Comedogenicity of cosmetics: a review

Adverse reactions associated with the use of cosmetics include comedones and folliculitis that substantiate the potential of cosmetic products to induce, aggravate or prolong acne.
Acne cosmetica is a particular facial variant of acne. It commonly affects young adult women who use cosmetics. Key to the management of acne cosmetica is the avoidance of comedogenic cosmetics. Thus, it is of crucial importance to evaluate cosmetics with respect to their comedogenicity. Methods of assessment include animal models, human models and clinical trials. Among them, the rabbit ear assay, although not ideal, is the best available.
Today, most commercial products are safe. However, dermatologists should remain vigilant and provide the guidelines for beneficial use of cosmetics to acne-prone individuals.     

Enhanced comedo formation in rabbit ear skin by squalene and oleic acid peroxides

The comedogenicity of UVA-irradiated and non-irradiated substances (squalene, oleic acid, tetradecane, isopropyl myristate, squalane and liquid paraffin) was evaluated by surface microscopy and histological examination after treating the ventral skin of rabbit ears with these substances. The lipid peroxide levels of these substances were also measured. Squalene itself was scarcely comedogenic but squalene peroxides were highly comedogenic. Both oleic acid and its peroxides were able to induce fairly large comedones and there was a good correlation between the lipid peroxide levels and the size of the comedones. The specimens biopsied from these comedones showed marked hyperplasia and hyperkeratosis of the epithelium in the follicular infundibulum and marked proliferation of the sebaceous glands. Although free fatty acids might play a role in the pathogenesis of acne, it is proposed that squalene and free fatty acids in sebum may be less comedogenic than their peroxides.     

痤疮消霜对兔耳痤疮模型的作用研究

目的:观察痤疮消霜对兔耳痤疮模型的影响。方法:选取新西兰兔30只,雌雄不限,分为正常对照组、模型组、痤疮消霜高剂量组、痤疮消霜低剂量组、维A酸霜组共5组。正常对照组3只不涂煤焦油,不用药;余下27只分别外涂煤焦油造模2周,并于造模成功后每天外涂乳膏基质、痤疮消霜(高、低剂量)、0.1%维A霜3周。于末次给药后24小时,以打孔器制作涂药处耳片标本,以10%甲醛溶液固定,苏木精-伊红染色,光学显微镜下观察组织病理学改变,并进行显微照相。结果:27只新西兰兔造模成功24只,未造模成功的3只归为正常对照组。经观察,在改善兔耳痤疮反应强度上,痤疮消霜高剂量组与模型组比较(t=2.62,P<0.05),说明痤疮消霜高剂量能明显降低兔耳痤疮反应强度,有很好的治疗痤疮的作用;痤疮消霜高剂量组与维A酸霜组相比较(t=0.06,P>0.05),两者无统计学差异。同时,在兔耳病理改变上,痤疮消霜高剂量组兔耳病变改善明显,其表皮增厚状况明显减轻,毛囊口扩张程度减轻,毛囊四周角化层明显减轻,炎性细胞减少,与模型组相比(χ~2=4.00,P<0.05),有统计学差异。痤疮消霜低剂量组兔耳病变程度与模型组相比(χ~2=1.09,P>0.05),无统计学差异,未见明显改善。维A酸霜组与痤疮消霜高剂量组相比(χ~2=0.34,P>0.05),无统计学差异。结论:痤疮消霜高剂量组对煤焦油所致兔耳痤疮模型有明显改善作用。     

Is the rabbit ear model,in its present state,prophetic of acnegenicity?

The rabbit ear model has been proposed as a useful bioassay to establish the comedogenic and acnegenic qualities of chemical compounds and finished products, pharmaceutical and cosmetic, for topical application. This review highlights the many problems in performance of the test method, the absence of correlation with experience in the human, and, consequently, the serious limitations of the conclusions that can reasonably be drawn, especially for the clinical dermatologist.     

Acne detergicans.

Popular brands of soaps and shampoos were assayed for comedogenicity in the rabbit ear. Only a small number produced hyperkeratosis when applied at a 25% concentration. Bacteriostatic substances, especially hexachlorophene, were mildly comedogenic. Conventional soaps include salts of fatty acids; the latter are known comedogens. The obsessive use of soaps by patients with acne vulgaris may aggravate the disease and result in its extension to unusual locations.     

IS SULPHUR HELPFUL OH HARMFUL IN ACNE VULGARIS?

