Treatments are often disappointing and may cause side effects. This article summarizes the existing treatments and evidence available to support their use. It should be noted that most trials have been conducted over short time periods for what is essentially a chronic, relapsing-remitting disease that frequently requires longterm therapy. Outcome measures in these trials are poorly defined and few studies report on patients’ subjective views.
Topical Treatments
Emollient Creams and Ointments
Topical treatments alone tend to be ineffective for PPP, although some patients may benefit from using emollient creams or ointments, particularly when the disease is mild. These can safely be used as frequently as the patient wishes.
Topical Corticosteroid Preparations
Superpotent topical corticosteroids may be effective in reducing the severity of PPP in the short term, and hydrocolloid gel occlusion has been shown to increase the numbers of patients who respond even when only a moderately potent steroid is used.2,3 Reapplication of cream under gel occlusion is applied every third day for a maximum of four weeks. In order to maintain remission, some physicians prescribe a weaker topical steroid for daily use, but evidence supporting this intervention is lacking. The potential side effects of topical steroids are well known to dermatologists: in particular, the skin around the medial longitudinal arch may be prone to atrophy.
Tar and Anthralins
Some dermatologists advocate the use of tar and anthralin preparations for PPP. There are no published randomized controlled trials (RCTs) that demonstrate their efficacy. In addition, treatment can be messy and irritating.
Topical Retinoids
Although systemic retinoid therapy is effective, there is no published evidence to support the use of topical retinoids for PPP. Tazarotene gel, which was recently introduced to treat mild to moderate plaque psoriasis, has not yet been formally evaluated in PPP.
Systemic Treatments
Systemic Retinoids
Oral etretinate, at a dose of 0.6mg/kg/day, produces objective improvement in about 2/3 of PPP patients and remission has been maintained in those who responded to initial treatment.6 There is evidence to show that acitretin, which has now superseded etretinate, is as effective in the treatment of PPP at the same dose.
Retinoids are highly teratogenic, and female patients must be warned of the risks. Acitretin, the hydrolysis product of etretinate, was developed because of the initial belief that it was eliminated from the body much more rapidly. However, subsequent analysis has shown that it may, under certain circumstances, be esterified in vivo into etretinate. Since terminal elimination of etretinate from body fat stores is very slow, contraceptive measures must be taken during treatment and for at least two years after discontinuing acitretin.
Side effects of acitretin include xerosis, photosensitivity, epistaxis and (reversible) alopecia. Fasting lipid and liver function tests should be checked prior to commencing and at intervals during treatment. There is a small risk of hyperostosis and extraosseous calcification in patients on long-term therapy.
Liarozole is a novel drug that inhibits breakdown of all-trans retinoic acid, causing elevation of all-trans retinoic acid levels in the skin and plasma. Its effects and side effects are similar to synthetic retinoids but it is not believed to have a prolonged action following withdrawal. A small pilot study suggests that it may be effective in the treatment of PPP and may be worthy of further investigation.
Source: skintherapyletter.com
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