basic amino acid salt. CONSTITUTION:An aqueous solution of urea is blended with a basic amino acid salt (e.g., histidine, lysine, ornithine, arginine, etc. as basic amino acid; hydrochloride, hydrobromide, pyrrolidonecarboxylate, urocanate, etc. as salt). An amount of it added is preferably =1/10-=3 times as much as urea by weight. Urea has raising action on moisture absorption of keratin of the skin and keratin-dissolving action, and is capable of being blended with pharmaceutical preparations for external use for ichthyosis, senile xeroderma, atopic dermatitis, etc. It may be blended with cosmetic to raise insulation effectiveness, and its simple aqueous solution can be orally administered as a diuretic.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for maintaining the stability of urea for a long period of time in a preparation containing an aqueous urea solution.

[Prior art] Urea has the effect of increasing the hygroscopicity of the stratum corneum of the skin and has a keratin-dissolving effect, so it is often incorporated into external preparations for diseases such as ichthyosis, senile xeroderma, and atopic dermatitis. It has also been incorporated into cosmetics to enhance its moisturizing effect. In addition, a simple aqueous solution may be taken orally as a diuretic.

However, it is known that urea gradually decomposes in the coexistence of water, and this decomposition is further accelerated in the coexistence of acids and alkalis. When urea decomposes, ammonia gas is generated, and as is well known, this gas has a strong pungent odor.
This was a major drawback.

[Problems to be Solved by the Invention] In view of the above circumstances, the present inventors have completed the present invention as a result of intensive studies to suppress the decomposition reaction of urea and develop a stable urea aqueous solution formulation.

[Means for Solving the Problems] That is, the present invention is a method for stabilizing urea, which is characterized by blending a basic amino acid salt into an aqueous urea solution.

The present invention will be explained in detail below.

The basic amino acids constituting the basic amino acid salt used in the present invention include histidine, lysine, ornithine, and arginine, and the salts include hydrochloride, hydrobromide, pyrrolidone carboxylate, and urocanate. Organic acid salts such as can also be used.

The amount of basic amino acid salt added can be selected appropriately depending on the amount of urea to be mixed, storage conditions, period, etc., and the desired degree of suppression of decomposition, but the amount of basic amino acid salt increases relative to the amount of urea. The greater the suppression effect. The amount of basic amino acid salt added for the purpose of improving stability is at least 1/10 times the weight of urea,
Desirably 3 times or less. However, care must be taken when adding an excessive amount of the basic amino acid salt, since the basic amino acid salt itself deteriorates, causing discoloration, odor, etc. Further, the concentration of the urea aqueous solution used in the present invention is arbitrary.

Furthermore, even if the urea aqueous solution is emulsified with an oil phase or the like to form an emulsion preparation, the effects of the present invention will not be affected at all.

In order to track the decomposition of minute amounts of urea, it is convenient and accurate to observe pH changes. That is, when urea decomposes, ρII increases. The pl (changes, etc.) of the system when urea and basic amino acid salts are used together are shown below. This is an evaluation result of pH value ratio change and ammonia odor of 8 liquids.In the case of an aqueous solution containing only urea without adding basic amino acid salt, the ρ11 value increases,
Along with this, an ammonia odor is generated. However, in the case where the basic amino acid salt of the present invention was added, although there was a slight change in pl+, it was suppressed to a fairly low level, and no ammonia odor was observed.

[Examples] Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example I A, Setanol 3.0% Solid Paraffin 5.0 Vaseline
15.0 Liquid paraffin
20. OB, urea
2.0゛1 Luginine Hydrochloride
5,0 Lysine acetate 1.0 Purified water Quantity with the total as 100 Mix the components contained in A, heat to 70°C, and add to the similarly heated component (3). After the emulsification treatment, a cooling treatment was performed to obtain a urea formulation for external use.

Comparative Example 1 4) in which no basic amino acid salt was added to the recipe of Example 1.

After storing the samples of Example 1 and Comparative Example 1 for two months at 40°C, urea was quantitatively determined.
While 99% of urea remained, in Comparative Example 1, 8.
It decreased from 0 to 85%.

Example 2 Urea 5.0% Refined sugar 2,01,-ornithine hydrochloride 3.0 Purified water
90.0 Mix and dissolve each component in purified water to prepare an internal diuretic.

Comparative Example 2 11. Products without ornithine hydrochloride added.

After storing the samples of Example 2 and Comparative Example 2 for two months at 40°C, urea was quantitatively determined.
While 99% of urea remained, in Comparative Example 2, it decreased to 76-83%.

Claims (1)

[Claims] A method for stabilizing urea, which comprises adding a basic amino acid salt to an aqueous urea solution.