Calcium Acetate

By Kayla Hyland, DVM; Rania Gollakner, BS, DVM, MPH

What is calcium acetate?

Calcium acetate (brand names: PhosLo®, Calphron®, Eliphos®) is a medication used to bind excess phosphate. This is primarily used in patients with chronic kidney disease, as abnormally high phosphate levels occur with this disease.

Its use in cats and dogs to treat high blood phosphorus levels is “off label” or “extra label”. Many drugs are commonly prescribed for off-label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully as their directions may be significantly different from those on the label.

How is calcium acetate given?

Calcium acetate is given by mouth and with food in the form of a tablet, a capsule, or a liquid solution. Your veterinarian may prescribe additional doses between meals, but it should primarily be given with meals. Measure liquids carefully.

This medication should take effect within 1 to 2 hours. However, its effects may not be visibly noticeable and so laboratory tests may need to be done to evaluate this medication’s effectiveness.

What if I miss giving my pet the medication?

If you miss a dose, give it when you remember; however, if it is close to time for the next dose, skip the dose you missed, give it at the next scheduled time, and return to the regular dosing schedule. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

Elevated calcium levels in the blood and calcium deposits in soft tissues are the most concerning side effects. Gastrointestinal upset such as nausea or vomiting are also possible.

This short-acting medication should stop working within 24 hours, although the effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

Phosphate binders that contain calcium should not be used when calcium levels are higher than normal or in pets that are allergic to it. Calcium acetate should be used cautiously, if at all, in conjunction with calcitriol. It should be used with caution in pregnant and lactating animals, as the effects are unknown; however, use during lactation is likely safe.

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with calcium acetate: aspirin, atenolol, calcitriol, calcium channel blockers (e.g., amlodipine), cefpodoxime, ceftriaxone, chlorothiazides, digoxin, fluoroquinolones, iron, ketoconazole, levothyroxine, sucralfate, tetracyclines, and verapamil.

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

Serum ionized calcium and phosphorus levels should be monitored every 2 to 6 weeks while initially using this medication, depending on the patient. If stable, these levels can be measured every 3 months. Phosphorus should be measured after your pet has fasted for 12 hours.

How do I store calcium acetate?

Store this medication at room temperature, at around 25°C (77°F).

What should I do in case of emergency?

Contact your veterinarian if you observe an increase in drinking and urinating, low energy levels, decreased appetite, or stomach pain.

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.

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