The rationale for the use of vitamin D derivatives in the treatment of psoriasis is based on the observation that patients with hypocalcemia often develop various forms of psoriasis, most notably the pustular form. In one case, a patient who had undergone thyroidectomy developed repeated flares of pustular psoriasis after decreases were made in her dosage of ergocalciferol (Vitamin D 2 ); each episode was related to severe hypocalcemia and resolved after her serum calcium levels normalized. 14 Another patient with osteoporosis experienced dramatic improvement in severe psoriasis after receiving an oral form of vitamin D. 15 This finding, along with the discovery that the bioactive form of 1,25-dihydroxycholecalciferol has been shown to inhibit keratinocyte proliferation and promote keratinocyte differentiation, 16 has led to the development of vitamin D analogs for the treatment of psoriasis.
Prescriptions written for topical steroids should include explicit instructions about where and how often to apply the preparation, and the body areas where use must be avoided. Pharmacists should ensure these directions are included on the dispensing label. Prescribers should bear in mind that patients may keep unused or leftover corticosteroid skin preparations for some time after they are prescribed and thus forget the original indication or instructions for use. The prescribing of unnecessarily large quantities should be avoided. Patients should be warned not to share their topical steroid preparation with other people as this may result in unsafe application to unsuitable areas such as the face, as well as the potentially inappropriate treatment of undiagnosed skin conditions.
Corticosteroids are generally teratogenic in laboratory animals when administered systemically at relatively low dosage levels. The more potent corticosteroids have been shown to be teratogenic after dermal application in laboratory animals. There are no adequate and well-controlled studies in pregnant women on teratogenic effects from topically applied corticosteroids. Therefore, topical corticosteroids should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus . Drugs of this class should not be used extensively on pregnant patients, in large amounts, or for prolonged periods of time.