Wuwei Shiliupi Powder veterinary grade API for tablets, injections, capsules, powders, granules, premix, and solutions is a standardized dry extract of Punica granatum L. pericarp. The material is released under two particle-size model designations: WSP-VA-100, with a D90 acceptance criterion of ≤150 µm, and WSP-VA-200, with a D90 of ≤250 µm. Total ellagitannins expressed as punicalagin are controlled at ≥20.0% w/w, total polyphenols by the Folin-Ciocalteu method at 35.0–55.0% w/w, and free ellagic acid at ≤2.0% w/w. The product differs from crude pomegranate rind powder in that methanol-insoluble residue is limited to ≤5.0%, total ash is limited to ≤10.0%, and aflatoxin B1 is controlled below 2 µg/kg. The material is supplied solely as a starting substance for licensed veterinary medicinal products, medicated premixes, and in-house formulation; it is not a finished dose form.

Published pharmacopoeial monographs specific to Wuwei Shiliupi powder are limited. Consequently, the release specification is aligned to general botanical extract methods: USP 〈561〉 for botanical identity, USP 〈731〉 for loss on drying, USP 〈233〉 for elemental impurities, USP 〈2021〉 for microbial limits, and ISO 13320:2020 for laser diffraction particle sizing. Certificate of analysis documentation should be reviewed for each batch because native pomegranate pericarp crop year and extraction lot influence the punicalagin-to-ellagic ratio even after standardization.

The milling route is air-jet classification, not mechanical grinding, because impact milling can raise product temperature above 55°C and initiate tannin degradation. In a production-scale fluidized-bed opposed-jet mill, the classifier speed is set to maintain D90 at the target band. The fine grade exhibits a bulk density of 0.35–0.55 g/mL and a tapped density of 0.55–0.75 g/mL; the resulting Carr index is 28–35%. This is an operational boundary for direct compression because formulations above 40% w/w API without glidant show mass variability exceeding 3% RSD on a rotary tablet press operating at 45 rpm.

What Analytical Specifications Separate the Veterinary Grade from Crude Pomegranate Rind?

Crude pericarp powders typically contain total ellagitannins in the range of 5–15% w/w and carry insoluble lignocellulosic fragments that can exceed 20% w/w. The WSP-VA-100 grade is produced by aqueous extraction at 50–70°C, filtration through 10 µm retentive media, and vacuum concentration below 85°C. The dried product is then air-jet milled to the target D90. This sequence reduces the risk of tablet lamination and capsule tamping pin wear caused by intact stone cells and bast fibres. Microscopic examination at 400× must show no intact seed oil globules and no pericarp fragments larger than 180 µm in the fine grade.

The HPLC release method for punicalagin uses a C18 column, 250 × 4.6 mm, 5 µm packing, with 0.1% formic acid and acetonitrile gradient at 1.0 mL/min. Punicalagin α and β anomers elute as separate peaks; total punicalagin is calculated as the sum of both anomers. System suitability requires resolution ≥1.5 between the anomers and tailing factor ≤2.0.

In a direct compression trial on a 16-station rotary press using 10 mm flat-faced bevel-edge punches, blends of 40% w/w API, 50% microcrystalline cellulose, 9% lactose monohydrate, 0.5% colloidal silicon dioxide, and 0.5% croscarmellose sodium produced tablets with hardness 65–85 N and friability 0.4–0.7%. When API content was increased to 60% w/w, capping at the precompression stage occurred within 10 minutes and ejection force doubled. This defines a practical upper API load of 50% w/w for direct compression unless dry granulation is used.

For hard capsule filling, a dosing-disc machine with size 0 capsules and tamping pin pressure set to 80 N showed stable fill weights when the API moisture was below 5.0%. At relative humidity above 60%, the powder formed a cohesive arch above the dosing disc and fill weight RSD exceeded 5%. Pre-drying in a vacuum shelf dryer at 45°C and −0.08 MPa for 4–6 hours restored fill variability to ≤2.5%.

Thermal Degradation Boundaries in Granulation, Pelleting, and Injection Sterilization

The ellagitannin fraction is thermally labile under alkaline or moist-heat conditions. Differential scanning calorimetry of the dry powder shows a broad endothermic event beginning near 68°C, followed by exothermic decomposition above 210°C. In a co-rotating twin-screw extruder with 24:1 L/D and pellet die temperature of 70°C, total ellagitannin loss after one pass was 4–7% w/w. At 85°C die temperature, loss increased to 11–14% and extrudate surface roughness exceeded Ra 25 µm. The processing window for wet granulation and pelleting is therefore considered to be ±5°C around a product temperature of 50°C; excursions above 55°C for more than 20 minutes produce measurable punicalagin degradation and color shift beyond Gardner YS450.

