SEVELAMER HYDROCHLORIDE

The active ingredient in Sevelamer Hydrochloride Tablets is sevelamer hydrochloride, a polymeric amine that binds phosphate and is meant for oral administration. Sevelamer hydrochloride is poly(allylamine hydrochloride) crosslinked with epichlorohydrin in which 40% of the amines are protonated. It is known chemically as poly(allylamine- co -N,N′-diallyl-1,3-diamino-2-hydroxypropane) hydrochloride. Sevelamer hydrochloride is hydrophilic, but insoluble in water. The structure is represented in Figure 1. Figure 1: Chemical Structure of Sevelamer Hydrochloride a, b = number of primary amine groups a + b = 9 c = number of crosslinking groups c = 1 n = fraction of protonated amines n = 0.4 m = large number to indicate extended polymer network The primary amine groups shown in the structure are derived directly from poly(allylamine hydrochloride). The crosslinking groups consist of two secondary amine groups derived from poly(allylamine hydrochloride) and one molecule of epichlorohydrin. Figure 1 - Chemical Structure Sevelamer hydrochloride tablets: Each film-coated tablet of sevelamer hydrochloride contains 800 mg of sevelamer hydrochloride on an anhydrous basis. The inactive ingredients are hypromellose, diacetylated monoglyceride, colloidal silicon dioxide, and stearic acid.

Sevelamer hydrochloride is indicated for the control of serum phosphorus in patients with chronic kidney disease (CKD) on dialysis. The safety and efficacy of sevelamer hydrochloride in CKD patients who are not on dialysis have not been studied. Sevelamer hydrochloride is a phosphate binder indicated for the control of serum phosphorus in patients with chronic kidney disease on dialysis. ( 1 )

Starting dose is one or two 800 mg tablets orally three times per day with meals. ( 2 ) Adjust by one tablet per meal in two-week intervals as needed to obtain serum phosphorus target (3.5 to 5.5 mg/dL). ( 2 ) Patients Not Taking a Phosphate Binder . The recommended starting dose of sevelamer hydrochloride is 800 mg to 1,600 mg orally, which can be administered as one or two 800 mg sevelamer hydrochloride tablets with meals based on serum phosphorus level. Table 1 provides recommended starting doses of sevelamer hydrochloride for patients not taking a phosphate binder. Table 1: Starting Dose for Dialysis Patients Not Taking a Phosphate Binder Serum Phosphorus Sevelamer Hydrochloride 800 mg >5.5 and <7.5 mg/dL 1 tablet three times daily with meals ≥7.5 and <9.0 mg/dL 2 tablets three times daily with meals ≥9.0 mg/dL 2 tablets three times daily with meals Patients Switching from Calcium Acetate . In a study in 84 CKD patients on hemodialysis, a similar reduction in serum phosphorus was seen with equivalent doses (approximately mg for mg) of sevelamer hydrochloride and calcium acetate. Table 2 gives recommended starting doses of sevelamer hydrochloride based on a patient's current calcium acetate dose. Table 2: Starting Dose for Dialysis Patients Switching from Calcium Acetate to Sevelamer Hydrochloride Calcium Acetate 667 mg (Tablets per meal) Sevelamer Hydrochloride 800 mg (Tablets per meal) 1 tablet 1 tablet 2 tablets 2 tablets 3 tablets 3 tablets Dose Titration for All Patients Taking Sevelamer Hydrochloride . Adjust dosage based on the serum phosphorus concentration with a goal of lowering serum phosphorus to 5.5 mg/dL or less. Increase or decrease by one tablet per meal at two-week intervals as necessary. Table 3 gives a dose titration guideline. The average dose in a Phase 3 trial designed to lower serum phosphorus to 5.0 mg/dL or less was approximately three sevelamer hydrochloride 800 mg tablets per meal. The maximum average daily sevelamer hydrochloride dose studied was 13 g. Table 3: Dose Titration Guideline Serum Phosphorus Sevelamer Hydrochloride Dose >5.5 mg/dL Increase 1 tablet per meal at 2-week intervals 3.5-5.5 mg/dL Maintain current dose <3.5 mg/dL Decrease 1 tablet per meal

Sevelamer hydrochloride is contraindicated in patients with bowel obstruction. Sevelamer hydrochloride is contraindicated in patients with known hypersensitivity to sevelamer hydrochloride or to any of the excipients. Bowel obstruction. ( 4 ) Known hypersensitivity to sevelamer hydrochloride or to any of the excipients. ( 4 )

