Lanthanum Carbonate

1 INDICATIONS AND USAGE Lanthanum carbonate chewable tablets are phosphate binder indicated to reduce serum phosphate in patients with end- stage renal disease (ESRD). Management of elevated serum phosphorus levels in patients with ESRD usually includes all of the following: reduction in dietary intake of phosphate, removal of phosphate by dialysis, and reduction of intestinal phosphate absorption with phosphate binders. Lanthanum carbonate chewable tablets are phosphate binder indicated to reduce serum phosphate in patients with end- stage renal disease (ESRD). ( 1 )

2 DOSAGE AND ADMINISTRATION Divide the total daily dose of lanthanum carbonate chewable tablets and take with or immediately after meals. The recommended initial total daily dose of lanthanum carbonate chewable tablets is 1,500 mg. Titrate the dose every 2 to 3 weeks until an acceptable serum phosphate level is reached. Monitor serum phosphate levels as needed during dose titration and on a regular basis thereafter. Lanthanum Carbonate chewable Tablets has the potential to bind other orally administered drugs: consider separating the administration of other oral medications [ see Drug Interactions (7) ] . In clinical studies of patients with ESRD, lanthanum carbonate chewable tablets doses up to 4,500 mg were evaluated. Most patients required a total daily dose between 1,500 mg and 3,000 mg to reduce plasma phosphate levels to less than 6.0 mg/dL. Doses were generally titrated in increments of 750 mg/day. Information for lanthanum carbonate chewable tablets Chew or crush lanthanum carbonate chewable tablets completely before swallowing. Do not swallow intact lanthanum carbonate chewable tablets. Consider using the oral powder formulation in patients with poor dentition or who have difficulty chewing tablets. The recommended initial total daily dose of lanthanum carbonate chewable tablets are 1,500 mg in divided doses. Titrate every 2 to 3 weeks based on serum phosphate level. ( 2 ) Take lanthanum carbonate chewable tablets with or immediately after meals. ( 2 ) Lanthanum carbonate chewable tablets: Chew or crush tablet completely before swallowing. ( 2 )

6 ADVERSE REACTIONS The following adverse reactions are discussed in greater detail in other sections of the labeling: Gastrointestinal Adverse Effects [see Warnings and Precautions (5.1) ] In controlled trials, the most common adverse reactions that were more frequent (≥ 5% difference vs. placebo) in lanthanum carbonate were nausea, vomiting, and abdominal pain. ( 6.1 ) The following adverse reactions have been identified during post-approval use of lanthanum carbonate: constipation, dyspepsia, allergic skin reactions, and tooth injury while chewing the tablet. ( 6.2 ) To report SUSPECTED ADVERSE REACTIONS, contact Exelan pharmaceutical,Inc. at 1-866-604-3268 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. Overall, the safety profile of Lanthanum carbonate chewable tablets has been studied in over 5,200 subjects in completed clinical trials. The most common adverse reactions for Lanthanum carbonate chewable tablets were gastrointestinal events,such as nausea,vomiting and abdominal pain and they generally abated over time with continued dosing. In double-blind, placebo-controlled studies where a total of 180 and 95 patients with ESRD were randomized to lanthanum carbonate chewable tablet and placebo, respectively, for 4 to 6 weeks of treatment, the most common reactions that were more frequent (≥5% difference) in the lanthanum carbonate group were nausea, vomiting, and abdominal pain (Table 1). Table 1. Adverse Reactions * That Were More Common on Lanthanum Carbonate in Placebo-Controlled, Double-Blind Studies with Treatment Periods of 4 to 6 Weeks LANTHANUM CARBONATE % (N=180) Placebo % (N=95) Nausea 11 5 Vomiting 9 4 Abdominal Pain 5 0 In an open-label, long-term 2- year extension study in 93 patients who had transitioned from other studies, resulting in a total of up to 6 years treatment, mean baseline values and changes in transaminases were similar to those observed in the earlier comparative studies, with little change during treatment. The safety of lanthanum carbonate was studied in two long-term, open-label clinical trials, which included 1,215 patients treated with lanthanum carbonate and 944 with alternative therapy. Fourteen percent (14%) of patients treated with lanthanum carbonate chewable tablets discontinued treatment due to adverse events. Gastrointestinal adverse reactions, such as nausea, diarrhea, and vomiting were the most common types of event leading to discontinuation. In pooled active comparator controlled clinical trials, hypocalcemia was noted with an incidence of approximately 5% in both lanthanum and active comparator groups. A nonclinical study and a phase 1 study have shown reduced absorption of calcium in the intestine with lanthanum carbonate treatment. In a crossover study in 72 healthy individuals comparing lanthanum carbonate chewable tablets to lanthanum carbonate oral powder, gastrointestinal adverse reactions such as nausea, diarrhea and vomiting were more common for the oral powder formulation (18%) than for the chewable tablets (7%). 6.2 Postmarketing Experience The following adverse reactions have been identified during post-approval use of lanthanum carbonate. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Cases of constipation, intestinal perforation, intestinal obstruction, ileus, subileus, dyspepsia, allergic skin reactions, hypophosphatemia, and tooth injury while chewing the tablet have been reported.

