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Calcium Acetate

Medically reviewed on Nov 15, 2018


(KAL see um AS e tate)

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product

Capsule, Oral:

PhosLo: 667 mg [DSC]

Generic: 667 mg

Solution, Oral:

Phoslyra: 667 mg/5 mL (473 mL) [contains methylparaben, propylene glycol]

Tablet, Oral:

Calphron: 667 mg

Eliphos: 667 mg [DSC]

Generic: 667 mg, 668 mg

Brand Names: U.S.

  • Calphron [OTC]
  • Eliphos [DSC]
  • PhosLo [DSC]
  • Phoslyra

Pharmacologic Category

  • Antidote
  • Calcium Salt
  • Phosphate Binder


Combines with dietary phosphate to form insoluble calcium phosphate which is excreted in feces


30% to 40%; requires vitamin D; minimal unless chronic, high doses are given; calcium is absorbed in soluble, ionized form; solubility of calcium is increased in an acid environment


Primarily feces (as unabsorbed calcium); urine (20%)

Use: Labeled Indications

Control of hyperphosphatemia in end-stage renal failure; does not promote aluminum absorption


Hypersensitivity to any component of the formulation; hypercalcemia, renal calculi

Dosing: Adult

Control of hyperphosphatemia (ESRD, on dialysis): Oral: Initial: 1334 mg with each meal, can be increased gradually (ie, every 2-3 weeks) to bring the serum phosphate value <6 mg/dL as long as hypercalcemia does not develop (usual dose: 2001-2668 mg calcium acetate with each meal); do not give additional calcium supplements

Dosing: Geriatric

Refer to adult dosing.

Dosing: Renal Impairment

No dosage adjustment necessary.

Dosing: Hepatic Impairment

No dosage adjustment provided in manufacturer’s labeling.


Administer with meals.

Dietary Considerations

Oral dosage forms must be administered with meals to be effective.

Drug Interactions

Alpha-Lipoic Acid: Calcium Salts may decrease the absorption of Alpha-Lipoic Acid. Alpha-Lipoic Acid may decrease the absorption of Calcium Salts. Consider therapy modification

Baloxavir Marboxil: Calcium Salts may decrease the serum concentration of Baloxavir Marboxil. Avoid combination

Bictegravir: Calcium Salts may decrease the serum concentration of Bictegravir. Management: Bictegravir, emtricitabine, and tenofovir alafenamide can be administered with calcium salts under fed conditions, but coadministration with or 2 hours after a caclium salt is not recommended under fasting conditions. Consider therapy modification

Bisphosphonate Derivatives: Calcium Salts may decrease the serum concentration of Bisphosphonate Derivatives. Management: Avoid administration of oral calcium supplements within: 2 hours before or after tiludronate/clodronate/etidronate; 60 minutes after oral ibandronate; or 30 minutes after alendronate/risedronate. Exceptions: Pamidronate; Zoledronic Acid. Consider therapy modification

Calcium Channel Blockers: Calcium Salts may diminish the therapeutic effect of Calcium Channel Blockers. Monitor therapy

Calcium Salts: May enhance the adverse/toxic effect of Calcium Acetate. Avoid combination

Cardiac Glycosides: Calcium Salts may enhance the arrhythmogenic effect of Cardiac Glycosides. Monitor therapy

CefTRIAXone: Calcium Salts (Intravenous) may enhance the adverse/toxic effect of CefTRIAXone. Ceftriaxone binds to calcium forming an insoluble precipitate. Management: Use of ceftriaxone is contraindicated in neonates (28 days of age or younger) who require (or are expected to require) treatment with IV calcium-containing solutions. In older patients, flush lines with compatible fluid between administration. Consider therapy modification

Deferiprone: Calcium Salts may decrease the serum concentration of Deferiprone. Management: Separate administration of deferiprone and oral medications or supplements that contain polyvalent cations by at least 4 hours. Consider therapy modification

DOBUTamine: Calcium Salts may diminish the therapeutic effect of DOBUTamine. Monitor therapy

Dolutegravir: Calcium Salts may decrease the serum concentration of Dolutegravir. Management: Administer dolutegravir at least 2 hours before or 6 hours after oral calcium. Administer dolutegravir/rilpivirine at least 4 hours before or 6 hours after oral calcium salts. Alternatively, dolutegravir and oral calcium can be taken together with food. Consider therapy modification

Eltrombopag: Calcium Salts may decrease the serum concentration of Eltrombopag. Management: Administer eltrombopag at least 2 hours before or 4 hours after oral administration of any calcium-containing product. Consider therapy modification

Estramustine: Calcium Salts may decrease the absorption of Estramustine. Consider therapy modification

Multivitamins/Fluoride (with ADE): May increase the serum concentration of Calcium Salts. Calcium Salts may decrease the serum concentration of Multivitamins/Fluoride (with ADE). More specifically, calcium salts may impair the absorption of fluoride. Management: Avoid eating or drinking dairy products or consuming vitamins or supplements with calcium salts one hour before or after of the administration of fluoride. Consider therapy modification

