The supplied veterinary-grade Sanwei Quanshen powder is handled as a multi-constituent botanical API whose downstream behaviour is governed by three release parameters: loss on drying, particle-size distribution d90 by ISO 13320:2020 laser diffraction, and a marker or extractable-solids assay. Because batch-to-batch variation in polyphenol, ash, and water-extractable substance content affects each dosage form differently, the formulator should freeze the API lot number, re-assay after any milling step, and calculate the unit dose on the basis of the actual marker content rather than a fixed weight percentage. The following application routes are ordered by the thermodynamic and mechanical severity of the downstream process, not by market volume.

Dry-granulation behaviour of the supplied powder on a forced-feeder rotary tablet press is governed by compactibility and die-wall friction rather than by chemical potency alone. Direct compression of the unmodified API above 30% w/w is not recommended for tablets; tannin-rich botanical powders exhibit low compactibility and high die-wall friction, with capping and lamination observed on rotary presses at turret speeds above 30 rpm and compression pressures above 180 MPa. The preferred pre-treatment is dry granulation in a roller compactor with roll force 8–12 kN/cm, roll gap 1.0–2.5 mm, and screen size 0.8 mm; the retained granule fraction is 200–800 µm. A typical core formula contains 25–45% w/w dry-granulated API, 30–50% w/w microcrystalline cellulose, 10–20% w/w lactose monohydrate, 3–5% w/w crospovidone, and 0.5% w/w magnesium stearate. For tablet cores above 750 mg, addition of 1.0% w/w colloidal silicon dioxide is required to maintain powder flow. Uniformity of dosage units is tested according to USP <905>; the acceptance value should be ≤ 15.0. A film coating of 3.0–4.0% w/w hydroxypropyl methylcellulose-based polymer is applied in a perforated pan at 60–65°C inlet air temperature. The terminal product is a veterinary oral tablet; dissolution is typically run with USP <711> apparatus 2 at 50 rpm in 0.1 M HCl with a Q=75% at 45 min endpoint, but the registered species-specific monograph must replace this target. If the blend is exposed to ambient relative humidity above 60%, pre-drying of the API at 45°C to loss on drying ≤ 5.0% is required before dry granulation. Avoid alkali-metal stearates above 1.0% w/w because over-lubrication can retard disintegration in USP <701> testing. Published compaction data for this specific powder are limited; the above window is derived from behaviour of polyphenol-rich dry extracts and must be confirmed on a laboratory roller compactor before scale-up.

Which Filtration and Stabilisation Parameters Govern Aqueous Veterinary Injectables?

Parenteral development for a polyphenol-containing botanical API is constrained first by the insoluble fraction, not by the active marker. The standard veterinary powder grade may contain plant cell-wall polysaccharides and high-molecular-weight tannins that are acceptable in oral products but unacceptable in injectables. Aqueous concentrates at 10–25 mg/mL are prepared in Water for Injection at 20–30°C under stirring for 45–60 min; the crude solution is then cooled to 2–8°C for 12–24 h to precipitate waxes, chlorophylls, and aggregated tannins. Clarification follows a two-stage filtration train: 0.45 µm polyvinylidene fluoride membrane followed by 0.22 µm polyethersulfone membrane; filterability is the critical control point because polyphenol aggregates foul the 0.22 µm membrane at concentrations above 25 mg/mL. The pH is adjusted to 5.0–6.0 with sodium hydroxide or hydrochloric acid; sodium metabisulfite 0.1% w/v and disodium edetate 0.01% w/v are added to suppress oxidation. Benzyl alcohol is not suitable for feline injectables because of dose-related neurotoxicity; if a preservative is required, methyl 4-hydroxybenzoate 0.1% w/v may be considered only where the target species permits. Sterility is achieved by filtration if the solution passes a filterability test; terminal steam sterilization at 121°C for 15 min is only acceptable if the post-sterilization assay shows marker loss ≤ 5.0% and no new peaks against the unsterilised control. Release testing includes Ph. Eur. 2.9.19 or USP <788> particulate matter, Ph. Eur. 2.6.1 or USP <71> sterility, and Ph. Eur. 2.6.14 or USP <85> bacterial endotoxins. The finished injectable product is a clear to opalescent aqueous solution for intramuscular or subcutaneous administration in cattle or swine, but only when the API batch is designated injectable-grade and residual solvent data meet VICH GL18 limits. For routine production, stainless-steel 316L vessels and polytetrafluoroethylene-lined transfer lines are required; iron-containing surfaces must be avoided because polyphenol iron chelation produces dark-coloured complexes that can fail visual inspection under Ph. Eur. 2.9.20. Published filterability data for this exact powder grade are limited; pilot filterability tests are mandatory before scale-up.

With milled botanical API at d90 < 100 µm, capsule filling on a dosator or tamping-pin machine demands strict control of moisture and lubricant level. Hard gelatin capsule shells are generally not the first-choice shell material because residual tannins can cross-link gelatin and slow disintegration in compendial disintegration testing; when the target species is a ruminant or piglet, hydroxypropyl methylcellulose capsules of size 0 or 1 are preferred. A flowable blend is produced by mixing 20–45% w/w API with pregelatinised starch 20–40% w/w, lactose monohydrate 20–30% w/w, crospovidone 2–4% w/w, colloidal silicon dioxide 0.5–1.0% w/w, and magnesium stearate 0.5% w/w for 3–5 min in a bin blender; the finished blend should have an angle of repose ≤ 40° and bulk density 0.45–0.65 g/mL. In-process weight variation is controlled by Ph. Eur. 2.9.5 or USP <905> with a target acceptance value ≤ 15.0. The filled capsules are sealed if the gelatin alternative is used, and the final product is a veterinary oral capsule. If the API has not been pre-dried to loss on drying ≤ 5.0%, the powder may adhere to dosator pins and cause weight drift during runs longer than 60 min. Avoid combination with aldehyde-bearing shell materials because residual aldehydes can accelerate polyphenol crosslinking and produce a pellicle in USP <701> disintegration testing.

