Tissue deposition of lanthanum has been shown with Fosrenol in animal studies. In 105 bone biopsies from patients treated with Fosrenol, some for up to 4.5 years, rising levels of lanthanum were noted over time (see Pharmacology: Pharmacodynamics under Actions). Cases of lanthanum deposition in gastrointestinal mucosa, mainly after long term use, have been reported. The clinical significance of this finding is yet unknown.
The use of Fosrenol in clinical studies beyond 2 years is currently limited. However, treatment of subjects with Fosrenol for up to 6 years has not demonstrated a change in the benefit/risk profile.
There have been cases of gastrointestinal obstruction, ileus, subileus, and gastrointestinal perforation reported in association with lanthanum, some requiring surgery or hospitalisation (see Adverse Reactions).
Exercise caution in all patients predisposed to gastrointestinal obstruction, ileus, subileus and perforation; for example those with altered gastrointestinal anatomy (e.g., diverticular disease, peritonitis, history of gastrointestinal surgery, gastrointestinal cancer and gastrointestinal ulceration), hypomotility disorders (e.g., constipation, diabetic gastroparesis) and when used with medications known to potentiate these effects.
During treatment with lanthanum carbonate, physicians and patients should remain alert for signs and symptoms of gastrointestinal disorders, especially constipation and abdominal pain/distension which may indicate bowel obstruction, ileus or subileus.
Treatment with lanthanum carbonate should be re-evaluated in patients who develop severe constipation or other severe gastrointestinal signs and symptoms.
Fosrenol tablets must be chewed completely and not swallowed whole (see Dosage & Administration). Serious gastrointestinal complications have been reported in association with unchewed or incompletely chewed Fosrenol tablets.
Patients with renal insufficiency may develop hypocalcaemia. Fosrenol does not contain calcium. Serum calcium levels should therefore be monitored at regular time intervals for this patient population and appropriate supplements given.
Lanthanum is not metabolised by liver enzymes but it is most likely excreted in the bile. Conditions resulting in a marked reduction of bile flow may be associated with incrementally slower elimination of lanthanum, which may result in higher plasma levels and increased tissue deposition of lanthanum (see Pharmacology: Pharmacokinetics and Toxicology: Preclinical safety data under Actions). As the liver is the principal organ of elimination of absorbed lanthanum monitoring of liver function tests is recommended.
Fosrenol should be discontinued if hypophosphataemia develops.
Abdominal x-rays of patients taking Lanthanum Carbonate may have a radio-opaque appearance typical of an imaging agent.
Patients with rare glucose-galactose malabsorption should not take this medicine.
Effects on ability to drive and use machines: Fosrenol may induce dizziness and vertigo, which may impair the ability to drive and use machinery.
Use in Children: Safety and efficacy of Fosrenol have not been established in children and adolescents; use in children and adolescents is not recommended (see Dosage & Administration).