| HS Code | 427119 |
| Productname | Magnesium Carbonate Pharma Grade API |
| Chemicalname | Magnesium carbonate hydroxide (basic hydrated magnesium carbonate) |
| Casnumber | 39409-82-0 (basic hydrate; anhydrous: 546-93-0) |
| Molecularformula | 4MgCO3·Mg(OH)2·4H2O (approximate) |
| Molecularweight | 467.63 g/mol |
| Appearance | White to almost white powder or granular powder |
| Odor | Odorless |
| Solubility | Practically insoluble in water and ethanol; soluble in dilute acids with effervescence |
| Assay | 40.0% to 43.5% as MgO on dried basis |
| Ph | 8.0 to 10.5 (aqueous suspension) |
| Bacterialendotoxins | Complies with pharmacopoeial requirements for parenteral use |
| Residualsolvents | ICH Q3C compliant |
| Chemical Name | Magnesium carbonate |
| Molecular Formula | MgCO3 |
| Molecular Weight | 84.31 g/mol |
| Cas Number | 546-93-0 |
| Appearance | White crystalline or amorphous odorless powder |
| Solubility | Practically insoluble in water and ethanol; dissolves with effervescence in dilute acids |
| Ph Of Aqueous Suspension | 10.5 to 11.5 |
| Assay As Mgo | 40.0% to 45.0% |
| Bulk Density | 0.15 to 0.60 g/mL depending on light or heavy grade |
| Particle Size | Fine powder with controllable particle size distribution for pharmaceutical dosage forms |
As an accredited Magnesium carbonate Pharma Grade API for Tablet / Capsule / Granule / Injection, Oral & Injectable factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in sealed double-lined polyethylene bags inside 25 kg fiber drums, ensuring purity and stability for pharmaceutical formulations. |
| Container Loading (20′ FCL) | 20′ FCL loaded with drummed Magnesium Carbonate Pharma Grade API, palletized and secured for pharmaceutical use, injection, oral, and tablet production. |
| Shipping | Shipped in sealed, moisture-proof containers to preserve purity and stability. Handle carefully to avoid extreme temperatures and humidity. Compliant with GMP and pharmaceutical transport regulations. Ensure tamper-evident packaging with complete documentation, suitable for oral and injectable grade API delivery worldwide. |
| Storage | Store in a well-closed, tightly sealed container, away from moisture, heat, and direct sunlight. Keep in a cool, dry, well-ventilated area at controlled room temperature (20–25°C). Protect from humidity and incompatible materials. For injectable grades, maintain sterile, contamination-free conditions and follow pharmacopoeial guidelines throughout storage. |
| Shelf Life | Shelf life is 36 months if stored in well-closed containers, protected from moisture, heat, and direct sunlight. |
In direct compression lines where magnesium carbonate constitutes 30–50 wt% of the tablet core, the choice between light carbonate and heavy carbonate determines weight variation at press speeds above 50,000 tablets/h. The light grade entrains air and can produce feed-frame flooding in rotary presses; the heavy grade is therefore typically selected when net weight variation must remain below 2% RSD and tablet hardness is held between 8 and 12 kp. A commercial formulation may combine magnesium carbonate 35–45 wt%, microcrystalline cellulose 30–40 wt%, crospovidone 2–5 wt%, colloidal silicon dioxide 0.5–1.0 wt%, and magnesium stearate 0.5–1.0 wt%. The magnesium stearate is added only after a 20 min V-blender preblend and is mixed for 3 min; exceeding 5 min at this step produces a hydrophobic lubricant film that retards acid penetration in USP <301> acid-neutralizing-capacity testing and raises disintegration time under USP <701> toward the 30 min limit. Compression force is normally adjusted to 10–20 kN on a 16–24 station rotary press, with friability controlled below 1.0% by USP <1216>. Because the carbonate can adsorb moisture, pre-drying at 60–70°C to loss on drying below 3.0% is used when storage RH exceeds 60%. The terminal tablet is a dry antacid or magnesium supplement; acid-neutralizing capacity is label-specific and commonly not less than 5 mEq per dose.
