Lyophilisation parameters limiting beta-lactam hydrolysis in sterile injectable powder for bovine and porcine infections

In feedlot and farrow-to-finish operations, sterile injectable combinations of ampicillin sodium and sulbactam sodium are manufactured where national registration permits their use against beta-lactamase-producing Pasteurella multocida, Bordetella bronchiseptica and Staphylococcus hyicus. The formulation addition ratio is fixed at 2:1 on an anhydrous active-mass basis, ampicillin sodium to sulbactam sodium, with mannitol added at 10% w/w to stabilize the lyophilised cake and reduce vial-neck crusting. Compliance for this sterile powder route is anchored to EU GMP Annex 1 aseptic processing requirements, Ph. Eur. 2209 for sulbactam sodium monograph quality, Ph. Eur. 2.6.14 bacterial endotoxins with a common veterinary injectable API limit of ≤0.15 EU/mg, and Ph. Eur. 2.6.1 sterility testing. During production, the bulk solution is prepared in water for injection at 20–25 °C, pH-adjusted with 1 M NaOH to 8.0–9.0, then clarified and sterilised by 0.22 µm PVDF membrane filtration before aseptic filling into Type I glass vials with grey butyl stoppers. The freeze-drying cycle uses shelf cooling to -40 °C at 0.5 °C/min, primary drying at -20 °C and 0.20 mbar chamber pressure, and secondary drying at 25 °C for 12 h; product temperature must remain below -18 °C during primary drying to avoid cake collapse and visible brown discoloration. Terminal dosage forms are single-dose vials containing 1 g/0.5 g and 3 g/1.5 g ampicillin-sulbactam sodium. Reconstituted solutions should be stored at 2–8 °C and used within 8 h; co-administration with aminoglycosides in the same infusion line is contraindicated because beta-lactam ring opening may inactivate the aminoglycoside component.

Companion animal dermatology and lower urinary tract protocols require dry granulation rather than wet massing because ampicillin trihydrate and sulbactam sodium hydrolyse during aqueous granulation. The registered oral tablet design uses a 2:1 active-moiety ratio of ampicillin trihydrate to sulbactam sodium, with croscarmellose sodium at 3.0% w/w as disintegrant and magnesium stearate at 0.75% w/w as lubricant. Compliance testing for this dosage form includes Ph. Eur. 2.9.1 disintegration in water at 37 °C with a limit of 15 min, Ph. Eur. 2.9.3 dissolution using paddle apparatus at 75 rpm, and Ph. Eur. 2.9.6 uniformity of content. Downstream production employs a 120 L bin blender for pre-blending, dry granulation by roller compactor at roll force 25 kN/cm and gap 2.0 mm, screening through a 1.0 mm sieve, and a rotary tablet press with precompression 8 kN and main compression 16 kN. Target hardness is 70–100 N and friability is maintained at ≤1.0%. The terminal products are 250 mg/125 mg and 500 mg/250 mg divisible tablets for dogs and cats. At relative humidity above 35% RH, the dry granulation becomes sticky on punch faces, so die-table dehumidification and immediate packing in aluminium–PVC blisters with desiccant are mandatory.

What governs granule stability when sulbactam sodium is prepared as water-soluble poultry medication?

In poultry flock medication delivered through drinking water, the critical process parameter is moisture uptake by the spray-dried carrier and the pH of the reconstituted solution. The addition ratio is ampicillin sodium and sulbactam sodium at 2:1 by active mass, buffered with anhydrous citric acid and sodium citrate to hold final drinking-water pH between 6.5 and 7.5. Regulatory compliance for this granule category requires Ph. Eur. 2.2.32 loss on drying with a limit of ≤2.0% w/w, VICH GL18 residual solvent control, and Ph. Eur. 2.9.40 uniformity of dosage units for single-dose sachets. Production occurs in a top-spray fluid-bed granulator with inlet air at 40 °C, product temperature limited to 28–32 °C, spray rate 25 g/min, and final drying to ≤1.5% w/w residual moisture. The terminal forms are 100 g and 1 kg polyethylene-lined sachets of water-soluble granules for flock administration. The primary operational boundary is that exceeding 2.0% w/w residual moisture causes granule clumping and beta-lactam ring opening; therefore the drying end-point must be verified by halogen moisture balance and not by fixed time alone.

