# Calcium carbonate

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Kiran Singh, M.D. [2]

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## Overview

Calcium carbonate is an antacid that is FDA approved for the treatment of heartburn, sour stomach, acid indigestion, upset stomach associated with these symptoms. Common adverse reactions include constipation, flatulence, swollen abdomen.

## Indications

• Calcium deficiency; Prophylaxis

## Dosage

• Calcium deficiency; Prophylaxis: 19 to 50 years, RDA is 1000 mg elemental calcium per day in divided doses of 500 mg or less each; max 2500 mg per day.
• Calcium deficiency; Prophylaxis: 51 to 70 years (men), RDA is 1000 mg elemental calcium per day in divided doses of 500 mg or less each; max 2000 mg per day.
• Calcium deficiency; Prophylaxis: 51 to 70 years (women), RDA is 1200 mg elemental calcium per day in divided doses of 500 mg or less each; max 2000 mg per day.

Calcium deficiency; Prophylaxis: greater than 70 years, RDA is 1200 mg elemental calcium per day in divided doses of 500 mg or less each; max 2000 mg per day.

### Off-Label Use and Dosage (Adult)

#### Guideline-Supported Use

There is limited information regarding Off-Label Guideline-Supported Use of Calcium carbonate in adult patients.

## Indications

• Chemical burn, Hydrofluoric acid
• Fracture of bone; Prophylaxis
• Heartburn
• Hypocalcemia, Chronic
• Postmenopausal osteoporosis

## Indications

Calcium deficiency; Prophylaxis

## Dosage

• Calcium deficiency; Prophylaxis: 0 to 6 months, RDA is 200 mg elemental calcium per day; max 1000 mg per day.
• Calcium deficiency; Prophylaxis: 6 to 12 months, RDA is 260 mg elemental calcium per day; max 1500 mg per day.
• Calcium deficiency; Prophylaxis: 1 to 3 years, RDA is 700 mg elemental calcium per day; max 2500 mg per day.
• Calcium deficiency; Prophylaxis: 4 to 8 years, RDA is 1000 mg elemental calcium per day; max 2500 mg per day.
• Calcium deficiency; Prophylaxis: 9 to 13 years, RDA is 1300 mg elemental calcium per day; max 3000 mg per day.

Calcium deficiency; Prophylaxis: 14 to 18 years, RDA is 1300 mg elemental calcium per day; max 3000 mg per day.

### Off-Label Use and Dosage (Pediatric)

#### Guideline-Supported Use

There is limited information regarding Off-Label Guideline-Supported Use of Calcium carbonate in adult patients.

• Heartburn

## Contraindications

There is limited information regarding Calcium carbonate Contraindications in the drug label.

## Warnings

Ask a doctor before use if you have

• Kidney stones
• A calcium-restricted diet

Ask a doctor or pharmacist before use if you are

• Now taking a prescription drug. Antacids may interact with certain prescription drugs.

When using this product

• Do not take more than 10 tablets in 24 hours
• Do not use the maximum dosage for more than 2 weeks

Keep out of reach of children.

## Common

Gastrointestinal:

• Constipation
• Flatulence
• Swollen abdomen

## Serious

Cardiovascular

Renal

Reproductive

• Prostate cancer

Other

• Milk alkali syndrome

### Postmarketing Experience

There is limited information regarding Calcium carbonate Postmarketing Experience in the drug label.

## Drug Interactions

There is limited information regarding Calcium carbonate Drug Interactions in the drug label.

## Use in Specific Populations

#### Pregnancy

Pregnancy Category (FDA): There is no FDA guidance on usage of Calcium carbonate in women who are pregnant.
Pregnancy Category (AUS): There is no Australian Drug Evaluation Committee (ADEC) guidance on usage of Calcium carbonate in women who are pregnant.

#### Labor and Delivery

There is no FDA guidance on use of Calcium carbonate during labor and delivery.

#### Nursing Mothers

There is no FDA guidance on the use of Calcium carbonate in women who are nursing.

#### Pediatric Use

There is no FDA guidance on the use of Calcium carbonate in pediatric settings.

#### Geriatic Use

There is no FDA guidance on the use of Calcium carbonate in geriatric settings.

#### Gender

There is no FDA guidance on the use of Calcium carbonate with respect to specific gender populations.

#### Race

There is no FDA guidance on the use of Calcium carbonate with respect to specific racial populations.

#### Renal Impairment

There is no FDA guidance on the use of Calcium carbonate in patients with renal impairment.

