Pyruvic Acid versus Salicylic Acid Peels in the Treatmentof Acne Vulgaris
Acne vulgaris is a common skin disorder affecting most individuals in the teenage years but also affecting anyone from childhood to middle age. The treatment for acne dates back to Egyptian times when sulfur was used, to recent times with new forms of treatment with peeling, lasers and lights(1).
The pathogenesis of acne involves: androgenic stimulation of sebaceous glands, abnormal follicular hyperkeratinization, obstruction of the pilosebaceous follicle, and inflammation. The obstructed pilosebaceous follicle is an ideal medium for the proliferation of Propionibacterium acnes. The obstructed follicle can rupture, leaking its contents into the dermis, causing inflammatory lesions such as papules and pustules(2).
Acne vulgaris resolves completely without major sequelae in most patients, but in a few, it may leave behind disfiguring scarring or hyperpigmentation, especially in patients with dark skins living in areas with high sun exposure.
Chemical peels are a mainstay in the cosmetic practitioner’s armamentarium because they can be used to treat some skin disorders and can provide an aesthetic benefit. Chemical peeling has been used for acne for many years. In addition to its epidermal resurfacing properties, it leads to remodeling of collagen and elastin fibers and deposition of glycosaminoglycans, thereby decreasing scars. Because of the resurfacing of the epidermis, the melanin content is decreased, and it is more evenly distributed, improving hyperpigmentation(3). In addition, chemical peels may be readily combined with other resurfacing and rejuvenation procedures, often providing synergistic treatment and more flexibility in tailoring treatments to specific patient needs(4).
Moreover, chemical peels acts as an adjunct to medical therapy in acne vulgaris because they produce complementary rapid therapeutic effects and improvement in skin appearance and texture(5). Briden(6) stated that superficial chemical peels offer great flexibility over a range of skin types and conditions with minimal to no “downtime”.
Superficial peels are useful in the treatment of mild dyschromias, acne, post-inflammatory pigmentation, and actinic keratosis and help in achieving skin radiance and luminosity. Superficial peels can be used in nearly all skin types, and exert their actions by decreasing corneocyte adhesion and increasing dermal collagen(7).
Salicylic acid is a hydroxy derivative of benzoic acid and represents a carboxy acid attached to an aromatic alcohol phenol known as a b-hydroxy acid and used in the treatment of various dermatologic diseases as a superficial peeling agent(4-6). Salicylic acid is considered as an organic solvent as it removes the intercellular lipids that are covalently linked to the cornified envelope that surrounds the cornified cells. It can extract integral proteins from the desmosomes, including desmogleins, and thus destroy the cohesion of the epidermal cells(8).
Moreover, salicylic acid may activate certain pathways involved in the normal hydrolytic shedding of cornified cells. It has a peculiar characteristic of lipophilicity that makes salicylic acid peel act mainly on superficial layers of the epidermis and sebaceous glands which are hyperactive in acne. In addition, salicylic acid at a high concentration exfoliates only the cornified cells of the epidermis and hair follicles without any degenerative or inflammatory changes, leading to regeneration of the epidermis and the papillary dermis. The comedolytic and anti-inflammatory effects of salicylic acid are suitable for both inflammatory and non-inflammatory acne lesions(9).
Alpha-keto acids are a group of compounds that have demonstrated a keratolytic action and therefore have been proposed as alternative peeling agents in the treatment of acne(10).
Pyruvic acid (CH3-CO-COOH) is an alpha keto acid that converts physiologically to the corresponding alpha hydroxy acid, lactic acid (2-Hydroxypropianoic acid) which is a good moisturizing and humectant agent. These properties make it a unique topical peeling agent, combining the keratolytic action of an alpha-keto acid and the humectant effect of lactic acid. Because of its low pKA of 2.39 and its small molecule dimension with 3 carbon atoms, it penetrates rapidly and deeply through the skin. The application of pyruvic acid in concentrations of 40% - 70% induce keratinocyte detachment with thinning of the upper layers of the epidermis ,then it penetrates down to the upper papillary dermis and causes dermo-epidermal separation with increased production of collagen, elastic fibers, and glycoproteins(11). In addition to its keratolytic and desmoplastic properties, pyruvic acid has a demonstrated antimicrobial activity. Ghersetich et al(10) stated that pyruvic acid, has been used as a medium depth chemical peeling agent in subjects with actinic keratosis, warts, greasy skin, inflammatory acne and moderate acne scars.
