Qingfei Powder Veterinary Grade API is supplied under the manufacturer designation QFP-VG-100 as a light tan to brown, multi-component botanical powder intended for further processing into tablets, capsules, injections, oral powders, granules, premixes, and solutions. The material is not a single chemical entity; it is a dried pulverized blend of botanical fractions standardized by high-performance thin-layer chromatography and high-performance liquid chromatography against a manufacturer reference batch. Because no harmonized compendial monograph assigns a single assay marker, release acceptance relies on orthogonal identity and purity tests rather than a single active-content value. This distinguishes it from synthetic veterinary active pharmaceutical ingredients such as florfenicol, tilmicosin phosphate, and tiamulin fumarate, for which a single-marker potency value and a pharmacopoeial monograph are available. Two manufacturer designations are used for the veterinary API: QFP-VG-100 for oral solid and premix applications, and QFP-VG-100M for micronized injection-precursor material with a D90 of ≤75 µm by laser diffraction.

For formulation development, the API is differentiated from feed-grade botanical powders by lower microbial burden, elemental impurity limits, aflatoxin controls, and controlled particle-size distribution. The release parameters in the following table apply to the standard oral-grade material; injection-grade material requires additional endotoxin and particulate controls.

What Physical Specifications Govern the Dry Powder API Before Formulation?

The Hausner ratio between 1.20 and 1.45 places the standard grade in the passable-flow category; when the ratio exceeds 1.35, direct compression is not recommended and wet granulation or roller compaction should be selected. Loss on drying above 5.0% alters the mass balance in formula compounding and can increase microbial risk. For particle-size analysis by laser diffraction under ISO 13320:2020, the powder is dispersed in a non-polar carrier with 0.1% lecithin; an obscuration range of 5–15% and pump speed of 2,000 rpm are used to avoid particle breakage. Published data for this specific configuration is limited; therefore, method transfer to a new site requires verification of the D90 value with a representative lot.

For tablet and capsule manufacturing, QFP-VG-100 is not typically suitable for direct compression when the Hausner ratio exceeds 1.35 and the D90 exceeds 250 µm. In a 500 L V-blender at 60–70% fill, segregation from free-flowing dextrose or lactose premix is observed when the bulk density difference between API and excipient exceeds 0.20 g/cm³ and the particle-size span is broad. Wet granulation in a high-shear mixer-granulator with impeller speed 150–250 rpm and chopper speed 1,500–3,000 rpm is used to reduce segregation; end-point is controlled by impeller torque rather than time. If aqueous granulation is used, the moisture content of the wet mass is held at 14–16% for extrusion-spheronization; above this range, paste blocking occurs, and below this range, granule hardness is insufficient for film coating. The resulting granules are dried in a fluid-bed dryer to a final LOD of ≤3.0% before compression. Roller compaction may be employed when the API is moisture-sensitive; published data for this specific botanical mixture under roller compaction is limited.

For capsule filling, the granulation is sieved through a 500 µm screen and filled by tamping or dosator equipment; fill weight variation is controlled under USP <905>. Capsule formulations containing hydrophilic botanical fractions should be evaluated for shell crosslinking because residual aldehydes in the botanical matrix can react with gelatin; this risk is not present with hypromellose capsules.

Injectable Solution Route and Endotoxin Burden

When QFP-VG-100M is intended for injectable solutions, the oral-grade powder is not acceptable without further processing. Injection precursor material must meet endotoxin acceptance of ≤0.5 EU/mg by Ph. Eur. 2.6.14 and must be sterilized by a validated terminal or aseptic process. Because the botanical matrix contains water-insoluble polysaccharides and lignified cell wall fragments, simple dissolution in water does not yield a true solution; a 0.45 µm prefilter followed by a 0.22 µm sterilizing filter is required, but membrane fouling may occur if the D90 is greater than 75 µm. Pre-drying is required when environmental relative humidity exceeds 60%; residual moisture above this level can support endotoxin proliferation and reduce filter throughput. The absence of visible particles after filtration does not demonstrate compliance; subvisible particulate testing under USP <788> and Ph. Eur. 2.9.19 is required for injectable preparations. The sterilizing filter must be validated for extractables and bacterial challenge in the presence of the botanical suspension because published data for this specific configuration is limited.