#### Hepatic Impairment

There is no FDA guidance on the use of Calcium carbonate in patients with hepatic impairment.

#### Females of Reproductive Potential and Males

There is no FDA guidance on the use of Calcium carbonate in women of reproductive potentials and males.

#### Immunocompromised Patients

There is no FDA guidance one the use of Calcium carbonate in patients who are immunocompromised.

• Oral

#### Monitoring

There is limited information regarding Calcium carbonate Monitoring in the drug label.

## IV Compatibility

There is limited information regarding the compatibility of Calcium carbonate and IV administrations.

## Overdosage

There is limited information regarding Calcium carbonate overdosage. If you suspect drug poisoning or overdose, please contact the National Poison Help hotline (1-800-222-1222) immediately.

## Pharmacology

Template:Chembox SolubilityProduct
Calcium carbonate
IUPAC name Calcium carbonate
Other names Limestone; calcite; aragonite; chalk; marble; pearl; oyster
Identifiers
CAS number 471-34-1
PubChem 10112
EINECS number 207-439-9
KEGG D00932
ChEBI 3311
RTECS number FF9335000
ATC code A02AC01,A12AA04
SMILES [Ca+2].[O-]C([O-])=O
InChI InChI=1/CH2O3.Ca/c2-1(3)4;/h(H2,2,3,4);/q;+2/p-2
Properties
Molecular formula CaCO3
Molar mass 100.0869 g/mol
Appearance Fine white powder; chalky taste
Odor odorless
Density 2.711 g/cm3 (calcite)
2.83 g/cm3 (aragonite)
Melting point

1,339 °C (2,442 °F; 1,612 K) (calcite)
825 °C (1517 °F; 1,098 K) (aragonite) [2]

Boiling point

decomposes

Solubility in water 0.0013 g/100 mL (25°C)[3][4]
Solubility in dilute acids soluble
Acidity (pKa) 9.0
Refractive index (nD) 1.59
Structure
Crystal structure Trigonal
Space group 32/m
Thermochemistry
Std enthalpy of
formation
ΔfHo298
−1207 kJ·mol−1[5]
Standard molar
entropy
So298
93 J·mol−1·K−1[5]
Hazards
MSDS ICSC 1193
EU Index Not listed
NFPA 704

0
1
0

LD50 6450 mg/kg (oral, rat)
Related Compounds
Other anions Calcium bicarbonate
Other cations Magnesium carbonate
Strontium carbonate
Barium carbonate
Related compounds Calcium sulfate
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

### Mechanism of Action

There is limited information regarding Calcium carbonate Mechanism of Action in the drug label.

### Structure

There is limited information regarding Calcium carbonate Structure in the drug label.

### Pharmacodynamics

There is limited information regarding Calcium carbonate Pharmacodynamics in the drug label.

### Pharmacokinetics

There is limited information regarding Calcium carbonate Pharmacokinetics in the drug label.

### Nonclinical Toxicology

There is limited information regarding Calcium carbonate Nonclinical Toxicology in the drug label.

## Clinical Studies

There is limited information regarding Calcium carbonate Clinical Studies in the drug label.

## How Supplied

There is limited information regarding Calcium carbonate How Supplied in the drug label.

### Storage

• Store at 20 - 25°C (68 - 77°F)

## Patient Counseling Information

There is limited information regarding Calcium carbonate Patient Counseling Information in the drug label.

## Precautions with Alcohol

Alcohol-Calcium carbonate interaction has not been established. Talk to your doctor about the effects of taking alcohol with this medication.

## Brand Names

• REGULAR STRENGTH ANTACID CALCIUM SUPPLEMENT ®[6]

## Look-Alike Drug Names

There is limited information regarding Calcium carbonate Look-Alike Drug Names in the drug label.

## References

The contents of this FDA label are provided by the National Library of Medicine.

1. Patnaik, Pradyot (2003). Handbook of Inorganic Chemical Compounds. McGraw-Hill. ISBN 0-07-049439-8. Retrieved 2009-06-06.
2. "Occupational safety and health guideline for calcium carbonate" (PDF). US Dept. of Health and Human Services. Retrieved 31 March 2011.
3. Gordon Aylward, Tristan Findlay. SI Chemical Data Book (4th ed.). John Wiley & Sons Australia, Ltd. ISBN 978-0-470-81638-7.
4. J. Rohleder, E. Kroker (2001). Calcium Carbonate: From the Cretaceous Period Into the 21st Century. Springer Science & Business Media. ISBN 3-7643-6425-4. Retrieved 2014-08-13.
5. Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A21. ISBN 0-618-94690-X.

