Extended release nicotinic acid - a novel oral agent for phosphate control

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.

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.

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.

Oral nicotinic acid may emerge as a safe, low cost yet powerful agent for phosphorus control in dialysis patients.