No well controlled studies have directly compared the efficacy of b-hydroxy acid and alpha keto acid in the treatment of mild to moderate acne vulgaris.
This study aims to evaluate the clinical efficacy and tolerability of pyruvic acid versus salicylic acid peels at gradually increasing concentrations in non-inflammatory and inflammatory acne vulgaris in a split-face design.
Patients and Methods
Forty patients (32 females and 8 males) with mild to moderate facial acne vulgaris were included in this study. All patients were of Fitzpatrick skin type III and IV. Their ages ranged from 12 to 25 years, with a mean (19.55± 2.72). The patients were clinically classified into 2 groups; group I (15 patients) with non-inflammatory facial acne vulgaris presenting mainly with comedones and group II (25 patients) with inflammatory facial acne vulgaris presenting mainly with papules and pustules. Exclusion criteria included patients using topical or systemic treatment for acne vulgaris within 4 weeks before the study, occupation that requires inevitable sun exposure, intolerability to sun, any contraindication for peeling such as recent or recurrent viral infection, hypertrophic scars or keloid formers, active bacterial or fungal infection. Ethical committee approval and Informed written consents were obtained from all patients. Digital photographs were taken for each patient before the first session as a baseline and at the end of treatment, and then during follow-up period.
Peels were performed using pyruvic acid versus salicylic acid in the same patient in a half face model at gradual increasing concentrations. The skin was cleaned and degreased before application of peeling agent by scrubbing with a cotton gauze soaked in 70% ethanol. Pyruvic acid (Aldrich chemical Co Ltd, England) was formulated at 40%, 50% and 60% concentrations in a hydroethanole solution.
Salicylic acid (El-Gomhuria Co, Egypt) was formulated in a hydroethanol vehicle at concentration of 20% and 30% on a weight-to-volume basis. Pyruvic acid peel was applied with a cotton tipped applicator to the right half of the face starting at the forehead progressing to the zygomatic cheeks , chin , upper lip and finally the nose , proceeding from central to periphery, it was neutralized after 2-4 min by application of solution of 10% sodium bicarbonate in water. Salicylic acid was applied to the left half of the face in the same manner by a wedge sponge, then inactivated by cold water soaks within 5-10 min. Post peel emollient cream was applied after neutralization of peeling agent.
Treatment sessions were repeated at a weekly interval for a total of 8 sessions. After each session patients were instructed to avoid sun exposure, use appropriate sun screen (at least SPF 30) and avoid friction or rubbing. Clinical evaluation of peeling efficacy was assessed in terms of percentage reduction of lesion count at each visit by two physicians. Efficacy was further graded as excellent (>80% improvement), very good (66-80%), good (51-65%), fair (25-50%) and poor (<25%).
Before each session all subjects were asked whether they experienced burning, redness, crusting or dryness after the previous session for safety evaluation. Moreover, they self-assessed their side effects by completing cards listing possible events such as of erythema, dryness, burning, stinging itching, crust or hyperpigmentation that occurred during the peeling period. Also, recurrence rate was evaluated during follow up period, monthly for 3 months.
Clinical efficacy evaluation
After the first peeling session: patients of both groups showed no skin changes or clinical improvement by using the lower concentration of pyruvic acid (40%) on the right hemiface and salicylic acid peel (20%) on the left hemiface (Fig. 1). So, all the patients were treated with the higher concentration in the subsequent sessions. Five patients in group I and 6 patients in group II was treated with 50% pyruvic acid from the second session to the end as they developed erythema after the second session, whereas 60% pyruvic acid was used for the rest of the patients from the third session to the end of peeling sessions. Salicylic acid 30% was used for all patients in both groups from the second session up to the end.
