8.4 Pediatric Use
The safety and efficacy of Renvela has not been established in pediatric patients.

8.5 Geriatric Use
Clinical studies of Renvela did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range.

10 OVERDOSAGE
Sevelamer hydrochloride, which contains the same active moiety as sevelamer carbonate, has been given to normal healthy volunteers in doses of up to 14 grams per day for eight days with no adverse effects. In CKD patients on dialysis, the maximum dose studied was 14 grams of sevelamer carbonate and 13 grams of sevelamer hydrochloride. There are no reports of overdosage with sevelamer carbonate or sevelamer hydrochloride in patients. Since sevelamer is not absorbed, the risk of systemic toxicity is low.

11 DESCRIPTION
The active ingredient in   Renvela is sevelamer carbonate, a polymeric amine that binds phosphate and is meant for oral administration. It was developed as a pharmaceutical alternative to sevelamer hydrochloride (Renagel®). Sevelamer carbonate is an anion exchange resin, with the same polymeric structure as sevelamer hydrochloride, in which carbonate replaces chloride as the counterion. While the counterions differ for the two salts, the polymer itself, the active moiety involved in phosphate binding, is the same.

Renvela (sevelamer carbonate) is known chemically as poly(allylamine- co -N,N’-diallyl-1,3-diamino-2-hydroxypropane) carbonate salt. Sevelamer carbonate is hygroscopic, but insoluble in water. The structure is represented in Figure 1.

Figure 1. Chemical Structure of Sevelamer Carbonate

a, b = number of primary amine groups     a + b = 9
c = number of crosslinking groups            c = 1
m = large number to indicate extended polymer network

Renvela® Tablets: Each film-coated tablet of Renvela contains 800 mg of sevelamer carbonate on an anhydrous basis. The inactive ingredients are hypromellose, diacetylated monoglycerides, microcrystalline cellulose, sodium chloride and zinc stearate. The tablet imprint contains iron oxide black ink.

Chemical Structure of Sevelamer Carbonate 12 CLINICAL PHARMACOLOGY
Patients with chronic kidney disease (CKD) retain phosphorus and can develop hyperphosphatemia. When the product of serum calcium and phosphorus concentrations (Ca x P) exceeds 55 mg2/dL2, there is an increased risk that ectopic calcification will occur. Hyperphosphatemia plays a role in the development of secondary hyperparathyroidism in renal insufficiency.

Treatment of hyperphosphatemia includes reduction in dietary intake of phosphate, inhibition of intestinal phosphate absorption with phosphate binders, and removal of phosphate with dialysis. Sevelamer carbonate taken with meals has been shown to control serum phosphorus concentrations in patients with CKD who are on dialysis.

12.1 Mechanism of Action
Renvela contains sevelamer carbonate, a non-absorbed phosphate binding crosslinked pol