Effects of various concentrations of glycolic acid at the corneoxenometry and collaxenometry bioassays

Background  Glycolic acid is an α-hydroxy acid used as a chemical peeling for more than a quarter century. The primary tissue target is the stratum corneum.
Objective  This study aims to assess the effects of various concentrations of glycolic acid on the stratum corneum and collagen fibers using two selected bioassays.
Methods  Corneoxenometry was performed to test the effects on human stratum corneum. Collaxenometry was similarly designed to quantify the effect on sheets of collagen fibers. Different glycolic acid concentrations ranging from 5% to 70% in alcohol were tested, respectively, for 3- and 10-min exposure times.
Results  Both bioassays showed consistent reactivities with a dose–effect relationship when using a 3-min exposure time. By contrast, the tests appeared unreliable or uninformative for the 10-min exposure time.
Conclusion  Corneoxenometry and collaxenometry appear useful for in vitro testing peeling agents during short exposure times.     

果酸在皮肤科的应用

果酸是一种天然无毒的酸,可以降低角质形成细胞的黏着性,加速表皮细胞脱落与更新,同时刺激真皮胶原合成、黏多糖增加及弹力纤维的修复,对抗光老化,改善皮肤干燥,修复屏障功能,已被广泛应用于美容护肤领域。本文就果酸的历史发展、化学种类、作用机制、临床应用、不良反应进行综述。     

The therapeutic value of glycolic acid peels in dermatology

Chemical peeling or chemexfoliation has become increasingly popular in recent years for treatment of a number of cosmetic skin problems. Topical glycolic acid in the concentration of 10-30% for 3-5 minutes at fortnightly intervals was investigated as a therapeutic peeling agent in 41 patients having acne (39%), melasma (36.5%), post inflammatory hyperpigmentation (12%) and superficial scarring of varied etiology (12%). A final evaluation done at 16 weeks revealed that this modality is useful especially in superficial scarring and melasma, moderately successful in acne patients with no response in dermal pigmentation. No significant untoward effects were seen.     

Biweekly serial glycolic acid peels vs. long-term daily use of topical low-strength glycolic acid in the treatment of atrophic acne scars

BACKGROUND AND OBJECTIVE: Treatment of atrophic acne scars is difficult and generally unsatisfactory. Although many clinical studies have been performed to investigate the efficacy of glycolic acid in the treatment of acne vulgaris, to the best of our knowledge no placebo-controlled study has been carried out to ascertain the effect of glycolic acid on atrophic postacne scars. DESIGN: A single, blind, placebo-controlled, randomized comparative clinical study was conducted in 58 women with atrophic acne scars. The subjects were randomly divided into three study groups. Glycolic acid peels with 20%, 35%, 50%, and 70% concentrations were applied serially at 2-week intervals to 23 patients in Group A. Twenty patients in Group B used a 15% glycolic acid cream once or twice daily for a period of 24 weeks. The remaining 15 patients in Group C applied a placebo cream twice daily during the same period. RESULTS: The differences between the results in the different groups were statistically significant at week 24 (P<0.001). Home application of low-strength glycolic acid was better tolerated and had less side-effects than glycolic acid peels; however, repeated short-contact 70% glycolic acid peels provided superior results compared with the maintenance regimen (P<0.05), and apparently good responses were observed only in the peel group (P<0.01). CONCLUSIONS: Glycolic acid peeling is an effective modality for the treatment of atrophic acne scars, but repetitive peels (at least six times) with 70% concentration are necessary to obtain evident improvement. Long-term daily use of low-strength products may also have some useful effects on scars and may be recommended for patients who cannot tolerate the peeling procedure.     

Efficacy of glycolic acid peels in the treatment of melasma

BACKGROUND: Melasma is an acquired hypermelanosis that is often recalcitrant to treatment with hypopigmenting agents. OBJECTIVE: To assess the efficacy of 4% hydroquinone cream vs 4% hydroquinone cream combined with glycolic acid peels as treatment for melasma. METHODS: Twenty-one Hispanic women with bilateral epidermal and mixed melasma were enrolled in a split-faced prospective trial lasting 8 weeks. Patients underwent 20% to 30% glycolic acid peels every 2 weeks to one side of the face only in addition to twice-daily full-face application of 4% hydroquinone cream and sun protective factor 25 UV-B sunscreen each morning. Pigmentation was measured objectively using a mexameter and the Melasma Area and Severity Index and subjectively using a linear analog scale and physician and patient global evaluation. RESULTS: Hydroquinone treatment alone and treatment with the combination of hydroquinone and glycolic acid had a significant effect in reducing skin pigmentation compared with baseline (P<.001). However, no significant difference was found using combination therapy compared with hydroquinone alone (P =.75). CONCLUSIONS: Use of 4% hydroquinone and a daily sunscreen is effective in the treatment of melasma; however, the addition of 4 glycolic acid peels did not enhance the hypopigmenting effect of hydroquinone treatment alone.     