With pyruvic acid peels, the mean numbers of acne lesions were significantly reduced by 31.04% and 46.67% in group I and II respectively at mid treatment sessions (4 sessions), (p< 0.05). After the end of peeling sessions, the mean number of acne lesions showed a further reduction to 44.38% and 69.21% in group I and II respectively. During the follow up period, the mean numbers of acne lesions reduction was 40.08% and 60.71% in group I and II respectively. The reduction in the number of acne lesions as well as the grades of efficacy in group II were significantly higher than in group I, (p<0.05), (Tables 1 & 2). The patients in group II showed excellent improvement in 24% of patients (Fig. 2), very good improvement in 36%, good improvement in 20%, fair improvement in 16% and poor improvement was seen in only 4% of patients after the end of pyruvic acid peeling sessions (Table 4). The patients in group I showed less favorable results with pyruvic acid peels, as excellent improvement was not observed in any of those patients, very good improvement in 6.67%, good improvement in 20%, fair improvement in 26.67% and poor improvement was seen in 46.67% of those patients, (Table 3). After the end of peeling sessions, patients of both groups reported a smooth skin texture with an overall improvement in their appearance and marked reduction of post-inflammatory pigmentation.
On the other hand, salicylic acid peel significantly decreased the mean number of acne lesions by 52.86% and 43.04% (p< 0.05) in group I and II respectively at the end of 4th session (mid treatment). After the end of treatment (8 peeling sessions), mean number of acne lesions reduction was 73.40% and 65.83% in group I and II, whereas they were 68.01% and 58.72% during the follow up period, in group I and II respectively (Tables 1 & 2). The reduction in the number of acne lesions and the grades of efficacy between both groups showed non-significant differences, (p > 0.05), (Tables 1 & 2). The patients of group I showed excellent improvement in one patient (6.67%), very good improvement in 6 patients (40%) (Fig. 3), good improvement in 4 patients (26.67%), fair improvement in 3 patients (20%), and poor improvement in one patient (6.67%) after the end of 8 sessions with salicylic acid 30% peels, (Table 3). While patients of group II showed excellent improvement in 4 patients (16%) (Fig. 4), very good improvement in 9 patients (36%), good in improvement in 7 patients (28%), fair improvement in 5 patients (20%), and none of the patients had poor improvement, (Table 4). There was non-significant difference regarding the clinical efficacy between patients of group I and group II, (Tables 3 & 4).
All patients of both groups reported that the sessions of salicylic acid peels also facilitated the resolution of facial post-inflammatory hyperpigmentation and lightening of the skin which was cosmetically acceptable and satisfactory to the patients.
Salicylic acid peels had a significantly higher reduction in the mean number of acne lesions and a higher clinical efficacy grades than pyruvic acid peels in patients of group I, (Table 1, Fig. 5). In contrast, non-significant difference in these parameters was found between salicylic and pyruvic acid peels in group II (Table 2, Fig. 6).
Tolerability and safety evaluation:
Pyruvic acid peeling (50% & 60%) was well tolerated and the patient compliance was excellent in both groups. Few patients suffered from mild stinging, burning and slight desquamation, (Tables 5 & 6). While during peeling with 30% salicylic acid, all patients of both groups complained of stinging, burning, and scaling. All patients of both groups had a facial tightness and smooth skin immediately after the peeling session.
In group I, itching occurred in 3 patients, (20%), erythema in12 patients, (80%), dryness in 8 patients (53.33%), intense desquamation in 6 patients, (40%), and crustation in 3 patients, (20%), (Table 5). In group II, itching occurred in 9 patients (36%), erythema in 22 patients, (88%), dryness in 10 patients (40%), intense desquamation in 18 patients, (72%), and crustation in 4 patients (16%), (Table 6). No post-inflammatory hyperpigmentation, infection, vesiculation, edema or scarring was noted in patients of both groups for both types of peels.
Pyruvic acid peels was better tolerated than salicylic acid peels with less adverse events with statistically significant difference as compared to each other, in patients of both groups (Tables 5 & 6).