Pruritus of polycythaemia vera: a place for pizotifen?

Generalised pruritus occurs in 25-50/ of cases of polycythaemia vera. Neither the cause nor the most effective treatment has been established. A relation with iron deficiency has been suggested and relief after iron treatment recorded.' Cholestyramine has been reported to have an antipruritic action in polycythaemia vera, which might imply an association with raised concentrations of conjugated bile acids.2 While generally thought to be related to disease activity, the pruritus also appears to be associated with raised histamine concentrations in blood and urine.3 Conventional antihistamines are seldom successful, however, and the place for cimetidine treatment is not yet clear4; despite this, the reported beneficial response to cyproheptadine has been attributed to its potent antihistamine effect.3 The complete relief of pruritus after the introduction of pizotifen prescribed for migraine prophylaxis and its relapse after withdrawal of the drug in a woman with active polycythaemia vera led us to examine the effect of pizotifen on the pruritus of polycythaemia vera. The association of iron deficiency, disease control (as judged by Coulter values), and concentrations of conjugated bile acids with the pruritus was also examined.