Hard gelatin capsule filling with magnesium carbonate blends is most often performed on tamping-pin dosators running at 50,000–120,000 capsules/h. Because magnesium carbonate has poor flow, a common fill formulation includes magnesium carbonate 40–60 wt%, lactose monohydrate or spray-dried mannitol 35–50 wt%, croscarmellose sodium 2–4 wt%, colloidal silicon dioxide 0.5–1.0 wt%, and magnesium stearate 0.5–1.0 wt%. The preblend is passed through a 0.8 mm screen before final lubrication to break agglomerates. Capsule size 0 or 00 is selected for fill weights of 350–500 mg. Tamping-pin height and pin number are adjusted to give plug heights of 8–12 mm; short plugs release too early, while long plugs produce high ejection forces and shell deformation. The empty gelatin shells are conditioned at 40–50% RH for 24–48 h before filling because a very dry fill can abstract bound moisture from the shell and cause brittleness at the cap-bending point. Weight variation is monitored at 10 min intervals against a ±3% target and capsule disintegration is tested by USP <701>; dissolution, when required, is run by USP <711> with 0.1 N HCl at 37°C. Over-lubrication above 1.5% magnesium stearate or blending beyond 5 min can delay acid-mediated dissolution. The terminal capsule is a magnesium supplement or antacid; elemental magnesium label content is calculated from the MgO assay of the carbonate batch, which for USP-NF grade is 40.0–43.5% MgO.
When single-dose oral granule sachets are produced for suspension, magnesium carbonate is usually wet-granulated to improve content uniformity and reduce dust. A production batch may contain magnesium carbonate 50–60 wt%, microcrystalline cellulose 15–25 wt%, povidone K30 3–5 wt%, croscarmellose sodium 2–4 wt%, and hypromellose 1–2 wt% as a dry binder. Granulation in a high-shear mixer is run at impeller tip speeds of 2–6 m/s with purified water as the granulation fluid; batch size and bowl fill ratio are controlled to 50–70% of nominal capacity to prevent overwetting and granule densification. The wet mass is milled through a 2.0 mm screen, dried in a fluid-bed dryer at 50–60°C to LOD below 2.5%, and sieved to 300–850 µm. The dried granules are blended with 0.5–1.0% colloidal silicon dioxide and filled into foil-laminate sachets at 500–1,000 mg nominal fill weight. For suspension, xanthan gum 0.2–0.5 wt% or microcrystalline cellulose/sodium carboxymethylcellulose co-processed suspending agents are included to produce an apparent viscosity at 10 rpm on a Brookfield LV viscometer of 150–300 cP after reconstitution. Content uniformity is controlled by USP <905>, and elemental impurities are limited by ICH Q3D. The finished product is a magnesium carbonate oral suspension with a dose-dependent antacid or laxative effect.
Effervescent granulation using magnesium carbonate depends on the assayed acid-neutralizing capacity of the carbonate rather than the theoretical molecular weight, because USP-NF magnesium carbonate is a hydrated or basic hydrated salt with MgO content 40.0–43.5%. The acid source is a citric acid/tartaric acid blend; formulation batches are titrated to a final reconstituted-solution pH of 4.0–5.5, with total acid mass generally in the range 1.5–2.5 times the mass of magnesium carbonate for light grade. Sodium bicarbonate is often included at 20–40 wt% of the carbonate charge to accelerate gas release and improve mouthfeel, but it increases sodium intake and may be incompatible with low-sodium label claims. Wet granulation is performed with anhydrous ethanol or isopropanol in a fluid-bed granulator at inlet temperature 35–45°C and room RH below 20%; water is excluded because residual moisture above 2.0% initiates premature acid-carbonate reaction, causing granule fizzing, package ballooning, and loss of acid-neutralizing capacity. The granulate is dried to LOD below 1.5%, sieved to 300–850 µm, and immediately packed into cold-form aluminum foil laminate with desiccant. The finished effervescent granules are dispersed in water before ingestion; the solution is clear to slightly turbid and has a pH not exceeding 6.0. The loss of CO₂ during storage is monitored by headspace gas analysis and by USP <301> acid-neutralizing capacity.
| Dosage form | Critical attribute | Test standard | Typical acceptance window |
|---|---|---|---|
| Incoming magnesium carbonate API | MgO assay | USP-NF monograph | 40.0–43.5% MgO |
| Tablet | Acid-neutralizing capacity | USP <301> | Label-specific; common antacid claim ≥5 mEq per dose |
| Tablet | Disintegration | USP <701> | ≤30 min in purified water or 0.1 N HCl |
| Tablet | Friability | USP <1216> | ≤1.0% weight loss after 100 revolutions |
| Capsule | Dissolution | USP <711> | As approved in 0.1 N HCl at 37°C |
| Oral granules for suspension | Uniformity of dosage units | USP <905> | Acceptance value ≤15 |
| Parenteral conversion solution | Particulate matter | USP <788> | Meets injectable limits for final salt solution |
| Parenteral conversion solution | Bacterial endotoxin | USP <85> | Meets final injectable limit as defined in NDA/ANDA |
Direct injection of magnesium carbonate is precluded by its aqueous solubility, which is below 0.02 g/100 mL at 25°C, and by the particulate burden that a suspension would impose in parenteral vessels. Therefore parenteral manufacturing uses the carbonate only as a chemical intermediate for magnesium chloride or magnesium sulfate solutions. The carbonate is suspended in purified water or water for injection, and dilute hydrochloric acid is added at 40–50°C until the pH remains below 2.0 and effervescence ceases; the resulting magnesium chloride solution is filtered through a 0.45 µm prefilter and a 0.22 µm sterilizing-grade membrane before further purification or crystallization. For magnesium sulfate injection, sulfuric acid is used instead of hydrochloric acid. The conversion step does not confer compendial acceptance for injection; the final salt solution must meet USP <788> injectable particulate matter, USP <85> bacterial endotoxin, and ICH Q3D elemental impurity limits in the finished injectable product. If the carbonate is intended for use in an injectable supply chain, additional endotoxin data are required from the supplier because the monograph does not automatically address parenteral criticality. The terminal product is an injectable magnesium chloride or magnesium sulfate solution for electrolyte correction; magnesium carbonate itself is not present in the parenteral formulation.
