Compression of the micronised 90:10 diosmin-hesperidin fraction into venotonic tablets is executed on high-shear wet-granulation lines rather than direct-compression stations because the jet-milled API exhibits low tapped density and poor flowability. A representative tablet core for the 500 mg label claim contains 450 mg diosmin and 50 mg hesperidin, giving a 90:10 flavonoid ratio; for the 1000 mg label claim, the active quantity is 900 mg diosmin and 100 mg hesperidin. The active mass fraction inside the compressed core typically falls between 62.0 wt% and 78.0 wt%, depending on the selected label claim and the amount of microcrystalline cellulose, lactose monohydrate, croscarmellose sodium, and povidone retained after drying. High-shear granulation proceeds with purified water or a 5–15 wt% starch paste as binder at impeller tip speeds of 3–8 m/s, followed by fluid-bed drying at 55–65 °C inlet air temperature to a final moisture content of ≤2.0 wt% as determined by Karl Fischer method per Ph. Eur. 2.5.12. The dried granules are dry-milled through a 0.8–1.2 mm screen, blended with 0.5–1.0 wt% magnesium stearate, and compressed on a rotary tablet press at 12–25 kN compression force; target hardness is 90–150 N, and friability should remain ≤1.0% according to Ph. Eur. 2.9.7. In production runs, batch-to-batch granule size distribution d(0.5) is maintained at 100–250 µm to avoid segregation in the rotary press feed frame and to achieve uniform die filling. API particle size is also monitored by laser diffraction according to Ph. Eur. 2.9.31, with the d90 controlled to align with the dissolution specification because the flavonoid agglomerates after excessive shear or over-drying. Disintegration is tested under Ph. Eur. 2.9.1 with a limit of 15 minutes in water at 37±2 °C. Dissolution control for this poorly soluble flavonoid combination requires a surfactant-containing medium; if a single-point specification is applied, a Q value of 75% dissolved at 45 minutes in pH 6.8 phosphate buffer with 0.5% w/v sodium lauryl sulfate may be used as an in-house release criterion, but the official limit must be validated under ICH Q2(R1). Residual solvents are controlled under ICH Q3C, elemental impurities under ICH Q3D, and the API is released under EU GMP Part II, with the finished tablet released under EU GMP Part I and, for US-bound cargo, 21 CFR 210/211. The terminal dosage form is a film-coated immediate-release tablet of 500 mg or 1000 mg label claim for oral administration.

What Limits Capsule Fill Weight When the 90:10 Flavonoid Fraction Is Encapsulated?

Encapsulation of a 90:10 diosmin-hesperidin blend on tamping-pin or dosator capsule machines is limited by the API's low bulk density and cohesive fines rather than by chemical degradation, because diosmin and hesperidin are comparatively stable under ambient temperature and moderate humidity. The micronised material typically has a bulk density of 0.35–0.55 g/mL and tapped density of 0.60–0.85 g/mL after aeration; these values depend on jet-milling pressure and residual moisture. The Hausner ratio of the as-received micronised API is generally 1.3–1.6; after addition of 0.2–0.8 wt% anhydrous colloidal silicon dioxide, the ratio is reduced to 1.15–1.25, improving feed-frame flow. For a size 0 or 00 shell, the active fill target is usually 450 mg diosmin plus 50 mg hesperidin for a 500 mg flavonoid dose per capsule, or 900 mg diosmin plus 100 mg hesperidin for a 1000 mg dose. The active mass fraction of the capsule contents is generally 68.0–82.0 wt%, with the remainder composed of pregelatinised starch or microcrystalline cellulose, anhydrous colloidal silicon dioxide, and 0.5–1.0 wt% magnesium stearate as a lubricant. Pre-sieving through a 0.425 mm stainless-steel sieve removes soft agglomerates before bag or bin blending. On a rotary tamping-pin machine, fill speed may be reduced to 30,000–70,000 capsules/h when the active mass fraction exceeds 70 wt% because feed-frame segregation and plug weight variability become process-limiting. In-process fill weight variation is controlled under Ph. Eur. 2.9.25 or USP <905>, and the capsule shell is checked for disintegration under Ph. Eur. 2.9.1, with a limit of 15 minutes in 37±2 °C water for gelatin shells; HPMC shells may require a different disintegration profile depending on gelling agent selection. Dissolution is evaluated under Ph. Eur. 2.9.3 or USP <711> using a pH 6.8 phosphate buffer with 0.5% w/v sodium lauryl sulfate and a validated quantitation method. Residual solvent and nitrosamine controls follow ICH Q3C and ICH M7, with the finished product released under EU GMP Part I, 21 CFR 211, and the API under EU GMP Part II. The terminal dosage form is a hard gelatin or HPMC capsule for oral administration, typically 500 mg or 1000 mg label claim.