Summary.— Suspensions and creams containing elemental sulphur were shown to be capable of inducing comedones in the rabbit ear and on human backs.Sulphur phur compounds, sulphides, sulphites, thiosulphates and thiols were inactive in this respect. Even though sulphur was not strongly comedogenic, the thesis is presented that its daily application in the treatment of acne vulgaris might perpetuate rather than ameliorate the disease. It is argued that sulphur has a dual paradoxical role in acne; it hastens the resolution of visible papulo-pustules while insidiously promoting the formation of new comedones from which inflammatory lesions spring, thus establishing a vicious cycle.     

Development of an objective comedogenicity assay

The rabbit ear comedogenicity assay is useful as a screening procedure for evaluating agents that come in contact with human skin. Controversy exists regarding the reliability of this assay because of differences in results from various laboratories. The subjective nature of the standard method of grading may also contribute to this variation. We use a more objective comedogenicity assay that utilizes increasing follicular orifice size on the rabbit ear as a measure of comedogenic activity. A generally linear increase in the degree of follicular orifice area was noted with several agents evaluated over a four-week application period. Further, a noninvasive Silastic elastomer mold was used to allow measurement of the same follicular orifice areas over time.     

复方紫金霜对兔耳粉刺模型治疗及P物质的影响

目的建立兔耳粉刺模型,观察复方紫金霜对实验性粉刺的治疗作用和对P物质(SP)的影响,以探讨其治疗机制。方法将2%煤焦油溶液外用于家兔左耳内侧,连续2周。2周后将家兔分为3组,分别在兔左耳内侧外涂复方紫金霜、5%硫磺粉刺洗剂和生理盐水治疗3周。同时,采用免疫组化SABC法检测治疗前后兔耳模型皮损中的SP。结果外涂煤焦油2周后,肉眼可见兔耳出现粉刺,在普通光镜下呈现与人类痤疮类似的病理改变;免疫组化染色可见SP呈阳性反应。外用药3周后紫金霜组兔耳粉刺大部分消退,基本接近正常对照兔,SP呈弱阳性或阴性;硫磺粉刺组粉刺部分减少,SP呈阳性或弱阳性;生理盐水组无明显变化,SP呈阳性。结论复方紫金霜对实验性粉刺治疗效果较好,可明显减少兔耳粉刺模型的毛囊角栓,减轻炎症反应,降低SP的表达。     

Acne and its Management Beyond the Age of 35 Years

Although acne is not usually considered to be a disorder that affects the elderly, the disorder occurs sufficiently often in mature individuals to be noteworthy. The variety known as 'persisting acne' is, as its name suggests, ordinary acne that continues into adult life. 'Chin acne' is a curious type that occurs premenstrually in mature women, while 'sporadic acne' describes the sudden development of significant acne in later life for no apparent reason. When acne develops in an individual outside the usual susceptible age group precipitating causes such as exposure to comedogenic substances or drugs must be excluded. Similarly, endocrine causes such as androgen-secreting tumors and the administration of anabolic steroids need to be considered. All inflammatory processes are decreased in the elderly and this may be one reason for the persistence and intransigence of acne lesions in older age groups. The principles of treatment of acne in the elderly do not differ from those in other age groups, although the emphasis during counseling needs to focus on explanation and reassurance rather than prognosis. Topical retinoids and benzoyl peroxide easily irritate elderly skin, so azelaic acid and even sulfur preparations are preferable. Low-dose systemic isotretinoin is reported to be helpful to patients in this age group and is certainly worth a trial.     

Tolerability and effectiveness of a dermocosmetic product containing Silybum marianum fruit extract in adolescents and young adults with acne-prone skin: An international,phase IV,longitudinal study

Background

Dermocosmetic products are often used to maintain or enhance the tolerance and effectiveness of medical anti-acne therapies. Recent discoveries about the pathophysiology of acne-prone skin indicate that skincare products may help maintain homeostasis around the sebaceous gland progenitor cells, thereby preventing microcomedone formation.

Aims

To evaluate the tolerance and effectiveness of a dermocosmetic product containing Silybum marianum fruit extract (SMFE) in adolescents and young adults with acne-prone skin.

Patients/Methods

This real-life, international, observational, multicenter study was conducted in patients aged 12–25 years with mild-to-moderate acne. Patients (N = 4230) used the product twice daily for 8–12 weeks, either alone before (“initial group”) or after an anti-acne therapy (“maintenance group”), or in association with their usual prescribed anti-acne therapies (“association group”). The tolerance, effectiveness, and cosmetic properties of the product were assessed. Patient quality of life (QoL) was also evaluated.

Results

Dermatologists rated the tolerance of the product as “good” or “very good” in about 95% of the patients and the effectiveness of the product as “effective” or “highly effective” in about 80% of the patients, with a significant reduction in the mean global evaluation of acne (GEA) grade (−36% ± 39%, p < 0.0001) at study end. The QoL of most patients (80%) improved by the end of the study, and the majority (79% to 94%) appreciated the cosmetic properties of the product. Overall, the product was a clinical success in >84% of patients.