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Magnesium carbonate of pharmacopoeial grade, supplied under model designations MG-CARB-PH-H for the heavy grade and MG-CARB-PH-L for the light grade, is a basic hydrated magnesium carbonate suitable for solid oral dosage forms and, after dissolution and conversion, for preparation of injectable magnesium salts. The material is controlled against the current USP-NF and Ph. Eur. magnesium carbonate monographs, with an ignited MgO assay within 40.0–43.5%. The substance is practically insoluble in water, dissolves in dilute mineral acid with effervescence, and therefore functions as an acid-neutralizing oral active as well as a high-surface-area, pH-modifying excipient in tablets, capsules, and granules. The heavy and light variants are chemically equivalent but differ in apparent volume, particle architecture, specific surface area, and in-process handling behavior.
Identity is confirmed by the compendial carbonate test and by formation of a white precipitate upon addition of sodium hydroxide to the acid-dissolved sample. The heavy grade is produced under conditions that yield a denser particle bed and is preferred where flow, bulk reduction, and die-fill uniformity dominate. The light grade is produced by rapid precipitation and retains higher internal porosity, greater adsorptive capacity, and lower settled density. The primary structural discriminator is apparent volume measured according to Ph. Eur. 2.9.34; particle size distribution is reported by laser diffraction under ISO 13320-1:2020.
| Parameter | Heavy grade | Light grade | Method or reference |
|---|---|---|---|
| Ignited MgO assay | 40.0–43.5% | 40.0–43.5% | Current USP-NF monograph |
| Apparent volume | ≤2.5 mL/g typical | 10–15 mL/g typical | Ph. Eur. 2.9.34 |
| Tapped density | 0.60–0.85 g/mL typical | 0.10–0.30 g/mL typical | USP <616> |
| Particle size D50 | 15–35 µm | 3–10 µm | ISO 13320-1:2020 |
| Specific surface area | 5–20 m²/g typical | 25–60 m²/g typical | Ph. Eur. 2.9.26 |
| Loss on drying | ≤1.0% after 2 h at 105°C | ≤1.0% after 2 h at 105°C | USP <731> |
The values in the table are representative manufacturing data, not pharmacopoeial acceptance criteria; where a compendial limit applies, the current monograph text is normative.
In granule and sachet manufacture, the light grade is used as an alkaline diluent and moisture-adsorbing carrier. Fluid-bed granulation with a top-spray nozzle, inlet air dew point below 5°C, and product bed temperature 35–45°C limits premature hydrate loss. Because the high specific surface area narrows the endpoint window, liquid addition is controlled by torque feedback and near-infrared moisture measurement rather than by fixed volume alone. Over-wetting presents as granule collapse at the discharge port of a conical mill fitted with a 3 mm rasping screen. For capsule filling, the heavy grade is better suited to tamping-pin machines because it settles more uniformly, whereas the light grade usually requires vacuum-assisted dosator retention to prevent fluidization under mechanical vibration.
Direct compression of magnesium carbonate is constrained by low bulk density, cohesive flow, and high elastic recovery. Flow characterization under USP <1174> should be reported as Carr index and Hausner ratio; a Carr index above 25 and a Hausner ratio above 1.25 identify a powder that cannot be run on high-speed rotary presses without a force feeder. The heavy grade performs better than the light grade, but both typically require colloidal silicon dioxide or a low-humidity glidant blend. Tablet weight variation should be controlled within ±5% RSD; in high-speed operation the limiting factor is deaeration rate of the powder inside the feed frame. If a formulation contains more than 20% w/w light magnesium carbonate, compaction simulation should be performed before transfer to production equipment.
