Tablet manufacture with Xiaoji Powder is constrained by the powder’s polysaccharide content and the corresponding impact on granule densification. Direct compression is rarely workable because the raw veterinary-grade API exhibits poor compactibility and a wide particle-size distribution, typically 45–150 µm for 90% cumulative volume. Wet granulation with a starch-paste binder at 5–10% w/w or povidone K30 at 2–5% w/w in purified water is therefore the primary route. The binder-to-API ratio is maintained at 0.02–0.05:1 on a dry solids basis to avoid over-wetting, which produces hard granules that resist tablet consolidation. Granulation is carried out in a high-shear granulator with impeller speed 150–300 rpm and chopper speed 1500–3000 rpm; wet mass is passed through a 1.2–2.0 mm screen and dried in a fluid-bed dryer with inlet air at 55–65°C until loss on drying reaches 1.5–2.5%. Dried granules are milled through a 0.8–1.0 mm screen before final blending with croscarmellose sodium 2–4% w/w, microcrystalline cellulose q.s., and magnesium stearate 0.5–1.0% w/w. Tablet compression is performed on a rotary press at 16–24 kN precompression and main compression force, targeting hardness 5–8 kp and friability not more than 0.8%. Content uniformity testing follows USP <905> with an acceptance value of ≤15; disintegration is assessed by USP <701> with a limit of ≤30 min in 0.1 N hydrochloric acid. Microbial limits for the finished tablet should meet USP <2021> and <2022>: total aerobic microbial count ≤10³ CFU/g, total combined yeasts and molds ≤10² CFU/g, and absence of Escherichia coli and Salmonella. The terminal finished product is a scored, light-brown to tan veterinary tablet for oral dosing in dogs, pigs, and ruminants.

What Limits Direct Dissolution of Xiaoji Powder in Aqueous Injection Vehicles?

At concentrations above 20 mg/mL, aqueous injection vehicles based solely on water for injection fail to produce physically stable solutions from Xiaoji Powder because non-extractable lignified fragments and high-molecular-weight polysaccharides remain as suspended colloids. Injectable development therefore follows a suspension-to-solution screening path rather than a simple dissolution step. Composition-specific solubility data for Xiaoji Powder are not published in consolidated monographs; each batch must be qualified for cold-water extractable matter before vehicle design. A working vehicle consists of water for injection, propylene glycol 10–30% v/v, and glycerin 5–10% v/v, adjusted to pH 5.5–7.0 with citrate or phosphate buffer. The API is pre-wetted with a small volume of vehicle and dispersed under high shear at 10,000–12,000 rpm for 15–30 min; the slurry is then filtered sequentially through 0.8 µm, 0.45 µm, and 0.22 µm polyethersulfone membranes. Terminal moist-heat sterilization at 121°C for 15 min is used only after confirming that the filtered solution does not precipitate or darken beyond the acceptance threshold; otherwise, an aseptic filtration route is selected. Particulate matter limits follow USP <788> for small-volume injections: not more than 6000 particles per container at ≥10 µm and not more than 600 particles per container at ≥25 µm. Bacterial endotoxin content should be below 0.5 EU/mg of API, and the finished injectable should be tested for sterility according to USP <71>. The terminal product is a clear to slightly opalescent, pale-amber sterile solution or a lyophilized cake intended for intramuscular or subcutaneous administration.

Operational boundaries are narrow. If tannin-containing fractions are present, divalent cations such as calcium and magnesium in the buffer system can generate insoluble complexes. The pH of the final vehicle should not exceed 8.0 because alkaline conditions accelerate oxidative browning of polyphenolic constituents. In-line 0.22 µm sterilization can remove colloidal active fractions and lower assay recovery; filter adsorption studies with polyvinylidene fluoride and polyethersulfone membranes are therefore run at bench scale using a 1:1 ratio of filter area to solution volume before scale-up.

