A re-evaluation of the comedogenicity concept

doi:10.1016/j.jaad.2005.11.1058

Journal of the American Academy of Dermatology

Volume 54, Issue 3, March 2006, Pages 507-512

https://doi.org/10.1016/j.jaad.2005.11.1058 Get rights and content

Background

Comedogenicity is an important consideration in the development of topical medications, cosmetics, and skin care products. The concept of “acne cosmetica” was developed to link the use of certain ingredients to comedo formation. Animal models were originally used to determine the comedogenic potential of raw materials with the assumption that finished formulations containing these ingredients would also be comedogenic. Based on this assumption, dermatologists were presented with lists of substances to avoid in patients with the ability to develop comedones.

Objective

We sought to use a modification of the Mills and Kligman human assay for assessing comedogenic potential of finished cosmetic products.

Methods

Six individuals with prominent follicular orifices and the ability to form comedones on the upper aspect of the back were enrolled. Each person received patches to the upper aspect of the back saturated with 0.2 to 0.5 mL of the finished cosmetic study products 3 times weekly for 4 weeks. Cyanoacrylate biopsies were performed to determine the number of follicles and microcomedones per square inch.

Limitations

Only a finite number of finished cosmetic products could be analyzed.

Conclusion

Finished products using comedogenic ingredients are not necessarily comedogenic.

Section snippets

Methods

Six individuals with prominent follicular orifices and the ability to form comedones on the upper aspect of the back were enrolled in each of the two study groups. Each participant received patches to the upper aspect of the back containing a finished product with a reported comedogenic material concurrently with positive and negative controls. Patches were saturated with 0.2 to 0.5 mL of the study product, left in place for 48 hours if placed on Monday and Wednesday and 72 hours if placed on

Results

Table I, Table II present data obtained for each of the two product groups evaluated. Data are expressed in terms of mean follicle to microcomedone ratio with baseline ratios compared with those obtained after 4 weeks of product application. For example, in Table I the positive control used was octyl palmitate. The mean prefollicle to microcomedone ratio was 34.29 follicles per 1 microcomedone (34.29:1). After 4 weeks of application, the mean postfollicle to microcomedone ratio changed to 17.90

Discussion

The results obtained from this study might at first appear to be confusing; however, differing results regarding comedogenicity testing are not new to the literature. Table III, Table IV were compiled from previously published data to show the comedogenic activity of each of the ingredients in the formulations tested and presented in Table I, Table II. It is important, however, to consider the difference between the models being compared, which are animal versus human, and the concentration at

References (7)

A.M. Kligman et al.
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Br J Dermatol
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W.E. Morris et al.
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(1983)

There are more references available in the full text version of this article.

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Each enrolled subject was given pads containing the tested products to apply to the upper aspect of the back. The positive control was the pad containing octyl palmitate which has been reported as a comedogenic material [3,4]. The negative control was a pad without any material.
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Comedogenicity is an important consideration in the development of topical medications, cosmetics, and skin care products. The term ’’acne cosmetica” was developed to link the use of certain substances to comedones formation, and animal models have been used to determine the comedogenic potential of finished formulations containing these substances [49]. Macroscopic observations made daily in the ears of rabbits suggested that there were no visible comedones and no irritative signs, such as erythema, epithelial desquamation, and inflammatory reactions, in any group treated with the base, base with BZ-3, and base with BZ-3-HPCD complex in the stoichiometric ratio of 1:2.
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Supported by Pharma Cosmetix Research LLC.

Conflicts of interest: None identified.

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Current Issues & OpinionA re-evaluation of the comedogenicity concept

Background

Objective

Methods

Limitations

Conclusion

Section snippets

Methods

Results

Discussion

Acne cosmetica

Arch Dermatol

An improved rabbit ear model for assessing comedogenic substances

Br J Dermatol

Use of the rabbit ear model in evaluating the comedogenic potential of cosmetic ingredients

J Soc Cosmet Chem

Current Issues & Opinion
A re-evaluation of the comedogenicity concept