Oral drench powders for neonatal pigs and preruminant calves present a different stability profile because the powder is reconstituted in water and administered immediately, so the point of failure is not storage moisture but the particle-size distribution of the dry blend and the absence of insoluble carbonate excipients. The formula ratio for sulbactam sodium is 1 part by active weight to 2 parts ampicillin trihydrate, diluted in water to produce a final dose of 10 mg/mL ampicillin and 5 mg/mL sulbactam at the point of oral delivery. Compliance testing includes Ph. Eur. 2.9.5 uniformity of mass for sachets and Ph. Eur. 2.9.19 particulate contamination for the reconstituted solution. The downstream process is low-shear tumble blending of dehydrated lactose monohydrate, colloidal silicon dioxide and the active premix under nitrogen; filling into single-dose sachets on a vertical form-fill-seal line with relative humidity held below 30% RH. The terminal product is a 10 g single-use oral powder sachet for piglets and calves. The main incompatibility is with hard water bicarbonate exceeding 200 mg/L, which raises the reconstituted pH above 8.5 and accelerates hydrolysis; softened water should be used where available.

When hard gelatin capsule fill weight falls below the logarithmic mean particle size of the dry blend

For equine and larger companion animal dosing, encapsulation reduces handling and protects the hygroscopic active blend from ambient moisture better than uncoated tablets. The fill formulation uses ampicillin trihydrate and sulbactam sodium at 2:1 active ratio, with pregelatinised maize starch at 10% w/w and sodium lauryl sulfate at 0.5% w/w to reduce static charge. Compliance relies on Ph. Eur. 2.9.6 uniformity of content, Ph. Eur. 2.9.5 uniformity of mass and VICH GL3(R) stability testing for veterinary medicinal products. Production line use is a dosator-type capsule filler with bed temperature maintained at 22–25 °C and 30–35% RH; tamping pin immersion depth is set at 3 mm; filling is carried out into size 0 hard gelatin capsules. The blend median particle size is controlled at approximately 120 µm by prior roller compaction. The terminal products are 500 mg/250 mg and 250 mg/125 mg capsules. If fill weight is reduced below 400 mg without adjusting bulk density, dosator reproducibility falls outside ±5%; a higher-density granulation should be used rather than reducing capsule size, because ampicillin trihydrate is abrasive to capsule dosator pins over extended filling campaigns.

Premix carrier chemistry, lipid overcoating and beta-lactamase inhibitor retention in feed matrices

Medicated feed premix for sulbactam-containing combinations is constrained by the instability of beta-lactam rings in high-moisture feed matrices and by uneven distribution in total mixed rations. The active addition ratio is 2 parts ampicillin trihydrate to 1 part sulbactam sodium, initially adsorbed onto precipitated silica at 5% w/w active-to-carrier loading before dilution into the final premix. Compliance falls under EU Regulation 2019/4 for veterinary medicated feed and requires mix uniformity testing with coefficient of variation ≤5.0%; residual solvent control is performed under VICH GL18. Production is a two-stage process: first, a horizontal plowshare mixer at 100 rpm disperses the silica-adsorbed actives into ground limestone, then hydrogenated vegetable oil heated to 55 °C is sprayed at 2.0% w/w of total batch mass to form a moisture barrier. The finished premix is cooled to 20 °C before bagging. Terminal product is a 25 kg premix in polyethylene-lined multiwall paper bags, suitable for dilution at 1:100 in complete feed. Because beta-lactam hydrolysis accelerates when water activity exceeds 0.60, the premix must not be combined with molasses, liquid co-products or steam-flaked grains; once incorporated into feed, consumption within 72 h is required. Published stability data for sulbactam in specific feed formulations is limited, so manufacturers frequently establish a short-dated shelf life and confirm batch potency by liquid chromatography before release.