Granulation for single-dose sachet presentation differs from tablet granulation in that the finished granulate is not compressed but directly filled into stick packs after fluid-bed drying and flavor adjustment. In the hemorrhoidal episode segment, the most common label claim is 900 mg diosmin plus 100 mg hesperidin per sachet, i.e., a 1000 mg total flavonoid dose. The active mass fraction in the filled granulate is typically 58.0–72.0 wt%, with the balance consisting of mannitol, sorbitol, maltodextrin, citric acid, sodium citrate or sodium bicarbonate as a pH modifier, and a noncariogenic sweetener such as sucralose or a steviol glycoside. The production line uses a top-spray fluid-bed granulator; the micronised API is pre-blended with diluents and sprayed with a 5–10 wt% aqueous binder solution of povidone K25 or maltodextrin at an inlet air temperature of 55–70 °C. The granulate is dried to a final moisture content of 1.5–3.0 wt% and sieved through a 0.5 mm screen, with the target granule size d(0.5) at 80–250 µm to ensure rapid dispersion and uniform sachet filling. Stick-pack filling is performed on vertical form-fill-seal equipment at 1.5–2.5 g fill weight per 1000 mg dose; fill weight variation is controlled under Ph. Eur. 2.9.25 or USP <905>, with an acceptance value ≤15. The dispersion time of the finished granulate in 200 mL water at 20±2 °C is controlled to ≤180 seconds as an in-process test, and the pH of the reconstituted suspension is typically 5.5–7.0 to avoid excessive bitterness. Residual solvent compliance follows ICH Q3C; elemental impurities are controlled under ICH Q3D Class 2A and Class 3; microbial quality follows Ph. Eur. 2.6.12 and Ph. Eur. 2.6.13, category 3B, with absence of Escherichia coli in 1 g. The terminal finished product type is oral granules in a single-dose sachet or stick pack, reconstituted in water before swallowing.

When Sterile Injectable Administration Is Required, Solubility Engineering Precedes Aseptic Filling

For injectable presentations of the 90:10 diosmin-hesperidin fraction, the formulation boundary is established by the aqueous solubility of the unconverted flavonoid mixture: diosmin is practically insoluble in water, and hesperidin is similarly poorly soluble in neutral aqueous vehicles, though it can be dissolved in dimethyl sulfoxide or dilute alkali prior to complexation. Therefore, the injectable process is not a simple dissolution step; it requires either wet-media milling to a nanosuspension, micellar solubilisation with polyoxyl castor oil derivatives, or cyclodextrin complexation in a buffered vehicle. A feasibility-grade pre-lyophilisation bulk may contain 10–25 mg/mL total flavonoids as a hydroxypropyl-β-cyclodextrin complex at a 1:2 to 1:3 molar ratio, with mannitol or trehalose at 20–50 mg/mL as lyoprotectant. The final lyophilised cake may contain 45–70 wt% active complex, depending on the ratio of lyoprotectant and residual moisture after freeze-drying. If a nanosuspension route is selected, wet-media milling should reduce the particle size to d90 ≤500 nm and d50 ≤200 nm, and the zeta potential should remain at or below −25 mV for electrostatic stabilisation; otherwise the suspension will aggregate during autoclaving or long-term storage. Sterile filtration is generally not feasible for micronised suspensions with a particle size above 0.22 µm; if a suspension is pursued, aseptic processing is the primary route because terminal steam sterilisation at 121 °C for 15 min may degrade the flavonoid glycosides. Filling of the sterile lyophilised presentation is performed in a Class A isolator under EU GMP Annex 1, with filtration of the bulk solution through 0.22 µm membranes before lyophilisation. Container closure integrity is verified by dye ingress or helium leak method according to USP <1207>; subvisible particulate matter is controlled per USP <788> or Ph. Eur. 2.9.19; bacterial endotoxin is controlled at <0.50 EU/mg if the product is intended for intravenous administration, or according to the dose-appropriate limit in the approved pharmacopoeial monograph. Residual solvents from any solubiliser or process aid must comply with ICH Q3C options, and elemental impurities with ICH Q3D. The terminal product type is a sterile lyophilised powder for reconstitution or an aseptically filled nanosuspension injection; published data for a conventional aqueous injection of unmodified diosmin-hesperidin are limited, so each formulation must be supported by phase-solubility studies and sterility validation according to Ph. Eur. 2.6.1 or USP <71>.

Powder-for-Suspension Blending and Sedimentation Control in Oral Liquids

Powder-for-suspension systems containing the 90:10 diosmin-hesperidin fraction are used when patients require a swallow-free oral route; the formulation differs from sachet granulate by including a suspending matrix that remains dispersed long enough for dose administration. The active quantity per unit dose is usually 450 mg diosmin plus 50 mg hesperidin or 900 mg diosmin plus 100 mg hesperidin, and the active mass fraction in the dry powder is lower than in tablets or capsules, generally 40.0–65.0 wt%, because the diluent matrix must accommodate suspending agents, sweeteners, buffering salts, and preservatives. The compounding process begins with low-shear tumble blending of the micronised API with sorbitol, mannitol, sodium carboxymethylcellulose or xanthan gum as a suspending agent, anhydrous citric acid, sodium citrate, and a preservative such as sodium methyl parahydroxybenzoate or potassium sorbate. The blend is then filled into multi-dose glass or PET bottles with a desiccant-lined closure; if a single-dose unit is preferred, the powder may be filled by vertical form-fill-seal into foil-laminated stick packs at a fill weight of 2.0–4.0 g per dose. The reconstituted suspension at the label direction should disperse within 60 seconds with gentle shaking; viscosity is typically adjusted to 50–200 mPa·s at 25 °C using a Brookfield rotational viscometer to balance pourability and sedimentation. The pH of the reconstituted liquid is maintained at 6.0–7.5 because the flavonoid glycosides are more stable in neutral to slightly acidic conditions. In-use stability is evaluated according to the relevant environment and market, with microbial challenge testing under Ph. Eur. 5.1.3 or USP <51> for preserved oral liquids. Release includes loss on drying under Ph. Eur. 2.2.32, fill weight under Ph. Eur. 2.9.25, and dissolution or dispersion testing under Ph. Eur. 2.9.3 or USP <711> as a product-specific method. Residual solvents and elemental impurities are controlled under ICH Q3C and ICH Q3D; heavy metals and arsenic limits follow the regional pharmacopoeial general chapters. The terminal finished product type is a powder for oral suspension, reconstituted before use.