In companion-animal oral care, veterinary-grade benzydamine hydrochloride API is formulated into a 0.15% w/v oromucosal solution for metered spray delivery to gingival, oropharyngeal, and post-dental-procedure mucosal surfaces in dogs and cats where such products are licensed or extemporaneously prepared under veterinary prescription. The hydrochloride salt is selected for aqueous systems because the free base is poorly water-soluble at formulation pH, while benzydamine hydrochloride is freely soluble in water at 20–25 °C. The formula addition ratio is fixed at 1.50 g benzydamine hydrochloride per litre, equivalent to 0.15% w/v; concentrations above 0.20% w/v are not used because the local anaesthetic effect intensifies without corresponding clinical benefit in veterinary patients and transient loss of gag reflex sensitivity may complicate post-operative oral assessment. The manufacturing process is run in a 500 L 316L stainless-steel mixing vessel equipped with a bottom-sweep agitator at 25–35 rpm and a high-speed rotor-stator disperser set at 1200 rpm for not more than 15 minutes to avoid foam entrapment and shear-induced degradation. Benzydamine hydrochloride is charged into 80% of the final volume of purified water at 20–25 °C under agitation until the assay is stable at 98.0–102.0% of label claim. When a preserved product is specified, methyl parahydroxybenzoate 0.10% w/v and propyl parahydroxybenzoate 0.02% w/v are incorporated and preservative efficacy is confirmed according to Ph. Eur. 5.1.3. The pH is adjusted to 5.5 ± 0.5 with 0.1 M hydrochloric acid or 0.1 M sodium hydroxide, the batch is made to volume, and the solution is passed through a 0.45 μm polyethersulfone cartridge filter. The liquid is filled into 30 mL amber high-density polyethylene bottles fitted with 0.15 mL metering spray pumps. In-process controls cover pH per Ph. Eur. 2.2.5, relative density at 20 °C, and benzydamine hydrochloride content by gradient high-performance liquid chromatography. Finished product release is governed by the current Ph. Eur. monograph for benzydamine hydrochloride, VICH GL18(R2) for residual solvents transferred from the API, and the relevant provisions of EU GMP Volume 4 Part I Chapters 3 and 5 concerning premises and production. Terminal products are 30 mL oromucosal spray units labelled 0.15% w/v benzydamine hydrochloride for companion-animal oral use.

How does wet granulation alter benzydamine HCl tablet uniformity at low dosage strengths?

Low-dose tablet manufacture of benzydamine hydrochloride at 3 mg per core introduces a blend-uniformity problem because the active ingredient is only 1.5% w/w of a 200 mg tablet core. Direct compression at this drug load produces segregation during hopper hold time and unacceptable assay variance; therefore wet granulation with povidone K30 is selected. The formulation consists of benzydamine hydrochloride 3.0 mg per tablet, lactose monohydrate 71.0% w/w, microcrystalline cellulose 20.0% w/w, povidone K30 5.0% w/w, croscarmellose sodium 2.0% w/w extragranular, and magnesium stearate 0.5% w/w. The API is pre-blended with lactose and microcrystalline cellulose for 15 minutes in a 600 L high-shear granulator at an impeller speed of 300 rpm and chopper speed of 1500 rpm; granulating fluid containing povidone K30 in purified water is added at 12–15% w/w over 6–8 minutes, and the wet mass is discharged through a 2.0 mm screen. Drying is performed in a fluid-bed dryer at an inlet air temperature of 60 ± 5 °C to a loss-on-drying value not exceeding 2.0% w/w, after which the granules are milled through a 0.8 mm screen. The milled granules are blended with extragranular croscarmellose sodium for 10 minutes and then with magnesium stearate for 3 minutes in a 300 L tumble blender at 10 rpm. Compression is performed on a 16-station D-tooling rotary tablet press with precompression 5 kN and main compression force 10 ± 2 kN, producing tablets with hardness 50–80 N and friability not more than 0.8%. Release testing includes uniformity of dosage units per Ph. Eur. 2.9.40 or USP <905> with acceptance value ≤15, dissolution per USP <711> using 900 mL 0.1 M hydrochloric acid at 37 ± 0.5 °C and apparatus 2 at 50 rpm with Q = 75% at 45 minutes, assay by HPLC, and related substances by the current Ph. Eur. monograph. Residual solvent control follows VICH GL18(R2), and elemental impurity risk is assessed under VICH GL58/ICH Q3D. Terminal products are 3 mg and 5 mg immediate-release veterinary tablets packed in aluminium/PVC-PVDC blisters or 100-count HDPE bottles with induction-sealed closures.

