Table of Contents   This Chapter   All Chapters

TOPICAL RETINOIDS

Tazarotene

Tazarotene is a topical retinoid efficacious for both acne and psoriasis. Several studies have found it to be more effective than both tretinoin and adapalene in the treatment of acne. It is usually applied once daily, but one study found it to still have significant benefit with alternate-day use. As with the other topical retinoids, its main effect is clearing the pore. For maximum benefit, it should be combined with antimicrobials that reduce Propionibacterium acnes counts (benzoyl peroxide, clindamycin, and erythromycin are discussed later in this chapter).

    Tazarotene may also be used in psoriasis, usually with once daily application. Irritation is the most frequent side effect and can be minimized with the concomitant use of a topical steroid (e.g. applied 12h later). An added benefit of this combination is that topical retinoids can reduce or prevent the atrophogenic effects of steroids. Finally, tazarotene 0.1% cream was found effective against photoaging, with benefit similar to that of tretinoin 0.05%.

    Pregnant women are prohibited from using tazarotene.

Tretinoin

Tretinoin (all- trans -retinoic acid or retinoic acid) was the first widely prescribed topical retinoid. Its chemical structure is cis-retinoic acid, but it has been shown to isomerize readily to 13- cis -retinoic acid (isotretinoin) on the skin. It was initially used in acne for its comedolytic effect, but later it was found to decrease wrinkles and improve the signs of aging. Over the years, it has been reported beneficial anecdotally in a wide variety of dermatoses. Older formulations were quite irritating, but recent advances in vehicle formulation have minimized side effects. It is applied once daily, usually at night.

    In acne, it should be given a full 12 weeks to see the maximum benefit and, as with other topical retinoids, it is usually prescribed in combination with an antimicrobial agent, for example benzoyl peroxide or an antibiotic (note, however, that benzoyl peroxide is also potentially irritant). Tretinoin helps open the pore, whereas the antimicrobial agent reduces the number of P.acnes .

Isotretinoin

Topical isotretinoin is used in treatment of acne; in some countries, it is also available as a combination topical product with erythromycin.

Adapalene

Adapalene is a naphthoic acid derivative that has retinoid-like activities, i.e. it mediates its effects via the retinoic acid receptors. It is both chemically and photochemically stable. It is applied once a day and is equivalent to tretinoin in terms of efficacy for acne. For many patients, irritancy is reduced compared with when using other topical retinoids. Adapalene has also been shown to reduce the signs of photodamaged skin, specifically actinic keratoses and lentigines (Fig. 3.7).

Bexarotene

Previously used orally, this has recently become available in the USA (not yet in the UK ) as a topical treatment for early stages of mycosis fungoides.

Figure. 3.7  Wrinkling and photodamage. A topical retinoid as well as a sunscreen can improve the appearance over many months

 

White/Cox: Diseases of the Skin, 2ed.(c) 2006, Elsevier Inc. All rights reserved.