Background: Hyperphosphatemia is common in hemodialysis patients. Recent animal studies show that nicotinamide inhibits the sodium dependent phosphate co-transport in the small intestine and thereby reduces serum phosphorus levels. Nicotinic acid which is the prodrug of nicotinamide is widely used as antihyperlipidemic agent. We examined in a prospective study whether it reduces serum phosphorus levels in hemodialysis patients.
Methods: Patients who were on maintenance hemodialysis were enrolled in to the study if their predialysis serum phosphorus was more than 6 mg/dl. During the pre-trial run in period of 1 week all phosphate binders were stopped. A single dose of extended release nicotinic acid (375 mg) tablet was given with meal. Repeat measurements of serum calcium, phosphorus and alkaline phosphatase were carried out after 8 weeks. Then the drug was stopped in a subgroup of patients and serum phosphorus remeasured after 2 weeks.
Results: There were 34 patients with varied etiological spectrum of end stage renal disease. They were on hemodialysis for a mean period of 8.7 months. Serum phosphorus levels changed significantly from a pre treatment level of 7.7 +/- 1.5 mg/dl to post treatment level of 5.6 +/-1 mg/dl (p < 0.001). There was no significant variance across age groups, sex, disease categories and dialysis duration. The calcium level increased from 8.1 +/- 1.0 to 8.5 +/- 1.0 mg/dl (p < 0.015). The serum alkaline phosphatase level decreased significantly from 107+/-66 IU/l to 82+/-46 IU/l (p < 0.001 ). There was a significant reduction of calcium phosphate product from 63.1 + 15.1 mg2 to 48.7 +/- 10.9 mg2/dl2 (p < 0.001). Oral nicotinic acid was well tolerated. Mild pruritus was encountered in 2 patients.
Conclusion: Oral nicotinic acid may emerge as a safe, low cost yet powerful agent for phosphorus control in dialysis patients.