Therapeutic effect of oral nicotinamide on refractory uremic pruritus: a randomized, double-blind study.

To determine the efficacy of oral nicotinamide with placebo to ameliorate uremic pruritus (UP), we conducted a prospective, randomized, double-blind, 4-week study in 50 chronic kidney disease patients with refractory UP. The patients were randomly allocated to nicotinamide tablet 500 mg twice/day or placebo. All anti-pruritic agents were discontinued at least two weeks before the study. All the patients completed the period of the study and their severity of pruritus was evaluated before the start of the study and at the end of each week for four weeks by using a traditional Visual Analogue Scale and a modified questionnaire method (pruritus score). The average pruritus score before administration of oral nicotinamide in the study group and that in the placebo group was 2.96 ± 0.45 and 2.72 ± 0.37, respectively. In the nicotinamide group, the average score of pruritus gradually reduced to 1.29 ± 1.08 and in the placebo group it gradually decreased to 1.52 ± 1.61 at the end of the fourth week. There was no significant difference between the reductions of pruritus in both groups, but the interaction effect using a linear mixed model was significant between drug and time ( P <0.026). We conclude that increasing the time of application of nicotinamide sodium to more than four weeks may be more effective than placebo in reducing itching in uremic patients.