Supplied as a white to off-white crystalline powder, Tiamulin Hydrogen fumarate Pharma Grade API for Tablet / Capsule / Granule / Injection, Oral & Injectable is a pleuromutilin diterpene antibiotic salt. The chemical entity is described as C28H47NO4S·C4H4O4, with CAS registry number 55297-96-2 and relative molecular mass 609.83 g/mol. The hydrogen fumarate counterion is selected over the free base for crystalline processability, aqueous solubility, and compatibility with dry oral and aqueous injectable production routes. The API is intended exclusively for veterinary medicinal products and must not be administered directly without dilution and finished-dose formulation. Potency is expressed as tiamulin hydrogen fumarate on an anhydrous, solvent-free basis; the conversion factor from tiamulin base to the hydrogen fumarate salt is 1.235 based on the relative molecular masses 493.76 g/mol and 609.83 g/mol.

The pleuromutilin class inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit near the peptidyl transferase center. Tiamulin is primarily active against Gram-positive bacteria, Mycoplasma spp., and certain anaerobic Gram-negative organisms including Brachyspira hyodysenteriae. Pharmacodynamic optimisation in finished formulations is based on the area under the concentration–time curve relative to minimum inhibitory concentration rather than on high peak concentrations alone. The hydrogen fumarate salt is milled and classified under temperature- and humidity-controlled conditions. Manufacturing is expected to follow ICH Q7 for active pharmaceutical ingredients and EU GMP Part II; analytical method transfers are conducted under ICH Q2(R1).

Commercially, the API is packaged in double polyethylene bags inside fibre drums. Retest dating of 24 months is assigned under storage conditions of 25°C and 60% RH; accelerated stability data at 40°C and 75% RH for 6 months support transport excursions. The product must be stored below 30°C, protected from light and moisture. For feed-grade processing, dust control and cross-contamination containment follow EU GMP Part II; extraction swab limits for tiamulin are calculated from permitted daily exposure. Because the drug is active at low inclusion rates, dedicated or validated multi-product facilities are normally required.

What Release Specifications Differentiate Oral Grade from Injectable Grade Tiamulin Hydrogen Fumarate?

Routine release testing is structured around pharmacopoeial methods and ICH Q3C residual solvent criteria. The table lists the release specification used to qualify the API for solid oral and parenteral manufacture. Injectable grade is differentiated by stricter microbial quality and bacterial endotoxin control. Manufacturers may tighten thresholds where finished product dose, route, or target species requires lower limits.

For solid oral dosage forms, particle size distribution is controlled by laser diffraction according to Ph. Eur. 2.9.31. A typical D90 for direct-compression blends is ≤300 µm; wet granulation routes frequently use a finer D90 of ≤180 µm to improve content uniformity and reduce visible specking. Water content at ≤0.5% is critical because free moisture in high-shear granulation can cause fumarate salt migration and hardness drift. Roller compaction is used for dry granulation at roll pressure 8–14 kN/cm, with mill screen aperture 0.8–1.2 mm; materials handling is conducted at relative humidity below 60% to prevent agglomeration. The API is compatible with lactose monohydrate and microcrystalline cellulose in standard pharmaceutical formulations. Amine-based excipients and strongly alkaline lubricants are avoided because the fumarate counterion can form salts and raise the local pH at moisture films, accelerating degradation. For capsule manufacture, powder blends with Hausner ratio 1.25–1.35 are processed on dosator or tamping-pin filling machines; colloidal silicon dioxide at 0.5% w/w is used as flow aid. Blend uniformity is assessed by stratified sampling and acceptance value ≤15 according to Ph. Eur. 2.9.40. Tablet compression is performed on rotary presses with main compression force 12–18 kN and precompression force 3–5 kN; ejection force is monitored to detect insufficient lubrication. Dissolution testing of finished tablets uses USP apparatus 2 at 50 rpm in 900 mL of pH 6.8 phosphate buffer, with the Q value set in the product-specific monograph.

