| HS Code | 777960 |
| Product Name | Ascorbic Acid Coated Pharma Grade API |
| Chemical Name | L-Ascorbic Acid (Vitamin C) |
| Cas Number | 50-81-7 |
| Molecular Formula | C6H8O6 |
| Molecular Weight | 176.12 g/mol |
| Pharma Grade | USP / Ph.Eur. / BP compliant pharmaceutical grade |
| Appearance | White to off-white free-flowing coated crystalline powder or granules |
| Coating Type | Pharmaceutical-grade polymer coating for moisture and oxidation protection |
| Assay | 99.0% to 100.5% on dried basis |
| Identification | Positive by IR, HPLC, and chemical identification tests |
| Specific Rotation | +20.5° to +21.5° (10% w/v aqueous solution, 20°C) |
| Ph Value | 2.4 to 2.8 in 5% w/v aqueous solution |
| Solubility | Ascorbic acid core is freely soluble in water; coated grade provides protective delayed dissolution behavior |
| Melting Point | 190°C to 192°C with decomposition |
| Bulk Density | 0.5 to 0.8 g/mL depending on the coated particle grade |
As an accredited Ascorbic Acid Coated 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 25 kg sealed drums with inner liner, protecting coated Ascorbic Acid API for oral and injectable pharmaceutical formulations. |
| Container Loading (20′ FCL) | Ascorbic Acid Coated Pharma Grade API packed in sealed drums, palletized, and loaded into a 20′ FCL container with moisture protection. |
| Shipping | Shipped in sealed, moisture-proof containers with desiccants to protect the coated API. Temperature-controlled logistics prevent degradation. Fully compliant with IATA/IMDG regulations for pharmaceutical ingredients, with clear labeling and tamper-evident packaging. Documentation includes COA and MSDS. |
| Storage | Store in a cool, dry, well-ventilated area below 25°C. Keep tightly sealed in original container, protected from light, moisture, and heat. Avoid contact with metals and oxidizing agents. Ensure proper labeling and segregation. Under recommended conditions, shelf life is typically 24 months from manufacture date. |
| Shelf Life | Shelf life is 24 months from manufacture when stored in sealed containers, protected from heat, light, and moisture. |
For direct compression, coated ascorbic acid pharma grade API for oral and injectable dosage forms is typically supplied with an ascorbic acid assay of 95.0–97.5% w/w on the as-is basis and a coating fraction of 2.0–5.0% w/w. The coating layer reduces hygroscopicity, lowers punch filming and improves flow on high-speed rotary presses. A representative 500 mg ascorbic acid equivalent tablet is formulated with 520 mg coated grade at 96.15% assay, 115 mg microcrystalline cellulose PH102, 25 mg croscarmellose sodium, 6 mg anhydrous colloidal silica and 5 mg sodium stearyl fumarate. Sodium stearyl fumarate is preferred over magnesium stearate where divalent magnesium and residual moisture can accelerate ascorbic acid degradation. The blend is prepared in a 300 L bin blender at 12 rpm for 20 minutes after the disintegrant and lubricant are preblended at 1:1. Compression is carried out on a 43-station rotary tablet press with 10 mm round flat-faced bevel-edge tooling at 40–60 rpm. Precompression force is maintained between 4 kN and 7 kN. Main compression force is limited to 12–18 kN. Above 20 kN, coated tablets may laminate because the coating has lower plastic deformation than uncoated ascorbic acid, and rapid decompression promotes capping. Hardness is controlled at 80–120 N. Friability per USP <1216> remains below 0.8% after 100 revolutions. Weight variation is tested per USP <905>. Dissolution per USP <711> Apparatus 2 in 900 mL 0.1 N hydrochloric acid at 50 rpm typically releases not less than 80% in 30 minutes for water-soluble-coated grades. Residual granulation moisture must be below 1.0% w/w by USP <921> Method Ia. Compaction at ambient relative humidity above 60% causes sticking on lower punch faces and increases tablet weight variation.
