In short
Calcium acetate is a phosphate-binding medicine used to lower blood phosphorus levels in people with end-stage renal disease. It is available as tablets and is authorised for use in patients on dialysis. The clinical trials registry contains one trial involving calcium acetate, but that trial is a Phase 3 study of sodium bicarbonate in critical illness, not a study of calcium acetate itself.
Key points
- Calcium acetate is a phosphate binder indicated for reducing serum phosphorus in patients with end-stage renal disease.
- It is available as 667 mg tablets for oral use.
- The most common side effects are hypercalcemia, nausea and vomiting.
- One Phase 3 trial in the registry involves sodium bicarbonate, not calcium acetate, in critically ill patients with metabolic acidosis and acute kidney injury.
- Calcium acetate is recommended as a first-line phosphate binder in several NHS formularies.
What is calcium acetate?
Calcium acetate is a phosphate-binding agent used to reduce serum phosphorus levels in patients with end-stage renal disease. It belongs to the drug classes of minerals and electrolytes and phosphate binders. The medicine is available as tablets containing 667 mg of calcium acetate per tablet. It is also known by the brand name Renacet.
How does calcium acetate work?
Calcium acetate works by binding phosphate in the digestive tract, preventing its absorption into the bloodstream. This helps lower elevated phosphorus levels in people whose kidneys can no longer remove phosphate effectively. The Nottinghamshire formulary notes that calcium acetate is more effective than Calcichew and contains less elemental calcium.
Which conditions is calcium acetate used for?
- End-stage renal disease — calcium acetate is indicated for the reduction of serum phosphorus in these patients.
- Hyperphosphataemia in chronic kidney disease — NHS formularies list calcium acetate for managing high phosphate levels in patients with chronic kidney disease.
- Hyperphosphataemia in patients on dialysis — the Somerset formulary specifically lists calcium acetate for hyperphosphataemia in patients with chronic renal failure on dialysis.
How is calcium acetate given?
Calcium acetate is given orally as tablets. The product information describes a starting dose of 2 tablets with each meal, with titration every 2 to 3 weeks until an acceptable serum phosphorus level is reached; most patients require 3 to 4 tablets with each meal. The tablets contain 667 mg of calcium acetate per tablet.
What do the clinical trials show?
The clinical trials registry contains one trial in which calcium acetate appears, but it is not the studied substance. The trial is a Phase 3 study investigating the effect of sodium bicarbonate on major adverse kidney events at day 90 in critically ill patients with metabolic acidosis and acute kidney injury. The trial has an enrollment of 660 participants and is currently authorised. Calcium acetate is not listed as an intervention in this trial; the interventions are various intravenous infusion solutions and sodium bicarbonate.
What side effects are known?
The most common adverse reactions, occurring in more than 10% of patients, are hypercalcemia, nausea and vomiting. In clinical studies, patients have occasionally experienced nausea during calcium acetate therapy. Hypercalcemia may aggravate digitalis toxicity, and severe hypercalcemia may require hemodialysis and discontinuation of calcium acetate tablets.
What drug interactions are known?
Calcium acetate may decrease the bioavailability of tetracyclines or fluoroquinolones. When clinically significant drug interactions are expected, the drug should be administered at least one hour before or at least three hours after calcium acetate.