Skin Therapy Letter

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Volume 2 • Number 4 • 1997
Contents: (Full text available in print edition.)
  • Tazarotene – A New Retinoid for Plaque Psoriasis
  • Use of Emollients
  • Current Approaches to the Management of Post Herpetic Neuralgia: Part 1 – Systemic
  • Update on Drugs
    • Tazarotene Gel 0.05mg, 0.1mg Tazorac® – Allergan
    • Tretinoin Cream 0.025% Avita® – Penederm
    • Tretinoin Gel Microsphere 0.1% Retin-A Micro® – Advanced Polymer Systems
    • Itraconazole solution Sporanox® – Janssen
    • Terbinafine HCl cream 1% Lamisil® – Novartis Canada
    • Calcipotriene hydrate solution Dovonex® 0.005% – Bristol Myers Squibb
    • Epilaser® – Palomar Medical Technologies
    • Dermagraft-TC® – Advanced Tissue Sciences
    • Imiquimod cream 5% Aldara® – 3M Pharmaceuticals
Use of Emollients
What is dry skin and what is the best way to treat it? These are basic questions not yet fully answered. Although clinical experience strongly suggests that treating the "dry skin" associated with psoriasis, icthyosis, xerosis, winter itch, some forms of atopic dermatitis, and other skin conditions is helpful, we feel that there must be better ways to treat this condition but don't yet know what they are.1

Pharmaceutical companies and cosmetic companies are promoting cosmeceuticals for treating dry skin, but very few scientific studies have been published to validate the claims made. Changes are made to increase the hydrophobicity and occlusive properties of formulations, but are these products any more effective than the present gold standard, petrolatum? Lipids may be absorbed but what effect does this have on structural components in the skin? Cell kinetics are probably more important than is generally understood. In diseases such as psoriasis, the turnover of cells can be much higher than in normal skin, preventing homeostatic mechanisms from maintaining an effective barrier. Possibly, local occlusion slows down cell turnover and allows the skin to repair itself.2

Repair of the Cutaneous Permeability Barrier

When the integrity of the cutaneous permeability barrier is perturbed, a homeostatic repair mechanism is stimulated that causes the rapid repair of barrier function. It has recently been suggested that barrier disruption stimulates the expression of amphiregulin and nerve growth factor and that these regulators of keratinocyte growth and differentiation may be responsible for the increased proliferative response that is associated with barrier disruption.3

New Developments

New compounds and new delivery systems for treating dry skin are under development. Dr. Peter Elias and his associates in San Francisco and at Cellegy Pharmaceuticals have been collaborating in the development of lipid mixtures for the skin. Their product Glylorin™ (monolaurin), which has just been licensed to Glaxo Wellcome, entered phase III clinical trials in January 1996 for non-bullous congenital ichthyosiform erythroderma (n-CIE). Its mode of action is unclear, but in phase II studies it exhibited surfactant, antimicrobial, anti-inflammatory, and anti-proliferative properties.

Glylorin™ (monolaurin) The US Food and Drug Administration has granted Orphan Drug status to Glylorin™ for congenital primary ichthyosis, a condition that affects approximately 100,000 persons in the USA. Other potential indications for monolaurin include seborrheic dermatitis and pruritic xerosis.
Basic research is gradually increasing our understanding of the barrier function of the epidermis. At present we know more about the homeostatic repair mechanism of the skin than we know about how to assist this repair proces. Advances in the understanding of basic skin processes will lead to improved therapy of disrupted skin barriers. In the meantime, the fruits of clinical experience and careful observation can be shared to the betterment of our patients.
S. Maddin, Editor

Practical Advice on Treating Dry Skin4

Dry skin becomes less irritable with emollient therapy, which should be considered as an adjunctive treatment for a wide range of itchy dermatoses. Emollients can serve as topical corticosteroid-sparing agents in diseases such as psoriasis, atopic hand dermatitis, and winter itch, and may also be used by those who are exposed to primary irritants in the home or workplace.

Preferred Agents and Reasons

Ask patients what they currently use. If this is an acceptable product, urge continued vigorous compliance.4

The length of time an application of emollient provides benefit varies with factors such as the time of season, patient occupation, and preparation used. Many patients have individual preferences that should be taken into account in choosing an emollient.4 Patients may respond well to Lac-Hydrin® or Lacticare® or traditional formulations such as Cetaphil®, Neutrogena Norwegian Formula Hand Cream,® or Vaseline Intensive Care Lotion® - Editor. Some patients prefer cosmetic elegance, some strong fragrance, whereas others are satisfied with petrolatum - an excellent agent but the antithesis of elegance.4 Products from reputable commercial companies are those that are most likely to deliver what they promise.4

Have We Improved on Petrolatum?