Direct-compression blends containing the carbonate should not be combined with hygroscopic acid salts unless triboelectric charge and moisture ingress are controlled, because surface moisture can initiate carbon dioxide release inside the press, producing punch filming and pitted tablet surfaces. Published production-scale data for high-dose direct compression of light magnesium carbonate is limited; process qualification batches and press-run mapping are therefore required before routine manufacture.
Wet granulation is used when direct compression is not feasible. The light grade absorbs granulation fluid rapidly, so binder addition is divided into an initial wetting phase at low impeller speed followed by a massing phase under torque control. In a 25 L high-shear mixer, the liquid-to-solids ratio may range from 0.25 to 0.40 depending on the batch; the endpoint is confirmed when impeller torque rises 8–15% from the dry-mix baseline. Drying is performed in a fluid-bed dryer with inlet air temperature 55–65°C and product temperature not exceeding 45°C, with loss-on-drying by USP <731> held between 0.5% and 1.5%. Overdrying below 0.3% generates electrostatic fines and lowers tablet tensile strength, while residual moisture above 2.0% may cause surface picking and browning if reducing sugars are present in the formulation.
The alkaline microenvironment of magnesium carbonate can stabilize acid-labile actives during wet granulation, but the same pH shift may accelerate hydrolysis of ester prodrugs. Stress storage at 40°C/75% RH according to ICH Q1A is therefore required, with degradant assay rather than dry-state compatibility alone used to determine suitability.
Native magnesium carbonate is not a direct injectable active. Its aqueous solubility is reported as approximately 0.01 g/100 mL at 25°C in carbon dioxide-free water, and the saturated solution is alkaline. Injectable preparation therefore requires conversion to a soluble magnesium salt, typically magnesium chloride. In a stainless-steel reactor, the carbonate is dispersed in water for injection and reacted with pharmaceutical-grade hydrochloric acid under pH control at pH 3.0–4.0 until carbon dioxide evolution ceases. The resulting solution is neutralized with sodium hydroxide to pH 5.5–7.0, clarified through a 0.22 µm sterilizing-grade filter, and filled into depyrogenated containers. Terminal sterilization by autoclaving at 121°C for 15 min is applicable only after confirmation of solution stability and container compatibility; the finished product must meet USP <788> particulate matter, USP <790> visible particulate, USP <71> sterility, and USP <85> bacterial endotoxin requirements.
Ready-to-use injectable suspensions containing magnesium carbonate are uncommon. Published data for this specific injectable configuration is limited, and native magnesium carbonate is not interchangeable with magnesium sulfate or magnesium chloride in critical care protocols.
Compared with other magnesium sources, the carbonate contains approximately 25.0% elemental magnesium in the basic hydrate, whereas magnesium oxide contains 60.3% and magnesium hydroxide contains 41.7%. The theoretical acid-neutralizing capacity of the basic carbonate formula 4MgCO₃·Mg(OH)₂·5H₂O is 20.6 mEq/g, close to calcium carbonate at 19.9 mEq/g and greater than sodium bicarbonate at 11.9 mEq/g. Neutralization is nevertheless slower because dissolution from the solid surface is rate-limiting. Calcium carbonate shares carbon dioxide release but contributes a calcium load and a risk of hypercalcemia with chronic high-dose use. Sodium bicarbonate imposes a sodium burden and rapid gas release, while magnesium carbonate does not contribute sodium. Magnesium oxide is less soluble and more strongly alkaline, producing a higher initial pH excursion; magnesium hydroxide has a more pronounced laxative action than the carbonate at equivalent acid-neutralizing dose.
For oral solid-dose design, magnesium carbonate is selected when a non-sodium, non-calcium acid-neutralizing or magnesium-supplementing material with a moderate neutralization rate is required. The heavy grade is preferred for direct compression and capsule tamping; the light grade is preferred for suspension reconstitution, dry powder adsorption, and low-dose granule carriage. Finished antacid products must meet the acid-neutralizing capacity test of USP <301>; the theoretical stoichiometric value alone is not sufficient for release.
Release testing includes identity, assay, chloride, sulfate, iron, arsenic, lead, loss on drying, acid-insoluble matter, and microbial enumeration under the current monograph. Elemental impurities are controlled by USP <232> and USP <233> according to ICH Q3D; residual solvents meet USP <467> Class 3 limits. The material is stored in tightly closed containers protected from moisture. When ambient humidity exceeds 60% RH, pre-drying at 60°C to loss-on-drying below 1.0% is required before dry blending. Magnesium carbonate is incompatible with strong acids in sealed containers because carbon dioxide liberation can generate pressure, and it should not be premixed with citric or tartaric acid in a dry state if the packaging headspace contains moisture.