Conclusions

This dermocosmetic product can be used by adolescents and young adults with acne-prone skin to limit the initial or chronic use of medical anti-acne therapies.     

Football acne--an acneiform eruption.

Football acne is a peculiar form of localized acneiform eruption of the chin that occurs in acne-prone individuals, as a result of the use of a protective chin strap under conditions of physical and emotional stress. Perhaps it is a locus minoris resistentiae phenomenon. The condition responds favorably to the removal of the chin strap and to the usual topical and systemic acne therapies.     

Hydroquinone therapy for post-inflammatory hyperpigmentation secondary to acne: not just prescribable by dermatologists

Post-inflammatory hyperpigmentation after acne can be as troublesome as the acne itself. Hydroquinone, a tyrosinase inhibitor, in a 4% cream can be used safely twice daily for up to 6 months to treat post-inflammatory hyperpigmentation. The efficacy of this treatment can be enhanced by using a retinoid nightly and a mid-potent steroid, which is applied twice daily for 2 weeks, then at weekends only. Combination creams help with compliance, but often lack the strongest individual ingredients. Because steroids should not be applied to the face for prolonged periods, care should be taken when a hydroquinone cream containing a steroid is chosen. If post-inflammatory hyperpigmentation consists of a few lesions, spot therapy is useful. If post-inflammatory hyperpigmentation consists of many lesions, field therapy is favored. Safety concerns with hydroquinone consist only of occasional irritation, which can be suppressed with topical steroid or a short drug holiday. Physicians should feel comfortable to use hydroquinone without consulting a dermatologist. Key words: hydroquinone; acne; adolescent; post-inflammatory hyperpigmentation.     

Topical retinoids in acne – an evidence‐based overview

Topical retinoids are important tools in the management of acne because they act against comedones and microcomedones and have direct anti‐inflammatory effects. The substances approved for acne treatment comprise tretinoin (all‐trans‐retinoic acid),isotretinoin (13‐cis retinoic acid) as well as the synthetic third‐generation polyaromatic retinoids adapalene and tazarotene,the latter being approved for acne treatment in the US only.Retinaldehyde is used in cosmetic preparations against acne. All topical retinoids are effective as single agents in mild to moderate acne but differ in efficacy and tolerability. Tazarotene 0.1% is more effective than tretinoin 0.025% or 0.1% microsphere gel or adapalene 0.1% gel or cream (EBM‐level 2c). Adapalene 0.1% is equally effective to tretinoin 0.025% or tretinoin microsphere 0.1% gel or tretinoin 0.05% cream or isotretinoin 0.05% gel (EBM‐level 2c). Adapalene 0.1% gel is significantly better tolerated than tazarotene 0.1% gel, tretinoin 0.025% and tretinoin 0.05% gel, tretinoin 0.05% cream,tretinoin microsphere 0.1% gel or isotretinoin 0.05% gel (EBM‐level 2c).The safety profile of topical retinoids differs from their systemic counterparts and is related mainly to local adverse effects, such as erythema, dry‐ness,itching and stinging.The currently available evidence justifies the use of topical retinoids in most types of acne and during maintenance treatment.     

Kosmetische und dermatologische Anwendung von Alpha‐Hydroxysäuren

Alpha hydroxy acids (AHAs), in particular glycolic acid, are a class of chemical compounds frequently used in cosmetics and dermatology. This review summarizes the current knowledge regarding chemistry, mechanism of action as well as the different indications ranging from cosmetic skin hydration to acne proven by clinical trials. Overall AHAs depending on the concentration used present an ingredient for cosmetic products or medical devices with proven efficacy.     

Cosmetic and dermatologic use of alpha hydroxy acids

Alpha hydroxy acids (AHAs), in particular glycolic acid, are a class of chemical compounds frequently used in cosmetics and dermatology. This review summarizes the current knowledge regarding chemistry, mechanism of action as well as the different indications ranging from cosmetic skin hydration to acne proven by clinical trials. Overall AHAs depending on the concentration used present an ingredient for cosmetic products or medical devices with proven efficacy.     

