Skin Therapy Letter HOME
Written for dermatologists by dermatologists. Indexed by the US National Library of Medicine.
Skin Information
NETWORK
Skin Therapy Letter About STL Subscribe Today SkinCareGuide Network Site Map
CUSTOM DERMATOLOGY SEARCH:
Loading

The Role of Cosmeceuticals in Anti-Aging Therapy

J. K. Rivers, MD, FRCPC
Department of Dermatology and Skin Science, University of British Columbia, Vancouver, BC
Pacific Dermaesthetics, Vancouver, BC

Background

As baby boomers reach retirement age, they have shown greater interest in anti-aging preparations (cosmeceuticals), and their purported ability for rejuvenation. Anti-aging topicals, with their multiple claims, seemingly limitless key active ingredients, and complex formulations are leading the way in this huge growth industry, especially as this segment of the population opts for less invasive, nonsurgical alternatives to slow the effects of aging on the skin.
  • The term cosmeceutical was introduced by Albert Kligman in 1984 to refer to substances that exerted both cosmetic and therapeutic benefits.1
  • This term is not applied universally, e.g., sunscreen is an OTC drug in North America but a cosmeceutical in Europe.
  • Efforts to address quality control and to establish industry standards and regulations have only recently begun.
  • Safety is generally assessed, but claims of efficacy are largely unsubstantiated.2
    • Limited research is being done in academic dermatology.
    • The best evidence on cosmeceuticals comes from industry.
  • Demonstrating the skin effect of a cosmeceutical can be difficult.
    • The vehicles used as placebos can affect skin texture.
    • It may take >3 months to see a difference.
  • Any therapeutic benefits derived from cosmeceuticals can only be maintained through sustained use.
  • Some types of cosmeceuticals include: hydroxy acids, moisturizers, retinoids, sunscreens, antioxidants, botanicals, exfoliants, and depigmenting agents.

Antioxidants

  • Antioxidants reduce free-radical damage, thereby preventing impairment at the cellular level.
  • They inhibit inflammation that leads to collagen depletion.
  • They offer protection against photodamage and skin cancer.
  • Combining antioxidants may create a synergistic effect that can enhance efficacy.
  • Important for formulation to maintain stability and active penetration.
  • Most research data showing therapeutic benefits was based on their use as dietary supplements.
  • Common antioxidants include:
    • Ascorbic acid (vitamin C)
      • Has been shown to improve fine lines and reduce both pigmentation and inflammation; however, some authors believe that cosmetic formulations should3:
        • contain L-ascorbic acid in a high enough concentration (at least 10%).
        • be stable. It is important to note that stabilizing ascorbic acid presents many formulary challenges.
        • have an acid pH of around 3.5 to optimize vitamin C absorption.
      • Newer formulations of stabilized derivatives may be more efficacious.
    • Niacinamide (vitamin B3)
      • Potent antioxidant that improves the lipid barrier component of the epidermis.
      • Studies showed significant reduction in fine lines, wrinkles, hyperpigmented spots, red blotchiness, skin sallowness, and improved skin elasticity.4
    • á-Tocopherol (vitamin E)
      • When taken orally, it protects membrane lipids from peroxidation.
      • Acts as a humectant and has been shown to reduce sunburn cells after UV exposure.
      • Once diminished, á-tocopherol’s activity can be restored by combining it with vitamin C.
    • Ubiquinone (coenzyme Q10)
      • Fat-soluble antioxidant that is a component of all cell membranes.
      • Good in vitro evidence that it can reduce periorbital wrinkles.5

Botanicals

  • Botanicals are the largest category of cosmeceutical additives found in the marketplace today.
  • Their use is unregulated and often unsupported by science. Their purported therapeutic properties remain largely unexplored.
  • Some botanicals that may benefit the skin include: aloe vera, tea tree oil, thujaplicin, ginkgo biloba, green tea, and grape seed.

Depigmenting Agents

  • Skin-lightening agents added to product formulations have become increasingly popular.
  • Improvement rate depends on whether the pigment is in the dermis or epidermis; at best it takes 2-4 months.
    • Concomitant use of broad spectrum sunscreens is required.
  • Common depigmenting ingredients include:
    • Ascorbic acid (vitamin C)
      • A naturally occurring antioxidant found in citrus fruits and leafy green vegetables.
      • Hydrophilic, so skin penetration is low.
    • Hydroquinone
      • The agent of choice for skin lightening.
      • The European Community countries have restricted its use in cosmetics to =2%.
      • The US FDA has proposed concentrations between 1.5% and 2% in skin lighteners.
      • There are concerns about exogenous ochronosis, permanent depigmentation, and possible carcinogenicity, especially at higher concentrations or use on larger body surface areas.
        • Based mainly on studies with animal models utilizing long-term exposure at high doses.6
    • NAG (N-acetyl glucosamine) 2% and Niacinamide 4%
      • Shown to reduce facial hyperpigmentation in 3 double-blind, vehicle-controlled clinical studies.7,8
      • Improvement was seen in 4-8 weeks and no adverse effects were reported.
  • Other depigmenting agents include: kojic acid and licorice extract (glabridin).

