Hydroxy-kojic acid skin peel

Abstract

The subject of the present invention is a hydroxy-kojic acid skin peel.

Description

[0001] The present application is a continuation-in-part of co-pending U.S. patent application Ser. No. 08 / 328,006 filed Oct. 24, 1994. The entire text of the above-referenced disclosures is specifically incorporated by reference herein without disclaimer.[0002] The present invention relates to skin peels utilizing alpha and beta hydroxy or keto acids as a topical treatment for hyperpigmentation, melasma, dyschromia, rhytides, photodamage and aging. Preferred peels contain alpha and beta hydroxy or keto acids with kojic acid or its derivatives in a dermatologically acceptable carrier such as an ethanoic / water mixture. Optionally, hydroquinone or its derivatives and other skin lighteners may also be employed in the peel when conditions warrant.DESCRIPTION OF RELATED ART[0003] Skin peels are classified into three general types: light or superficial, medium and deep.[0004] The deep peel utilizes phenol as a primary ingredient. Phenol (C.sub.6H.sub.5OH) obtained from coal tar and also c...

AI Technical Summary

Benefits of technology

[0015] It is another object of this invention to provide a safe and efficient peel in the treatment of regional hyperpigmentation caused by melanocytic hyperactivity, such as idiopathic melasma occurring during pregnancy or melasmas secondary to estrogen-progesterone contraception. The peels of the present invention are also effective for localized hyperpigmentation and benign melanocytic proliferations, such as senile pigmentary spots, actinic photosensitization and post-lesion scarring.

[0017] The present invention relates to alpha and beta hydroxy or keto acid skin peels with kojic acid or derivatives thereof in an ethanol / water carrier. Skin peels of the present invention utilizing alpha and beta hydroxy or keto acids with kojic acid induce beneficial biomolecular events in the skin such as stratum corneum separation in sheetlike fragments due to reduced comeocyte cohesion. This sheetlike separation is histologically found to occur at the innermost level of the stratum corneum just above the stratum granulosum, resulting in a beneficial thinning of the stratum corneum. In aged skin the thickness of the stratum corneum may reach as high as 70 to 80 cells thick due to lowered activity of certain desquamatory regulating enzymes. Periodic therapeutic skin peels with the present invention will result in a stratum corneum that is more resilient with a thickness of 16 to 20 cells thick which is more typical of 20 year old skin. Stratum corneums rebuilt utilizing the therapeutic skin peels of the present invention will exhibit improved barrier function due to increased levels of ceramides produced by keratinocytes. The stratum corneum barrier is largely dictated by extracellular lipids consisting of a mixture of ceramides, cholesterol and fatty acids together with smaller amounts of cholesterol sulphate, glucosyl ceramides and phospholipids. In addition to their pivotal role in barrier function, these lipids are also important for the desquamatory and mechanical properties of the stratum corneum. The levels of stratum corneum lipids, especially ceramides and their subtypes, are optimized by the correct selection of the most appropriate skin peel based on the Fitzpatrick skin type classification, Glogau photodamage classification system and whether the patient has a desquamatory disorder or other skin condition. Stratum corneum rebuilding allows the atrophic epidermis caused by intrinsic and extrinsic aging to regain normal or near-normal thickness and appearance. Dermal alterations due to application of the preferred embodiment of the present invention include increased accumulation of dermal glycosaminoglycans, including hyaluronic acid. Accelerated formation of collagen will ensue with periodic application of the present invention. Clinically visible increased plumpness of the skin will occur in most patients, resulting in a more attractive, youthful appearance.

[0039] Ascorbic acid is a lactone form of 3-keto-2,4,5,6-tetrahydroxyhexan-oic acid, which is both an alpha hydroxy acid and a beta keto acid. L-ascorbic acid is both a regulator and stimulator of collagen synthesis and plays a vital role in the performance of the peel in several preferred embodiments of the present invention because of the potent antioxidant and skin lightening effect.

[0044] Malic acid is a dicarboxylic acid with one hydroxyl group at the alpha position of the acid, similar to the compound formed from one molecule of glycolic acid and one molecule of acetic acid. Malic acid is nontoxic and is present as a carbohydrate metabolite in the skin. Certain embodiments of the present invention utilize malic acid to increase mucopolysaccaride production.

[0045] Hydroquinone, hydroquinone monobenzyl ether, and hydroquinone monethyl ether act as substitute substrate for the melanization enzyme tyrosinase and may be included in certain peels to enhance the skin lightening ability of said peel. The addition of citric acid and malic acid in peeling containing hydroquinone or its derivatives serve to act as antioxidants to help stabilize the hydroquinone in the peel and to enhance the penetration and the efficacy of hydroquinone.

Problems solved by technology

Phenol is directly toxic to the myocardium and cardiac arrhythmias have been reported with many phenol peels.

If a high dose is used they are also hepatotoxic and nephrotoxic.

The possibility of complications from the aforementioned deep phenol peels is significant.

Unsightly pigmentary occurrences that may result from the said phenol peels include hyperpigmentation, hypopigmentation, porcelain depigmentation, visible lines of demarcation with unpeeled skin and nevi accentuation.

Medium depth peeling with trichloroacetic acid does not require hospital care and general anesthesia as the phenol deep peels do, nor is there near the number of possible complications and adverse results, however, there is a significant risk of scarring at high concentrations of trichloroacetic acid.

None of the prior art, to applicant's knowledge, discloses a superficial peel utilizing alpha and beta hydroxy or keto acids with kojic acid or its derivatives to treat photodamage, rhytides and pigmentary dyschromias.

Further, prior art relating to therapeutic skin peeling does not disclose use of citric acid, a major component of the Kreb's cycle, tricarboxylic acid cycle or citric acid cycle as it is variously referred to in mammalian metabolism.

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