Calcium carbonate
Other names Limestone; calcite; aragonite; chalk; marble
Identifiers
CAS number 471-34-1
Properties
Molecular formula CaCO3
Molar mass 100.087 g/mol
Appearance White powder.
Density 2.83 g/cm³, solid.
Melting point

825 °C

Boiling point

Decomposes

Solubility in water Insoluble
Structure
Molecular shape Linear
Hazards
Main hazards Not hazardous.
R-phrases R36, R37, R38
S-phrases S26, S36
Flash point Non-flammable.
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references
 Articles WikiDoc Resources for Calcium carbonate

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [3]

## Overview

Calcium carbonate is a chemical compound, with the chemical formula CaCO3. It is a common substance found as rock in all parts of the world, and is the main component of shells of marine organisms, snails, and eggshells. Calcium carbonate is the active ingredient in agricultural lime, and is usually the principal cause of hard water. It is commonly used medicinally as a calcium supplement or as an antacid.

## Occurrence

Calcium carbonate is found naturally as the following minerals and rocks: Aragonite, Calcite, Vaterite or (μ-CaCO3), Chalk, Limestone, Marble and Travertine

To test whether a mineral or rock contains calcium carbonate, strong acids, such as hydrochloric acid, can be added to it. If the sample does contain calcium carbonate, it will fizz and produce carbon dioxide and water. Weak acids such as acetic acid will react, albeit less vigorously. All of the rocks/minerals mentioned above will react with acid.

## Chemical properties

Calcium carbonate shares the typical properties of other carbonates. Notably:

1. it reacts with strong acids, releasing carbon dioxide:
CaCO3 + 2HCl → CaCl2 + CO2 + H2O

Calcium carbonate will react with water that is saturated with carbon dioxide to form the soluble calcium bicarbonate.

CaCO3 + CO2 + H2O → Ca(HCO3)2

## Preparation

The vast majority of calcium carbonate used in industry is extracted by mining or quarrying. Pure calcium carbonate (e.g. for food or pharmaceutical use), can be produced from a pure quarried source (usually marble).

Alternatively, calcium oxide is prepared by calcining crude calcium carbonate. Water is added to give calcium hydroxide, and carbon dioxide is passed through this solution to precipitate the desired calcium carbonate, referred to in the industry as precipitated calcium carbonate (PCC):[1]

CaCO3 → CaO + CO2
CaO + H2O → Ca(OH)2
Ca(OH)2 + CO2 → CaCO3 + H2O

## Uses

### Health and dietary applications

Calcium carbonate is widely used medicinally as an inexpensive dietary calcium supplement or antacid.[2] It may be used as a phosphate binder for the treatment of hyperphosphatemia (primarily in patients with chronic renal failure) when lanthanum carbonate is not prescribed. It is also used in the pharmaceutical industry as an inert filler for tablets and other pharmaceuticals.[3]

As a food additive, it is used in some soy milk products as a source of dietary calcium; one study concludes that calcium carbonate is as bioavailable as ordinary cow's milk.[4]

## Solubility

### With varying pH

We now consider the problem of the maximum solubility of calcium carbonate in normal atmospheric conditions ($\mathrm{CO}_2$ = 3.5 × 10−4 atm) when the pH of the solution is adjusted. This is for example the case in a swimming pool where the pH is maintained between 7 and 8 (by addition of NaHSO4 to decrease the pH or of NaHCO3 to increase it). From the above equations for the solubility product, the hydratation reaction and the two acid reactions, the following expression for the maximum [Ca2+] can be easily deduced:

$Ca}^{2+}]_\mathrm{max} = \frac{K_\mathrm{sp}k_\mathrm{H}} {K_\mathrm{h}K_\mathrm{a1}K_\mathrm{a2}} \frac{[\mathrm{H}^+]^2}{P_{\mathrm{CO}_2}$

showing a quadratic dependence in [H+]. The numerical application with the above values of the constants gives

 pH 7 7.2 7.4 7.6 7.8 8 8.2 8.27 8.4 [Ca2+]max (10-4mol/L or °F) 1590 635 253 101 40 15.9 6.35 4.7 2.53 [Ca2+]max (mg/L) 6390 2540 1010 403 160 63.9 25.4 18.9 10.1

• decreasing the pH from 8 to 7 increases the maximum Ca2+ concentration by a factor 100
• note that the Ca2+ concentration of the previous table is recovered for pH = 8.27
• keeping the pH to 7.4 in a swimming pool (which gives optimum HClO/OCl ratio in the case of "chlorine" maintenance) results in a maximum Ca2+ concentration of 1010 mg/L. This means that successive cycles of water evaporation and partial renewing may result in a very hard water before CaCO3 precipitates. Addition of a calcium sequestrant or complete renewing of the water will solve the problem.

