LANTHANUM Drug Interactions: What You Need to Know

INTERACTIONS There is a potential for lanthanum carbonate chewable tablets 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 chewable tablets. ( 7.1 ) Oral quinolone antibiotics must be taken at least 1 hour before or 4 hours after lanthanum carbonate chewable tablets. ( 7.2 ) Do not take thyroid hormone replacement therapy within 2 hours of dosing with lanthanum carbonate chewable tablets. 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 chewable tablets 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 chewable tablets. 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 chewable tablets 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 chewable tablets in a single-dose study in healthy volunteers. Administer oral quinolone antibiotics at least 1 hour before or 4 hours after lanthanum carbonate chewable tablets. When oral quinolones are given for short courses, consider eliminating the doses of lanthanum carbonate chewable tablets 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 chewable tablets. Administer thyroid hormone replacement therapy at least 2 hours before or 2 hours after dosing with lanthanum carbonate chewable tablets 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 chewable tablets 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.

Contraindicated in patients with: - hypersensitivity to lanthanum carbonate chewable tablets or to any ingredient in the formulation. - bowel obstruction, including ileus and fecal impaction. Hypersensitivity to lanthanum carbonate chewable tablets or to any ingredient in the formulation. ( 4 ) Bowel obstruction, ileus, and fecal impaction. ( 4 )

AND PRECAUTIONS Serious cases of gastrointestinal obstruction, ileus, subileus, gastrointestinal perforation, and fecal impaction. Risks include altered gastrointestinal anatomy, hypomotility disorders, and concomitant medications. Advise patients to chew or crush the tablet completely. ( 5.1 ) Lanthanum carbonate chewable tablets have radio-opaque properties and, therefore, may give the appearance typical of an imaging agent during abdominal X-ray procedures. ( 5.2 )

5.1 Gastrointestinal Adverse Effects Serious cases of gastrointestinal obstruction, ileus, subileus, gastrointestinal perforation, and fecal impaction have been reported in patients taking lanthanum, some requiring surgery or hospitalization. Consider discontinuing lanthanum carbonate chewable tablets in patients without another explanation for severe gastrointestinal symptoms. Risk factors for gastrointestinal obstruction and gastrointestinal perforation identified from post-marketing reports in patients taking lanthanum carbonate chewable tablets include abnormal gastrointestinal anatomy (e.g., diverticular disease, peritonitis, history of gastrointestinal surgery, gastrointestinal cancer, gastrointestinal ulceration), hypomotility disorders (e.g., constipation, ileus, subileus, diabetic gastroparesis), and the use of medications known to potentiate these effects. Some cases were reported in patients with no history of gastrointestinal disease. Patients with acute peptic ulcer, ulcerative colitis, Crohn’s disease, or bowel obstruction were not included in lanthanum carbonate chewable tablets clinical studies <span class="opacity-50 text-xs">[see Contraindications ( 4 )]</span> . Advise patients who are prescribed lanthanum carbonate chewable tablets to chew the tablet completely and not to swallow them whole. Serious gastrointestinal complications have been reported in association with unchewed or incompletely chewed tablets <span class="opacity-50 text-xs">[see Adverse Reactions ( 6.2 )]</span> .

5.2 Diagnostic Tests Lanthanum carbonate chewable tablets have radio-opaque properties and therefore may give the appearance typical of an imaging agent during abdominal X-ray procedures. Postmarketing reports of product residue have been reported during endoscopic imaging.