Sulphaguanidine Pharma Grade API is supplied as an unsterile active pharmaceutical ingredient for downstream manufacture of tablets, capsules, granules, and injectable dosage forms. The molecular entity is 4-amino-N-(diaminomethylidene)benzenesulfonamide, CAS 57-67-2, with the sulfaguanidine monohydrate represented by the formula C₇H₁₀N₄O₂S·H₂O and an anhydrous molecular weight of 214.25 g/mol. The product line is separated into model designations by intended route: SGN-101 for tablet and capsule manufacturing, SGN-102 for granule and dry suspension processing, SGN-201 for injectable-grade purification, and SGN-301 for micronised solid-dosage and suspension applications. The monohydrate appears as a white to faintly cream crystalline powder with very slight aqueous solubility and pH-dependent dissolution, becoming more soluble in dilute mineral acids through protonation of the amino and guanidine functions. Sulphaguanidine is a bacteriostatic sulfonamide that inhibits dihydropteroate synthase in susceptible enteric bacteria. Because absorption from the gastrointestinal tract is limited, the molecule acts predominantly within the intestinal lumen rather than as a systemic sulfonamide. This distinction defines the formulation logic for oral and injectable grades: oral grades are specified for intraluminal exposure, while the injectable grade requires conversion to a soluble salt or controlled pH adjustment because the free acid solubility is too low for direct parenteral use.

What analytical limits separate the tablet, capsule, granule, and injection grades?

Batch release of the API is performed under ICH Q7 good manufacturing practice. The certificate of analysis includes identification by infrared absorption spectrophotometry according to Ph. Eur. 2.2.24, assay by liquid chromatography or non-aqueous titration, water determination by Ph. Eur. 2.5.12, related substances by liquid chromatography according to Ph. Eur. 2.2.29, and residue on ignition according to Ph. Eur. 2.4.16. Particle-size distribution is measured by laser diffraction using ISO 13320:2020. Bulk and tapped density are determined by Ph. Eur. 2.9.34 or USP 616. Residual solvents are controlled according to ICH Q3C, and elemental impurities are assessed using ICH Q3D. For the injectable model, bacterial endotoxins are determined by Ph. Eur. 5.1.10, and the downstream sterilisation process is the responsibility of the finished-product licence holder under Ph. Eur. 5.1.1.

Particle-size control is the principal physical discriminator between the oral and injectable models. Micronisation to D90 ≤25 µm increases the specific surface area of SGN-301 and SGN-201; this accelerates dissolution and salt formation but can reduce powder flow and increase triboelectric charging during transfer. For tablet and capsule manufacture, SGN-101 is supplied with a coarser particle-size distribution to limit segregation and improve die filling. The granule model SGN-102 is controlled for sieve fraction rather than sub-sieve fines alone because sachet fill weight and reconstitution behaviour depend on the proportion of particles between 180 µm and 850 µm. In all models, the monohydrate requires storage in airtight containers; exposure to relative humidity above 60% can initiate surface hydration and agglomeration, particularly in micronised grades. Pre-drying is required when the material has equilibrated under high-humidity conditions before dry blending or encapsulation.

Granule growth and compression force respond to particle-size and moisture variables

Direct compression of SGN-101 is generally unsuitable on high-speed rotary tablet presses when the ratio of bulk to tapped density falls below 0.75, because die-fill variability produces unacceptable weight variation. Wet granulation is the preferred process for tablet formulations. In production-scale high-shear granulation using a top-drive mixer with impeller speed of 300 rpm and chopper speed of 1500 rpm, a binder solution containing 2.5–4.0% w/w povidone K30 produces granules with bulk density in the range 0.55–0.65 g/cm³ and a Hausner ratio below 1.25. Fluid-bed drying should maintain product temperature below 65°C; higher bed temperatures can liberate surface water from the monohydrate and create friable granules with increased fines. Magnesium stearate is used as a lubricant at 0.5–1.0% w/w. Below 0.5% w/w, picking on the lower punch face is observed at turret speeds above 40 rpm on some tablet presses. Croscarmellose sodium at 2–5% w/w as a disintegrant gives uncoated tablet disintegration times below 15 min in purified water at 37°C under Ph. Eur. 2.9.1.