皮果酸治疗黄褐斑的临床疗效观察

目的:观察羟基乙酸(果酸)治疗黄褐斑的临床疗效和安全性,掌握果酸治疗的适应证及方法.方法:应用质量浓度分别为20%、35%、50%、70%的果酸对64例黄褐斑患者进行治疗,每2周1次,4次治疗为1个疗程.由两名资深皮肤科医生对患者进行黄褐斑皮损面积和严重程度指数(MASI)评分,采用自身前后对照进行疗效观察,记录患者出现的不良反应.结果:随着疗程的增加,患者的MASI评分逐渐下降.共有63例患者完成第1个疗程,表皮型黄褐斑有效率81.82%,混合型有效率40.00%,表皮型比混合型患者MASI下降更显著(P < 0.05);Ⅲ型皮肤黄褐斑患者有效率39.13%,Ⅳ型有效率75.00%,Ⅳ型皮肤比Ⅲ型皮肤患者MASI下降更显著(P<0.05).完成2个疗程的41例患者中,第1个疗程结束时有效率为41.46%,第2 个疗程结束时有效率为78.05%,MASI值下降有统计学差异(P<0.05).63例患者能耐受质量浓度为70%的果酸.刺痛、瘙痒等不良反应均在对症处理后消失.结论:果酸治疗黄褐斑,是一种安全有效且不良反应少的治疗方法;对于表皮型黄褐斑患者及Ⅳ型皮肤黄褐斑患者疗效尤佳.     

Interest of the association retinaldehyde/glycolic acid in adult acne

Background  Topical retinoids have been successfully used in the treatment of acne vulgaris but may induce irritation when used twice daily. The association of retinaldehyde (RAL) with glycolic acid (GA) have complementary activities, which could be of interest for adult women with acne because of a better tolerance/efficacy ratio. The aim of this study was to evaluate the tolerance and the efficiency of RAL (0.1%)/GA (6%) in adult women with acne when used alone or in combination with their usual acne products except retinoids.
Methods  Three hundred ninety-seven women with acne (aged between 30 and 40 years old) were included in this open multicentric study. They had to apply cream containing RAL/GA for 90 days without stopping their previous acne treatment (except topical retinoids). The tolerance was the main criteria and the second one is the efficacy, which was assessed by counting inflammatory and retentional lesions after 30 and 90 days of treatment.
Results  Used alone or in association with other anti-acne treatments, RAL/GA was considered to be highly tolerated. A significant decrease in both inflammatory and retentional lesions between day 0 and day 90 indicates that RAL/GA can be used as monotherapy for mild acne or could potentate the efficiency of other anti-acne products used at the same time by patients suffering from moderate acne. Complaints about side-effects were rare. The subjective evaluation of the preparation's efficacy by investigators and patients was strongly favourable.
Conclusion  These data show that a combination of RAL 0.1% and GA 6% may be used in association with other topical anti-acne treatments with an excellent tolerance.     

Effects of glycolic acid on desquamation-regulating proteinases in human stratum corneum

In order to investigate the mechanism of glycolic acid (GA) function in human stratum corneum, we monitored changes in cathepsin D-like (CD) and chymotrypsin-like (SCCE) proteinases for 3 weeks following topical GA application (50% w/v, pH 0.9) for 30 min to human skin. In the early phase, weakened stratum corneum cohesion in the lower layers was observed on day 2 and the amount of active CD in the upper layer of the stratum corneum was significantly decreased from 30 min until day 2, whereas that in the lower layer remained normal. In contrast, the amount of active SCCE showed no change during the experimental period. The surface pH of the stratum corneum drastically decreased to pH 2 at 30 min and slightly recovered to around pH 3 until 1 day after treatment. From 9 to 19 days, a decrease in corneocyte cell area and a remarkable long-term increase in the amount of active CD in the upper layer were observed. In an in vitro study, the activities of desquamation-regulating proteinases were shown to have remarkably increased at around pH 3, due to activation of CD at its optimal pH. These results suggest that GA functions via at least two different mechanisms, acute activation of CD in the lower layer by acidification around pH 3, along with inactivation of CD in the upper layer, and long-term enhancement of de novo CD production in the few weeks following GA treatment.     

