SKIN CARE: TREATMENT OF PSORIASIS
The overall aim of treatment is to inhibit or reduce the mitotic activity of the cells, so that they slow down their rate of reproduction or ‘turnover’. Along with this, the associated inflammation must be suppressed. Topical or surface treatment is the most logical form of treatment. The most useful substances for this are tar preparations and a closely related substance known as dithranol These preparations may come in various forms, and one of the most important considerations when using these substances is the choice of vehicle. That is to say, some bases, whether cream or ointment, are better absorbed than others, hence enabling the tar or dithranol to adequately penetrate the skin. The vehicle is particularly important when the preparation is intended for use on the scalp. If, for example, an ointment were to be used here, it may be difficult to wash out in the morning, and therefore cosmetically unsuitable; ointment, therefore, would not be used. The precise purpose of tars and dithranol is to reduce or inhibit mitoses, and therefore slow down reproduction of cells. Frequently, these preparations may be used in conjunction with salicylic or retinoic acids which are very useful in reducing the surface scaliness and allowing the preparations to adequately penetrate the tissues.
Topical steroids, ‘cortisone’ creams, are very commonly used in the treatment of psoriasis. The advantage of these preparations is, firstly, that they are cosmetically the most acceptable. Furthermore they are excellent for decreasing mitoses, decreasing surface scaliness, and reducing inflammation. However the weaker creams do not work effectively and the stronger ones, if used over large surfaces for prolonged periods, may occasionally result in side-effects. The other perhaps more important disadvantage is that the condition frequently recurs, or relapses, when their use is ceased. Ultraviolet light (UVB) is very useful as an adjunct to the treatment of psoriasis with these topical preparations: the UVB tends to decrease mitoses and reduce excessive cell reproduction. The sun is a better source of ultraviolet light than the artificial lamps available. Occasionally, however, sufferers with psoriasis are sensitive to sunlight, and then of course it should not be used. Systemic or oral treatment of psoriasis is also available for the more severe cases. This type of treatment should only be carried out by dermatologists who are prepared to carefully monitor the patient’s general health and carefully control the dosage of the drugs used. Oral cortisone has no place in the routine management of psoriasis because of its possible side-effects with continued use. Furthermore, with acute pustular psoriasis it may aggravate the condition. Various cytotoxic agents (like methotrexate), which in large doses are used for the treatment of certain cancers, may be most useful when used in low dosage. They act by inhibiting mitoses and slowing down cell reproduction. Methotrexate is used in very small doses which are given once a week. It is a very useful drug if there are no blood or liver abnormalities, which must be regularly checked for. Obviously it affects not only the skin but also the liver, bone marrow, bowel, and reproductive organs. It must therefore never be used during reproductive years unless appropriate contraceptive precautions are taken. However, if used with care and appropriate supervision, methotrexate is a most useful treatment for severe psoriasis. There are other similar drugs, such as hydroxyurea, which may be used if methotrexate proves unsatisfactory.
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