Lanthanum

There is a potential for LANTHANUM CARBONATE to interact with compounds that bind to cationic antacids (i.e., aluminum-, magnesium-, or calcium-based); therefore, do not take such compounds within 2 hours of dosing with LANTHANUM CARBONATE. ( 7.1 ) Oral quinolone antibiotics must be taken at least 1 hour before or 4 hours after LANTHANUM CARBONATE. ( 7.2 ) Do not take thyroid hormone replacement therapy within 2 hours of dosing with LANTHANUM CARBONATE. Monitoring of TSH levels is recommended in patients receiving both medicinal agents.

( 7.3 ) For oral medications where a reduction in the bioavailability of that medication would have a clinically significant effect on its safety or efficacy, consider separation of the timing of the administration of the two drugs. ( 7.4 )

7.1 Drugs Binding to Antacids There is a potential for LANTHANUM CARBONATE to interact with compounds which bind to cationic antacids (i.e., aluminum-, magnesium-, or calcium-based); therefore, do not administer such compounds within 2 hours of dosing with LANTHANUM CARBONATE. Examples of relevant classes of compounds where antacids have been demonstrated to reduce bioavailability include antibiotics (such as quinolones, ampicillin, and tetracyclines), thyroid hormones, ACE inhibitors, statin lipid regulators, and anti-malarials.

7.2 Quinolone Antibiotics Co-administration of LANTHANUM CARBONATE with quinolone antibiotics may reduce the extent of their absorption. The bioavailability of oral ciprofloxacin was decreased by approximately 50% when taken with LANTHANUM CARBONATE in a single-dose study in healthy volunteers. Administer oral quinolone antibiotics at least 1 hour before or 4 hours after LANTHANUM CARBONATE. When oral quinolones are given for short courses, consider eliminating the doses of LANTHANUM CARBONATE that would normally be scheduled near the time of quinolone intake to improve quinolone absorption [see Clinical Pharmacology (12.3) ] .

7.3 Levothyroxine The bioavailability of levothyroxine was decreased by approximately 40% when taken together with LANTHANUM CARBONATE. Administer thyroid hormone replacement therapy at least 2 hours before or 2 hours after dosing with LANTHANUM CARBONATE and monitor thyroid stimulating hormone (TSH) levels [see Clinical Pharmacology (12.3) ] .

7.4 Use with Other Oral Medications There are no empirical data on avoiding drug interactions between LANTHANUM CARBONATE and most concomitant oral drugs. For oral medications where a reduction in the bioavailability of that medication would have a clinically significant effect on its safety or efficacy, consider separation of the timing of the administration of the two drugs. 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.

Consider monitoring clinical responses or blood levels of concomitant medications that have a narrow therapeutic range.

8.1 Pregnancy Risk Summary Available data from case reports with use of LANTHANUM CARBONATE in pregnant women are insufficient to identify a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes. In animal reproduction studies, oral administration of lanthanum carbonate to pregnant rats and rabbits during organogenesis at doses 3 and 2.5 times, respectively, the maximum recommended human dose (MRHD), resulted in no adverse developmental effects.

In rabbits, lanthanum carbonate doses 5 times the MRHD was associated with maternal toxicity and resulted in increased post-implantation loss, reduced fetal weights, and delayed fetal ossification ( see Data ). Deposition of lanthanum into developing bone, including growth plate, was observed in juvenile animals in long-term animal studies with lanthanum carbonate [see Use in Specific Populations (8.4) ] . Use a non-lanthanum containing phosphate binder in a pregnant woman. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S.

general population, the estimated background risk of major birth defect and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Data Animal Data In pregnant rats, oral administration of lanthanum carbonate at doses as high as 2,000 mg/kg/day during organogenesis resulted in no evidence of harm to the fetus. The MRHD for LANTHANUM CARBONATE is 5,725 mg, representing a dose of 95.4 mg/kg, or 3,530 mg/m 2 for a 60-kg patient. The 2,000-mg/kg/day dose in the rat is equivalent to 12,000 mg/m 2 , 3 times the MRHD.

In pregnant rabbits, oral administration of lanthanum carbonate at 1,500 mg/kg/day (18,000 mg/m 2 ; 5 times the daily MRHD) during organogenesis was associated with increased post-implantation loss, reduced fetal weights, and delayed fetal ossification. No effects on the pregnant rabbits or fetuses were observed at 750 mg/kg/day (9,000 mg/m 2 ; 2.5 times the MRHD). In a pre- and postnatal development study in the rat, pregnant rats were dosed at up to 2,000 mg/kg/day (12,000 mg/m 2 /day; equivalent to 3 times the MRHD) from day 6 of pregnancy through 20 days postpartum (including lactation).

At 2,000 mg/kg/day, no maternal toxicity was observed, nor were any changes seen with respect to gestational length or delivery; however, piloerection/pallor, delayed eye opening, decreased body weight, and delayed sexual development were observed in the offspring…