Feed-mill integration of Xiaoji Powder as a veterinary premix requires a carrier system that can survive auger metering, dust generation, and cross-contamination controls. The powder is first reduced to a uniform particle size through a 60-mesh screen and then geometrically diluted with a low-moisture carrier such as rice husk, corncob grit, or calcium carbonate to produce an intermediate premix containing 5–20% w/w API. Mixing is performed in a ribbon mixer at 20–30 rpm for 10–15 min; the acceptable coefficient of variation for the marker compound in the premix is ≤5%, with samples taken from 10 separate locations using a grain thief. The final feed inclusion rate is typically 0.5–2.0 kg/ton of complete feed, depending on the target dose and the animal species. Finished premix moisture is controlled below 10% to prevent clumping in silos, and the product is packed in multi-wall paper bags with a polyethylene liner. Regulatory compliance for medicated feed premixes in the United States falls under 21 CFR 225 and 226 for current good manufacturing practice; where the product is exported, EU feed hygiene rules under Regulation (EC) No 183/2005 and sampling protocols under ISO 6497 apply. The terminal finished product is a free-flowing dry premix for blending in commercial feed mills or on-farm vertical mixers.

Batch-changeover cross-contamination is managed by flushing the mixer with a sacrificial carrier and verifying that carryover of the previous medicated premix is ≤0.5% in the next non-medicated batch. Dust extraction systems must maintain airborne dust below 5 mg/m³ as an industrial hygiene threshold, and operators should use NIOSH-approved respirators when handling undiluted API.

When Xiaoji Powder Is Filled Into Hard Gelatin Capsules Without Prior Granulation

Without prior granulation, direct encapsulation of Xiaoji Powder produces weight variation across filling heads because the raw powder typically has an angle of repose above 40° and a Carr index above 25%. The formulation is therefore shifted to dry granulation or slugging before capsule filling. A working dry-granulation formula contains API 40–60% w/w, microcrystalline cellulose 30–50% w/w, colloidal silicon dioxide 0.5–1.5% w/w, sodium starch glycolate 2–4% w/w, and magnesium stearate 0.25–0.75% w/w. Roller compaction is operated to achieve ribbon density 1.1–1.3 g/cm³; the ribbons are milled to granules between 0.6 mm and 1.0 mm. Capsule filling on a tamping-pin or dosator machine targets a fill weight of 300 mg with a weight variation limit of ±5% for individual capsules. The filled capsules are tested for dissolution by USP <711> apparatus II at 50 rpm in 900 mL of 0.1 N hydrochloric acid or pH 6.8 phosphate buffer; the acceptance criterion is Q ≥75% at 45 min. Hard gelatin or hydroxypropyl methylcellulose capsules can be used, but if the fill moisture exceeds 5%, gelatin shell softening and cross-linking may occur. The terminal finished product is a size-3 to size-1 capsule containing a free-flowing granular fill that reduces segregation of the multi-component botanical powder.

The moisture barrier requirement is more severe for capsules than for tablets because the shell itself is hygroscopic. Blister packs using polyvinyl chloride/polyvinylidene chloride film with a water vapor transmission rate below 0.1 g/m²/24 h at 38°C/90% RH are specified to protect the product through a 24-month shelf life when stored below 30°C. Accelerated stability studies at 40°C/75% RH for 6 months are used to confirm physical and chemical stability.

For oral solution development, aqueous preparations containing Xiaoji Powder present a biphasic distribution problem that is often misclassified as simple dissolution. The insoluble fibrous fraction settles within 2 h in an unpreserved aqueous vehicle, producing a hard sediment that is difficult to redisperse. A structured suspension vehicle is therefore prepared with sorbitol 10–20% w/v, glycerin 5–15% w/v, microcrystalline cellulose and carboxymethylcellulose sodium 1–2% w/v as suspending agent, polysorbate 80 0.05–0.2% w/v as wetting agent, sodium benzoate 0.1% w/v, and potassium sorbate 0.1% w/v. The pH is adjusted to 4.5–6.5 with citric acid or sodium citrate. Dry Xiaoji Powder is first wet with a portion of the vehicle containing the wetting agent and mixed under high shear at 8,000–10,000 rpm for 15–30 min; the slurry is then homogenized at 150–250 bar to reduce the dispersed phase to <50 µm. Quality criteria for the terminal oral suspension include viscosity 50–200 mPa·s at 25°C, sedimentation volume >0.9 after 7 days without shaking, and redispersibility after <20 manual inversions. Preservative effectiveness is tested according to USP <51>, and the nonsterile preparation is assigned a beyond-use date of 30 days when stored at controlled room temperature. The finished product is an opaque brown suspension delivered by oral syringe or drench nozzle.

