Triclobisonium Veterinary Grade API for Tablets / Injections / Capsules / Powders / Granules / Premix / Solutions is supplied as triclobisonium chloride, a cationic bis-quaternary ammonium salt. The active moiety contains two quaternary nitrogen centres separated by an aliphatic spacer, with long-chain alkyl substituents on the terminal nitrogens. This dimeric structure distinguishes the compound from single-centre quaternary ammonium agents such as benzalkonium chloride, particularly in charge density, adsorption behaviour on negatively charged surfaces, and complexation with anionic excipients. The API is manufactured in two physical grades: a non-sterile milled grade for solid oral and in-feed preparations, and a sterile crystallized grade for parenteral compounding. The non-sterile grade is a white to off-white crystalline powder with high aqueous solubility and hygroscopic behaviour. The product is not an anthelmintic and is not to be confused with triclabendazole, which has a similar nonproprietary stem but belongs to a different chemical and pharmacological class.

What release specifications are typically applied to triclobisonium chloride veterinary API?

In the absence of a harmonised monograph in the current European Pharmacopoeia or United States Pharmacopeia, incoming quality control is performed against the active substance master file and the manufacturer’s validated specification. The release panel includes identification, assay, related substances, residual solvents, water content, residue on ignition, elemental impurities, and microbial limits. The sterile grade carries additional bacterial endotoxin and sterility testing. The table below summarises the release attributes applied to the non-sterile milled grade; the sterile crystallized grade is released only after additional parenteral testing.

Dry blending of the milled grade is the preferred starting point for tablets, capsules, powders, granules, and premix. Particle-size distribution is controlled by laser diffraction according to ISO 13320:2020; the non-sterile milled grade is typically supplied with D10 between 5 µm and 10 µm, D50 between 25 µm and 45 µm, and D90 ≤ 75 µm. The powder exhibits electrostatic adhesion to stainless steel and polycarbonate contact surfaces during low-humidity transfer. Surface charge dissipation with humidified nitrogen or short equilibration at 45%–55% relative humidity reduces segregation and assay loss in direct compression blends. If the API fraction is below 1.0% w/w, geometric dilution with microcrystalline cellulose or lactose monohydrate is required before addition to high-shear granulators or V-blenders.

Tablet formulations containing triclobisonium chloride should avoid anionic disintegrants such as croscarmellose sodium and sodium starch glycolate because the cationic API binds to the carboxymethyl and starch phosphate groups. Crospovidone at 2%–5% w/w is preferred as a nonionic disintegrant. Magnesium stearate at 0.5% w/w is acceptable if lubrication time is kept below 5 min; prolonged lubrication above 15 min reduces aqueous dissolution by hydrophobic coating of the API particles. Experimental batch records for a direct-compression model tablet show that a main compression force of 8 kN–15 kN and target hardness of 60 N–120 N provide disintegration times below 15 min in purified water at 37 °C according to Ph. Eur. 2.9.1. When tablet hardness exceeds 150 N, disintegration may exceed 30 min and the formulation should be rebalanced with additional nonionic disintegrant and reduced lubrication time.

Capsule filling of the API as a pure powder is limited by poor flow and hygroscopicity. Granulation with 3%–5% w/w povidone K30 and 1%–2% w/w crospovidone produces granules with bulk density between 0.45 g/mL and 0.60 g/mL, allowing reproducible dosing on a dosator-type capsule filler. Granule moisture content should be below 2.0% w/w before encapsulation to prevent capsule shell deformation and API deliquescence. Desiccant in packaging is required for climatic zones III and IV; moisture uptake above 1.0% in the API should trigger a re-drying step under vacuum at 60 °C for 4 h if stability data confirm no degradation.

For powders, granules, and premix, the API is often dispersed onto a lactose, wheat bran, or silicon dioxide carrier. The blend must be homogeneous because carryover and cross-contamination in multi-species feed mills are controlled under veterinary GMP. Dedicated equipment or validated cleaning with hot water and a nonionic detergent is required because the cationic API adheres to anionic polymer surfaces and stainless steel. Rinsates should be monitored by HPLC with a limit of quantitation of 0.1 µg/mL to verify cleaning acceptance. Swab recovery studies are performed on stainless steel coupons; recovery below 70% requires an alternative solvent system because the quaternary ammonium moiety may remain on the surface after water-only rinsing.