Exfoliants

  • Exfoliants promote skin turnover by removing accumulations of dead cells and thickened outer layers.
  • Side-effects include skin irritation and photosensitization.
    • Repeated use could increase penetration of dermis and epidermis by UV radiation.
    • Patients must be warned to use adequate sun protection.
  • Common exfoliants used in cosmeceuticals include: salicylic acid, alpha hydroxy acids, beta hydroxy acids, lactic acid, and glycolic acid.

Hydroxy Acids (alpha, beta, poly)

  • Also referred to as fruit acids.
  • Exert exfoliating and hydrating effects, although mechanisms of action are not well understood.
  • Examples include:
    • Citric acid
    • Gluconalactone
    • Glycolic acid
    • Lactic acid
    • Malic acid
    • Pyruvic acid
    • Salicylic acid
    • Tartaric acid
  • Potential to increase sensitivity to the sun; due to their exfoliating action rather than true photosensitivity.

Moisturizers

  • Moisturizers restore water content in the epidermis and improve barrier function.
    • Emollients provide a soothing protective film.
    • Humectants aid in absorption and retention of moisture.
  • They improve the appearance and tactile properties of dry and aging skin.
  • They reduce the release of inflammatory cytokines.
  • They are important for the management of various skin conditions (e.g., eczema, psoriasis, pruritus, aged skin).

Retinoids

  • Natural and synthetic derivatives of vitamin A include retinol, retinyl-propionate and retinaldehyde, among others.
  • Cosmeceutical claims are based mainly on data from studies on tretinoin and other classes of retinoid drugs.
  • Retinoids reduce hyperpigmentation and inhibit enzymes from breaking down collagen.
  • Retinol (vitamin A)
    • Is oxidized into retinaldehyde and then into retinoic acid, the biologically active form of vitamin A.
    • In vivo studies showed that topical retinol had only a modest retinoid-like biologic activity compared with topical retinaldehyde and retinoic acid.9
    • Randomized, controlled trials showed significant improvement in fine lines after 12 and 24 weeks of treatment.10,11
  • Retinaldehyde
    • Can produce significant clinical improvement in the appearance of fine lines and deep wrinkles.9

Sunscreens

  • This is the single most important cosmeceutical.
    • Should be part of a daily skin care regimen.
    • Should provide broad spectrum coverage that includes UVA blocking agents to inhibit photoaging.
  • They contain active ingredients that act as ultraviolet filters.
  • Recommended application is 2mg/cm2, though this is rarely achieved in real-life practice.12
  • Labeling changes proposed by the US FDA on sunscreen products are forthcoming. Health Canada is monitoring developments from the FDA’s proposal and recognizes the need for international standardization.
  • Photoprotection of cosmetic formulations that incorporate a sunscreen has not been adequately studied.

Formulation Considerations

Safety, efficacy, and formulation consistency are areas that have been neglected and necessitate regulation. To evaluate the merits of claims made by the producers of cosmeceutical formulations, consider the following questions13:
  • Can the active ingredient penetrate the stratum corneum?
  • Are the concentrations of the active ingredients sufficient to provide the intended therapeutic benefits?
  • Can their mechanism of action be explained by well-designed research supported by the scientific community?
Cosmeceuticals can play an integral part of an effective anti-aging regime. However, clinicians need to be diligent in ensuring the products they recommend are supported by rigorous studies and published in peer reviewed publications. Efforts should be made to establish methods to reliably evaluate their claims of efficacy.

References

  1. Kligman AM, et al. J Am Acad Dermatol 15(4 Pt 2):836-59 (1986 Oct).
  2. US FDA, Office of Cosmetics and Colors Fact Sheet, Feb 3, 1995; rev Feb 24, 2000.
  3. Burke KE; in Draelos ZD (ed): Cosmeceuticals. Philadelphia: Elsevier Saunders pp 71-8 (2005).
  4. Bissett DL, et al. Dermatol Surg 31:860-5 (2005 Jul).
  5. Burke KE. Dermatol Ther 20(5):314-21 (2007 Sep-Oct).
  6. Levitt J. J Am Acad Dermatol 57(5):854-72 (2007 Nov).
  7. Bissett D, et al. Presented at: the 64th Annual Meeting of the American Academy of Dermatology, San Francisco, CA; March 3-7, 2006. Poster #236.
  8. Kimball AB, et al. Presented at: the 64th Annual Meeting of the American Academy of Dermatology, San Francisco, CA; March 3-7, 2006. Poster #235.
  9. Sorg O, et al. Dermatol Ther 19(5):289-96 (2006 Sep-Oct).
  10. Piérard-Franchimont C, et al. Skin Res Technol 4:237-43 (1998).
  11. Kafi R, et al. Arch Dermatol 143(5):606-12 (2007 May).
  12. Rivers JK. Skin Therapy Lett Pharm 2(1):6-7 (2007 Mar).
  13. Kilgman D. Dermatol Clin 18(4):609-15 (2000 Oct).