Dry blending of benzydamine hydrochloride into hard capsules at 1 mg per unit is performed with a 1:10 geometric trituration series followed by low-shear tumble blending because the API is added at 1.0% w/w and ordinary V-type blending without stepwise dilution produces end-of-batch assay variance above 6.0%. The capsule fill formulation consists of benzydamine hydrochloride 1.0 mg, lactose monohydrate 77.0 mg, maize starch 20.0 mg, colloidal silicon dioxide 0.5 mg, and magnesium stearate 1.5 mg per size 3 hydroxypropyl methylcellulose capsule, giving a total fill weight of 100.0 mg. The first trituration is 1 part API blended with 9 parts lactose monohydrate for 10 minutes in a 20 L polyethylene drum blender at 12 rpm; the second trituration is 1 part first mixture blended with 9 parts lactose monohydrate under the same conditions. The final blend is discharged into a 100 L stainless-steel tumble blender and mixed for 30 minutes at 12 rpm. Capsule filling is carried out on an intermittent-motion dosator machine with 0.4 mm dosator nozzles and capsule tamping pins set to 3 mm compression depth, followed by metal detection using 0.8 mm ferrous and 1.0 mm non-ferrous test spheres. In-process controls include weight variation at 15-minute intervals and blend uniformity testing by sampling 10 points with acceptance value ≤15.0 per Ph. Eur. 2.9.40. Dissolution is run in 900 mL phosphate buffer pH 6.8 at 37 °C using USP apparatus 2 at 50 rpm with Q = 75% at 45 minutes. Residual solvent compliance follows VICH GL18(R2), and elemental impurity risk is assessed under VICH GL58/ICH Q3D. Terminal products are 1 mg and 3 mg veterinary capsules packed in 100-count HDPE bottles with heat-sealed induction liners and silica gel desiccant.

Equine in-feed granules and segregation during bulk transport

Granules containing 5 mg benzydamine hydrochloride per gram are produced by top-spray fluid-bed granulation to achieve a mean particle size of 250–500 μm, which reduces segregation when the product is distributed into feed for non-food equine use. The addition ratio is 0.5% w/w benzydamine hydrochloride; the dry substrate contains lactose granules 89.5% w/w, pregelatinised starch 6.0% w/w, and colloidal anhydrous silica 1.0% w/w, while povidone K30 3.0% w/w and the API are dissolved in purified water and sprayed onto the fluidised matrix. The process is run in a Glatt GPCG 30 fitted with a 1.5 mm nozzle, atomising air pressure 2.0 bar, inlet air temperature 65 ± 5 °C, product temperature 34–38 °C, and airflow 600–800 m³/h. The spray rate is held at 180–220 g/min to prevent overwetting and localised recrystallisation of benzydamine hydrochloride on the granule surface. After spraying, the granules are dried to a moisture content below 2.0% w/w and discharged through a 1.0 mm sieve. Segregation control is a critical process concern during bulk transport; the granule size distribution is controlled at D10 ≥ 150 μm, D50 250–500 μm, and D90 ≤ 710 μm to limit percolation of fines through void spaces between larger particles. Bulk density is recorded in the range 0.45–0.55 g/mL and fines generated during a standard 30-minute rotational abrasion test are limited to less than 5.0% w/w. Packing in 2 kg HDPE jars with 1 g silica gel desiccant maintains water activity below 0.6. Compliance testing includes benzydamine hydrochloride content by HPLC aligned to the current Ph. Eur. monograph, loss on drying per Ph. Eur. 2.2.32, residual solvents per VICH GL18(R2), and uniformity of content per Ph. Eur. 2.9.5 where single-dose containers are used. Terminal products are 5 mg/g oral granules for in-feed administration to non-food equine patients under veterinary supervision.

