Liweisan Veterinary Grade API is supplied as a purified active pharmaceutical ingredient under two manufacturer designations: LWI-VAPI-01 for tablets, capsules, powders, granules, premixes, and non-parenteral solutions, and LWI-VAPI-01I for injectable and other endotoxin-controlled applications. The product is not a final formulation, not a feed additive, and not a technical-grade intermediate. Release specifications are defined by high-performance liquid chromatography with ultraviolet detection at 254 nm on a C18 column (150 mm × 4.6 mm, 5 µm) and by headspace gas chromatography for residual solvents. Assay limits are 98.0%–102.0% on the dried, solvent-free basis for the oral grade and 98.5%–101.5% for the injectable grade. Related substances by area normalization are limited to ≤0.5% total for oral grade and ≤0.3% total for injectable grade, with any single unspecified impurity controlled at ≤0.10%. Residual solvents comply with USP <467> and ICH Q3C, with methanol limited to ≤3000 ppm in oral grade and ≤1500 ppm in injectable grade; acetone and isopropanol are limited to ≤5000 ppm oral and ≤2500 ppm injectable. Loss on drying is ≤0.5% after 4 h at 105 °C according to USP <731>. The material is packaged in 25 kg fibre drums with double low-density polyethylene liners, and an outer moisture barrier is required when relative humidity exceeds 60% during storage or transfer.

Can one Liweisan grade serve both sterile injectable and oral granule manufacturing?

A single grade is not assigned across the full dosage-form range. The injectable sublot LWI-VAPI-01I is released with a bacterial endotoxin limit of ≤0.50 EU/mg by limulus amebocyte lysate assay according to USP <85> and EP 2.6.14. Total aerobic microbial count for this sublot is ≤10¹ CFU/g, and total combined yeasts and moulds are ≤10¹ CFU/g per USP <61> and USP <62>. The same sublot is tested for subvisible particulate matter after reconstitution according to USP <788> Method 1; for large-volume parenterals the light obscuration limits are 25 particles/mL at ≥10 µm and 3 particles/mL at ≥25 µm, while for small-volume parenterals the counts are 6000 particles/container at ≥10 µm and 600 particles/container at ≥25 µm. The oral dosage forms use LWI-VAPI-01, which is not required to meet the injectable endotoxin threshold. Applying one grade across both routes would either burden oral solid manufacture with LAL and subvisible particulate testing or leave injectable manufacture without the requisite endotoxin and particulate data. The distinction is operational: a dry powder with acceptable oral microbial limits can still produce a reconstituted solution that fails USP <788>, particularly if the API has been milled under uncontrolled conditions and contains aggregated particles or glass-like fines.

For injectable compounding, the preferred method is aseptic dissolution in water for injection at a concentration of 10 mg/mL, followed by filtration through a 0.22 µm polyvinylidene fluoride membrane and aseptic filling into depyrogenated vials. Terminal sterilization by steam at 121 °C for 15 min is not a default option for this active; published data for aqueous degradation kinetics under autoclave conditions are limited, and therefore the manufacturer specifies aseptic filtration rather than moist-heat terminal sterilization. If a production line uses a sterile filling train with a 0.45 µm prefilter and 0.22 µm final filter, the maximum allowable pressure differential across the final filter should be ≤2.0 bar to avoid rigid particle breakthrough from the membrane cartridge. Solutions prepared in this way are held under nitrogen overlay when the pH exceeds 6, and amber glass is specified because photostability data in dilute solution have not been fully characterized under ICH Q1B.

Direct compression and capsule-filling processes require control of flow, bulk density, and particle-size distribution because the active is a crystalline powder with variable cohesion depending on residual moisture and electrostatic charge. The oral grade is characterized by USP <1174> powder flow test methods; Carr index is specified at ≤25% and Hausner ratio at ≤1.25. These are specification limits, not batch performance data. On a rotary tablet press with 16 stations operated at 25–40 rpm, the compression force window for a 10 mm round flat-faced bevel-edged tablet is typically 8–18 kN; tablets are released only when hardness is 6–10 kp and friability is ≤0.5% after 4 min in a USP <1216> friabilator. Disintegration is evaluated according to USP <701> in purified water at 37 ± 2 °C, with complete disintegration in ≤15 min for uncoated tablets. The tablet formula includes microcrystalline cellulose as a dry binder, croscarmellose sodium as a disintegrant, and magnesium stearate as a lubricant; magnesium stearate is limited to 0.75% w/w because higher levels can delay disintegration through hydrophobic film formation on the API particles. This is a known processing boundary, not a product-specific failure.

Capsule blends are prepared by mixing the API with lactose monohydrate or dicalcium phosphate dihydrate in a low-shear tumble blender for 10 min, sieving through a 500 µm screen to break agglomerates, and blending for an additional 10 min. On a dosator-type capsule filler, the powder bed height is maintained above the dosator nozzle by 25 mm to control weight variation. Content uniformity is tested by USP <905>; the acceptance value is ≤15.0% for the first stage and ≤25.0% when the second stage is required. For immediate-release capsules, dissolution is evaluated with USP <711> Apparatus 2 at 50 rpm in 900 mL of 0.1 N HCl at 37 ± 0.5 °C, with a specification target of not less than 80% dissolved in 30 min. Published data for this specific Liweisan capsule formulation are limited; the stated target is aligned with compendial expectations for soluble veterinary actives rather than a batch certificate.

