Sijunzi Powder Veterinary Grade API is a dry standardised extract of the four-herb Sijunzi prescription, manufactured for incorporation as an active ingredient in tablets, injections, capsules, powders, granules, premixes, and oral solutions. The botanical input consists of Codonopsis pilosula root, Atractylodes macrocephala rhizome, Poria cocos sclerotium, and Glycyrrhiza uralensis root and rhizome. Extraction is aqueous or hydroalcoholic, followed by clarification, concentration, and spray drying or vacuum drying. The resulting powder is not a crude herb powder; fibre and insoluble resin are removed before drying, and the remaining material is standardised to marker content rather than raw herb weight alone. Model identification follows the supplier batch prefix, usually SJZ-VET-API combined with an extraction-ratio code and a mesh-fraction code; the API is therefore controlled by its pharmacopoeial markers, microbial load, endotoxin level where applicable, and particle-size specification rather than by a single catalogue number.

Differences from unstandardised Sijunzi powder become measurable in the first downstream operation. Crude powder often retains particles above 250 µm and shows poor die filling in direct compression, whereas the API is milled to ≥95% through 80 mesh (180 µm). The same particle profile permits the API to be blended with microcrystalline cellulose and crospovidone at 2–5 wt% disintegrant for immediate-release tablet cores. For capsules, the reduction of fibrous debris allows more uniform volumetric filling and less dust generation. The residual hygroscopicity remains an operational boundary: above 60% RH the extract absorbs moisture and cakes, so sealed aluminium-foil laminate packaging and controlled-humidity dispensing suites are required. For injection-grade lots, endotoxin control begins at the extraction-water stage and is confirmed by limulus amebocyte lysate testing; published data for this specific configuration are limited across target species, and each injectable formulation requires separate depyrogenation validation.

Spray-dried lots are produced with inlet air at 160–180 °C and outlet air at 80–90 °C to preserve marker content while achieving target moisture. Vacuum-dried lots may have higher bulk density and slower dissolution. Milling is performed under dehumidified air below 40% RH because the amorphous polysaccharide fraction can soften above 55 °C. Over-milling increases the fraction below 45 µm, which may improve dissolution but worsens flow and dusting. Granular extracts with lower fines reduce caking but can require longer dispersion in solution.

What Pharmacopoeial Marker Limits Are Applied at Batch Release?

Batch release is built on marker quantification rather than botanical identity alone. Lobetyolin is used as the Codonopsis-derived marker, glycyrrhizic acid as the Glycyrrhiza marker, and total water-extractable polysaccharides as the main non-starch polysaccharide fraction. Atractylenolide III may appear on supplier certificates but is not universally required by all veterinary monographs. The following limits represent common veterinary monograph alignment; buyer specifications should be confirmed against the relevant national veterinary pharmacopoeia because residue limits for heavy metals and pesticide markers can differ between jurisdictions.

The marker limits are not simple interchangeability thresholds. A lot with 0.09% lobetyolin may be acceptable for oral premix but should not be assigned to an injectable batch without a supplementary blending study, because low marker content can shift the composition of the final sterile solution away from the validated formula. High moisture is particularly destabilising in hard-shell capsules; it accelerates gelatin cross-linking and promotes tablet sticking. The release decision for capsules and tablets should therefore be linked to the loss-on-drying value and to forced-degradation data showing marker stability at the proposed packaging shelf life.

In veterinary practice, the product is used for supportive management of reduced feed intake, loose stool, and post-weaning performance decline associated with spleen-qi deficiency in traditional Chinese veterinary evaluation. The treated species documented in monographs and field literature include pig, chicken, cattle, dog, and cat; formal efficacy trials in modern production species remain limited. Swine protocols usually use the API in feed or drinking water, poultry applications favour solution or premix administration, and companion-animal doses are commonly delivered as capsules or flavoured granules. Injectable administration is the least documented route and requires pyrogen control, sterility, and species-specific compatibility because published safety data for this configuration are limited across target species. The API is not a substitute for antimicrobial therapy in confirmed bacterial enteritis and should be used under veterinary supervision.