Wet granulation with 3–5% w/w polyvinylpyrrolidone solution as binder and an inlet air temperature of 55–60°C produced granules with bulk density 0.45–0.55 g/mL and angle of repose 32–38°. Fluid-bed drying endpoint at 3.0–4.5% moisture was reached in 25–35 minutes. A longer drying time at 60°C beyond 45 minutes did not further reduce moisture but increased oversize fraction above 850 µm by 7%, indicating surface crusting of the granule shell.

For injectable solutions, terminal steam sterilization at 121°C for 15 minutes is associated with a punicalagin α-anomer loss of 12–16% and an increase in free ellagic acid to above 2.0% w/w. Aseptic filtration through a 0.22 µm PVDF membrane is preferred when the solution has been prefiltered through 0.45 µm polypropylene. The pH must be maintained below 4.0 during filtration because higher pH promotes deprotonation of phenolic hydroxyl groups and increases membrane fouling.

When the API Is Converted to a Solution or Suspension Concentrate

Solution concentrates are prepared in 30–50% ethanol or propylene glycol-water blends. In aqueous systems, the solubility of the dried extract is approximately 28–42 g/L at 25°C, but solubility decreases sharply below pH 3.0 and above pH 6.5. A suspension concentrate containing 100 g/L API remains physically stable for 14 days at 40°C when 0.15% xanthan gum and 1.0% microcrystalline cellulose/carboxymethyl cellulose coprocessed stabilizer are used; after 28 days, sediment volume exceeded 5% and redispersion time increased beyond 60 seconds. The product is not compatible with strong oxidizing agents, ferric salts, or gelatin-based clarifiers because tannin-protein and tannin-iron complexes precipitate.

Filterability studies through 0.45 µm PVDF at constant pressure 0.2 MPa showed flux decline of 12–18% after 100 L/m² throughput for a 50 g/L solution at pH 4.0. Polyethersulfone membranes showed higher fouling and are not recommended without a prefilter.

For premix and granule manufacture, the API is deposited on a feed-grade carrier such as ground corn cob or maltodextrin. In a vertical ribbon mixer of 1000 L capacity, a two-phase mixing sequence—first as a 20% intermediate premix with sieving through 500 µm, then dilution to final concentration—reduces the relative standard deviation of marker content to ≤3%. The same powder can be incorporated in medicated feed at low inclusion rates, but homogenous distribution requires a minimum premix cycle of 15 minutes after the final addition.

Traditional veterinary use of pomegranate rind preparations is associated with intestinal astringency and mitigation of non-specific diarrhea in swine, ruminants, and companion animals. Published dose-response data for this specific standardized API in target species are limited. Regulatory approval requires target animal safety, residue, and efficacy studies under the relevant regional framework, such as EU 2019/6 or the applicable national veterinary medicinal product regulation.

Chelation and Protein Binding Constraints in Excipient Blends

The API is rich in hydrolysable tannins, which bind to salivary proteins and form chelates with trivalent metal ions. This property explains the astringent effect but also imposes formulation constraints: alkaline-earth metal salts, including calcium carbonate, magnesium oxide, and zinc sulfate, reduce free punicalagin by 8–15% in aqueous admixture after 2 hours at 25°C. Ferric chloride at 0.5 mM produces immediate blue-black precipitate. Pyridoxine hydrochloride and thiamine hydrochloride are generally compatible at ≤5% w/w when the final water activity remains below 0.6, but direct contact in solution causes degradation of the B-vitamin fraction.

Alkaloid-containing feed additives and APIs, such as berberine or matrine, should not be co-ground with this extract unless compatibility has been demonstrated, because tannin-alkaloid salts can form poorly soluble complexes. If the formulation requires both, separate granulation or microencapsulation of the alkaloid component is recommended. Compatibility with ionizable drugs such as enrofloxacin or oxytetracycline in solution is not assumed; published data for this specific API configuration are limited, so separate administration or stability screening is required.

How Does the Standardized Extract Compare with Non-Standardized Rind Powder and Hydrolysable Tannic Acid?

Comparison of WSP-VA-100 with crude rind powder and commercial hydrolysable tannic acid shows three operationally significant differences: reduced insoluble fibre, controlled punicalagin content, and improved compaction behavior. These distinctions determine selection for tablet, capsule, and injection intermediates.

During fluid-bed drying of granules containing 10% w/w API, the exhaust air temperature should not exceed 60°C, and the product moisture endpoint is 3.0–4.5%. At moisture below 2.5%, electrostatic charging increases and dry sieving losses through 150 µm screens can reach 6%. At moisture above 5.0%, the granules cake during storage in lined multiwall paper sacks at 40°C and 75% relative humidity. Packaging should therefore use aluminium foil laminate or HDPE drums with desiccant when the logistically expected storage period exceeds 3 months in tropical conditions.

For aqueous injectable solutions, final pH adjustment to 3.8–4.2 with citric acid or acetic acid is used to maintain punicalagin stability during storage at 25°C. The solution should be protected from light because ultraviolet exposure accelerates ellagic acid formation under ICH Q1B conditions. Amber glass or opaque polymer containers are specified for light-sensitive formulations.