Study on pruritus in hemodialysis patients and the antipruritic effect of neurotropin: plasma levels of C3a, C5a, bradykinin and lipid peroxides.

The causes of pruritus in patients undergoing hemodialysis and the mechanism of the antipruritic effect of Neurotropin, an extract isolated from the inflamed dermis of rabbits inoculated with vaccinia virus and clinically used in Japan as an analgesic and antiallergic drug, were investigated by measuring the levels of C3a, C5a, bradykinin and lipid peroxides in venous blood collected before dialysis, and at 15 min and 4 hr after starting hemodialysis. C3a increased considerably in pruritic patients compared to non-pruritic patients at 15 min after starting hemodialysis. Neurotropin significantly suppressed the C3a level and improved the condition of pruritic patients. There was no significant difference in the level of bradykinin between pruritic patients and non-pruritic patients. Therefore, bradykinin was not thought to be related to the incidence of pruritus in such patients. A tendency towards lowering of the levels of lipid peroxides in the patients' plasma by Neurotropin was also observed. It seems possible that elevation of C3a may be one of the underlying causes for the appearance of pruritus, and that Neurotropin may exert its antipruritic effect through suppression of the activation of C3 in patients undergoing hemodialysis.