Local treatments entail the use of ointments and pastes, usually containing tar in various forms. It is much easier to apply them in hospital than at home if patients can make the time for hospital visits. Inpatient treatment can be more intensive and closely regulated; it also has the advantage of taking the patient completely away from the stresses of the everyday environment. In some units a "five day ward" enables patients to return home at weekends, which is particularly important for parents with young children.
Coal tar preparations are safe and effective for the stable plaque-type psoriasis but will irritate acute, inflamed areas. However, tar may not be strong enough for thicker hyperkeratotic lesions. Salicylic acid, which helps dissolve keratin, can be used in conjunction with tar for thick plaques. Refined coal tar extracts can be used for less severe areas of psoriasis.
Ichthammol, prepared from shale rather than coal tar, is less irritating and has a soothing effect on inflamed skin. It is therefore useful for "unstable" or inflamed psoriasis, when tar would not be tolerated.
Dithranol, obtained originally from the Goa tree in south India, is now made synthetically. It can easily irritate or burn the skin, so it has to be used carefully and should be kept from contact with normal skin as far as possible. For hospital treatment pastes are used and the lesions surrounded by petroleum jelly to protect the normal skin. Dithranol creams can be used at home—they are applied for 30 minutes and then washed off. A low concentration (0-1%) is used initially and gradually increased to 1% or 2% as necessary. All dithranol preparations are irritants and produce a purple-brown staining that clears in time. If used in the scalp dithranol stains red or fair hair purple.
Emollients soften dry skin and relieve itching. They are a useful adjunct to tar or dithranol.
Corticosteroid preparations produce an initial clearing of psoriasis, but there is rapid relapse when they are withdrawn and tachyphylaxis (increasing amounts of the drug having a diminishing effect) occurs. Strong topical steroids should be avoided. Only weak preparations should be used on the face but moderately potent steroids can be used elsewhere:
(a) if there are only a few small lesions of psoriasis;
(b) if there is persistent chronic psoriasis of the palms, soles, and scalp (in conjunction with tar paste, which is applied on top of the steroid at night); and (c) in the treatment of psoriasis of the ears, flexures, and genital areas. In flexural psoriasis secondary infection can occur and steroid preparations combined with antibiotics and antifungal drugs should be used, such as Terra-Cortril with nystatin and Trimovate.
Systemic corticosteroids should not be used, except in life threatening erythroderma, because of the inevitable "rebound" that occurs when the dose is reduced. The management of psoriasis in patients taking steroids for an unrelated condition may require inpatient or regular outpatient attendances to clear the skin lesions.
Calcipotriol and tacalcitol, vitamin D analogues, are calmodulin inhibitors used topically for mild or moderate plaque psoriasis. They are non-staining creams that are easy to use but can cause irritation. Sometimes a plateau effect is seen with the treatment becoming less effective after an initial response. If so, other agents, such as tar preparations, have to be used as well to clear the lesions completely. It is important not to exceed the maximum recommended dose so as to prevent changes in calcium metabolism.
Short contact dithranol
• Stable plaque psoriasis on the trunk and limbs
• Those available are in a range of concentrations such as Dithocream (0-1%, 0-25%, 0-5%, 1-0%, 2-0%) or Anthranol (0-4%, 1-0%, 2-0%)
• Start with the lowest concentration and increase strength every five to six days if there are no problems
• Apply cream to affected areas and then wash it off completely 20-30 minutes later
• Apply a bland emollient immediately after treatment
• Do not apply to inflamed plaques, flexures, or the face
• Avoid contact of the dithranol with clothing and rinse the bath well after use to avoid staining
• Never leave the cream on for longer than 30 minutes (60 minutes is not twice as effective)
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