Particle-size controls for feed premix and solution dosage forms.

Premix applications impose a narrower particle-size specification than general oral powders. The premix grade is controlled by laser diffraction according to EP 2.9.31 and by analytical sieving according to USP <786>. The specified particle-size distribution requires D10 ≥ 5 µm, D50 15–45 µm, and D90 ≤ 100 µm. Material retained on a 60-mesh (250 µm) sieve is limited to ≤1.0%, and material passing through a 325-mesh (45 µm) sieve is limited to ≤60% to avoid excessive fines that can segregate during discharge. In a 100 L low-shear ribbon blender filled to 65% working volume and operated at 25 rpm for 15 min, the active content in 10 sampled locations must remain within a coefficient of variation of ≤5.0%. The main failure mode in premix manufacture is not chemical instability but segregation during mixer discharge and transport; the API fraction is therefore pre-blended with silicon dioxide at 0.5% w/w when carriers such as calcium carbonate are used, because calcium carbonate charges electrostatically under low-humidity conditions below 30% RH and may coat mixer surfaces rather than blend.

For solution dosage forms, the API is dissolved in purified water or a propylene glycol–water co-solvent system. The aqueous solubility at 25 °C is 12 mg/mL. Oral solutions requiring higher strength are formulated with propylene glycol and water at a ratio up to 20:80 v/v; pH adjustment is not a reliable solubilization strategy across the full veterinary dose range because no published pH-solubility curve is available for all target species. The final solution is passed through a 0.45 µm membrane to remove undissolved active and incidental particulate matter. Preserved oral solutions are challenged by USP <51> antimicrobial effectiveness testing. The package is amber glass or an opaque high-density polyethylene bottle with a foil induction seal; light protection is specified because photostability data for the diluted solution are not fully established.

When residual solvent thresholds are compared across dosage forms, the injectable limit tightens.

The oral, premix, and injectable grades share the same chromatographic procedure but not the same acceptance limits. Methanol is ≤3000 ppm for oral grade and ≤1500 ppm for injectable grade. Acetone and isopropanol are ≤5000 ppm oral and ≤2500 ppm injectable. The limits are derived from ICH Q3C Option 2 permitted daily exposure values scaled to body weight and maximum daily dose in the target species. The method uses USP <467> procedures A and B with headspace gas chromatography and flame-ionization detection. Ethylene oxide is controlled at ≤1 ppm for injectable packaging components according to ISO 10993-7. This is a differentiating feature when compared with technical-grade or feed-grade active substances: many such materials are sold with no batch-resolved solvent certificate or with a single unspecified “≤0.5%” total volatile figure that cannot be used to demonstrate compliance with VICH GL18 or European maximum residue limit dossiers. The absence of solvent-specific data is a common reason for regulatory rejection of veterinary premix and injection submissions.

The separation from feed-grade powders is most visible in injectable manufacturing. Feed-grade material may have adequate chemical purity for some oral uses but is not produced under the same endotoxin, bioburden, particulate, and solvent controls. Liweisan injectable sublot LWI-VAPI-01I is not simply a repacked oral grade; it is tested against a reduced impurity ceiling, lower residual solvent thresholds, and a defined endotoxin limit. For oral dosage forms, the difference is primarily in particle-size control and polymorph consistency. The product is controlled by X-ray powder diffraction to a single crystalline pattern and by differential scanning calorimetry for amorphous content; technical-grade material may vary between polymorphs and amorphous fractions, which changes dissolution and blend behavior. These controls are not rhetorical distinctions but part of the data required to use the substance in a registered veterinary medicinal product.

Storage conditions follow ICH Q1A long-term testing at 25 °C ± 2 °C and 60% RH ± 5% RH for oral grade, with an accelerated condition of 40 °C ± 2 °C and 75% RH ± 5% RH. The injectable sublot is stored at 2–8 °C after opening to minimize moisture uptake and microbial ingress. The manufacturer assigns a retest period of 24 months for oral grade and 18 months for the injectable sublot when stored in the original unopened packaging. Above 60% RH, pre-drying of the oral grade at 40 °C for 2 h is required before dry blending to avoid flow defects and weight variation during tableting.

Wet granulation of LWI-VAPI-01 for powders and granules is performed with a 5% w/w povidone K30 aqueous binder in a top-spray fluid-bed granulator using a 1.2 mm two-fluid nozzle and inlet air temperature of 60 °C. The product temperature during spraying is held at 30–35 °C, and drying continues to a final moisture limit of ≤2.0%. The dried granules are calibrated through a 1000 µm sieve with not more than 10% retained. For premixes on corn cob carriers, the API is first blended with a small portion of the carrier and 0.5% w/w colloidal silicon dioxide before addition to the remaining carrier; this step is specified because direct addition of the API to a large-volume mixer can produce API-rich pockets that persist even after prolonged mixing. The final premix is released only after the coefficient of variation across 10 sampling points is ≤5.0%.