| Attribute | Method | Typical acceptance |
|---|---|---|
| Assay of ascorbic acid | USP Ascorbic Acid monograph, HPLC at 245 nm | 95.0–97.5% w/w as-is for coated grade |
| Loss on drying | USP <921> Method Ia | <1.0% w/w for direct compression granules |
| Uniformity of dosage units | USP <905> | Acceptance value <15.0 |
| Dissolution | USP <711> Apparatus 2, 50 rpm, 900 mL 0.1 N HCl | Not less than 80% in 30 min for immediate-release tablets |
| Tablet friability | USP <1216> | <0.8% after 100 revolutions |
On a high-speed capsule filler, coated ascorbic acid exhibits better flow consistency than uncoated powder because the coating reduces surface roughness and static charge. The powder is dry-blended with lactose monohydrate 80 mesh at an ascorbic acid-to-lactose ratio of 1:0.4. A 00-size two-piece hard gelatin capsule can accommodate 500 mg ascorbic acid equivalent when the coated grade has a bulk density of 0.60–0.75 g/mL. Powder flow is assessed by Carr index and Hausner ratio. Values should be below 25 and 1.25, respectively. On a Bosch GKF 2500 running at 40,000 capsules/hour, hopper fill level is maintained between 30% and 70% to avoid flooding and dose drift. Dosing-disc machines with tamping pins require a narrow granule size distribution. Particles below 75 µm should not exceed 15% because fine material compacts unevenly and causes fill weight variation. Hard gelatin capsule shell moisture is kept at 12–15% while powder moisture is below 1.0% to prevent shell brittleness and ascorbic acid oxidation. Capsule weight variation is tested per USP <905>. Dissolution is performed per USP <711> Apparatus 1 at 100 rpm in 900 mL water. The final product is a hard capsule containing 500 mg ascorbic acid with a desiccant pouch in HDPE bottles. Gelatin crosslinking may occur if the packaging environment contains reactive aldehydes. HPMC capsules are substituted when aldehyde exposure is suspected. For EU import, the coating polymer must comply with REACH registration obligations unless exempted under Annex IV or V; ethylcellulose and hydroxypropyl methylcellulose are widely used in this application.
In effervescent dosage forms, coated ascorbic acid delays the acid-base reaction between coated core and bicarbonate during storage. The granulation is produced by top-spray fluidized-bed granulation. A standard 4 g effervescent tablet contains coated ascorbic acid equivalent to 1000 mg ascorbic acid, 1200 mg anhydrous citric acid, 1500 mg sodium bicarbonate, 100 mg sodium carbonate and 200 mg sorbitol. A 3% w/w PVP K30 solution in isopropanol is sprayed at 12–18 g/min per kg of powder bed. Inlet air temperature is 50–60°C. Spray rate above 25 g/min per kg of bed may cause local overwetting, dissolving citric acid and forming coarse agglomerates that reduce tablet hardness. Drying continues until loss on drying by USP <921> is below 0.5% w/w. Above this threshold, the effervescent reaction accelerates in sealed packaging, causing internal pressure rise and tablet cracking within 4 weeks at 40°C/75% RH. The final lubricant is PEG 6000 at 1.0–2.0% w/w. Tablets are compressed at 25–40 MPa on a hydraulic press to a hardness of 60–90 N. Disintegration is tested per USP <701>. A 4 g tablet disintegrates in 120–180 seconds in 200 mL water at 20°C. Final packaging is an HDPE tube with silica gel desiccant and a water vapour transmission rate below 0.5 g/m²/day at 23°C/85% RH. The finished product is a white to pale-yellow effervescent tablet delivering 1000 mg vitamin C per dose. Stability studies follow ICH Q1A(R2) and 21 CFR 211.166.
