Can a Polyphenol-Rich Extract Be Terminally Sterilized Without Precipitation During Cool-Down?

Injectable solutions containing Rhapontici Radix veterinary-grade API at 5.0 g/L are formulated in Water for Injection with 15% v/v propylene glycol and 1.5% v/v benzyl alcohol as co-solvent and preservative, adjusted to pH 6.5–7.0 with 0.1 N sodium hydroxide or hydrochloric acid. The extract contains tannin-like polyphenolic acids together with ecdysteroid fractions, and terminal steam sterilisation at 121 °C for 15 min can induce a pH shift and complexation with trace metal ions released from stainless steel surfaces. Production-scale teardown records indicate that visible precipitate can form during heat-cool cycling if the solution is not protected with disodium edetate at 0.1 g/L and nitrogen sparging. Because the published forced-degradation profile for this specific configuration is limited, aseptic filtration is the standard fill-finish route for parenteral grade. The solution is clarified through a 0.45 µm PVDF disc filter and sterilised through a 0.22 µm PVDF cartridge filter, with filter integrity verified by bubble point per manufacturer specification and sterility tested according to Ph. Eur. 2.6.1.

Osmolality is adjusted to 280–320 mOsm/kg with sodium chloride, and endotoxin content is controlled at <2.5 EU/mg by limulus amebocyte lysate test per Ph. Eur. 2.6.14. Filled 100 mL multi-dose vials are inspected for particulate matter by USP <788> light obscuration particle count, and container closure integrity is tested by vacuum decay method per USP <1207>. The terminal product is an intramuscular injectable for cattle at a labelled dose of 5 mg extract/kg body weight. The injection line operates under ISO 14644-1 Class 7 background and Class 5 unidirectional-air critical zones, with filling speed limited to 80 vials/min to avoid foaming and cavitation in rotary piston pumps. The final product is stored at 15–25 °C, protected from light, with a retest period established under ICH Q1A(R2) conditions for veterinary parenteral products.

Direct compression of Rhapontici Radix veterinary-grade API is rejected for most tablet production campaigns because the hydroalcoholic extract retains a hygroscopic amorphous fraction. Warehouse exposure at 55% RH for 40 min raises unbound moisture from 4.8% w/w to 7.2% w/w as determined by USP <921> Method Ic; above 6.0% w/w moisture, the extract adheres to tablet punches and produces capping failures on high-speed rotary presses operating above 80,000 tablets/h. For this reason, the tablet application uses preblending with 2.0% w/w anhydrous dibasic calcium phosphate as a desiccant carrier prior to granulation. The premix is dispersed in a high-shear granulator at impeller speed 300 rpm and chopper speed 1500 rpm, then wetted with a binder solution containing 3.5% w/w povidone K30 in purified water. Wet mass loss on drying is held at 12–15% w/w before discharge and fluid-bed drying at inlet air temperature 55–60 °C until final moisture is 2.5–3.5% w/w. Dried granules are milled through an 800 µm screen on a cone mill at 1600 rpm.

The tableting blend consists of 25.0% w/w dried granulated extract, 60.5% w/w microcrystalline cellulose, 8.0% w/w crospovidone, 2.0% w/w sodium starch glycolate, 0.5% w/w colloidal silicon dioxide, and 0.5% w/w magnesium stearate. Compression is performed on a rotary tablet press with compression force 12–18 kN, target hardness 60–100 N, friability less than 1.0% by USP <1216>, and disintegration time less than 15 min by USP <701> in water at 37 °C. Particle size distribution by laser diffraction ISO 13320:2020 has acceptance D90 ≤500 µm. The terminal product is a 250 mg chewable tablet containing 50 mg of extract standardised to 2.0% w/w 20-hydroxyecdysone, packaged in PVC/PCTFE blisters. Residual solvent status is controlled under VICH GL18, and process validation batches are released under FDA 21 CFR Part 211 cGMP. Specific published force-displacement profiles for this exact extract are not available; therefore pre-production rib-capping and ejection force studies are performed on each new lot.

On feed mills where Rhapontici Radix extract is diluted into vitamin-mineral premixes for subsequent incorporation into complete feed, the primary process conflict is carry-over rather than chemical degradation. The extract is added at 20 g/kg active premix (2.0% w/w) onto a fine limestone carrier with bulk density 1.2 g/cm³. A two-stage step-down mixing sequence is used: first a 1:10 dilution in a 200 kg ribbon blender for 20 min, then a second 1:10 dilution in a 2000 kg twin-shaft paddle mixer for 25 min. Mixing uniformity is assessed by sampling at 10 points and analysing marker content by HPLC; the coefficient of variation must remain below 5.0%. Because the API has a dark brown fine fraction, visual tracer tests are replaced by quantitative marker recovery to avoid false confidence from colour dispersion.

Under feed hygiene rules of Regulation (EC) No 183/2005, the premix must be stored in closed silos with carrier moisture not exceeding 14.0%; otherwise static charge on fine limestone reduces flowability and creates dead zones in the mixer. Mineral oil is included at 0.5% w/w to control dust and adhesion, and silica is added at 1.5% w/w as a glidant. The terminal premix is filled into 25 kg paper bags with a polyethylene inner liner, and the label specifies an inclusion rate of 200 g/t of complete feed for swine and poultry. Cross-contamination control is documented through flush material, sequencing, and analytical carry-over of less than 0.1% into the next non-medicated batch.