12.3 Pharmacokinetics Absorption and Distribution - Following single- or multiple- dose oral administration of lanthanum carbonate to healthy subjects, the concentration of lanthanum in plasma was very low (bioavailability <0.002%). Following oral administration in patients, the mean lanthanum C max was 1.0 ng/mL. During long-term administration (52 weeks) in patients with ESRD , the mean lanthanum concentration in plasma was approximately 0.6 ng/mL. There was a minimal increase in plasma lanthanum concentrations with increasing doses within the therapeutic dose range. The timing of food intake relative to lanthanum administration (during and 30 minutes after food intake) has a negligible effect on the systemic level of lanthanum. Systemic exposure to lanthanum was approximately 30% higher following administration of Lanthanum Carbonate Oral Powder when compared to Lanthanum Carbonate Chewable Tablets. However, systemic exposure to lanthanum from both formulations in this study was within the range seen in previous pharmacokinetic studies of Chewable Tablets in healthy individuals. In vitro , lanthanum is highly bound (>99%) to human plasma proteins, including human serum albumin, α1-acid glycoprotein, and transferrin. Binding to erythrocytes in vivo is negligible in rats. In animal studies, lanthanum concentrations in several tissues, particularly gastrointestinal tract, mesenteric lymph nodes, bone, and liver, increased over time to levels several orders of magnitude higher than those in plasma. The level of lanthanum in the liver was higher in renally impaired rats due to higher intestinal absorption. Lanthanum was found in the lysosomes and the biliary canal consistent with transcellular transport. Steady state tissue concentrations in bone and liver were achieved in dogs between 4 and 26 weeks. Relatively high levels of lanthanum remained in these tissues for longer than 6 months after cessation of dosing in dogs. There is no evidence from animal studies that lanthanum crosses the blood-brain barrier. In 105 bone biopsies from patients treated with lanthanum carbonate for up to 4.5 years, rising levels of lanthanum were noted over time. Estimates of elimination half-life from bone ranged from 2.0 to 3.6 years. Steady state bone concentrations were not reached during the period studied. Metabolism and Elimination - Lanthanum is not metabolized. Lanthanum was cleared from plasma of patients undergoing dialysis with an elimination half-life of 53 hours following discontinuation of therapy. No information is available regarding the mass balance of lanthanum in humans after oral administration. In rats and dogs, the mean recovery of lanthanum after an oral dose was about 99% and 94%, respectively, and was essentially all from feces. Biliary excretion is the predominant route of elimination for circulating lanthanum in rats. In healthy volunteers administered intravenous (IV) lanthanum as the soluble chloride salt (120 mcg), renal clearance was less than 2% of total plasma clearance. Drug Interactions Lanthanum carbonate has a low potential for systemic drug-drug interactions because of the very low bioavailability of lanthanum and because it is not a substrate or inhibitor of major cytochrome P450 enzyme groups involved in drug metabolism (CYP1A2, CYP2C9/10, CYP2C19, CYP2D6,and CYP3A4/5). Lanthanum carbonate does not alter gastric pH; herefore, lanthanum carbonate drug interactions based on altered gastric pH are not expected. In an in vitro investigation, lanthanum did not form insoluble complexes when mixed in simulated gastric fluid with warfarin, digoxin, furosemide, phenytoin, metoprolol, and enalapril. Clinical studies have shown that lanthanum carbonate (three doses of 1,000 mg on the day prior to exposure and one dose of 1,000 mg on the day of co-administration) administered 30 minutes earlier did not alter the pharmacokinetics of oral warfarin (10 mg), digoxin (0.5 mg), or metoprolol (100 mg). Potential pharmacodynamic interactions between lanthanum and these drugs (e.g., bleeding time or prothrombin time) were not evaluated. None of the drug interaction studies were done with the maximum recommended therapeutic dose of lanthanum carbonate. No drug interaction studies assessed the effects of drugs on phosphate binding by lanthanum carbonate. Ciprofloxacin In a randomized, two–way crossover study in healthy volunteers examining the interaction potential of a single oral dose of ciprofloxacin (750 mg) alone and with lanthanum carbonate (1 g three times a day), the maximum plasma concentration of ciprofloxacin was reduced by 56% and the area under the ciprofloxacin plasma concentration-time curve was reduced by 54%. The 24-hour urinary recovery of ciprofloxacin was reduced 52% by lanthanum carbonate [see Drug Interactions (7.2) ]. Levothyroxine In a single-dose crossover study of levothyroxine (1 mg) with or without simultaneous administration of a single dose of lanthanum carbonate (500 mg) in six euthyroid normal healthy volunteers, the area under the serum T4 concentration-time curve was decreased by 40% [see Drug Interactions (7.3) ]. Fat -Soluble Vitamins Lanthanum carbonate chewable tablets appears not to affect the availability of fat- soluble vitamins (A, D, E, and K) or other nutrients [see Clinical Studies (14.2) ]. Citrate Citrate did not increase the absorption of lanthanum.