For feed granules, published data on this specific API configuration are limited; pilot-scale trials typically use fluid-bed rotor processors with inlet air temperature 50–60°C and spray rate adjusted to maintain product temperature below 40°C. The granule carrier is usually calcium carbonate or pregelatinised starch; API is spray-layered from an aqueous binder solution containing hydroxypropyl methylcellulose. Granule assay uniformity is verified by extraction of 10 samples and liquid chromatography. Bulk granule density is controlled between 0.45 g/mL and 0.65 g/mL for consistent metering into feed. Because the drug is active at low inclusion rates, multi-step geometric dilution in feed is required to avoid segregation.

Injectable grade tiamulin hydrogen fumarate is further controlled for bacterial endotoxin and bioburden. Aqueous solutions are prepared in Water for Injections, with pH adjusted to 4.0–6.0 using citrate or phosphate buffer. The fumarate counterion reduces the quantity of acidifying agent required to achieve this window. Terminal steam sterilisation may be limited by thermal degradation; aseptic filtration through 0.22 µm polyethersulfone membrane is therefore specified for sterile solutions. A 0.45 µm bioburden-reducing prefilter is used before the sterile membrane. Nitrogen sparging and disodium edetate at 0.05% w/v are used to suppress oxidative degradation in liquid preparations. Particulate matter in the sterile finished product is controlled according to Ph. Eur. 2.9.19 and Ph. Eur. 2.9.20. The solution contact time should be minimised; for non-buffered process intermediates, an in-process hold of not more than 8 h at 15–25°C is applied unless forced degradation data support a longer hold. Avoid contact with iron and copper ions because soluble transition metal species can catalyse oxidation of the thioether side chain. Multi-dose veterinary injectable formulations may include benzyl alcohol as preservative; compatibility and preservative efficacy testing are conducted according to Ph. Eur. 5.1.3.

The Differential Salt Form Rationale and Processing Boundaries in Tiamulin Formulations

Tiamulin hydrogen fumarate differs from tiamulin base principally in aqueous solubility, wettability, and powder flow. The salt form is freely soluble in water, which permits soluble powder and injectable solution manufacture without organic cosolvents; the free base alone is suitable mainly for lipid-based or non-aqueous formulations. The molecular mass difference must be accounted for in dispensing calculations, with the base-to-salt conversion factor 1.235. Compared with valnemulin hydrochloride, both compounds are semisynthetic pleuromutilins that bind the 50S ribosomal subunit at the peptidyl transferase center, but tiamulin hydrogen fumarate has a broader regulatory and production history in swine and poultry and a different C-14 side chain. Cross-resistance to valnemulin and other pleuromutilins can occur through transferable methyltransferase genes such as cfr; susceptibility testing by broth microdilution according to CLSI VET01 is required to confirm clinical utility.

Relative to macrolide APIs such as tilmicosin, tiamulin acts at a different region of the ribosome, but the absence of complete cross-resistance is not guaranteed for all isolates. The hydrogen fumarate salt avoids chloride ion in the API, which reduces pitting corrosion of stainless steel processing vessels compared with hydrochloride salts of other veterinary antimicrobials. This does not alter the microbiological spectrum but is relevant to cleaning validation and equipment life-cycle maintenance. Tiamulin hydrogen fumarate also differs from tiamulin base in solid-state stability and aqueous solubility; exact thermodynamic values are not fixed in public pharmacopoeial monographs.

Concurrent administration with ionophore coccidiostats—specifically monensin, salinomycin, and narasin—is contraindicated in swine and poultry; documented toxic interactions produce myopathy and may be fatal. Cleaning validation for multi-product facilities must address tiamulin carryover, with swab limits derived from permitted daily exposure or toxicological cleanup thresholds. Published data for direct-compression and roller-compaction processing of this specific API remain limited; development batches should therefore include shear cell flow testing, accelerated stability, and forced degradation studies before scale-up. The product is not intended for human use and is not classified as a sterile API unless purchased as injectable grade with endotoxin control.