Calcium SaltsRx

Last updated: November 24, 2014

Trade Names
Calcium carbonate: Generic, Caltrate, Os-Cal, Tums E-X
Calcium citrate: Generic, Calcitrate
Calcium glubionate: Generic, Calcionate
Calcium lactate: Generic
Calcium phosphate dibasic: Generic
Calcium phosphate tribasic: Generic,  Posture

Drug Class: Calcium supplement

Calcium carbonate: Tablets: 500-, 650-, 667- mg; 1.25- and 1.5- g; chewable tablets: 420-, 500-, 750-mg
Calcium citrate: Tablets 950 mg; effervescent tablets: 2,376 mg
Calcium glubionate: Syrup 1.8 g/5 mL
Calcium lactate: Tablets 325 and 650 mg
Calcium phosphate dibasic: 500-mg tablet
Calcium phosphate tribasic: 300- and 600-mg tablets

Dose: Prevention and treatment of osteoporosis in adults requires at least
1–1.5 g of elemental calcium/day. Various salts contain the following amounts of elemental calcium:
Calcium carbonate: 400 mg elemental calcium/g
Calcium citrate: 220 mg elemental calcium/g
Calcium glubionate: 64 mg elemental calcium/g
Calcium lactate: 130 mg elemental calcium/g
Calcium phosphate dibasic: 115 mg elemental calcium/g
Calcium phosphate tribasic: 400 mg elemental calcium/g
Dietary sources rich in calcium include the following approximate amounts of elemental calcium: 8 oz yogurt 400 mg, 1.5 oz cheese 300 mg, cup of  milk 300 mg, cup of calcium-fortified orange juice 300 mg.

Indications: Prevention of osteoporosis, hypocalcemia

Mechanism of Action: Calcium supplement helps prevent osteoporosis in patients with inadequate intake. Calcium in bone is in exchange with calcium in plasma, so bone stores are depleted if intake is inadequate.

Contraindications: Renal calculi, hypercalcemia, digoxin toxicity, renal failure

Monitoring: Consider measuring serum calcium before treatment and annually

Pregnancy Risk: C; has been used in pregnancy to supplement calcium intake

Adverse Effects
Common: Constipation, flatulence
Uncommon: Nausea, hypercalcemia, renal stones

Drug Interactions
Calcium channel antagonists: Doses of calcium that increase serum calcium concentrations may antagonize the effects of calcium channel antagonists.
Digoxin: Doses of calcium that increase serum calcium concentrations may increase the risk of cardiac arrhythmias.
Iron supplements: Oral absorption is decreased if taken together.
Tetracyclines: Oral absorption is decreased if taken together.

Patient Instructions: Best taken with a large glass of water before or during a meal. Do not take calcium within 1–2 hours of taking another medication (may impair absorption).

Comments: Most studies show that calcium and vitamin D do not increase bone density. In subjects with inadequate calcium intake, they may slow bone loss. Calcium with vitamin D supplementation has led to a  small reduction in fractures in some studies (often populations likely to have low calcium intake)  but  not others. Dietary intake  is preferred but calcium and vitamin D supplements are  used if needed  to ensure adequate intake in patients with osteoporosis. Controversial inconsistent evidence links calcium supplementation (usually without vitamin D) to increased cardiovascular risk.

Clinical Pharmacology: Poor absorption; 20% is eliminated renally and 80% appears in the stool. Vitamin D enhances absorption.

Cost: $ (see Table 1)

Chapter 3:2 / Specific Agents
Table 1: Calcium Tablets and Costs
Elemental Calcium (mg) Vitamin D (IU) Tablets/Day a. b. Cost c.
Calcium carbonate, generic price 600 400 2 $2.99
Caltrate + D 600 800 2 $5.99
Os-Cal 500+D 500 200 2 $7.25

Tums Ultra

400 3 $3.00
Calcium Citrate + D 315 250 4 $13.49
Calcium phosphate


600 500 2 $10.99
a.Amount of elemental calcium and Vitamin D per tablet are shown
b.Needed to provide 1,000–1,200 mg elemental calcium daily.
c.Cost for a 30-day supply from an internet pharmacy (Walgreens) accessed Aug 2014


Bauer DC. Clinical practice. Calcium supplements and fracture prevention. N Engl J Med. 2013 Oct 17;369(16):1537-43.PMID:24131178


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