Zihua Hezi Powder, Veterinary Grade API, is supplied as a milled botanical active pharmaceutical ingredient intended for further pharmaceutical processing into tablets, injections, capsules, powders, granules, premixes, and solutions. The product model is the veterinary-grade API powder; within that model, the particle-size subgrade is selected in the purchase specification to match the intended dosage form and manufacturing route. The veterinary-grade designation indicates that the powder is released under a specification covering particle-size distribution, residual moisture, microbial burden, heavy metal content, and marker constituents. It is not a finished dosage form and is not used directly in animals without appropriate formulation and release testing. As a multi-component botanical API, it differs from synthetic single-entity APIs in that the active fraction is not defined by a single chemical purity assay; instead, chromatographic fingerprinting and marker assay are used to control batch-to-batch consistency. The material is intended for use by manufacturers operating under veterinary good manufacturing practice, and it must be qualified before use in any dosage form because the critical material attributes will interact with the selected unit operations.

Specification envelope and analytical test designations for release

Release of the veterinary-grade powder is controlled by a specification that includes macroscopic appearance, identification by thin-layer chromatography or high-performance liquid chromatography, and physico-chemical determinations appropriate for botanical APIs. Particle-size distribution is controlled using laser diffraction according to ISO 13320:2020 or USP <429>. The target D90 is not a fixed value for all dosage forms; it is set by the receiving manufacturer in the purchase specification. Direct-compression tablet blends typically require a D90 of 75 µm or less to ensure uniform distribution in low-dose tablets and rapid dissolution. Dry-granulated formulations may accept a D90 of 180 µm to 250 µm because the compaction step reduces the influence of coarse particles. Suspension and injectable research grades require additional particle-size reduction before use.

Loss on drying is determined by USP <731> at 105°C or by the corresponding Chinese Veterinary Pharmacopoeia general chapter. Total ash and acid-insoluble ash are assessed to limit non-marker plant matrix and mineral contamination. Heavy metals are controlled by atomic absorption spectrophotometry or inductively coupled plasma-mass spectrometry under USP <233>, Ph Eur 2.4.8, or the current veterinary pharmacopoeia alternative. Aflatoxin B1, ochratoxin A, and multi-residue pesticide screenings follow the relevant compendial or national residue control methods. Microbial limits are evaluated under USP <61> and USP <62> or Ph Eur 2.6.12 and 2.6.13, with absence of specified pathogens required for material used in oral powders and premixes. For material intended for injectable or ophthalmic applications, additional bioburden and bacterial endotoxin testing according to USP <85> may be required on the processed intermediate rather than the raw powder.

Tablet and capsule manufacturing through dry blending, wet granulation, or direct compression requires the powder to be evaluated for bulk density, tapped density, compressibility index, and flow through an orifice. Bulk density is determined by USP <616>. Dry blending with microcrystalline cellulose, lactose monohydrate, croscarmellose sodium, and magnesium stearate is usually carried out in a bin blender or drum mixer; the feed frame of a rotary tablet press must be adjusted when the bulk density is below 0.35 g/cm³ because low density increases segregation risk in the hopper. Wet granulation may be performed in a high-shear mixer granulator or fluid-bed granulator when the API exhibits poor flow or low bulk density. Overwetting of botanical powders can produce hard granules that resist disintegration and reduce drug release. Fluid-bed drying at inlet temperatures below 60°C is generally used for heat-sensitive botanical constituents, but the actual limit must be confirmed by marker assay before and after drying. Roller compaction is an alternative when the powder is moisture-sensitive; the roll force, roll speed, and screen size determine granule density and tablet friability according to USP <1216> and USP <1174>. Capsule filling is conducted on tamping or dosator equipment; granule size distribution is matched to fill weight control limits, and moisture content is kept low to avoid hard gelatin capsule brittleness or sticking. Dissolution performance should be tested according to USP <711> or the applicable veterinary dissolution chapter once the formulation is developed.

What limits direct application of the powder in injectable and solution presentations?

Solution and injectable dosage forms impose constraints not encountered in solid oral manufacturing. A crude botanical powder contains insoluble plant cell wall materials, lipophilic constituents, and proteinaceous residues that cannot be dissolved to yield a clear, filterable solution. For this reason, the API is incorporated into solutions only after extraction, clarification, or the selection of a standardized soluble fraction; the powder itself is more typically used as a suspension in oral pastes or as an input to a subsequent extraction step. Where a solution dosage form is needed, the manufacturer must define the solvent composition, pH, ionic strength, and temperature during extraction, then clarify through depth filtration followed by membrane filtration at 0.45 µm or 0.22 µm.

If the powder is used to prepare an injectable through extraction, the resulting extract must meet particulate matter limits under USP <788> or Ph Eur 2.9.19. Sterility assurance must be achieved by moist-heat terminal sterilization if the extract is sufficiently stable, or by aseptic filtration through a 0.22 µm sterilizing-grade membrane. Bacterial endotoxins are controlled by USP <85> or Ph Eur 2.6.14, with an acceptance criterion based on the maximum dose in the target species. Because botanical extracts may contain surface-active saponins and proteins, filter-clogging should be evaluated on a production-scale filter train using a constant-pressure integrity test. The final solution should be monitored for color shift and precipitate after terminal sterilization and during storage at 25°C/60% RH and 40°C/75% RH. Published data for this specific configuration is limited.

