A randomized, double-blind, placebo-controlled trial of niacinamide for reduction of phosphorus in hemodialysis patients.

Randomized, double-blind, placebo-controlled trial in adults on long-term maintenance hemodialysis with serum phosphorus at least 5.0 mg/dl despite stable phosphorus binder therapy. The niacinamide arm randomized 33 participants and 25 were analyzed per protocol; enrollment occurred at two urban dialysis units in St. Louis, Missouri.

Niacinamide was given as oral capsules in addition to stable phosphorus binder therapy. The active arm started at 250 mg twice daily, was increased to 500 mg twice daily at week 3 and 750 mg twice daily at week 5 if phosphorus remained elevated, and was dose-adjusted down for hypophosphatemia; the same titration scheme was repeated after washout beginning in week 11.

Niacinamide lowered serum phosphorus and the calcium-phosphorus product, and it increased HDL cholesterol when added to binder therapy. In the niacinamide arm, phosphorus decreased from 6.26 +/- 1.28 at week 1 to 5.47 +/- 1.49 at week 9 (P = 0.02), calcium-phosphorus product decreased from 58.72 +/- 12.42 to 51.56 +/- 13.48 (P = 0.02), and HDL increased from 50 +/- 17 to 61 +/- 21 (P = 0.04). The authors concluded it was generally well tolerated and supported further larger randomized trials.

The active arm was small, with only 25 participants analyzed per protocol after 33 were randomized. The treatment period was short, and the study was conducted in a limited hemodialysis population at two urban centers, which restricts generalizability. Cohort-wide ethnicity data were reported, but not arm-specific demographics, and longer-term efficacy and safety remain uncertain.