Multivitamins/Minerals (with ADEK, Folate, Iron): May increase the serum concentration of Calcium Salts. Monitor therapy

Phosphate Supplements: Calcium Salts may decrease the absorption of Phosphate Supplements. Management: This applies only to oral phosphate and calcium administration. Administering oral phosphate supplements as far apart from the administration of an oral calcium salt as possible may be able to minimize the significance of the interaction. Exceptions: Sodium Glycerophosphate Pentahydrate. Consider therapy modification

Quinolones: Calcium Salts may decrease the absorption of Quinolones. Of concern only with oral administration of both agents. Exceptions: LevoFLOXacin (Oral Inhalation); Moxifloxacin (Systemic). Consider therapy modification

Strontium Ranelate: Calcium Salts may decrease the serum concentration of Strontium Ranelate. Management: Separate administration of strontium ranelate and oral calcium salts by at least 2 hours in order to minimize this interaction. Consider therapy modification

Tetracyclines: Calcium Salts may decrease the serum concentration of Tetracyclines. Management: If coadministration of oral calcium with oral tetracyclines can not be avoided, consider separating administration of each agent by several hours. Exceptions: Eravacycline. Consider therapy modification

Thiazide and Thiazide-Like Diuretics: May decrease the excretion of Calcium Salts. Continued concomitant use can also result in metabolic alkalosis. Monitor therapy

Thyroid Products: Calcium Salts may diminish the therapeutic effect of Thyroid Products. Management: Separate the doses of the thyroid product and the oral calcium supplement by at least 4 hours. Consider therapy modification

Trientine: Calcium Salts may decrease the serum concentration of Trientine. Trientine may decrease the serum concentration of Calcium Salts. Consider therapy modification

Vitamin D Analogs: Calcium Salts may enhance the adverse/toxic effect of Vitamin D Analogs. Monitor therapy

Adverse Reactions


Endocrine & metabolic: Hypercalcemia

Gastrointestinal: Diarrhea (oral solution)

1% to 10%: Gastrointestinal: Nausea, vomiting

Postmarketing and/or case reports: Dizziness, edema, pruritus, weakness


Concerns related to adverse effects:

• Gastrointestinal effects: Constipation, bloating, and gas are common with calcium supplements (especially carbonate salt).

• Hypercalcemia: Mild-to-severe hypercalcemia may occur; decrease calcium acetate dose or temporarily discontinue, depending on severity of hypercalcemia; in addition, decrease or discontinue any concomitant vitamin D therapy. Chronic hypercalcemia may result in vascular calcification and other soft-tissue calcification.

Disease-related concerns:

• Arrhythmias: Use with caution in patients who may be at risk of cardiac arrhythmias.

• CKD-associated conditions (vascular calcification, adynamic bone disease): In CKD patients with vascular (arterial) calcification and/or adynamic bone disease and/or serum PTH levels that are persistently low, consider using non-calcium-based phosphate binders (eg, sevelamer, lanthanum) as an alternative to calcium-based phosphate binders (eg, calcium acetate, calcium carbonate) or restricting the dose of the calcium-based phosphate binder (Allison 2013; KDIGO 2009). A meta-analysis observed a trend towards a decrease in all-cause mortality in CKD patients receiving non-calcium-based phosphate binders compared with those receiving calcium-based phosphate binders (Jamal 2013); however, further research is needed to identify causes of mortality and fully assess safety of long-term use based on binder type.

• Hypoparathyroid disease: Hypercalcemia and hypercalciuria are most likely to occur in hypoparathyroid patients receiving high doses of vitamin D.

Concurrent drug therapy issues:

• Digitalis: Use with caution in digitalized patients; hypercalcemia may precipitate cardiac arrhythmias.

• Minerals/other oral drugs: Calcium administration interferes with absorption of some minerals and drugs; use with caution.

Dosage form specific issues:

• Maltitol: Oral solution may contain maltitol (a sugar substitute) which may cause a laxative effect.

Other warnings/precautions:

• Appropriate product selection: Multiple salt forms of calcium exist; close attention must be paid to the salt form when ordering and administering calcium; incorrect selection or substitution of one salt for another without proper dosage adjustment may result in serious over or under dosing.

Monitoring Parameters

Serum calcium (twice weekly during initial dose adjustments), serum phosphorus; serum calcium-phosphorus product; intact parathyroid hormone (iPTH)

Pregnancy Risk Factor


Pregnancy Considerations

Animal reproduction studies have not been conducted. Calcium crosses the placenta. The amount of calcium reaching the fetus is determined by maternal physiological changes. Intestinal absorption of calcium increases during pregnancy. If use is required in pregnant patients with end stage renal disease, fetal harm is not expected if maternal calcium concentrations are monitored and maintained within normal limits as recommended (IOM, 2011).

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience nausea. Have patient report immediately to prescriber signs of high calcium (weakness, confusion, fatigue, headache, nausea and vomiting, constipation, or bone pain) (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.