Oral Powder Carrier Systems and In-Line Blending Criticality

For oral water-dispersible powders, the limiting variable is the cold-water solubility of the native polyphenol fraction. The API is usually milled to d90 < 75 µm and dry-blended with a water-soluble carrier such as dextrose monohydrate 60–80% w/w, sodium citrate tribasic 5–10% w/w as the alkaliser, and anhydrous colloidal silica 0.5–1.0% w/w as the flow control agent. The API load in the powder is typically 5–15% w/w; higher loadings above 20% w/w can produce an oily-looking wet paste when diluted in cold drinking water rather than a stable suspension. Dry blending is carried out in a double-ribbon or paddle mixer for 15–20 min at 20–30 rpm; blend uniformity is evaluated by taking 10 stratified samples and testing a marker or extractable-solids content with a relative standard deviation ≤ 5.0%. The terminal product is a single-dose or multi-dose oral powder for pigs or poultry. Because the powder is dispersed in drinking water at the farm, in-use stability is time-limited: the medicated water should be consumed within 24 h, and hard water with calcium carbonate above 300 mg/L can precipitate polyphenol calcium complexes and reduce the effective dose at the drinker line.

When Wet Granulation Is Required for Veterinary Granules

High-shear wet granulation of the API is only justified when the target dose is high or when dust control is mandatory. The granulation solvent is water or a water-ethanol mixture; water content 10–15% w/w is added to a pre-mix containing 30–50% w/w API, 20–40% w/w microcrystalline cellulose, 10–20% w/w lactose monohydrate, and 3–5% w/w povidone K30 as binder. Granulation is performed in a high-shear mixer with impeller speed 150–250 rpm and chopper speed 1500–2500 rpm for 3–5 min; the wet mass should have a torque rise of 20–30% above the dry-mix baseline. Drying is performed in a fluid-bed dryer at inlet air temperature 50–60°C until loss on drying is 2.0–3.0%; higher temperatures above 70°C are not recommended because polyphenol marker content may shift by more than 5%. The dried granules are screened through 1.0 mm and lubricated with 0.5% w/w magnesium stearate. The terminal product is a veterinary oral granule for direct administration or mixing with feed. The main incompatibility is with iron-containing equipment; dark granule discoloration during drying is a visual indicator of iron contamination exceeding 10 ppm in the water or excipient.

Segregation risk in medicated feed premixes increases when the active particle-size distribution does not overlap with the carrier and when the active density differs from the carrier by more than 0.3 g/mL. The API is milled to d50 100–200 µm and diluted in two stages: a 1:10 pre-blend with ground rice hulls or wheat bran in a ribbon mixer for 10 min, followed by a 1:100 dilution with the same carrier in a double-ribbon mixer for 15 min. The final premix is assayed for marker content at 10 sampling points; the coefficient of variation should be ≤ 15% under Regulation (EU) 2019/4 for medicated feed homogeneity. If the premix is pelleted, conditioning at 70–85°C for 20–60 s with 10–15% steam is expected to reduce heat-labile markers by 5–15%; in that case, the overage is set during process validation, not arbitrarily. Carryover is controlled by flushing the line with 2% salt or ground limestone and by verifying residual active levels below 1% of the minimum effective dose in the next non-medicated batch. Iron-containing equipment is excluded; stainless-steel 316L contact surfaces are required because polyphenolic components chelate ferric ions and form black complexes. The terminal product is a medicated feed premix for swine, poultry, or ruminants; exact inclusion rate must be determined from the approved species-specific dose and the batch marker assay, not from a fixed percentage.

Drinking Water Solutions Require pH Buffering and In-Use Stability Control

In drinking-water applications, water matrix pH and hardness govern the solubility and stability of the active fraction. A stock solution is prepared with propylene glycol 10–20% v/v or glycerol 5–10% v/v as co-solvent, sodium hydroxide or triethanolamine to pH 7.5–8.5, and purified water to volume; the target undiluted concentration is 5–10% w/v. At the farm, the stock solution is dosed through a proportional dosing pump to give 0.1–0.5% v/v in the drinking water, but the exact field concentration is species- and indication-specific and must follow the registered summary of product characteristics. The finished product is an oral solution or concentrate for drinking-water application in poultry or swine. In-use stability is limited to 24 h; after 24 h, microbial growth and polyphenol oxidation can reduce active content by more than 10% unless a preservative is used. If the farm water has total hardness above 300 mg/L as CaCO₃, a chelating acid such as citric acid 0.1–0.3% w/v is added to the stock solution to prevent calcium-tannate precipitation in the drinker lines. The product is packed in light-resistant containers because polyphenols are light-sensitive; amber polyethylene terephthalate or high-density polyethylene bottles with oxygen-barrier caps are used.