Effect of glycolic acid on UVB-induced skin damage and inflammation in guinea pigs

OBJECTIVES: Recently the use of glycolic-acid-containing cosmetics has received increased public interest in their supposed ability to reduce wrinkles, roughness, age spots and other skin damage. However, the safety of such products when used excessively or chronically, especially by photosensitive people, is being questioned. The purpose of this study was to examine the effects of glycolic acid alone or in combination with UVB on skin damage and inflammatory response. METHOD: Guinea pigs were treated with glycolic acid (from 1 to 7 mg/cm(2)) alone or in combination with UVB (0.4 or 3 J/cm(2)) for 14 days. Skin damage was evaluated by scoring the skin irritation value by the method of Draize and by histopathological observations. Cyclooxygenase 2 (COX-2) expression and prostaglandin E(2) (PGE(2)) production were also assessed. RESULTS: Glycolic acid caused an increase in the level of skin damage in a dose- and time-dependent manner. Lower doses (1 and 3 mg/cm(2)) of glycolic acid mostly caused erythema and eschar, and these consequently formed scales, whereas higher doses (5 and 7 mg/cm(2)) of glycolic acid caused redness, edema and necrotic ulceration. Glycolic acid also increased the thickness of the epidermal layer, reduced the organization of the stratum corneum and eventually destroyed some parts of the epidermal layer at 7 mg/cm(2). UVB (0.4 and 3 J/cm(2)) caused redness and edema as well as reduced the integrity of the stratum corneum. Glycolic acid enhanced the UVB-induced skin damage. The magnitude of the damage caused by combined UVB and glycolic acid treatment was much greater than that caused by glycolic acid or UVB alone. Moreover, partial destruction of the epidermal layer was observed in skin treated with 3 J/cm(2) UVB and 3 mg/cm(2) glycolic acid. However, glycolic acid did not change the basal and UVB-induced PGE(2) production and COX-2 protein expression. CONCLUSION: These results show that glycolic acid causes skin damage in a dose- and time-dependent manner and that it enhances UVB-induced skin damage without accompanying PGE(2) production or COX-2 protein expression. Therefore, caution should be exercised by those using glycolic acid on a chronic basis or excessively. Moreover, those with photosensitive skins and those more exposed to the sun should be particularly careful.     

Safety and efficacy of glycolic acid facial peel in Indian women with melasma

BACKGROUND: Melasma is a common disorder of facial hyperpigmentation. Many modalities of treatment are available, but none is satisfactory. MATERIALS AND METHODS: Twenty-five nonpregnant female patients with a minimum melasma area and severity index (MASI) of 15 were recruited in the study. After a detailed history and clinical examination under natural light and Wood's light, MASI was calculated and color photographs were taken of all patients. Patients were advised to carry out a prepeel program of daily application of topical sunscreens (sun protection factor-15, SPF-15) and 10% glycolic acid lotion at night for 2 weeks. Patients were then treated with 50% glycolic acid facial peel once per month for three consecutive months. At regular intervals and at the end of the follow-up period (3 months) after the last peel, the degree of improvement in pigmentation was assessed by remeasuring MASI. Side-effects, if any, were also recorded. The data obtained were statistically analyzed using Student's paired t-test and Spearman rank correlation coefficient test. RESULTS: Improvement in melasma (reduction in MASI) was observed in 91% of patients (P < 0.01). Patients with epidermal-type melasma demonstrated a better response to treatment than those with mixed-type melasma (P < 0.05). CONCLUSIONS: The prepeel program followed by 50% glycolic acid facial peel once per month for three consecutive months proved to be an effective treatment modality in Indian patients without any significant side-effects.     

果酸联合丹参酮治疗痤疮疗效评价

目的:评价果酸联合丹参酮治疗寻常痤疮的疗效。方法:90例寻常痤疮患者随机分成两组,治疗组采用果酸治疗,每周2次,同时口服丹参酮胶囊,4粒/次,3次/d;对照组单纯用果酸治疗,8周后观察疗效。结果:治疗组有效率为80.43%,对照组为61.36%,两组疗效比较差异有显著性(P0.05),两组均未发现明显不良反应。结论:果酸联合丹参酮治疗寻常痤疮疗效较好。     

Comparative effects of retinoic acid, glycolic acid and a lipophilic derivative of salicylic acid on photodamaged epidermis.

BACKGROUND: Studies comparing purported antiaging compounds are rare. OBJECTIVE: To compare in a randomized, placebo-controlled double-blind study 10% glycolic acid (GA), 2% 2-hydroxy-5-octanoyl benzoic acid (beta-lipohydroxy acid, LSA) and 0.05% all-trans-retinoic acid (RA). METHODS: Women volunteers treated one forearm twice daily with one of the active products and the other one with the vehicle. Comparative evaluations of efficacy were made using histochemistry and quantitative immunohistochemistry. RESULTS: Improvement in the various epidermal compartments was the most prominent finding at the RA-treated site. The LSA-treated site also exhibited similar positive changes, although to a lesser degree. GA showed no significant effect. CONCLUSION: In the presently tested concentrations and formulations, RA had a beneficial impact upon the aging epidermis. LSA mimicked RA but with somewhat lesser efficacy. By contrast, GA appeared almost inactive.