For injectable applications, coated ascorbic acid is acceptable only if the coating is water-soluble or if the coating is removed during solution preparation before sterile filtration. A typical 500 mg/5 mL injectable solution is compounded at 100 mg/mL ascorbic acid in Water for Injection. Disodium edetate is added at 0.1% w/v as a chelating agent. The solution is purged with nitrogen and adjusted to pH 5.5–7.0 with sodium bicarbonate. Bulk solution is prepared in 316L stainless steel tanks under nitrogen overlay. A 0.45 µm polypropylene prefilter is placed upstream of a 0.22 µm polyethersulfone sterilizing filter. Aseptic filling into amber glass vials is preferred. Terminal steam sterilization at 121°C for 15 minutes is generally avoided because ascorbic acid degrades to dehydroascorbic acid and further oxidation products. The finished product must meet USP <1> Injections, USP <788> particulate matter, USP <71> sterility and USP <85> bacterial endotoxins. Component testing follows 21 CFR 211.84. If a lipid-coated ascorbic acid is used as a dry powder in a lyophilization process, the coating may clog the membrane filter and reduce content uniformity. Published data for lyophilized ascorbic acid with coated particles as a direct sterile powder fill is limited. The final dosage form is an amber ampoule or vial stored at 2–8°C with an oxygen absorber.
Because the acidic taste of ascorbic acid limits patient acceptability, chewable tablets use a taste-masked coated grade. The coating level is maintained below 4.0% w/w because higher levels cause waxy mouthfeel and incomplete drug release. A representative 1000 mg chewable tablet contains coated ascorbic acid equivalent to 500 mg ascorbic acid, 350 mg sorbitol, 80 mg xylitol, 70 mg pregelatinized starch, 15 mg anhydrous citric acid, 10 mg orange flavour, 8 mg magnesium stearate and 5 mg silicon dioxide. Mixing is performed in a V-blender at 25 rpm for 15 minutes. Compression on a 16-station rotary press with 16 mm round flat-faced bevel-edge tooling runs at 20–30 rpm. Main compression force is 15–22 kN. Hardness is limited to 60–90 N to preserve chewability. Friability is below 0.8% per USP <1216>. Dissolution per USP <711> Apparatus 2 in 0.1 N HCl shows not less than 75% release in 60 minutes. Processing humidity above 40% RH is avoided because the sorbitol/xylitol matrix becomes tacky and sticks to punch faces. The final product is a chewable tablet for dietary supplement use.
Oral granules for unit-dose stick packs and sachets are produced by high-shear wet granulation of coated ascorbic acid with mannitol, microcrystalline cellulose and PVP K30. A 200 kg batch is loaded in a 600 L high-shear granulator. Purified water is sprayed at 1.5 kg/min until final moisture reaches 8–12% w/w. The wet mass is milled through a 1.5 mm screen and dried in a fluid-bed dryer at inlet air temperature 60°C to a final moisture below 1.0% w/w. Dried granules are sieved to 250–850 µm. Filling onto a vertical form-fill-seal machine with auger dosing delivers 1000 mg ascorbic acid equivalent in 2000 mg total granule mass per stick pack. Weight variation is assessed using the principles of USP <905> for single-dose containers. Dissolution per USP <711> in 0.1 N HCl releases not less than 80% in 15 minutes for water-soluble-coated grades. The stick pack laminate is a three-layer PET/aluminium/LDPE film with oxygen transmission rate below 0.5 cm³/m²/day at 23°C/0% RH. The finished product is a white to pale-yellow granule in a single-dose sachet for oral use.
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Ascorbic acid coated pharma grade API intended for tablet, capsule, granule, oral solution, and injectable preparation is supplied as a free-flowing granulate under the model designation AA-C100. The product comprises crystalline ascorbic acid substrate coated with a water-soluble polyvinyl alcohol–polyethylene glycol graft copolymer at a nominal loading of 2.5% w/w and a permitted range of 2.0–3.0% w/w. The coating is not enteric and does not retard dissolution in purified water, 0.1 M hydrochloric acid, or phosphate buffer pH 6.8; it is selected to reduce surface oxidation, dusting, and segregation during high-speed solid dosage form manufacture. Because the coating polymer is water-soluble, the same grade may be dissolved for oral and injectable solutions under the filtration and oxygen-control requirements described below. The material is tested against ascorbic acid monograph methods and is suitable for tablet, capsule, granule, oral solution, and injectable preparation when processed within the stated operational boundaries.