In the past, petrolatum was assumed to be occlusive, blocking transcutaneous water loss and trapping water under the skin's surface. In human volunteers, studies of barrier recovery following acetone-induced barrier disruption, plus tracer and staining studies have shown that petrolatum neither forms nor acts like an epicutaneous impermeable membrane. Petrolatum permeated through the stratum corneum interstices, allowing normal barrier recovery despite its occlusive properties.5

Lipids in emollients help restore the normal barrier function of the skin and protect it from outside influences. Lipids also retard transepidermal water loss and allow more complete hydration of the skin. They also play an anti-inflammatory role in the skin. Humectants bind water and thus attract water to the skin and temporarily hold it there. The role of other ingredients such as urea and alpha hydroxy acids is incompletely understood, but expanding. These latter agents likely enhance the activity of the emollients.4

Avoiding Side Effects4

Avoidance of side effects is best accomplished by suggesting fragrance and dye-free agents from reputable companies. When applying agents with high alcohol concentrations, burning sensations may trouble patients with extremely irritated skin. Thus, the initial use of less irritating products can help. Once the skin has its barrier function restored, lotions that were previously irritating may be tolerated.

Other Advice4

Routinely recommend the use of emollients on a repeated basis. Patients sometimes need to hear more than once that they need to use these products. Men in particular may be reluctant to use emollients, but should be directed to do so. Professor Fleischer tells patients with asteatotic dermatitis of the legs: "We can make this go away, but without prevention it is guaranteed to come back."4

Best Technique for Application4

Apply immediately after tepid bathing and patting dry with a towel. Application can be repeated again during the day. For patients with hand dermatitis, urge them to keep containers of their favorite emollient at their desk, in their car, and at every sink in their house. To paraphrase Louis XIV, "out of site, out of mind." Use of emollients must be convenient.4

How can the Effect of Emollients be Prolonged?

Products with higher concentrations of lipids are valuable for prolonging the emollient effect. The thickness of a lotion or cream may be deceiving, since thickening agents may have been added so that products can remain elegant. With emollients there is no free lunch. The more lipid, the better the therapeutic effect and the worse the elegance. The less lipid, the better the elegance, and the worse the therapeutic effect.4

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  1. Kitson N. Personal communication. February 1997.
  2. Redelmeier TE. Personal communication. January 1997.
  3. Liou A, Elias PM, Grunfeld C, et al. Amphiregulin and nerve growth factor expression are regulated by barrier status in murine epidermis. J Invest Dermatol 1997; 108: 73-77.
  4. Fleischer A, The Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, NC, USA Personal communication. August 1996.
  5. Ghadially R, Halkier-Sorenson L, Elias PM. Effects of petrolatum on stratum corneum structure and function. J Am Acad Dermatol 1992; 26: 387-396.

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Update on Drugs
Class Name/Company Approval Dates and Comments
Hair Removal Epilaser®
Palomar Medical Technologies
Approved by the FDA for removing body hair. The laser targets the pigment in a hair follicle and heats it, destroying the hair shaft. The procedure does not work well on blond hair that is the same color as the skin.
Wart Removal Imiquimod cream 5%
3M Pharmaceuticals
Approved by the FDA February 21, 1997 for the treatment of external genital & perianal warts/condyloma acuminata in adults.

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EDITOR: Stuart Maddin Associate Editor: David I. McLean INTERNET EDITOR: Harvey Lui PRINCIPAL MEDICAL WRITER: Susan Kingsley Manuscript Editor: Rodger Hall Editorial Advisory Board: Kenneth A. Arndt, Beth Israel Hospital & Harvard Medical School, Boston; Wilma Fowler Bergfeld, Cleveland Clinic, Cleveland; Jan D. Bos, University of Amsterdam, Amsterdam; Enno Christophers, Universitäts-Hautklinik, Kiel; Hugo Degreef, Catholic University, Leuven; Richard L. Dobson, Medical University of South Carolina, Charleston; Boni E. Elewski, Case Western Reserve University, Cleveland; Barbara A. Gilchrest, Boston University School of Medicine, Boston; W. Andrew D. Griffiths, St. Johns Institute of Dermatology, London; Vincent C.Y. Ho, University of British Columbia, Vancouver; James J. Leyden, University of Pennsylvania, Philadelphia; Howard I. Maibach, University of California Hospital, San Francisco; Larry E. Millikan, Tulane University Medical Center, Louisiana; Takeji Nishikawa, Keio University School of Medicine, Tokyo; Constantin E. Orfanos, Freie Universitäts Berlin, Universitätsklinikum Benjamin Franklin, Berlin; Stephen L. Sacks, Viridae Clinic Sciences, Vancouver; Alan R. Shalita, SUNY Health Sciences Center, Brooklyn; Stephen K. Tyring, University of Texas Medical Branch, Galveston; John Voorhees, University of Michigan, Ann Arbor; Klaus Wolff, University of Vienna, Vienna
Skin Therapy Letter®. (ISSN 1201-5989) Copyright 1997 by International Skin Therapy Newsletter Inc. All rights reserved. Reproduction in whole or in part by any process in whole or in part is strictly forbidden without prior consent of the publisher in writing.
Published six times yearly by International Skin Therapy Newsletter Inc., 835 West Tenth Avenue, Vancouver, British Columbia, Canada V5Z 4E8. Tel: (604) 874-6112. Fax: (604) 873-9919. Annual subscription: Canadian $85 individual; $155 institutional (GST included). US $60 individual; $110 institutional. Outside North America: US$80 individual; $130 institutional. Quotes on multiple subscriptions and student rates supplied upon request.
Skin Therapy Letter Editor: Dr. Stuart Maddin Vol. 2 No. 4
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