When dry granulation is selected over wet granulation for tablet and capsule manufacture

When dry granulation is selected over wet granulation, the process avoids water exposure, which may reduce hydrolysis of susceptible constituents and reduce microbial proliferation during holding. However, dry granulation generates fines after milling; if the fines exceed 20% by weight, downstream segregation in the tablet press hopper may produce content uniformity failures. Tablet hardness is maintained in the range of 40 N to 80 N for many veterinary tablet formulations, but the exact target is set by tablet size and dissolution profile. Disintegration is evaluated according to USP <701> or the applicable veterinary pharmacopoeia general chapter. The granulated API may also be blended with palatable carriers and compressed into chewable veterinary tablets; in such cases, compressibility index and Hausner ratio are used to predict powder flow under high-speed compression. Dry granulated material for capsules should have a controlled fines fraction to ensure uniform fill weight and prevent dusting during long encapsulation runs.

Marker content is controlled by chromatographic fingerprint rather than a single purity value

Marker content is controlled by chromatographic fingerprint rather than a single purity value. A botanical API is a multi-component matrix; active constituents may include tannins, phenolic acids, polysaccharides, and other secondary metabolites. The certificate of analysis therefore reports a marker assay by high-performance liquid chromatography or ultraviolet-visible spectrophotometry, supported by a chromatographic fingerprint. The assay is not a single chemical purity value; it is a quality-control tool that ensures batch-to-batch consistency relative to a qualified reference standard. This analytical model also influences stability testing. Synthetic APIs are typically tracked for degradation products under ICH Q1A(R2) storage conditions; botanical APIs require additional assessment of marker loss, moisture uptake, color change, and microbial outgrowth under the same conditions. A change in the fingerprint or a marker content outside the release range may indicate substitution, poor drying, or oxidation during storage. Published data for this specific configuration is limited, so the receiving applicant should generate retention samples and real-time stability data for the intended market.

Assessing excipient compatibility before production scale-up

Assessing excipient compatibility before production scale-up is required because the powder contains polyphenolic constituents that may chelate transition-metal ions and discolor in the presence of ferric salts or copper sources. Strong oxidizing agents, including chlorinated disinfectants and peroxide-based sanitizers, should be removed from contact surfaces before processing to avoid oxidative degradation. Because botanical powders with residual sugars and tannins often show moisture uptake above 60% relative humidity, production areas should be maintained below this value unless the supplier’s moisture sorption isotherm indicates otherwise; the product should be double-bagged with desiccant when stored for more than 30 days in humid regions. Prolonged mixing with strongly alkaline excipients should be avoided because alkaline hydrolysis can reduce marker content and generate brown degradation products. For premix production, mineral carriers such as calcium carbonate or dicalcium phosphate may be acceptable if the final pH of the premix remains near neutral; acidic carriers should be avoided because they may protonate tannins and alter solubility. The finished blend must be assessed for segregation using sampling probes at defined points and for homogeneity according to current good manufacturing practice. The product should not be mixed with mineral acids, strong oxidizing agents, or amine-based feed additives unless compatibility has been demonstrated in a forced degradation study.

Premix and granule presentations for oral administration in feed or drinking water use the powder as an intermediate. Medicated feed premixes are prepared by stepwise dilution with ground corn, soybean meal, or a mineral carrier in a double-ribbon mixer or paddle mixer. The API is first passed through a sieve of 0.5 mm to break soft agglomerates, then preblended with a small quantity of carrier to achieve geometric dilution. Mixing times are validated by sampling ten points and measuring assay relative standard deviation; a typical acceptance criterion is not more than 5% RSD. When granulated for dry feed use, the API may be loaded onto inert carriers with a binder solution and dried in a fluid-bed drier. For drinking-water solutions, the powder is not directly dissolved; instead a water-soluble extracted fraction or a granulated effervescent formulation must be developed. The presence of water-insoluble plant residues makes direct addition to metered water systems prone to sedimentation and line blockage. Equipment should be cleaned with potable water followed by a solvent rinse when residues remain; the cleaning validation must demonstrate removal of marker compounds to below the acceptance threshold.

Compendial testing creates the boundary between a crude botanical and a veterinary API

Compendial testing creates the boundary between a crude botanical and a veterinary API. Raw dried herbs purchased from commodity markets may show large variations in moisture, total ash, foreign matter, and microbial load, and they are not suitable for pharmaceutical formulation without additional processing. The veterinary-grade API is milled, sieved, blended, and tested to confirm identity, marker content, purity, and microbial quality. This does not mean the API is chemically standardized to a single molecule; rather, it is chemically characterized to match a defined fingerprint and specification. The resulting material supports reproducible tablet hardness, capsule fill weight, premix homogeneity, and solution extract performance. Because the powder is derived from a botanical source, batch-to-batch variation cannot be eliminated entirely; therefore, the formulated-product release specification should include a marker assay and a defined acceptable range for critical excipient ratios. Formulators should not substitute a crude herb powder for the veterinary-grade API without re-qualification of the manufacturing process and stability profile.