Mahuang Guizhi Powder Veterinary Grade API is a standardised dual-herb dry extract of Ephedra sinica Stapf aerial parts and Cinnamomum cassia Presl bark. The manufacture is controlled to yield a powder with a plant-to-extract ratio of 10:1 and a model designation MG-GZ-1010. The extract is standardised for total ephedrine alkaloids at not less than 5.0% w/w expressed as ephedrine base and for cinnamaldehyde at not less than 1.5% w/w. The material is supplied as a pale buff to light brown hygroscopic powder with a characteristic cinnamon odour and is intended for incorporation into tablets, hard capsules, injectable solutions after additional purification, oral powders, granules, premixes, and liquid solutions for veterinary use.

The extraction train for this API employs purified water or 30–60% v/v ethanol in a multi-stage counter-current extractor at 90–95 °C for 2–3 h. Elevated temperature improves extraction of cinnamon bark proanthocyanidins, but sustained operation above 100 °C under pressure increases ephedrine alkaloid degradation and dark-coloured polymeric by-products. The clarified extract is concentrated in a falling-film evaporator at 50–60 °C and 0.08–0.09 MPa vacuum to a feed solids content of 15–25% w/w before spray-drying.

Spray-drying parameter control exerts the greatest influence on downstream tablet compression. The feed concentrate is atomised through a rotary or two-fluid nozzle into a drying chamber with inlet air at 140–160 °C and outlet air at 75–85 °C. Deviation above 85 °C outlet temperature causes partial volatilisation of cinnamaldehyde and may reduce assay recovery below the 1.5% w/w release limit. Deviation below 70 °C outlet temperature increases residual moisture and produces amorphous particles with a glass transition temperature below 40 °C, leading to wall adhesion, poor flow, and capping during compression. The dried powder is discharged from a cyclone and sieved to D90 ≤ 75 µm. Larger particles reduce blend uniformity in low-dose tablets; finer particles increase dusting and can raise tablet weight variation under high-speed rotary press conditions above 60 rpm.

The spray-dried extract typically exhibits bulk density of 0.38–0.48 g/mL and tapped density of 0.52–0.68 g/mL, with a Carr index between 22–30, indicating fair to poor flow. Wet granulation with 2.0–4.0% w/w hydroxypropyl cellulose or povidone K30 in a fluid-bed granulator at 45–55 °C product temperature improves densification and reduces segregation of the dual-herb matrix. Granules are passed through a 1.0 mm oscillating sieve, and fines below 75 µm are recycled to the next batch at not more than 20% w/w to avoid content uniformity drift.

For tablet and capsule manufacture, the API is pre-blended with microcrystalline cellulose at 1:0.5–1:1.5 ratio, croscarmellose sodium at 2.0–5.0% w/w, and magnesium stearate at 0.5–1.0% w/w. Direct compression is acceptable for low-dose tablets up to 120 mg total weight when the API fraction does not exceed 35% w/w; above this level, wet granulation is required to control segregation and sticking. Capsule filling on a dosator or tamping-pin machine requires the granulate to maintain a mean particle size of 150–400 µm and moisture below 4.0% to avoid humidity-induced cinnamaldehyde migration into the shell.

For oral powders and premix, the API is dispersed onto a maize starch or silicon dioxide carrier to achieve a final marker content of 0.2–2.0% w/w total ephedrine alkaloids. The dry concentrate is combined in a ribbon blender or V-type blender at 60–80% working volume and mixed for 15–20 min at 12–18 rpm. Premix gas flushing with nitrogen is recommended because the cinnamaldehyde fraction undergoes oxidative degradation in ambient oxygen, with headspace oxygen target < 3.0%.

Which processing step most influences extract consistency for tablet compression?

Spray-drying outlet temperature is the dominant control point. The critical threshold range lies between 75 °C and 80 °C. At this setting, the atomised droplets dry rapidly enough to form discrete, flowable particles while cinnamaldehyde retention remains above 90% of the theoretical yield. The atomiser speed is typically set at 12,000–18,000 rpm for a rotary atomiser, producing a Sauter mean droplet diameter of 30–60 µm. Chamber pressure is held at -0.2 to -0.5 kPa to prevent powder accumulation on the chamber wall. A production-scale failure mode observed with this product is bearding around the rotary atomiser when the feed viscosity exceeds 250 mPa·s at 25 °C; the feed tank is therefore maintained at 40–50 °C to reduce viscosity below 150 mPa·s.