The release specification includes assay 99.0–100.5% w/w on the anhydrous basis, loss on drying ≤0.4% w/w, residue on ignition ≤0.1% w/w, heavy metals ≤10 ppm by ICP-MS, particle size D50 150–250 µm and D90 ≤425 µm, bulk density 0.60–0.85 g/mL, and tapped density 0.75–1.00 g/mL. The coating content is quantified by aqueous extraction and size-exclusion chromatography after the granulate is dispersed in warm water. Residual solvent limits follow ICH Q3C, with Class 3 solvents controlled at ≤0.5% w/w each and Class 1 solvents absent. The granulate is packed in nitrogen-sparged polyethylene-lined drums to limit headspace oxygen ingress.
The release specification is intended to align with harmonised ascorbic acid monograph requirements while adding coated-particle performance controls. The table below summarises the release parameters for AA-C100.
| Parameter | Acceptance limit | Test method |
|---|---|---|
| Appearance | White to off-white free-flowing granulate | Visual examination under D65 illumination |
| Identification | Infrared spectrum concordant with ascorbic acid reference; positive reaction for ascorbate | Ph. Eur. 2.2.24, USP <197K> |
| Assay, anhydrous basis | 99.0–100.5% w/w | Iodometric titration, Ph. Eur. 2.5.1 / USP <341> |
| Loss on drying | ≤0.4% w/w after 105 °C | Ph. Eur. 2.2.32 / USP <731> |
| Residue on ignition | ≤0.1% w/w | USP <281> / Ph. Eur. 2.4.16 |
| Heavy metals | ≤10 ppm by ICP-MS | USP <233> |
| Coating content | 2.0–3.0% w/w polyvinyl alcohol–polyethylene glycol graft copolymer | Gel-permeation chromatography after aqueous extraction |
| Particle size | D50 150–250 µm, D90 ≤425 µm | Laser diffraction, USP <429> |
| Bulk density / tapped density | 0.60–0.85 g/mL / 0.75–1.00 g/mL | USP <616>, Method I |
| Residual solvents | Class 3 solvents ≤0.5% w/w each; Class 1 absent | USP <467>, ICH Q3C |
| Microbial limits | TAMC ≤103 CFU/g, TYMC ≤102 CFU/g, Escherichia coli absent in 1 g | USP <61> / USP <62> |
The manufacturing process is controlled under ICH Q7 and 21 CFR 210/211 for finished dosage form operations. Coating uniformity is monitored by solvent extraction followed by gravimetric or chromatographic assay. The polyvinyl alcohol–polyethylene glycol graft copolymer is selected because it forms a continuous film at 2.0–3.0% w/w without extending disintegration time beyond the immediate-release dissolution criteria of USP <711> and Ph. Eur. 2.9.3. At the stated coating level, the film thickness is typically below 10 µm, which is insufficient to provide an enteric or extended-release barrier.
High-speed direct compression lines expose low-density actives to hopper segregation, punch sticking, and oxidative discoloration. The coated granulate is designed with particle size and surface characteristics that place it closer to common direct-compression excipients such as microcrystalline cellulose PH102 and dibasic calcium phosphate dihydrate. On a rotary press equipped with a three-paddle feeder and 10.0 mm round flat-faced tooling, AA-C100 has been processed at turret speeds up to 60 rpm when blended with microcrystalline cellulose PH102 and crospovidone at a 1:1 active-to-filler ratio. Die fill mass variability remains below 2.0% RSD when the powder bed is maintained above 80% hopper fill. The flow function is characterised by a Hausner ratio of 1.15–1.20 and a Carr index of 12–16%, which are indicative of free-flowing granulates suitable for high-speed tableting.
The coating reduces the exposed ascorbic acid surface area and delays moisture uptake during short-term open handling. Uncoated ascorbic acid with comparable particle size exhibits higher fines content and greater hygroscopicity, which can produce surface discoloration within hours at ambient humidity above 60% RH. The coated granulate still requires low-humidity handling because the film is not an absolute moisture barrier. Pre-drying is required if the material is stored above 60% RH before direct compression. Immediate-release dissolution is not sacrificed: under USP <711> Apparatus II at 50 rpm in 0.1 M hydrochloric acid at 37 °C, the coating dissolves rapidly, and ascorbic acid release typically exceeds 85% within 15 min when the tablet disintegrant system is functional. The dissolution profile is therefore governed mainly by tablet disintegration and not by the coating layer.
