Alpha-Hydroxy Acids: Unapproved Uses or Indications

Marcia Ramos-e-Silva, MD, PhD; Maria Cristina Ribeiro de Castro, MD; Sueli Coelho da Silva Carneiro, MD, PhD

In This Article

Unapproved Uses

Known as chemical exfoliation, the procedure is done in medical offices so doctors can control the process and prevent deep-skin burns from the highly acidic solutions. The chemical peels cause the skin to lose its outer layer, or peel off, revealing a fresher-looking layer of skin. It also helps to remove undesirable signs of skin aging, such as discoloration, roughness, and wrinkling.[1] Skin peeling products typically contain combinations and different concentrations of several acids such as resorcinol, phenol, salicylic acid, lactic acid, trichloroacetic acid, GA, as well as other AHAs.

Laser treatment of striae rubra and striae alba with the 585-nm pulsed dye laser and topical treatment of striae rubra with 0.1% tretinoin are proven therapeutic options. Unfortunately, laser treatment is not a good alternative for darker skin types, and the efficacy of tretinoin is low. A study was performed to evaluate the effectiveness of topical application of 20% GA for 12 weeks, comparing it to other products. Histopathologic analysis was performed, and the conclusion was that GA and tretinoin produced similar improvement in the appearance of stretch marks: both are safe and effective with minimal irritation. There is increased epidermal thickness and decreased papillary dermal thickness in treated stretch marks when compared with untreated stretch marks, and elastin content within the reticular and papillary dermis can increase with topical 20% GA combined with 0.05% tretinoin emollient cream therapy.[9]

Certain human beings are consistently more attractive to mosquitoes than others. A study was performed with samples of animals and humans. The application of lactic acid markedly increased the degree of attractiveness of formerly less attractive human odor samples. There was almost no response to animal odor samples, and they were preferred at the end over those which were originally the most attractive. In contrast to human samples, which contain a high amount of lactate, this compound could not be detected in samples from the other tested mammals; however, when skin emanations from animals were combined with lactic acid, as many mosquitoes responded to animal samples as they did to human odors. All these data demonstrate that olfactory-based host preference of the anthropophilic mosquito Aedes aegypti is to a large extent due to differences in the amount of lactic acid in the odor samples.[17]

On the other hand, there are studies on human and mouse skin, such as the one by Shirai et al.,[18] showing a repellent effect of L-lactic acid on the mosquito Aedes albopictus, and the repellent effect depended on the concentration of the substance.

Since these insects may be transmitters of diseases, such as yellow fever and dengue fever, this effect must be studied further.

Treatment of postinflammatory hyperpigmentation in patients of Fitzpatrick's skin types IV, V, and VI is very difficult. Although GA peels are useful for hyperpigmented dyschromia in whites, there are no controlled studies examining their safety and efficacy in dark-complexioned individuals. Burns, et al.[19] in 1997, demonstrated that serial GA peels provide an additional benefit with minimal adverse effects for the treatment of post-inflammatory hyperpigmentation in dark-complexioned individuals.

AHA is used with good results for ichthyosis, severe xeroderma, and epidermolytic hyperkeratosis, alone or in association with other oral or topical drugs. A study was performed with these diseases using two different formulations -- a regular and a strong AHA blend cream -- compared with a non-AHA moisturizing lotion. Better results were found with the AHA preparations.[20]

Two patients with confluent and reticulated papillomatosis responded to oral isotretinoin and 10% lactic acid lotion.[21]

A study was organized to evaluate the efficacy, tolerability, and safety of a GA-containing scalp lotion in conjunction with a betamethasone (17-valerate) for psoriasis. In this study, AHAs were clinically investigated as therapeutic modalities, adjuvant to corticosteroids, to diminish systemic and topical adverse side effects most frequently associated with use of the latter. Twenty patients suffering from scalp psoriasis and other psoriatic conditions were included in a double-blind, split-face clinical study using combinations of a 10% (w/w) GA scalp lotion, placebo lotion (excipients only), and a 0.1% (w/w) betamethasone scalp application applied twice daily without any bandage for a period of 8 weeks. Clinical assessments were carried out by highly experienced physician evaluations based on a four-grade scale before treatment and after 2, 4, 6, and 8 weeks. The results demonstrate the efficacy and tolerability of GA scalp lotions, which was improved when used in conjunction with a 0.1% betamethasone scalp application against scalp psoriasis.[22]

Borbujo et al.[23] treated 15 children with facial flat warts, who had been submitted to other unsuccessful therapies previously, with 15% GA gel. There was total disappearance of the flat warts in 14 subjects. The authors concluded that because of its effectiveness and few side effects, 15% GA should be a first choice therapy for verruca plana on the face.