Terminal sterilisation of a 5 mg/mL benzydamine hydrochloride injection is carried out only after thermal stability evaluation because published data for this specific veterinary configuration is limited. The solution is formulated with 5.0 g benzydamine hydrochloride per litre, equivalent to 0.5% w/v, and 9.0 g sodium chloride per litre as isotonicity agent in water for injection; pH is adjusted to 5.5 ± 0.3 with 0.1 M hydrochloric acid or 0.1 M sodium hydroxide. The solution is prepared in a Grade C environment and filtered through a 0.22 μm PVDF membrane into depyrogenated 10 mL Type I borosilicate glass vials under Grade A air supply. If the batch is terminally sterilised, saturated steam autoclaving is performed at 121 °C for 15 minutes, provided forced degradation studies confirm assay retention ≥95% and no related substance exceeding the reporting threshold under the current Ph. Eur. monograph. Producers that avoid terminal sterilisation due to thermal sensitivity use aseptic filtration and filling under EU GMP Volume 4 Annex 1 with pre-use post-sterilisation filter integrity testing; however the terminal steam cycle is preferred when product stability permits because it reduces sterility-assurance reliance on environmental monitoring. The release panel includes sterility per Ph. Eur. 5.1.1, bacterial endotoxins per Ph. Eur. 2.6.14 with a limit calculated from the maximum veterinary bolus dose, pH per Ph. Eur. 2.2.5, particulate contamination per Ph. Eur. 2.9.19, and benzydamine hydrochloride assay by HPLC. Residual solvent controls follow VICH GL18(R2) and elemental impurities follow VICH GL58. Terminal products are 10 mL single-dose vials labelled 5 mg/mL benzydamine hydrochloride injection for veterinary clinic use where parenteral benzydamine is registered or compounded under regulatory authority oversight.

When a 1:1000 trituration premix is required for non-food animal oral dosing

Powder premixes containing 0.1% w/w benzydamine hydrochloride are manufactured as intermediate triturations for subsequent dilution into final oral powders, granules, or capsules in non-food animal pharmacies and feed-mixing facilities. The addition ratio is 1.0 g benzydamine hydrochloride per kg, carried on spray-dried lactose monohydrate 99.8% w/w with colloidal anhydrous silica 0.1% w/w. Geometric dilution is performed in three stages: 1 part API is blended with 9 parts lactose in a 5 L laboratory V-blender for 10 minutes; the first mixture is blended with 90 parts lactose in a 100 L V-blender for 20 minutes; the second mixture is diluted with 900 parts lactose in a 500 L V-blender rotating at 10 rpm for 45 minutes. The final blend is discharged through a 0.5 mm conical screen to remove soft agglomerates and packed into 20 kg polyethylene-lined kraft sacks. In-process blend uniformity is determined by taking 20 thief samples and applying acceptance value ≤15.0 per Ph. Eur. 2.9.40; any result outside this range requires reblending for an additional 10 minutes and resampling. The process is qualified for non-sterile manufacturing under EU GMP Volume 4 Part II, with residual solvent control according to VICH GL18(R2) and a stability-indicating HPLC method aligned to the current Ph. Eur. monograph. Terminal products are 0.1% w/w benzydamine hydrochloride oral premixes for further compounding into non-food animal dosage forms, not intended for direct administration without dilution.