### Solubility in a strong or weak acid solution

Solutions of strong (HCl) or weak (acetic, phosphoric) acids are commercially available. They are commonly used to remove limescale deposits. The maximum amount of CaCO3 that can be "dissolved" by one liter of an acid solution can be calculated using the above equilibrium equations.

• In the case of a strong monoacid with decreasing concentration [A] = [A], we obtain (with CaCO3 molar mass = 100 g):
 [A] (mol/L) 1 10−1 10−2 10−3 10−4 10−5 10−6 10−7 10−10 Initial pH 0 1.00 2.00 3.00 4.00 5.00 6.00 6.79 7.00 Final pH 6.75 7.25 7.75 8.14 8.25 8.26 8.26 8.26 8.27 Dissolved CaCO3 (g per liter of acid) 50 5.00 0.514 0.0849 0.0504 0.0474 0.0471 0.0470 0.0470

where the initial state is the acid solution with no Ca2+ (not taking into account possible CO2 dissolution) and the final state is the solution with saturated Ca2+. For strong acid concentrations, all species have a negligible concentration in the final state with respect to Ca2+ and A so that the neutrality equation reduces approximately to 2[Ca2+] = [A] yielding $Ca}^{2+}] \simeq \frac{[\mathrm{A}^-]}{2$ . When the concentration decreases, [HCO3] becomes non negligible so that the preceding expression is no longer valid. For vanishing acid concentrations, we recover the final pH and the solubility of CaCO3 in pure water.

• In the case of a weak monoacid (here we take acetic acid with pKA = 4.76) with decreasing concentration [A] = [A]+[AH], we obtain:
 [A] (mol/L) 1 10−1 10−2 10−3 10−4 10−5 10−6 10−7 10−10 Initial pH 2.38 2.88 3.39 3.91 4.47 5.15 6.02 6.79 7.00 Final pH 6.75 7.25 7.75 8.14 8.25 8.26 8.26 8.26 8.27 Dissolved CaCO3 (g per liter of acid) 49.5 4.99 0.513 0.0848 0.0504 0.0474 0.0471 0.0470 0.0470

We see that for the same total acid concentration, the initial pH of the weak acid is less acid than the one of the strong acid; however, the maximum amount of CaCO3 which can be dissolved is approximately the same. This is because in the final state, the pH is larger that the pKA, so that the weak acid is almost completely dissociated, yielding in the end as many H+ ions as the strong acid to "dissolve" the calcium carbonate.

• The calculation in the case of phosphoric acid (which is the most widely used for domestic applications) is more complicated since the concentrations of the four dissociation states corresponding to this acid must be calculated together with [HCO3], [CO32−], [Ca2+], [H+] and [OH]. The system may be reduced to a seventh degree equation for [H+] the numerical solution of which gives
 [A] (mol/L) 1 10−1 10−2 10−3 10−4 10−5 10−6 10−7 10−10 Initial pH 1.08 1.62 2.25 3.05 4.01 5.00 5.97 6.74 7.00 Final pH 6.71 7.17 7.63 8.06 8.24 8.26 8.26 8.26 8.27 Dissolved CaCO3 (g per liter of acid) 62 7.39 0.874 0.123 0.0536 0.0477 0.0471 0.0471 0.0470

where [A] = [H3PO4] + [H2PO4] + [HPO42−] + [PO43−]. We see that phosphoric acid is more efficient than a monoacid since at the final almost neutral pH, the second dissociated state concentration [HPO42−] is not negligible (see phosphoric acid ).

## References

1. "Solvay Precipitated Calcium Carbonate: Production". Solvay S. A. 2007-03-09. Retrieved 2007-12-30.
2. "Calcium Carbonate". Medline Plus. National Institutes of Health. 2005-10-01. Retrieved 2007-12-30.
3. Herbert A. Lieberman, Leon Lachman, Joseph B. Schwartz (1990). Pharmaceutical Dosage Forms: Tablets. p. 153. ISBN 0824780442.
4. Y. Zhao, B. R. Martin and C. M. Weaver (2005). "Calcium Bioavailability of Calcium Carbonate Fortified Soymilk Is Equivalent to Cow's Milk in Young Women". J. Nutr. 135 (10): 2379–2382.