Hydroxyurea in the management of therapy resistant psoriasis.

Eighty-five patients with extensive chronic plaque psoriasis, unresponsive to conventional topical therapy, were treated with long-term hydroxyurea in a dose of 0.5-1.5 g daily. Fifty-two (61%) had a satisfactory remission during treatment without significant adverse effects. Treatment was discontinued in 33 patients (39%), due to an inadequate response or significant relapse during treatment and because of adverse reactions (19%). Four (4.7%) patients on hydroxyurea developed actinic psoriasis. Significant haematological abnormalities occurred in 30 patients (35%), but these became normal following a reduction in the dose of hydroxyurea or temporarily stopping the drug. In only six was it considered necessary to discontinue treatment because of bone marrow suppression. Our experience suggests that hydroxyurea is an effective long-term treatment for psoriasis that is refractory to conventional topical therapy and that the incidence of serious adverse effects compares favourably with other cytotoxic drugs.