Hyperphosphatemia is a common complication of end-stage renal disease and particularly affects haemodialysis patients. Elevated serum phosphorus contributes to the development of secondary hyperparathyroidism, Mineral bone disorders,metastatic calcifications and calcific uremic arteriolopathy. There is a significant association between hyperphosphatemia and increased morbidity and mortality in end stage renal disease patients including cardiovascular morbidity and mortality ,also it's associated with hospitalization of haemodialysis patients.

Hyperphosphataemia is mainly due to impaired renal phosphate excretion and primary increase in renal phosphate reabsorption,due to acute or chronic renal insufficiency. Renal excretion is so efficient in normal subjects that balance can be maintained with only a minimal rise in serum phosphorus concentration even for a large phosphorus load. Therefore, acute hyperphosphataemia usually resolves within few hours if renal function is intact.

Although, there is multiple lines of treatment of hyperphosphatemia in end stage renal disease patients undergoing Hemodialysis but still inadequate. As Calcium containing phosphate binders may sometimes result in adverse effects such as hypercalcemia. Non-calcium containing phosphate binders, such as sevelamer and lanthanum, are expensive. Aluminum-containing agents are efficient but no longer widely used because of their toxicity. Several trials have shown that nicotinamide and niacin are capable of remarkably reducing serum phosphate levels in patients undergoing haemodialysis.

Niacin is a water-soluble vitamin, and a part of the B complex vitamin, both nicotinamide and niacin (nicotinic acid) are forms of vitamin B3 . As a broad-spectrum drug that can affect lipid levels, niacin reduces levels of total cholesterol, triglyceride, and low-density lipoprotein cholesterol, while increasing high-density lipoprotein cholesterol levels. Niacin also lowers serum phosphorus levels in patients with chronic kidney disease, dyslipidemia, and diabetes mellitus. Furthermore, niacin plays a key role in cardiovascular diseases and cardiovascular-related mortality by modifying both dyslipidemia and phosphorus levels.

Recently, nicotinic acid and related compounds such as nicotinamide have also been shown to decrease phosphorus absorption in the gastro-intestinal tracts of animals by a different mechanism than the traditional phosphate binders.

The major side effects of niacin are vasodilation and flushing, which appear to be mediated through prostaglandin production, and thus can be attenuated by premedication with aspirin.

Inclusion Criteria:

1. end stage renal disease patients aged from 18-60 years old.
2. Duration of Hemodialysis >6 months.
3. Serum phosphorus level >5 mg/dl

Exclusion Criteria:

• 1)patients on sevelamer or cinacalcet. 2)Hepatitis C virus +ve patients. 3)Connective tissue disease. 4)Active malignancy. 5) pregnancy 6) active peptic ulcer disease 7) treatment with carbamazepine.