Compatibility with metal drench guns should be assessed because polyphenolic fractions can chelate iron and aluminum, causing dark precipitates at the nozzle. A dose-volume range of 1–10 mL per animal is typical for small ruminants and swine; higher volumes can cause feed refusal if the suspension is applied as a topdress.

Bulk oral powders are prepared by dry blending Xiaoji Powder with dextrose monohydrate, lactose monohydrate, and citric acid in a V-blender or double-cone blender. The working formulation contains API 10–30% w/w, dextrose monohydrate 60–85% w/w, citric acid 0.5–2% w/w, colloidal silicon dioxide 0.5–1.0% w/w, and a species-appropriate flavor 0.1–0.3% w/w. Geometric dilution is performed in 3 stages to achieve a coefficient of variation ≤5% for the marker compound; blending time is 15–20 min at 25 rpm for a 200 kg batch. The powder is passed through a 0.30 mm screen before filling into high-density polyethylene jars or heat-sealed foil pouches. Fill weight for the dosing scoop is targeted at ±5% of label claim. Moisture content is controlled below 5%, and desiccant pillows are added when the powder contains more than 10% dextrose because dextrose monohydrate can cake above 60% RH. The terminal finished product is a free-flowing, water-dispersible oral powder for direct topdressing or for reconstitution in drinking water at the farm.

Compliance follows USP <795> for nonsterile compounding and USP <1231> for water quality when the powder is reconstituted. Content uniformity testing follows the sampling plan described in USP <905> with 10 samples per lot; acceptance is AV ≤15. The product should be stored below 30°C and protected from moisture ingress, because the botanical fraction contains hygroscopic polysaccharides that can harden in the container.

Granule-Sachet Processing and Moisture Barrier Selection

A fluid-bed top-spray granulator operating at an inlet-air temperature of 60–70°C provides the drying capacity needed to convert Xiaoji Powder into free-flowing granules for sachet packaging. The granulation liquid is purified water or a 2–5% w/w maltodextrin solution sprayed at 10–20 g/min/kg of substrate, with atomization air pressure 1.5–2.5 bar. Granulation proceeds until the final moisture content is ≤2.5%, which is low enough to prevent microbial growth and sachet clumping. A representative dry-granule formula contains API 10–30% w/w, maltodextrin or dextrin 40–70% w/w, sucrose 5–15% w/w, citric acid 0.5–2% w/w, and a species-appropriate flavor 0.1–0.3% w/w. The granule fraction between 0.3 mm and 1.0 mm is selected for packaging; material below 0.15 mm is recycled to the granulator or discarded to limit dust. Sachet fill weights range from 5 g to 50 g depending on the target species and water medication system. Packaging uses aluminum foil laminate with water vapor transmission rate below 0.1 g/m²/24 h at 38°C/90% RH, and seal integrity is verified by ASTM F88. The terminal finished product is a unit-dose dry granule that disperses in drinking water within 3 min at 25°C without high-shear mixing.

Granule-sachet products for veterinary water medication must also meet the dissolution or dispersion standard of the target delivery system. Field data from poultry and swine operations indicate that nozzle clogging occurs when granule residue on a 200-mesh screen exceeds 1% of the nominal dose after 5 min of recirculation; therefore, a screen retention test is added to the release specification. The finished sachet should be labeled for use only in clean drinking-water lines, because hard water above 250 ppm calcium carbonate can precipitate minor organic acids in the vehicle and reduce dispersion performance.