Oral nicotinamide reduces serum phosphorus, increases HDL, and induces thrombocytopenia in hemodialysis patients: a double-blind randomized clinical trial.

BACKGROUND: Recently, nicotinamide has been suggested as an effective drug for hyperphosphatemia in hemodialysis patients. The authors assessed the efficacy and safety of nicotinamide in these patients with lower doses and longer duration than other studies.

METHODS: Forty eight patients with fasting serum phosphorus >5 mg/dl enrolled in this randomized clinical trial study and were randomly assigned to two equal-sized groups of nicotinamide or placebo. The study lasted 8 weeks. In the first four weeks, nicotinamide was administered at 500 mg/day, and in the second four weeks at 1,000 mg/day. Blood samples were tested at baseline, week 4, and week 8.

RESULTS: In nicotinamide group, the mean phosphorus level decreased from 5.9 ± 0.58 mg/dl to 4.77 ± 1.43 mg/dl in week 4 (P = 0.002) and to 4.66 ± 1.06 mg/dl in week 8 (P = 0.000). The mean calcium-phosphorus product decreased significantly with the same pattern as phosphorus. High-density lipoprotein level increased from 42.46 ± 8.01 mg/dl to 55.71 ± 11.88 mg/dl in week 4 (P = 0.000) and to 65.25 ± 20.18 mg/dl in week 8 (P = 0.000). Levels of serum calcium, uric acid, SGOT, SGPT, and iPTH didn't change significantly. Compared to baseline, the platelet counts were decreased in both week 4 and week 8. No significant changes were observed in placebo group.

CONCLUSIONS: In our patients, nicotinamide effectively decreased phosphorus, increased high-density lipoprotein, and caused thrombocytopenia. Since nicotinamide lowered platelet counts and caused thrombocytopenia in lower doses than other studies in these patients, it is necessary to plan other studies for assessing the safety of the drug especially in different populations.