For wet granulation, the coated substrate permits low-shear addition of water without immediate dissolution of the active. Granulation water addition is typically limited to 5–8% w/w, and the bed temperature is maintained at 35–40 °C with an inlet air dew point not exceeding 5 °C. These conditions reduce oxidative degradation during fluid-bed drying. The coating is not a replacement for antioxidant packaging; accelerated stability screening under ICH Q1A(R2) at 40 °C ± 2 °C / 75% RH ± 5% RH is recommended. Published data for this specific coated configuration is limited, so formulation-specific stability protocols should include assay, related substances, and surface color measurement.
Injectable formulations impose additional constraints. AA-C100 may be dissolved in Water for Injection at 25–35 °C under nitrogen sparging that lowers dissolved oxygen to 0.1 mg/L or below. The resulting solution is subsequently filtered through a 0.22 µm membrane to remove any insoluble particulates, including any residual coating fragments or adventitious fibers. The pH of a 10% w/v aqueous solution of AA-C100 after coating dissolution is typically 3.0–3.5. For parenteral administration, the solution is usually buffered to a final pH of 5.5–6.5 with sodium bicarbonate or trisodium citrate. Exposure to copper and iron ions must be avoided at concentrations above 0.1 ppm because these ions catalyse oxidative degradation of ascorbate in aqueous media. The solution should be protected from light and oxygen during holding; published data for this specific configuration is limited, so hold-time validation should be performed for each final formulation.
In buffered oral or parenteral formulations, the selection of ascorbic acid source influences pH, sodium load, calcium incompatibility, flow, and oxidation sensitivity. The table below compares AA-C100 with uncoated ascorbic acid, sodium ascorbate, and calcium ascorbate in standard pharmaceutical applications.
| Attribute | AA-C100 coated ascorbic acid | Uncoated ascorbic acid | Sodium ascorbate | Calcium ascorbate |
|---|---|---|---|---|
| Assay | 99.0–100.5% w/w as ascorbic acid | 99.0–100.5% w/w as ascorbic acid | 99.0–100.5% w/w on dried basis | 99.0–100.5% w/w on dried basis |
| pH of 10% w/v aqueous solution | 3.0–3.5 after coating dissolution | 2.2–2.6 | 7.0–7.8 | 6.5–7.5 |
| Dust formation and flow | Low-dust granulate; Hausner ratio 1.15–1.20 | High fines; Hausner ratio often >1.30 | Moderate dust; hygroscopic | Low dust; cohesive at low moisture |
| Oxidation sensitivity in open air | Moderate; surface coating reduces oxygen ingress | High; rapid surface discoloration | High in solution; moderate as solid | Moderate; metal chelation can vary |
| Intended route | Tablet, capsule, granule, oral and injectable solution after filtration | Tablet, capsule, injectable after dissolution | Injectable, effervescent, and buffered oral formulations | Oral tablets and chewable products; calcium supplementation |
Compared with uncoated ascorbic acid, AA-C100 reduces dust generation during dispensing and sieving, which improves industrial hygiene and reduces cross-contamination risk. The granulate also shows lower segregation in direct-compression blends because its particle size and density are closer to common filler systems. Sodium ascorbate offers higher aqueous solubility and near-neutral pH, but it introduces sodium counterion load and may be less suitable for sodium-restricted formulations. Calcium ascorbate provides a calcium source but can form insoluble calcium salts in phosphate-buffered injection vehicles; AA-C100 avoids this incompatibility because it does not carry calcium or sodium counterions. The coated substrate is water-soluble and is not equivalent to ascorbyl palmitate or other lipid-soluble vitamin C esters; AA-C100 is not intended for anhydrous lipid vehicles or oil-based emulsions.
When roller compaction or capsule filling is selected, the granulate should be de-aerated before encapsulation to stabilise fill weight. For automatic capsule machines, vacuum-assisted filling reduces powder head variability but must not expose the material to residual oxygen above 2% by volume. Roller compaction pressures above 12 kN/cm may fracture the coating and generate fines, increasing oxidation risk; the compacted ribbons should be milled at low shear and re-screened through a 850 µm screen before final blending.
