In tablet manufacturing, the micronized diosmin/hesperidin 90/10 fraction is processed on high-speed rotary presses at target potencies of 450 mg diosmin and 50 mg hesperidin per unit, giving a 500 mg total flavonoid load. A representative 800 mg core formulation contains 62.5% w/w API, 28.5% w/w microcrystalline cellulose, 4.0% w/w crospovidone split as 2.0% w/w intragranular and 2.0% w/w extragranular, 3.5% w/w povidone K-30, 1.0% w/w colloidal silicon dioxide, and 0.5% w/w magnesium stearate. Direct compression of the as-received micronized powder is not recommended because bulk density values below 0.45 g/mL and Hausner ratios above 1.35 commonly produce erratic die filling and segregation. High-shear wet granulation with an 8% w/w aqueous povidone K-30 solution is performed in a Lödige MGT-250 or equivalent jacketed horizontal granulator at an impeller speed of 120–150 rpm and a chopper speed of 1500–2000 rpm. Granulation endpoint is determined by torque rise of 25–35% above dry-mix baseline and visual confirmation of a compact wet mass. The wet mass is discharged through a Quadro Comil equipped with a 6.35 mm square mesh screen, transferred to a Glatt fluid bed dryer, and dried at inlet air temperature of 55–60°C until loss on drying by Ph.Eur. 2.2.32 is 1.5–2.5% w/w. Dried granules are milled through a 1.0 mm screen and blended with extragranular crospovidone and magnesium stearate in a V-blender at 12 rpm for 3–5 min. Compression is carried out on a Fette 2090i rotary press with D tooling at a main compression force of 15–22 kN, pre-compression force of 4–6 kN, and turret speed of 40–60 rpm. Tablet hardness is maintained between 80 N and 120 N, friability is below 0.5% by USP 1216, and disintegration time in purified water at 37°C is below 15 min by USP 701. Because no harmonised pharmacopoeial dissolution monograph exists for this fixed-dose combination, an in-house USP 711 apparatus 2 method using 900 mL of 0.5% w/v sodium lauryl sulfate in purified water at 75 rpm and 37°C is typically employed. Content uniformity must satisfy USP 905 acceptance values for 10 tablets. Residual solvents are controlled under ICH Q3C, elemental impurities under ICH Q3D, and microbiological quality under Ph.Eur. 2.6.12 and 2.6.13. Tableting areas with relative humidity above 60% require moisture-controlled feed frames because the micronized flavonoid fraction is hygroscopically sensitive after granulation and can adhere to punch faces. Anti-adherent punch coatings of chrome or ferritic nitrocarburised steel are used to reduce picking at turret speeds above 45 rpm.

What Limits Direct Capsule Filling of Micronized Diosmin/Hesperidin 90/10 Without Prior Densification?

Hard gelatin or hypromellose capsule filling of the micronized 90/10 flavonoid fraction without prior densification is limited by powder fluidisation and high cohesion, which produce weight variation outside the USP 905 limit for capsules. On a MG2 Planeta tamping-pin filling machine configured with type 00 or 00el capsules, the agitator housing and tamping pins generate electrostatic adhesion of the micronized powder to stainless steel surfaces. Bulk density values below 0.45 g/mL and Carr index values above 35% result in dose recovery below 90% when a 500 mg API fill is attempted. The usual corrective step is roller compaction, not direct fill. A Chilsonator fitted with smooth rolls at a roll pressure of 4–6 kN/cm and a roll gap of 2.0–2.5 mm densifies the API into ribbons that are milled through a 1.0 mm screen. The resulting granules have bulk density of 0.55–0.65 g/mL and flow function coefficient above 4, allowing fill weight variation below 3%. Fill weight is set at 650 mg for a 500 mg API load. Empty capsule moisture is maintained at 13–16% w/w for gelatin capsules or 3–6% w/w for HPMC capsules to prevent brittle cap fractures on high-speed closing stations. In-process checks include weight variation per USP 905, visual inspection for split or dented cap shoulders, and gravimetric verification of the tamping pin settings at 15 min intervals. Dissolution testing on capsule products uses the same apparatus 2 method described for tablet cores but with sinker wires, because granules of diosmin/hesperidin 90/10 can adhere to the vessel bottom and produce falsely low release. Terminal dose unit moisture after packaging is controlled below 5% w/w for hard gelatin and below 4% w/w for HPMC products.