This grade-based differentiation is an operational difference from single-entity synthetic APIs that can be dissolved or directly compressed after particle-size reduction alone. For QFP-VG-100M, endotoxin control is a formulation constraint, not a storage afterthought; micronization after endotoxin control can raise surface area and complicate filter throughput, so particle-size reduction is conducted before depyrogenation in the manufacturing sequence. If terminal sterilization by moist heat is selected, the botanical suspension is heated to 121°C for 15 minutes; however, thermal stress can hydrolyze ester-linked marker constituents. Aseptic filtration is therefore preferred when the product is heat-labile. Because the botanical matrix can bind to membrane filters, compatibility screening is performed with polyethersulfone, polyvinylidene fluoride, and nylon membranes. If marker recovery falls below 90% after filtration, a change in membrane polymer or prefilter sequence is required.

For oral powders and premixes, QFP-VG-100 is blended with carriers such as dextrose monohydrate or lactose monohydrate; blend uniformity is assessed under USP <905>. When the D90 exceeds 250 µm, the coefficient of variation for active marker in 1 g unit-dose samples increases, particularly when the carrier particle-size distribution is narrow. The standard oral grade is suitable for dry powder dosing and for granule formulations by wet granulation; a final granule LOD of ≤3.0% is used to minimize clumping in high-humidity environments. For solution preparation, reconstituted product must be checked for pH, clarity, and redispersibility; clarity is assessed by visual comparison against a standard suspension of known turbidity. Because the botanical mixture is not a simple soluble salt, “solution” in this context requires a stabilized suspension or co-solvent system, not dissolution in water alone.

Premix applications require an even distribution of the botanical marker in a medicated feed premix. The API is diluted stepwise to avoid segregation; the first dilution is typically 1:10 with a carrier matched in bulk density within 0.10 g/cm³. When final feed concentration is below 0.1%, the API should be incorporated as a granulated intermediate rather than as raw powder because the marker assay becomes sensitive to sampling error. Cross-contamination is controlled by cleaning validation; residual marker detection by HPLC is required because visual inspection cannot detect botanical residues on contact surfaces. When a drum mixer is used at 30 rpm for 15 minutes, the blend is discharged through a 500 µm screen to break soft agglomerates. If milling is omitted, agglomerated API particles can cause superpotent spots in the finished feed. Content uniformity of the finished premix is verified by taking 10 sample points per 500 kg batch; the acceptance value under USP <905> must not exceed 15 for the first stage. Published data for this specific product in feed mill conditions is limited; therefore, each new carrier lot requires a blend uniformity study.

When Qingfei Powder Is Processed Through a Wet-Granulation Line Instead of Direct Compression

In wet granulation, the processing window is narrow because the API contains hygroscopic botanical oligosaccharides. A granulating fluid addition rate of 0.5–1.0 mL/min per kg of dry blend is used during the initial high-shear phase; addition above this range produces paste that cannot be discharged from the bowl. The binder solution is typically 5% hydroxypropyl methylcellulose or starch paste; the use of amine-based additives is avoided because residual polyphenolic constituents can form intractable complexes and reduce marker recovery. After granulation, wet mass is transferred to a fluid-bed dryer with inlet air temperature 50–60°C; process air dew point below -40°C is maintained to avoid moisture pickup. Drying end-point is confirmed by LOD of ≤3.0% using a halogen moisture balance. Milling through a conical mill with a 1.0 mm rasping screen yields granules with a target D50 of 180–250 µm. If the D50 falls below 150 µm, tablet hardness increases but disintegration may extend beyond 30 minutes; if the D50 exceeds 400 µm, content uniformity fails under USP <905>. This threshold conflict is specific to multi-component botanical APIs and is not observed with crystalline synthetic molecules.

