Psoriasis topical agents

Pharmacologic alternatives for psoriasis include topical agents, phototherapy, and systemic agents including the use of biologic response modifiers. 

Calcipotriol is a vitamin D3 derivative which is used as a topical agent in the treatment of psoriasis. Although not completely elucidated its mechanism of action seems to be based on inhibition of the proliferation and stimulation of the differentiation of epidermal keratinocytes. Adverse effects include irritation of the skin but also urticarial reactions. Calcipotriol has 100 fold less vitamin D activity as its active vitamin D3 metabolite calcitriol. However, calcipotriol in overdose can cause symptoms of hypercalcemia. 

Dantron (danthron 1,8-dihydroxyanthraquinone) (Figure 3.34) is known as a natural product, but for drug use is produced synthetically. It is prescribed to relieve constipation in geriatric and terminally ill patients. Dithranol (1,8-dihydroxyanthrone) is used as topical agent to treat troublesome cases of psoriasis. Diacetylrhein is marketed in some countries for the treatment of osteoarthritis. 

These include atypical or subtle manifestations of dermatologic conditions such as seborrheic dermatitis, rosacea, psoriasis, atopic dermatitis, and ichthyosis. Classic manifestations of such diseases are diagnosed with relative ease. However, diagnostic difficulty arises in the presence of atypical morphology, lesions masked by topical therapy (e.g., corticosteroids), or exacerbations due to other topical agents (e.g., skin care products).2,10... 

Ultraviolet B light is effective in guttate psoriasis and potentiates the effects of topical agents such as calcipotriol and dithranol. A psoralen followed by ultraviolet light (PUVA) is used in severe cases (see Psoralens, p. 306). 

Multiple pharmacotherapeutic approaches to psoriasis management include first-line therapy for mild to moderate psoriasis with topical agents. In severe psoriasis, photochemotherapy and... 

Pimecrolimus and tacrolimus are calcineurin inhibitors capable of exerting a local immunomodulating effect that may serve to normalize hyperproliferation of epidermis. As topical agents, tacrolimus and pimecrolimus are approved for the treatment of atopic dermatitis however, regulatory approval regarding the efficacy of these agents in psoriasis is yet to be completed. 

Tremblay, J.F. and Bissonnette, R. (2002) Topical agents for the treatment of psoriasis, pasf present and future, J. Cutan. Med. Surg., 6 8-11. 

VD as monotherapy had a satisfactory resporrse rate between 22 and 96% and a treatment success rate ranging from 4 to 40%. VDS had a satisfactory response rate between 35 and 53%. A meta-analysis found a probability of success twice higher with VDS than with VD in adult plaque psoriasis, while the cost/efficacy ratio was evaluated as 1.2 to 1.8 times higher for VDS than for VD. In conclusion VDS is twice more effective than VD, although additional studies are needed to clarify maintenance treatment, impact on quality of life and treatment of non-plaque psoriasis. It will be important to harmonise outcome measures in future studies with topical agents in psoriasis to better appraise their efficacy. 

Keratolytic agents such as salicylic acid are often added to bath oil or shampoos (typically 3% to 4%) for scalp psoriasis.10 Salicylic acid can also be added to topical corticosteroid preparations to enhance steroid penetration (salicylic acid breaks down keratin). 

Topical corticosteroids may be used for short-term treatment of acute flare-ups (see Table 16-1 in Chap. 16 on Psoriasis). Most corticosteroids are applied once or twice daily. High-potency agents are used for less than 3 weeks for flare-ups or for lichenified (thickened) lesions. Moderate-potency steroids may be used for more chronic conditions, and low-... 

Numerous glucocorticosteroids for topical application are available. Essentially they all suppress the symptoms of inflammatory and hypersensitivity reactions and their mechanism of action is similar. Their indications include seborrhoeic and atopic dermatitis, phototoxic reactions, psoriasis, chronic discoid lupus, hypertrophic lichen planus and alopecia areata. However it has to be kept in mind that the use of corticosteroids for these conditions in most cases only gives symptomatic relieve and that the problem tends to recur on cessation of therapy. Traditionally topical corticosteroid formulations are grouped according to approximate relative efficacy. This efficacy is determined by both the potency of the agent and the concentration in which the corticosteroid is used. 

The remarkable efficacy of topical corticosteroids in the treatment of inflammatory dermatoses was noted soon after the introduction of hydrocortisone in 1952. Numerous analogs are now available that offer extensive choices of potencies, concentrations, and vehicles. The therapeutic effectiveness of topical corticosteroids is based primarily on their antiinflammatory activity. Definitive explanations of the effects of corticosteroids on endogenous mediators of inflammation await further experimental clarification. The antimitotic effects of corticosteroids on human epidermis may account for an additional mechanism of action in psoriasis and other dermatologic diseases associated with increased cell turnover. The general pharmacology of these endocrine agents is discussed in Chapter 39. 

Urea is used as an osmotic to treat problems like high pressure in the eye ball (glaucoma). It is also used as a diuretic and as a topical dermatological agent in treating psoriasis, and other dry, scaly conditions. 

Alka-Seltzer aspirin sodium bicarbonate. Alkeran melphalan. allantoin [ban, usan) (glyoxylic dlureide) occurs in allantoic fluid. It is a product of purine metabolism, very widely distributed in biological systems, including numerous plants. It has antiinflammatory activity and was formerly used topically as a dermatological agent in preparations for the treatment of psoriasis and other skin conditions (though its efficacy is disputed). 

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