Capsule filling of SGN-101 is performed on dosator or tamping-pin machines. Low-dose capsules generally require a 1:5 to 1:10 pre-blend with lactose monohydrate or microcrystalline cellulose to maintain content uniformity. Blend uniformity is monitored by stratified sampling and liquid chromatography. For granule and dry suspension applications, SGN-102 is released with not less than 90% of the fraction retained between 180 µm and 850 µm; fines below 150 µm are limited to 10% to reduce dusting and sachet weight variation. Reconstitution should be carried out in purified water with gentle stirring; the suspension should be used immediately because the active ingredient has limited physical stability in non-buffered aqueous media.

Parenteral compounding with Sulphaguanidine requires a soluble salt or controlled pH adjustment because the free acid solubility is insufficient for therapeutic concentrations. A sterile solution can be prepared from the sodium salt with a final pH above 9.0. Alkaline sulfonamide solutions are sensitive to oxidation and must be protected from light and headspace oxygen. Terminal sterilisation at 121°C for 15 min may be applied only after the finished-product manufacturer confirms solution stability; otherwise sterilising filtration through a 0.22 µm membrane is used. The injectable model SGN-201 is not supplied sterile. It is an API with controlled bioburden and endotoxin burden intended for downstream aseptic processing or terminal sterilisation.

If injectable administration is specified, purification barriers shift from residual solvents to endotoxins and bioburden

Injectable-grade Sulphaguanidine differs from the oral models in that every campaign must satisfy bacterial endotoxin and bioburden criteria before release. Equipment used for the final purification train is validated for steam-in-place cycles with thermocouples placed at the slowest-to-heat point. Purified water used for final washing is monitored to meet Ph. Eur. 5.1.10 limits. Packaging for SGN-201 consists of double low-density polyethylene bags inside a fibre drum, with desiccant where specified. The API is not claimed to be sterile, and the finished pharmaceutical product must be sterilised by the marketing authorisation holder. Published data for direct physicochemical comparison of Sulphaguanidine injection-grade material with other parenteral sulfonamides is limited, because parenteral sulfaguanidine is not a widely licensed finished product in many markets.

Comparative pharmacokinetic and solubility boundaries among sulfonamide APIs

Compared with sulfadiazine and sulfamethoxazole, Sulphaguanidine has a substantially lower oral absorption fraction and a higher intraluminal concentration. This difference arises from the polar guanidine side chain, which reduces passive permeability across intestinal epithelium and increases hydrogen-bonding capacity. Sulfadiazine is sufficiently absorbed to achieve systemic plasma concentrations and is used with pyrimethamine in certain toxoplasmosis regimens. Sulfamethoxazole is co-formulated with trimethoprim for systemic and urinary tract infections. The route-specific API grade therefore differs in purpose: Sulphaguanidine is intended for enteric delivery, while other sulfonamides in the same class are selected for systemic or urinary exposure.

Sulphaguanidine should not be dry-mixed with strong oxidising agents or with amine-reactive excipients if prolonged storage is intended. The unsubstituted aromatic amino group can form coloured condensation products with reducing sugars, so tablets and granules should avoid direct contact with dextrose monohydrate or lactose under high-humidity storage. Compatibility studies for the oral grades show acceptable stability with microcrystalline cellulose, pregelatinised starch, povidone, croscarmellose sodium, and magnesium stearate at the stated concentrations. For the injectable grade, solution compatibility is limited to pH-adjusted aqueous systems; organic co-solvents may be introduced only after the finished-product manufacturer demonstrates compliance with ICH Q3C residual-solvent limits and the relevant parenteral finished-product monograph. The uncoated oral dosage forms should be stored in airtight containers protected from light at controlled room temperature with excursions permitted between 15°C and 30°C; the injectable-grade packaging should be resealed immediately after sampling to prevent moisture ingress and bioburden ingress.

For oral solid dosage forms, the dissolution time is not controlled by the API alone; it is a function of wet granulation endpoint, disintegrant concentration, lubricant level, and tablet hardness. Batches compressed to hardness above 120 N may show prolonged disintegration if the granule fines were over-dried. Production experience with SGN-101 indicates that a granule moisture content of 1.5–2.5% before compression provides the best balance between flow and tablet hardness. If the moisture content exceeds 3.0%, the material can adhere to punches and dies even at moderate turret speeds. For SGN-102 granules, the unpacked bulk density is typically 0.45–0.55 g/cm³, and the angle of repose is generally below 35° after drying; these values support reproducible sachet filling on auger-type equipment.