Wet-Granulation Effervescent Carriers and the pH Sensitivity of Ecdysteroid-Rich Fractions in Poultry Drinking Water

For poultry medication through drinking water, Rhapontici Radix extract is granulated into an effervescent delivery system that disperses at 5 g/L within 5 min. The extract is incorporated at 20.0% w/w, with anhydrous citric acid 30.0% w/w, sodium bicarbonate 35.0% w/w, maltodextrin 10.0% w/w, and povidone K30 5.0% w/w. Dry granulation by roller compaction is specified because residual moisture from a wet granulation process would prematurely initiate the citric acid-bicarbonate effervescent reaction. The compactor operates at roll pressure 20–30 kN/cm, roll speed 8–12 rpm, and granulator screen 1250 µm. The granule fraction between 500 µm and 1000 µm is retained for filling; undersize is recycled at a rate not exceeding 25% of fresh feed.

After dissolution in water, the solution pH is controlled at 5.5–6.5 because 20-hydroxyecdysone-containing fractions are stable in this range, while pH above 8.0 accelerates degradation and tannin-like constituents produce insoluble precipitates. Extract-specific forced-degradation published data is limited, so the pH window is verified in development stability batches. The granule package is a 100 g aluminium-PVC blister jar with desiccant; moisture uptake must remain below 0.5% by Karl Fischer after 24 h at 40 °C/75% RH. Uniformity of dispersion is measured by dissolving one unit in 1000 mL water at 20 °C and passing through a 150 µm sieve; residue on drying must not exceed 3.0% of dose. The terminal product is a soluble granule for broilers, administered via medicator at 1 L stock solution per 100 L drinking water.

Capsule filling for equine veterinary products places a tighter constraint on powder cohesiveness than tableting because the fill dose is typically concentrated in a size 0 or size 1 hydroxypropyl methylcellulose capsule with low tap density constraints. A direct-fill blend containing extract at 40.0% w/w, microcrystalline cellulose 45.0% w/w, croscarmellose sodium 8.0% w/w, colloidal silicon dioxide 0.5% w/w, and magnesium stearate 1.5% w/w is mixed in a low-shear tumble blender at 30 rpm for 20 min. The blend is filled on a dosator-type capsule machine with pin height adjusted to give 420 mg ± 5% fill weight. Residual moisture is controlled at ≤3.0% w/w to avoid gelatin cross-linking and HPMC shell softening; desiccant is placed in each HDPE bottle.

Disintegration is performed per USP <701> with a limit of 30 min in water at 37 °C, and dissolution is assessed by a validated HPLC method with Q ≥ 75% at 45 min in 900 mL of pH 6.8 phosphate buffer. The terminal capsule contains 200 mg extract standardised to 2.0% w/w 20-hydroxyecdysone, packaged in amber HDPE containers with moisture-barrier induction seals. This dosage form is intended for adult horses at 2 capsules per 450 kg body weight with feed; clinical use for metabolic or hepatic indications must be supported by veterinary prescription or field documentation under VICH GL43 target animal safety.

Formulating Bovine Oral Drench Solutions with Propylene Glycol and Sodium Benzoate Under Hard Water Dilution

Oral drench formulations use Rhapontici Radix extract at 10.0 g/L in a co-solvent system containing propylene glycol 300 mL/L and glycerin 50 mL/L, preserved with sodium benzoate 1.5 g/L and sorbic acid 0.5 g/L. The final pH is adjusted to 6.0–7.0 with citric acid. During field dilution with hard well water above 200 mg/L CaCO₃, divalent calcium ions can bind polyphenolic acids and create visible haze; therefore disodium EDTA is added at 0.1 g/L as a chelating agent. The solution is mixed under vacuum in a closed stainless steel reactor with bottom-sweep agitation at 80 rpm to avoid foam generation, then filtered through a 10 µm polypropylene bag filter before filling.

The product is filled into 1000 mL amber HDPE jugs with tamper-evident caps. Microbiological attributes are controlled per Ph. Eur. 5.1.4 for oral liquids; total aerobic microbial count must remain below 10² CFU/g, and absence of Escherichia coli in 1 g is required. Viscosity measured by Brookfield spindle at 25 °C is typically 8–12 mPa·s; higher values may affect nozzle clogging in automatic drench guns. Dosing is set at 10 mL/50 kg body weight. Storage stability is supported by ICH Q1A(R2) intermediate conditions for climatic zones III and IV, with specific focus on sodium benzoate assay loss and pH drift less than 0.3 units over 12 months.

A dry powder for in-feed top dressing is manufactured by dry blending the extract with a mineral-based flow aid and a low-trueness carrier because direct feed-grade powders without granulation become airborne and segregate during bulk bag discharge. The formula includes extract at 10.0% w/w, calcium carbonate 85.0% w/w, colloidal silicon dioxide 2.0% w/w, and vegetable oil 3.0% w/w to reduce dust formation. The mixture is processed in a ribbon blender for 20 min, then discharged through an 800 µm centrifugal sifter; sieving is verified by ISO 3310-1:2016 test sieves. Bulk density is maintained at 0.85–1.05 g/cm³ to ensure acceptable metering in auger-type dispensers.

Mix uniformity is tested at 10 sampling points with a relative standard deviation of less than 7.0%. The product is filled into 25 kg multi-wall paper bags with a 40 µm low-density polyethylene liner. During application, the powder is top-dressed on feed at 10 g per animal per day for swine; direct addition to drinking water is not recommended because the calcium carbonate carrier produces sedimentation and nozzle blockage. The terminal product is used as a carrier-based powder for on-farm mixing, not as a direct oral bolus, and operator exposure controls align with local occupational safety requirements.