The most common reasons for discontinuing treatment were gastrointestinal adverse reactions. ( 6.1 ) In a parallel design study of 12 weeks duration, treatment-emergent adverse reactions to sevelamer hydrochloride tablets in peritoneal dialysis patients included dyspepsia (12%), peritonitis (8%), diarrhea (5%), nausea (5%), constipation (4%), pruritus (4%), abdominal distension (3%), vomiting (3%), fatigue (3%), anorexia (3%), and arthralgia (3%). ( 6.1 ) Cases of fecal impaction and, less commonly, ileus, bowel obstruction, and bowel perforation have been reported. ( 6.2 ) To report SUSPECTED ADVERSE REACTIONS, contact Genzyme Corporation at 1-800-847-0069 and or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In a parallel design study of sevelamer hydrochloride with treatment duration of 52 weeks, adverse reactions reported for sevelamer hydrochloride (n=99) were similar to those reported for the active-control group (n=101). Overall adverse reactions among those treated with sevelamer hydrochloride occurring in >5% of patients included: vomiting (22%), nausea (20%), diarrhea (19%), dyspepsia (16%), abdominal pain (9%), flatulence (8%), and constipation (8%). A total of 27 patients treated with sevelamer and 10 patients treated with comparator withdrew from the study due to adverse reactions. Based on studies of 8 to 52 weeks, the most common reason for withdrawal from sevelamer hydrochloride was gastrointestinal adverse reactions (3%-16%). In 143 peritoneal dialysis patients studied for 12 weeks, most adverse reactions were similar to adverse reactions observed in hemodialysis patients. The most frequently occurring treatment-emergent serious adverse reaction was peritonitis (8 reactions in 8 patients [8%] in the sevelamer group and 2 reactions in 2 patients [4%] on active control). Thirteen patients (14%) in the sevelamer group and 9 patients (20%) in the active-control group discontinued, mostly for gastrointestinal adverse reactions. Patients on peritoneal dialysis should be closely monitored to ensure the reliable use of appropriate aseptic technique with the prompt recognition and management of any signs and symptoms associated with peritonitis. 6.2 Postmarketing Experience The following adverse reactions have been identified during postapproval use of sevelamer hydrochloride: hypersensitivity, pruritus, rash, abdominal pain, bleeding gastrointestinal ulcers, colitis, ulceration, necrosis, fecal impaction and uncommon cases of ileus, intestinal obstruction, and intestinal perforation. Appropriate medical management should be given to patients who develop constipation or have worsening of existing constipation to avoid severe complications. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to estimate their frequency or to establish a causal relationship to drug exposure.

There are no empirical data on avoiding drug interactions between sevelamer hydrochloride and most concomitant oral drugs. For oral medication where a reduction in the bioavailability of that medication would have a clinically significant effect on its safety or efficacy (e.g., cyclosporine, tacrolimus, levothyroxine), consider separation of the timing of the administration of the two drugs [see Clinical Pharmacology (12.3) ] . The duration of separation depends upon the absorption characteristics of the medication concomitantly administered, such as the time to reach peak systemic levels and whether the drug is an immediate-release or an extended-release product. Where possible monitor clinical responses or blood levels of concomitant drugs that have a narrow therapeutic range. Table 4: Sevelamer Drug Interactions Oral drugs for which sevelamer did not alter the pharmacokinetics when administered concomitantly Digoxin Enalapril Iron Metoprolol Warfarin Oral drugs that have demonstrated interaction with sevelamer and are to be dosed separately from sevelamer hydrochloride Dosing Recommendations Ciprofloxacin Take at least 2 hours before or 6 hours after sevelamer Mycophenolate mofetil Take at least 2 hours before sevelamer When clinically significant drug interactions are expected, separate the timing of administration and monitor clinical responses or blood levels of the concomitant medication. ( 7 ) Sevelamer did not alter the pharmacokinetics of digoxin, enalapril, iron, metoprolol, and warfarin. ( 7 ) Sevelamer binds ciprofloxacin and mycophenolate mofetil; dose these drugs separately from sevelamer hydrochloride. ( 7 )

Storage: Store at 25°C (77°F): excursions permitted to 15°C–30°C (59°F–86°F). Do not use Sevelamer hydrochloride tablets after the expiration date on the bottle. [See USP controlled room temperature] Protect from moisture.