Lanthanum Carbonate
Lanthanum carbonate (octa-hydrate)
Also known as: Fosrenol · Lantharenol · Renalzin · Bay-78-1887 · Lanthanum
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Chronic kidney disease (Hyperphosphataemia) | 100 mg/kg/day | PO | divided between meals | Chronic | 🌍 EU |
- Chronic kidney disease (Hyperphosphataemia): Dose adjustments should be based on serum phosphate levels monitored at 4-6 week intervals.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Phosphate binder | 200 mg (total dose) PO (on/in food) 2-3 times daily. | PO | 2-3 times daily | — | 🌎 NA |
| Phosphate binder (using Renalzin) | 2 mLs (400 mg) applied in the cat's food, once or twice daily depending on the cat's feeding regimen. | PO | once or twice daily | — | 🌎 NA |
| Chronic kidney disease (Hyperphosphataemia) | 400-800 mg/cat/day | PO | divided according to feeding schedule (give some with every meal) | Chronic | 🌍 EU |
- Phosphate binder: Anecdotally appears safe and effective.
- Chronic kidney disease (Hyperphosphataemia): Recommended starting dose is 400 mg per day. It is important to give some with every meal.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Lanthanum carbonate is an orally administered phosphate-binding agent primarily used to manage hyperphosphatemia in patients with end-stage renal disease (ESRD).
While dietary phosphorus restriction remains the cornerstone of managing chronic kidney disease (CKD), phosphate binders are indicated when diet alone is insufficient or refused by the patient.
Clinical Pearl: Unlike calcium-based binders (which can cause hypercalcemia) or aluminum-based binders (which carry a risk of aluminum toxicity with long-term use), lanthanum is a non-calcium, non-aluminum binder, making it an attractive option for chronic management of hyperphosphatemia in veterinary patients.
Mechanism of action
Lanthanum carbonate acts locally in the gastrointestinal tract.
- It dissociates in the acidic environment of the upper GI tract (stomach) to release lanthanum ions (La³⁺).
- These ions bind to dietary phosphate → forming highly insoluble lanthanum phosphate complexes.
- These complexes cannot cross the intestinal mucosa and are subsequently eliminated in the feces, thereby reducing net intestinal absorption of phosphorus.
Safety & warnings
Contraindications
- Patients with non-intact GI tract (e.g., GI ulcers, colitis) - use with caution due to increased risk of systemic absorption
- Acute renal crisis (patients should be stabilized first)
Adverse effects
- Inappetence
- None known according to the monograph
- Gastrointestinal upset (nausea, vomiting, diarrhea, or constipation) may occur (Clinical Pearl)
Precautions
There are no listed absolute contraindications, but it should be used with caution in patients where the GI tract is not intact (e.g., GI ulcers, colitis) as there is an increased chance for oral absorption. Safe for use during pregnancy and nursing.
Drug interactions
Potential decreased absorption; separate dosing by 2 hours
Potential decreased absorption; separate dosing by 2 hours
Potential decreased absorption; separate dosing by 2 hours
Potential decreased absorption; separate dosing by 2 hours
Potential decreased absorption; separate dosing by 2 hours
Potential decreased absorption; separate dosing by 2 hours
Potential decreased absorption; separate dosing by 2 hours
Potential decreased absorption; separate dosing by 2 hours
Potential decreased absorption; separate dosing by 2 hours
Potential decreased absorption; separate dosing by 2 hours
Potential decreased absorption; separate dosing by 2 hours
Potential decreased absorption; separate dosing by 2 hours
Potential decreased absorption; separate dosing by 2 hours
Lanthanum may bind to other drugs in the GI tract, reducing their absorption. Should be given at least 1 hour before or 3 hours after other medications.
Monitoring
- Serum phosphorous
- Serum potassium
- Serum bicarbonate
- Serum chloride
- Serum phosphate levels (at 4-6 week intervals to adjust dosage and achieve target concentrations)
- Renal parameters (BUN, Creatinine, SDMA)
- Serum calcium levels
Pharmacokinetics
Half-life
Absorption
Following oral doses, lanthanum bioavailability is very low (less than 0.002%).
Distribution
Systemically available lanthanum is very highly bound to plasma proteins (>99%). Tissue levels increase over time and can be several orders of magnitude higher than plasma levels. Highest levels found in GI tract, bone, and liver.
Metabolism
Not metabolized. It is an inorganic salt.
Elimination
Absorbed lanthanum is cleared primarily via biliary excretion into the feces. In dogs, mean recovery of an oral dose averages 94%.
Overdose
No specific information located, but acute overdose is likely tolerated with potential for GI effects. Only supportive treatment should be required. In cats, oral dosages up to 1 gram/kg were tolerated, but repeated vomiting occurred at 2 grams/kg.
Available products
Formulations
- Chewable tablets
- Pump gel/paste
- 500 mg chewable tablet
- 750 mg chewable tablet
- 1 g chewable tablet
Veterinary
- Renalzin (lanthanum carbonate, kaolin, vitamin E) pump gel/paste (200 mg/mL) - Available in some countries outside USA/Canada
- Lantharenol (General sale / Feed additive - availability varies)
Human-labeled
- Fosrenol Oral Chewable Tablet 500 mg, 750 mg, & 1,000 mg
- Fosrenol 500 mg chewable tablets
- Fosrenol 750 mg chewable tablets
- Fosrenol 1 g chewable tablets
Regulatory status
Fosrenol is POM; Lantharenol has been marketed as a general sale feed additive.
Fosrenol is POM; Lantharenol has been marketed as a general sale feed additive.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store tablets at room temperature (25°C, 77°F); excursions are permitted to 15°-30°C (59°-86°F). Protect from moisture.
Client information
- Administration: Do not allow the animal to swallow tablets whole. Crush the tablets and mix them thoroughly with the animal's food.
- Timing: It is crucial that this medication is given with meals so it can bind to the phosphorus in the food.
- Commercial Veterinary Products: If using a specific veterinary gel/paste, follow the exact administration directions provided on the label.
- Side Effects: Monitor for vomiting or loss of appetite and contact your veterinarian if these occur.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.