Comedogenic lupus: a rare variant of chronic cutaneous lupus erythematosus – case series

BackgroundComedogenic lupus is an uncommon variant of cutaneous lupus, clinically characterized by the presence of comedones, papules and erythematous-infiltrated plaques, cysts and scars in photo-exposed areas, mimicking acne vulgaris and acneiform eruptions.ObjectivesTo report clinicopathological characteristics of patients with comedogenic lupus in a tertiary dermatology service over a 15-year period and review cases described in the literature.MethodsRetrospective study of patients with clinical and histopathological diagnoses of comedogenic lupus between the years 2006 and 2021. The literature search was carried out in the PubMed and VHL Regional Portal databases, using the terms: “comedogenic lupus” and “acneiform lupus” in Portuguese and English.ResultsFive patients were diagnosed during the described period, all female, with a mean age of 56.6 years. Smoking was observed in three cases, as well as pruritus. The most affected site was the face, especially the pre-auricular, malar and chin regions. Follicular plugs, epidermal thinning and liquefaction degeneration of the basal layer were predominant histopathological findings. Hydroxychloroquine was used as the first-line treatment; however, other medications were used, such as dapsone, methotrexate, tretinoin cream, and topical corticosteroids. The literature search identified 17 cases, with a mean age of 38.9 years, 82% of which were women. Only 23% had a diagnosis of systemic lupus erythematosus. Hydroxychloroquine was the most recommended systemic medication.Study limitationsRetrospective, single-center study. The literature search was carried out in two databases.ConclusionsDermatologists should be aware of acneiform conditions with poor response to the usual treatment. Early diagnosis and treatment reduce the risk of unaesthetic scars.     

Multicenter study to evaluate efficacy and irritation potential of benzoyl peroxide 4% cream in hydrophase base (Brevoxyl) in acne vulgaris

In this multicenter, open, non-comparative study, the efficacy and irritation potential of 4% benzoyl peroxide cream in hydrophase base (Brevoxyl) was evaluated for the treatment of acne vulgaris. All evaluable patients (n=567) received treatment with 4% benzoyl peroxide cream in hydrophase base for six weeks. The investigators evaluated the patients at baseline and at 1,2,4 &6 weeks. Patients also rated their improvement and adverse effects. Doctor's assessment showed that at the end of 6'h week 85.6% had good to very good effect of the treatment. The profile of side effects observed by doctors revealed that 53.8% of total patients did not have any irritation whereas only 11.6% had moderate to severe irritation. 53.8% of patients did not report any irritation: 41.4% had some irritation whereas only 4.8% patients reported troublesome irritation. A satisfactory response was reported as ear;y as two weeks and most of the patients had a very satisfactory response after six weeks and were willing to continue the treatment. This supports the theory that the hydrophase formulation in 'Brevoxyl helped to enhance efficacy and decrease the irritation associated with use of benzoyl peroxide.     

Sulfur revisited

Sulfur is a time-honored therapeutic agent useful in a variety of dermatologic disorders. Its keratolytic action is due to formation of hydrogen sulfide through a reaction that depends upon direct interaction between sulfur particles and keratinocytes. The smaller the particle size, the greater the degree of such interaction and the greater the therapeutic efficacy. When applied topically, sulfur induces various histologic changes, including hyperkeratosis, acanthosis, and dilatation of dermal vasculature. One study showed that sulfur was comedogenic when applied onto human and rabbit skin, findings that were not reproduced in other studies. About 1% of topically applied sulfur is systemically absorbed. Adverse effects from topically applied sulfur are uncommon and are mainly limited to the skin. In infants, however, fatal outcome after extensive application has been reported.     

清肺饮颗粒对家兔实验性耳痤疮影响的研究

目的建立家兔实验性耳痤疮模型,观察复方清肺饮颗粒治疗痤疮的作用。方法家兔左耳内侧涂浓煤焦油溶液0.5ml,1次/d,连续2周,建立耳痤疮动物模型。耳痤疮模型建立成功后将家兔随机分为清肺饮颗粒大、中、小剂量组、解毒痤疮丸组、模型实验组、正常对照组,分别灌饲清肺饮颗粒、解毒痤疮丸和蒸馏水2周,在造模前后及药物治疗前后,取家兔左右耳廓相同部位耳片,称重后计算耳片重量差值,光镜下观察耳廓组织病变。结果外涂煤焦油1周后,兔耳表面粗糙,增厚,可见粉刺、丘疹,组织学改变与人类痤疮相似;给药2周后,清肺饮颗粒不同剂量组和解毒痤疮丸组均可不同程度抑制痤疮模型家兔耳重量的增加,并明显改善耳痤疮炎性病理变化。结论清肺饮颗粒对家兔实验性耳痤疮有治疗作用,可用于痤疮的防治。     

An improved rabbit ear model for assessing comedogenic substances

A simplified comedogenic assay is described in which test materials are applied for 2 weeks to the ears of rabbits just external to the ear canal. Excised tissue is thus immersed in water at 60 degrees C for 2 min, yielding a sheet of epidermis with microcomedones attached. The magnitude of follicular hyperkeratosis is extracted with the stereomicroscope. Sixteen materials were evaluated by the new and old model which required histological sectioning. Agreement was excellent.