The granulation endpoint is not time-fixed; it is recorded when impeller torque increases by 20–30% over the dry-mix baseline and the wet mass can be compressed into a ball that fractures without crumbling. Torque overshoot above this range produces non-dischargeable paste, a batch failure mode observed on production-scale high-shear granulators equipped with end-point torque sensing. If a twin-screw wet granulator is used instead of a high-shear granulator, the screw configuration is limited to 25:1 L/D with kneading blocks occupying no more than 20% of the screw length. Higher kneading input increases barrel temperature and causes thermoplastic-like paste formation from the natural botanical gums. The barrel temperature is maintained below 40°C with chilled water jackets; exceeding this threshold has been associated with marker loss due to heat-induced oxidation rather than volatilization.

Comparative Deficiency of Single-Marker Assays in Botanical Veterinary APIs

A material difference between QFP-VG-100 and single-entity veterinary antibiotics is that no single-marker HPLC assay can fully describe potency. The material is released against a multi-band HPTLC or HPLC fingerprint; acceptance is not based on a single active content value such as 98.0–102.0% on the dried basis. Therefore, substitution of QFP-VG-100 in a formulation intended for tilmicosin phosphate or florfenicol is not possible without revalidation of the extraction and detection methods. The absence of a Clinical and Laboratory Standards Institute veterinary MIC breakpoint for the botanical mixture means that antimicrobial susceptibility data generated for synthetic antibiotics cannot be extrapolated to QFP-VG-100. Regulatory submissions should reference the marker-based approach in USP <561> or the relevant region-specific botanical monograph; if a monograph is not available, the API must be controlled by a manufacturer’s validated in-house method.

The veterinary-grade API also differs from feed-grade Qingfei powder in microbial limits, elemental impurities, and aflatoxin controls. Feed-grade material may be accepted on the basis of visual and organoleptic criteria alone; the API requires full release against the table above before use in injectable or oral dosage forms. Residual solvent control under USP <467> is required if extraction solvents are used in any upstream concentration step. Pesticide residue control under USP <561> is required for botanical articles of commerce; if the botanical fractions are sourced from multiple geographical regions, a batch-specific risk assessment is necessary. Compared with a standardized extract powder, QFP-VG-100 retains native botanical cell wall material and therefore requires more aggressive sample preparation before HPLC injection. Extraction is performed with 70% methanol in an ultrasonic bath at 40°C for 30 minutes; incomplete extraction yields low marker recovery and batch rejection. The non-extracted native powder also has higher water-holding capacity, which changes granulation fluid demand relative to an extract powder.

QFP-VG-100 should not be milled in a high-energy air-jet mill without inert gas when the oil content of the botanical matrix exceeds 5%; oxidative degradation of residual terpenoid fractions can produce peroxides and lower marker recovery. The material is incompatible with strong oxidizing agents in dry blending and should be stored in airtight high-density polyethylene containers at or below 25°C and ≤60% relative humidity. If storage at RH > 60% is unavoidable, pre-drying is required. The operational boundary for the oral-grade material in dry blending is a D90 of 250 µm; beyond this value, segregation and content uniformity risk increase. The operational boundary for injection precursor is a D90 of 75 µm; beyond this value, sterilizing filter fouling and occlusion are likely. During air-jet milling of QFP-VG-100M, the classifier speed is set to deliver a D90 of ≤75 µm; increasing classifier speed beyond this target can raise the fraction below 10 µm above 30%, which creates airborne dust and poor packing. Electrostatic charge is controlled by ionizing bars in the collection cyclone; static dissipation failure results in adherence to stainless steel surfaces and variable yield. The powder is discharged from the mill only after the relative humidity of the milling gas is below 30%. These limits are stated as manufacturing boundary conditions for the current manufacturer designation.