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Pronunciation:

(KAL see um AS e tate)

U.S. Brand Names:

PhosLo®

Generic Available:

Yes: Solution for injection

Use:

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

I.V.: Calcium supplementation in parenteral nutrition therapy

Pregnancy Risk Factor:

Contraindications:

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

Warnings/Precautions:

Calcium absorption is impaired in achlorhydria; administration is followed by increased gastric acid secretion within 2 hours of administration. While hypercalcemia and hypercalciuria may result when therapeutic replacement amounts are given for prolonged periods, they are most likely to occur in hypoparathyroid patients receiving high doses of vitamin D.

Adverse Reactions:

Mild hypercalcemia (calcium: >10.5 mg/dL to 12 mg/dL) may be asymptomatic or manifest itself as constipation, anorexia, nausea, and vomiting

More severe hypercalcemia (calcium: >12 mg/dL) is associated with confusion, delirium, stupor, and coma

Postmarketing and/or case reports: Pruritus, allergic reaction

Overdosage/Toxicology:

Acute single ingestions of calcium salts may produce mild gastrointestinal distress, but hypercalcemia or other toxic manifestations are extremely unlikely

Treatment is supportive

Drug Interactions:

Calcium channel blockers (eg, verapamil) effects may be diminished; monitor response.

Digitalis: Calcium acetate may potentiate digoxin toxicity.

Levothyroxine: Calcium carbonate (and possibly other calcium salts) may decrease T4 absorption; separate dose from levothyroxine by at least 4 hours

Polystyrene sulfonate: Potassium-binding ability is reduced; avoid concurrent use.

Tetracycline, atenolol (and potentially other beta-blockers), iron, quinolone antibiotics, alendronate, sodium fluoride, and zinc absorption is significantly decreased; space administration times.

Thiazide diuretics: High doses of calcium with thiazide diuretics may result in milk-alkali syndrome and hypercalcemia; monitor response.

Stability:

Admixture incompatibilities: Carbonates, phosphates, sulfates, tartrates

Mechanism of Action:

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

Pharmacodynamics/Kinetics:

Absorption: 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

Distribution: Crosses placenta; enters breast milk

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

Dosage:

Dietary Reference Intake:

0-6 months: 210 mg/day

7-12 months: 270 mg/day

1-3 years: 500 mg/day

4-8 years: 800 mg/day

Adults, Male/Female:

9-18 years: 1300 mg/day

19-50 years: 1000 mg/day

51 years: 1200 mg/day

Female: Pregnancy: Same as for Adults, Male/Female

Female: Lactating: Same as for Adults, Male/Female

Oral: Adults, on dialysis: Initial: 1334 mg with each meal, can be increased gradually to bring the serum phosphate value <6 mg/dL as long as hypercalcemia does not develop (usual dose: 2001-2868 mg calcium acetate with each meal); do not give additional calcium supplements

I.V.: Dose is dependent on the requirements of the individual patient; in central venous total parental nutrition (TPN), calcium is administered at a concentration of 5 mEq (10 mL)/L of TPN solution; the additive maintenance dose in neonatal TPN is 0.5 mEq calcium/kg/day (1.0 mL/kg/day)

Neonates: 70-200 mg/kg/day

Infants and Children: 70-150 mg/kg/day

Adolescents: 18-35 mg/kg/day

Administration:

Administer with meals.

Monitoring Parameters:

Serum calcium, serum phosphate; for control of hypophosphatemia, serum calcium times phosphate should not exceed 66

Reference Range:

Serum calcium: 8.4-10.2 mg/dL

Due to a poor correlation between the serum ionized calcium (free) and total serum calcium, particularly in states of low albumin or acid/base imbalances, direct measurement of ionized calcium is recommended

In low albumin states, the corrected total serum calcium may be estimated by this equation (assuming a normal albumin of 4 g/dL)

Corrected total calcium = total serum calcium + 0.8 (4.0 - measured serum albumin)

Corrected calcium = measured calcium - measured albumin + 4.0

Dietary Considerations:

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

Patient Education:

Inform prescriber of any other medications or dietary supplements you are taking. Do not take any new medication during therapy without consulting prescriber. Follow exact instructions for dosing. Take with a full glass of water or juice, 1-3 hours after meals and other medications, and 1-2 hours before any approved iron supplements. Avoid alcohol, other antacids, caffeine, or other calcium supplements unless approved by prescriber. May cause constipation (increased exercise, fluids, fiber, or fruits may help) or dry mouth (frequent mouth care, chewing gum, or sucking lozenges may help). Report severe, unresolved GI disturbances and unusual emotional lability (mood swings). Pregnancy precaution: Inform prescriber if you are or intend to become pregnant.

Additional Information:

Calcium acetate binds to phosphorus in the GI tract better than other calcium salts due to its lower solubility and subsequent reduced absorption and increased formation of calcium phosphate.

12.7 mEq calcium/g; 250 mg/g elemental calcium (25% elemental calcium)

Cardiovascular Considerations:

Hypercalcemia is evident on ECG by shortening of the QT interval and possibly lengthening of the PR interval. Hypocalcemia causes prolongation of the QT interval. This prolongation is due to lengthening of the ST segment; the T waves remain unchanged. However, in severe hypocalcemia, T waves may be inverted. Note that only hypocalcemia and hypothermia lengthen the ST segment without altering T-wave duration. Hypocalcemia may also present clinically with skeletal muscle spasm.

Dental Health: Effects on Dental Treatment:

No significant effects or complications reported

Dental Health: Vasoconstrictor/Local Anesthetic Precautions:

No information available to require special precautions

Mental Health: Effects on Mental Status:

May cause confusion and delirium (as a consequence of hypercalcemia)

Mental Health: Effects on Psychiatric Treatment:

None reported

Dosage Forms:

Note: Elemental calcium listed in brackets:

Gelcap (PhosLo®): 667 mg [169 mg]

Injection, solution: 0.5 mEq/mL (10 mL, 50 mL, 100 mL)

Tablet (PhosLo®): 667 mg [169 mg]

References

Kaiser W, Biesenbach G, Kramar R, et al, "Calcium Free Hemodialysis: An Effective Therapy in Hypercalcemic Crisis - Report of Four Cases,"Intensive Care Med, 1989, 15(7):471-4.

Mokhlesi B, Leikin JB, Murray P, et al, "Adult Toxicology in Critical Care: Part II: Specific Poisonings,"Chest, 2003, 123(3):897-922.

Texier D, Chevallier P, Perrotin D, et al, "Hypercalcemia Associated With Resorbable Haemostatic Compresses,"Lancet, 1982, 1(8273):688-9.

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