Batch-to-batch marker variation is controlled by blending the spray-dried intermediate in a bin blender for 20–30 min at 10–12 rpm. The target total ephedrine alkaloid range is 4.5–5.5% w/w, with an inter-lot RSD below 5.0% in validated production campaigns. Cinnamaldehyde is monitored separately because its volatility creates a greater risk of lot-to-lot drift than the ephedrine alkaloid fraction.

If cinnamaldehyde recovery falls below 1.0%, formulation adjustments become necessary

When HPLC assay of a retained sample shows cinnamaldehyde below 1.0% w/w, the powder should not be released for oral syrup or injection formulation without reformulation. The loss is typically caused by prolonged storage above 25 °C at relative humidity above 60%, or by exposure to ambient oxygen in non-barrier packaging. Oxidative degradation products include cinnamic acid, benzaldehyde, and polymeric brown species that increase extract colour intensity and reduce aqueous solubility. The powder should then be packaged in aluminium foil laminate with a polyethylene inner layer and nitrogen flush; silica gel desiccant at 2–4 g/kg of product maintains headspace relative humidity below 40%. Material that fails the cinnamaldehyde limit may be reconditioned by dry blending with a higher-assay lot only if the total ephedrine alkaloid ratio remains within the registered specification range and the blending protocol is validated under 21 CFR 211.84 for component control.

Injectable solutions require a separate grade of the API with reduced endotoxin burden and controlled sub-visible particle content. The concentrate is dissolved in water for injection at 20–40 mg/mL, adjusted to pH 5.0–5.8 with citrate or acetate buffer, and clarified through 0.45 µm followed by 0.22 µm polyethersulfone membrane filters. Terminal sterilisation at 121 °C for 15 min is acceptable only when cinnamaldehyde recovery is monitored because the compound is volatile and may partition into headspace; alternatively, aseptic filtration is employed. The injection-grade API should contain bacterial endotoxins < 0.5 EU/mg and particulate matter meeting USP <788> limits after reconstitution.

During preparation of liquid oral solutions, the API is dispersed under high-shear mixing at 1,500–3,000 rpm for 20–30 min in a stainless-steel tank charged with purified water at 35–40 °C. The solution is cooled to 20–25 °C before pH adjustment because ephedrine base partitions poorly into water at pH above 7.0, while acidic pH below 4.0 may hydrolyse cinnamoyl esters. A pH of 5.0–5.5 balances both markers. The liquid is protected from light with amber glass or opaque high-density polyethylene containers because cinnamaldehyde undergoes photo-oxidation under ultraviolet light.

Feed premix manufacture requires dust control because ephedrine alkaloid-containing particulate can become airborne and creates cross-contamination risk. A dedicated negative-pressure blending suite with differential pressure of -5 to -10 Pa relative to adjacent corridors is specified. Cleaning validation for ephedrine residues is conducted with a limit of no more than 10 ppm in subsequent non-medicated feed batches, or the acceptable daily exposure limit derived under the target animal safety assessment.

The product differs from raw botanical powders in microbial quality and assay reproducibility. In a production-scale comparison, raw powders showed total aerobic microbial counts of 10⁴–10⁶ CFU/g, whereas the extracted API typically exhibits counts at or below 10³ CFU/g with Salmonella and Escherichia coli absent in 25 g. The marker content in raw powder varies with harvest season and geographical origin; the extracted API is blended to a target total alkaloid range of 4.5–5.5% w/w, reducing batch-to-batch variance to an RSD below 5.0% in validated campaigns.

The release documentation includes a certificate of analysis reporting residual solvent levels according to USP <467> or Ph. Eur. 5.4, whichever applies to the destination region. For export to jurisdictions that classify ephedrine alkaloids as scheduled precursors, the supplier must provide end-user certificates, import permits, and quantity reconciliation records under local narcotics control legislation. The veterinary API is not intended for food-producing animals in all jurisdictions without a withdrawal period; regulatory status must be confirmed under the applicable national residue limits.

Long-term stability data for the dual-marker injection-grade API under tropical humid conditions above 75% RH are limited; real-time stations are maintained at 25 °C/60% RH and 30 °C/65% RH for 24-month evaluations. In alu-laminate packaging with nitrogen flush, cinnamaldehyde retention and total ephedrine alkaloid retention are monitored using a stability-indicating HPLC method validated according to ICH Q2(R1). Release under quarantine is maintained until endotoxin, microbial enumeration, and marker assay results are reviewed against the registered specification.