For tablet and capsule manufacture, the powder is blended at 10–30 wt% of the final core weight, depending on the intended dose and extract marker concentration. Direct compression formulations using the API require a filler such as microcrystalline cellulose, a disintegrant such as crospovidone at 2–5 wt%, and magnesium stearate at 0.5–1.0 wt%. The spray-dried API has a bulk density of approximately 0.45–0.65 g/mL; variation within this range changes fill depth in a rotary tablet press and can produce weight variation above ±5% if the powder blend has not been conditioned. When wet granulation is selected, an aqueous binder solution may be used, but the polysaccharide fraction hydrates rapidly and can raise granulation viscosity; a binder addition rate above 6% water relative to dry blend may cause sticking. Granule drying should be kept below 60 °C to limit marker degradation in the presence of residual moisture. Hard-shell capsule filling at 0.50–0.60 g fill weight benefits from the addition of 0.5% colloidal silicon dioxide to improve flow and reduce capsule-to-capsule mass variation.

For powder and granule dosage forms, the API is dry-mixed with dextrose or lactose carriers and filled into foil sachets. Homogeneity is tested by sampling at 10 points across the ribbon blender; the typical acceptance range is 90–110% of labelled marker content with relative standard deviation ≤5.0%. The bitter taste contributed by glycyrrhizin and saponins is partially masked by the carrier, but palatability agents are usually necessary for swine and poultry oral administration because voluntary intake can fall when the unmasked extract is offered. In premix manufacture, inclusion levels of 5–25 kg/tonne of complete feed require carrier particle-size matching to prevent segregation during pneumatic conveying; static charge on the API may also require grounding of the transfer lines.

Injectable Polysaccharide Filtration Boundaries and Endotoxin Control

Injectable preparations based on the API are produced by reconstituting injection-grade powder in water for injection and filtering through 0.22 µm polyethersulfone membranes before aseptic filling. The polysaccharide fraction complicates filtration because water-extractable polysaccharides load the membrane and reduce throughput. A 5% reconstituted API solution may process less than 20 L/m² of membrane area before flux declines by half, depending on polysaccharide molecular weight distribution and pre-filter configuration. To improve filterability, clarified extract is pre-filtered through 0.45 µm membranes and the API is specified with low insoluble particulate limits. Terminal sterilisation of finished ampoules at 121 °C for 15 min may increase colour intensity, indicating polysaccharide or amine-sugar degradation; therefore sterile filtration is preferred for injection-grade lots, provided bioburden before filtration is below 10 CFU/100 mL according to current good manufacturing practice. The endotoxin limit of ≤0.50 EU/mg is the release gate for injection-grade powder; oral premix lots may carry a higher endotoxin limit where the national veterinary monograph permits. Published multi-species safety data for injectable Sijunzi formulations are limited, so each target species and route requires separate pyrogen and compatibility validation.

For oral solutions, the API is dissolved in purified water with a cosolvent such as propylene glycol at 10–20% of the final volume and a preservative system. Precipitation of poorly soluble atractylenolides may occur below 4 °C; this is controlled by maintaining ethanol content above 15% or by using a carrier such as hydroxypropyl-beta-cyclodextrin. The finished solution is adjusted to pH 5.5–6.5; alkaline conditions above pH 8 accelerate hydrolysis of ester-linked constituents and should be avoided during long-term storage.

When the Extract Is Compared With Crude Sijunzi Powder and Single-Herb Extracts

The following comparison separates the veterinary API from raw herb powder and from single-herb Codonopsis extract. The data are comparative characterisations, not clinical superiority claims.

Compared with other spleen-tonifying formulas, Sijunzi Powder API contains only four botanicals and lacks the lifting herbs in Bu Zhong Yi Qi Tang or the dampness-draining seeds in Shen Ling Bai Zhu San. This narrower composition reduces the number of marker compounds and simplifies quality control. However, the absence of additional dispersing or aromatic herbs also means the formula may be less suited to presentations with pronounced dampness or stagnation when the clinical pattern departs from simple spleen-qi deficiency. The API is rarely combined with strongly alkaline mineral premixes during dry blending because the extract contains acidic saponins and flavonoids that may agglomerate; pre-blending with calcium carbonate or silica at 1–2 wt% reduces tack.

The API differs from physical mixtures of individual herbal extracts because co-extraction and concentration may alter solubility, drying behaviour, and bulk density. A physical blend of single-herb extracts can segregate during tableting because of density differences among the individual powders, whereas the co-extracted Sijunzi API has a single set of particle and bulk-density specifications. In premix applications, the four-herb profile requires a broader analytical method than a single-marker raw material. The absence of a standardised marker for Atractylodes and Poria remains a practical limitation; many suppliers use total polysaccharide content as a surrogate, but total polysaccharide content does not distinguish Poria glucans from added maltodextrin. An incoming-material identification test should therefore include thin-layer chromatography or HPLC fingerprinting in addition to the marker assay, and the supplier’s botanical species certificate should be checked against the national pharmacopoeia before use.