Fluid bed top-spray granulation of the 90/10 diosmin/hesperidin ratio for oral sachet presentation is constrained by electrostatic charging of the micronized feedstock during pre-blending. The charge increases with decreasing particle size below D90 10 µm and is mitigated by pre-conditioning the raw API and large-particle mannitol in a jacketed ribbon blender at 25–30°C and 40–50% RH for 20–30 min. A representative sachet granule formula contains 50.0% w/w API, 42.5% w/w mannitol 200 SD, 3.0% w/w hydroxypropyl cellulose LF, 2.5% w/w croscarmellose sodium, 1.0% w/w citric acid anhydrous, and 1.0% w/w aspartame. The dry blend is loaded into a GPCG-5 top-spray granulator at a batch size of 5 kg, and pre-heated to product temperature 32–35°C. The binder solution is 10% w/w hydroxypropyl cellulose in purified water, sprayed through a 1.2 mm two-fluid nozzle at a spray rate of 20–30 g/min, atomising air pressure of 1.5–2.0 bar, and inlet air temperature of 60–65°C. Granulation endpoint is controlled by product bed temperature and pressure drop across the filter, with final moisture of 1.5–2.5% w/w. The dried granules are screened through 850 µm and 149 µm sieves to remove oversized material and fines. The target granule size distribution by sieve analysis per Ph.Eur. 2.9.38 is D10 180–220 µm, D50 350–420 µm, and D90 below 850 µm. A single-dose sachet containing 1000 mg granules delivers 500 mg flavone fraction. Uniformity of mass of filled sachets is verified by Ph.Eur. 2.9.40 for 20 units. Sachet filling is performed on a form-fill-seal machine with vertical filling speed limited to 40 strokes/min because higher speeds induce particle segregation and dust generation. The finished sachet is a powder-or-granule product for oral suspension after dispersion in 100 mL water; dispersion time is below 120 s at 25°C with gentle stirring. Packaging material is a four-layer laminate of PET/aluminium/low-density polyethylene/heat-seal layer with moisture vapour transmission rate below 0.5 g/m²/24 h at 38°C/90% RH. Stability storage at 25°C/60% RH for 24 months requires moisture-impermeable primary packaging to prevent granule hardening.

When the 90/10 Flavonoid Fraction Is Converted to an Injectable Nanosuspension Under Aseptic Conditions

Because both diosmin and hesperidin show extremely low aqueous solubility, parenteral development of the 90/10 fraction requires a nanosuspension or lipid-based carrier. Published data for this specific configuration is limited, but preformulation screening shows that aqueous solutions cannot achieve therapeutic concentrations at physiologically acceptable pH without high levels of organic cosolvents. A typical aseptic nanosuspension approach uses high-pressure homogenisation of the API in an aqueous vehicle containing poloxamer 188 at 1.0–2.0% w/v and sodium citrate buffer adjusted to pH 6.5–7.5. The micronized API is first dispersed with an Ultra-Turrax T25 rotor-stator at 8000–12000 rpm for 15 min, then processed in a Microfluidics M-110P high-pressure homogeniser at 1000–1500 bar for 15–25 discrete passes. Particle size after processing is measured by laser diffraction per ISO 13320:2020 and dynamic light scattering; an acceptable batch has D90 below 200 nm and D50 below 100 nm. Sterile filtration through 0.2 µm polyethersulfone membranes is not feasible for nanosuspensions, so the formulation is sterilised by moist heat reverse autoclaving at 121°C for 15 min only if particle aggregation is absent. Alternatively, heat-sensitive formulations require aseptic milling with sterile API and sterile vehicle. The filled injectable must meet particulate matter limits per USP 788, sterility per USP 71, and bacterial endotoxins per USP 85 with a product-specific limit determined by risk assessment. Osmolality is adjusted to 280–320 mOsm/kg with mannitol. Terminal stability is limited by physical instability; flocculation and Ostwald ripening are monitored by zeta potential and mean particle size over 14 days at 5°C and 25°C. The injectable route is reserved for clinical settings where oral absorption is not possible; published human efficacy data for injectable diosmin/hesperidin 90/10 is limited.

Extruded-Spheronised Pellet Cores for Multi-Particulate Oral Delivery of Diosmin/Hesperidin 90/10

For pelletisation routes, multi-particulate cores containing the 90/10 diosmin/hesperidin fraction are prepared by low-shear extrusion and spheronisation when the final dosage form requires a divisible or gastro-resistant coating option. A wet mass is prepared from 50.0% w/w API, 40.0% w/w microcrystalline cellulose spheres grade, 5.0% w/w lactose monohydrate, and 5.0% w/w crospovidone. Purified water is added to 70–80% w/w of dry solids, and the wet mass is extruded through a 0.8 mm screen at screw speed 50–80 rpm on a Caleva extruder. Spheronisation on a Caleva spheroniser at plate speed 800–1200 rpm for 8–12 min yields pellets with D50 800–1000 µm. The pellets are dried in a forced-air oven at 50°C until moisture is below 2.0% w/w by Ph.Eur. 2.2.32. Dried pellets are screened, and the 710–1180 µm fraction is retained for coating or filled into size 0 capsules as uncoated multi-particulates. Crushing strength is measured by texture analysis with a 2 mm cylindrical probe; values below 0.5 N/mm² indicate friable pellets that fracture during air-assisted capsule filling. Coating with ethylcellulose 7 cps at 3–5% w/w weight gain is performed in a Wurster column with inlet air temperature 45–50°C and coat solution solids 6% w/w in ethanol-water 80:20. Coated pellets are cured at 45°C for 12 h to prevent agglomeration during storage. Residual ethanol is controlled under ICH Q3C as a Class 3 solvent with a permitted daily exposure of 50 mg/day. Release testing on coated pellets uses USP 711 apparatus 1 at 100 rpm in 900 mL of 0.5% w/v sodium lauryl sulfate at 37°C. The multi-particulate product is a single-dose capsule containing 650 mg pellets equivalent to 500 mg API. The main processing bottleneck is yield loss in the milled fraction below 710 µm; this fines fraction can exceed 15% w/w if spheronisation plate speed is increased above 1200 rpm.