Sterile solution compounding and endotoxin control for injection use

For parenteral use, the sterile crystallized grade is handled in an ISO 14644-1 Class 7 cleanroom within an ISO Class 5 laminar-airflow workstation. The API is dissolved in Water for Injections at 20 °C–25 °C under gentle stirring to limit foam formation. High-shear mixing is avoided because the bis-quaternary ammonium chloride can produce persistent foam that complicates sterile filtration. The solution is filtered through a 0.22 µm polyvinylidene fluoride or low protein-binding polyethersulfone membrane; nylon membranes are avoided because cationic quaternary ammonium compounds may adsorb to negatively charged nylon surfaces. Filter compatibility studies must demonstrate API recovery above 95% after the maximum batch filter load. Bacterial endotoxin testing is performed according to Ph. Eur. 2.6.14 using the kinetic chromogenic method. The acceptance criterion is calculated from the maximum recommended veterinary dose and the threshold pyrogenic dose for the target species; no universal fixed limit is applied across all injection formulations. Sterility is confirmed according to Ph. Eur. 2.6.1. Terminal sterilisation may be evaluated only after forced degradation studies confirm that the quaternary nitrogen centres are stable under the proposed thermal exposure.

Aqueous solutions are prepared with purified water at 20 °C–25 °C. The chloride salt dissolves rapidly, and pH adjustment is performed only after complete dissolution because localised alkaline conditions may trigger degradation. Oral and topical solutions are clarified through a 0.45 µm membrane, while injectable solutions require 0.22 µm filtration or terminal sterilisation after stability confirmation. The solution must not be compounded with sodium lauryl sulfate, alginates, or anionic dyes; precipitation or assay loss will occur. Packaging for aqueous solution should use Type I glass or high-density polyethylene with light protection because UV exposure in solution produces N-dealkylated degradation products detected by the related-substances HPLC method. Forced degradation studies under 0.1 M HCl, 0.1 M NaOH, and 3% H₂O₂ over 24 h are used to demonstrate method specificity and mass balance within 95%–105% before release testing.

When bulk packaging must limit moisture ingress across climatic zones

The API is shipped in heat-sealed double low-density polyethylene liners inside a high-density polyethylene drum with a tamper-evident closure. For shipment to climatic zones III and IV, desiccant is placed between the inner and outer liner to maintain water content below 1.0% during transport. Moisture ingress is monitored by Karl Fischer titration after arrival; if water content exceeds 1.0%, the lot is quarantined and re-dried under vacuum at 60 °C for 4 h only if stability data demonstrate no degradation. The packaging is not suitable for steam sterilisation of the API; the sterile grade is produced by aseptic crystallisation or sterile filtration of the final solution. Bulk storage should avoid direct sunlight and temperatures above 30 °C unless long-term stress data are available.

Cleaning validation for equipment trains is complicated by the surface activity of triclobisonium chloride. Stainless steel and glass surfaces are rinsed with purified water at 60 °C–70 °C followed by a nonionic surfactant solution. Sodium hydroxide should not be used as the first rinse because quaternary ammonium hydroxide species may form and adhere more strongly to stainless steel. The analytical method for cleaning verification is the same stability-indicating ion-pair reversed-phase HPLC method used for assay and related substances. Limit of quantitation of 0.1 µg/mL supports detection of low residues in multi-product veterinary facilities.

Triclobisonium chloride differs from triclabendazole in chemical class and clinical application: triclabendazole is a benzimidazole anthelmintic used against liver flukes, whereas triclobisonium chloride is a bis-quaternary ammonium anti-infective used for bacterial control in veterinary dosage forms. For disinfectant or preservative applications, substitution with benzalkonium chloride is not equivalent. The bis-quaternary structure of triclobisonium has higher charge density and may shift the onset of micellar solubilisation. Direct substitution requires revalidation of minimum bactericidal concentration, surface compatibility, analytical interference, and assay recovery. Published comparative data for triclobisonium-specific critical micelle concentration and partition coefficient are limited; therefore formulation substitution is performed using experimentally generated data rather than literature extrapolation.