Akio Iida

Ferric Citrate Hydrate, a New Phosphate Binder, Prevents the Complications of Secondary Hyperparathyroidism and Vascular Calcification

Background/Aims: Ferric citrate hydrate (JTT-751) is being developed as a treatment for hyperphosphatemia in chronic kidney disease patients, and shows serum phosphorus-reducing effects on hyperphosphatemia in hemodialysis patients. We examined whether JTT-751 could reduce phosphorus absorption in normal rats and prevent the progression of ectopic calcification, secondary hyperparathyroidism and bone abnormalities in chronic renal failure (CRF) rats. Methods: Normal rats were fed a diet containing 0.3, 1 or 3% JTT-751 for 7 days. The effects of JTT-751 on phosphorus absorption were evaluated with fecal and urinary phosphorus excretion. Next, a CRF model simulating hyperphosphatemia was induced by feeding rats a 0.75% adenine diet. After 21 days of starting the adenine diet feeding, 1 or 3% JTT-751 was administered for 35 days by dietary admixture. The serum phosphorus levels and mineral parameters were measured. Calcification in the aorta was examined biochemically and histopathologically. Hyperparathyroidism and bone abnormalities were evaluated by histopathological analysis of the parathyroid and femur, respectively. Results: In normal rats, JTT-751 increased fecal phosphorus excretion and reduced phosphorus absorption and urinary phosphorus excretion. In CRF rats, JTT-751 reduced serum phosphorus levels, the calcium-phosphorus product and calcium content in the aorta. Serum intact parathyroid hormone levels and the incidence and severity of parathyroid hyperplasia were also decreased. JTT-751 reduced femoral bone fibrosis, porosity and osteoid formation. Conclusions: JTT-751 could bind with phosphate in the gastrointestinal tract, increase fecal phosphorus excretion and reduce phosphorus absorption. JTT-751 could prevent the progression of ectopic calcification, secondary hyperparathyroidism and bone abnormalities in rats.

The utility of the phosphate binder, ferric citrate hydrate (JTT-751), about phosphorus absorption-reducing effect in normal rats

Abstract Hyperphosphatemia is a risk factor for arterial calcification contributing to the high-cardiovascular mortality in patients with chronic kidney disease (CKD). Ferric citrate hydrate (JTT-751) is being developed as a treatment for hyperphosphatemia with chronic renal failure and has shown a serum phosphorus-lowering effect in CKD patients. In this study, we evaluated the combination effect of JTT-751 with the phosphorus absorption-reducing effect of calcium carbonate and compared phosphorus absorption-reducing efficacy between three phosphate binders including JTT-751. Normal rats were fed a diet containing either 1% calcium carbonate, 1% JTT-751 or 1% JTT-751 with 1% calcium carbonate, for 7 days. Both 1% calcium carbonate and 1% JTT-751 alone reduced urinary phosphorus excretion, and the combined treatment reduced it more than each single-treatment, without clearly influencing calcium or iron-metabolism. Next, normal rats were fed a diet containing either 0.3, 1 and 3% lanthanum carbonate or 2.3% JTT-751, for 7 days. Either 3% lanthanum carbonate or 2.3% JTT-751 reduced urinary phosphorus excretion. Finally, we compared the reduced amount of urinary phosphorus excretion per dose of compound, of which JTT-751 is comparable to that of calcium carbonate and is greater than that of the lanthanum carbonate. In conclusion, JTT-751 showed an additive effect on the phosphorus absorption-reducing effect of calcium carbonate without influencing calcium- and iron-metabolism, and had a phosphorus absorption-reducing efficacy comparable to or greater than other existing phosphate binders.