Retinoids, topical

Tretinoin (a retinoid topical vitamin A acid) is a comedolytic agent that increases cell turnover in the follicular wall and decreases cohesiveness of cells, leading to extrusion of comedones and inhibition of new comedo formation. It also decreases the number of cell layers in the stratum corneum from about 14 to about five. 

Retinoids, topical as well as systemic, have been tried in EHK but were often found to be irritating. Nonetheless some patients are improved by oral acitretin,39 but the dose must be kept low in order to avoid the epidermolytic side effect of the drug. If correctly used, topical tretinoin and tazarotene may also be effective in some patients with EHK (Figure 8.7). Interestingly, the response to retinoid therapy seems to be partially determined by which keratin gene (Kl, K2e, or K10) is mutated patients with K2e and K10 mutations have the best response probably because they tolerate a retinoid-induced down-regulation of K2e expression better than other patients.40 However the... 

Topical retinoids Topical antibiotics Benzoyl peroxide Chemical peels Emergent topical therapy Oral retinoids Oral antibiotics Hormonal therapy in women... 

The topical and oral use of retinoids for treatment of hyperkeratotic disorders such as psoriasis and Darier s disease has long been established. Systemic retinoid therapy is often combined with topical diugs such as corticosteroids, dithranol, tar, and also UVA/UVB phototherapies where synergistic effects have been reported. 

Among retinoids, 13-cis-retinoic acid is known to have not only anti-inflammatory but also sebostatic effects. Therefore it is one of the most potent topical and also systemic agents for therapy of acne. 

Drug treatment of photoaged skin can be categorized as antioxidants, a-hydroxy acids and topical retinoids. Of these three approaches only topical retinoids, particularly retinaldehyde and alWrans-retinoic acid, have a well documented ability to restorethe repair... 

Actinic keratoses were the first skin lesions to be treated topically with all-frans-retinoic acid. In various clinical trials, retinoids have been shown to be active in chemoprevention and treatment or prevention skin malignancies [2]. 

Use of topical retinoids (tretinoin, tazaro-tene, retinol formulations) for 2-6 weeks prior... 

When treating acne vulgaris, topical and systemic therapies (if indicated) are initiated 2 to 4 weeks prior to peeling. Topical antibiotics and benzoyl peroxide based products can be used daily and discontinued 1 or 2 days prior to peeling. However, unless a deeper peel is desired, retinoids should be discontinued 7-10 days prior to salicylic acid peeling. Broad-spectrum sunscreens (UVA and UVB) should be worn daily (see Photo damage. Sunscreen section). 

Use of topical retinoids (tretinoin, tazaro-tene, retinol formulations) for 2 to 6 weeks prior to peeling thins the stratum cornemn, reduces the content of epidermal melanin, and expedites epidermal healing. Retinoids also enhance the penetration of the peeling agent. They should be discontinued several days prior to the peeling procedure. Retinoids can be resumed post-operatively after all evidence of... 

Topical retinoids acting on gene transcription regulate cell proliferation and differentia-... 

Hydroquinone is usually more effective when utilized in combination with other agents such as topical retinoids alone or topical retinoids and topical steroids (see Table 14.1). The addition of a weak topical steroid reduces the irritant effect of hydroquinone, but the treat-... 

Apply a topical retinoid once every 2 days... 

Monotherapy with topical retinoids has been shown to facilitate resolution of PIH. A random-... 

Topical therapy is the initial drug treatment strategy for patients with mild to moderate psoriasis. It is estimated that approximately 70% to 80% of all patients with psoriasis can he treated adequately with use of topical therapy.1 Topical therapies include corticosteroids, coal tar products, anthralin, vitamin D3 analogues such as calcipotriol, retinoids such as tazarotene, and topical immunomodulators such as tacrolimus and pime-crolimus.18 Vitamin D3 analogues and topical retinoids all affect keratinocyte functions and the immune response. Currently, these are in wider use than is either anthralin or coal tar preparations. 

Retinoids, which are highly effective in the treatment of acne, stimulate epithelial cell turnover and aid in unclogging blocked pores. Retinoids also exhibit anti-inflammatory properties through the inhibition of neutrophil and monocyte chemotaxis.8 Because of these comedolytic and antiinflammatory effects, topical retinoids are recommended as first-line treatment for mild to moderate comedonal and inflammatory acne.3 While success is seen with monotherapy, using a retinoid in combination with benzoyl peroxide or topical antibacterials is also an appropriate and effective therapeutic treatment option.3 Tretinoin, adapalene, and tazarotene are topical retinoids available for use in the treatment of acne. Table 62-2 describes the strengths and formulations of these agents. 

Adverse effects are likely with the use of topical retinoids. Although transient, erythema, irritation, dryness, and peeling at the site of application are all common effects. Photosensitivity can also occur with retinoid use, causing increased skin irritation and redness.14... 

The topical retinoid selected should be used once daily at bedtime, beginning with a low-potency formulation. Increased strengths are then initiated according to treatment results and tolerance. Patients should be advised that a worsening of acne symptoms generally occurs in the first few weeks of therapy, with lesion improvement occurring in 3 to 4 months.16 The use of topical retinoids should be avoided in children less than 12 years old and in pregnant women.14... 

With antibacterial and anti-inflammatory properties, and the ability to stabilize keratinization, azelaic acid is an effective alternative in the treatment of mild to moderate acne in patients who cannot tolerate benzoyl peroxide or topical retinoids.3,21 It also has a hypopigmentation effect that may prove effective in patients who are prone to post-inflammatory hyperpigmentation resulting from acne.22... 

While these agents may cause less skin irritation than benzoyl peroxide or the topical retinoids, several disadvantages exist. Sulfur preparations produce an unpleasant odor when applied to the skin, while resorcinol may cause brown scaling. And although rare, the possibility of salicylism exists with continual salicylic acid use.3,12... 

TABLE 62-2. Topical Retinoids Available for the Treatment of Acne15... 

BPO = benzoyl peroxide AA = azelaic acid TR = topical retinoid SA = salicylic acid OA = oral antibiotic TA = topical antimicrobial... 

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