| HS Code | 248418 |
| Productname | RESOMER LG 857 S |
| Brand | RESOMER |
| Manufacturer | Evonik |
| Chemicalname | Poly(L-lactide-co-glycolide) |
| Abbreviation | PLGA |
| Monomerratio | 85:15 (L-lactide:glycolide) |
| Endgroup | Ester terminated |
| Medicalgrade | Yes |
| Appearance | White to off-white granules |
| Inherentviscosity | 0.5-0.7 dL/g |
| Glasstransitiontemperature | 50-60 °C |
| Solubility | Soluble in chloroform, dichloromethane, and tetrahydrofuran |
| Degradationproducts | Lactic acid and glycolic acid |
| Storageconditions | Store at -20 °C, protect from moisture |
| Sterilizationmethod | Gamma irradiation or ethylene oxide |
| Regulatorycompliance | USP Class VI, ISO 10993 |
| Application | Implantable medical devices and drug delivery systems |
| Casnumber | 26780-50-7 |
| Density | 1.2-1.3 g/cm³ |
| Bioresorbability | Bioabsorbable/resorbable |
As an accredited RESOMER LG 857 S Bioresorbable PLGA Medical Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | RESOMER LG 857 S is supplied in 1 kg, 5 kg, or 10 kg quantities, nitrogen-flushed, heat-sealed aluminum foil laminate bags inside fiber drums. |
| Container Loading (20′ FCL) | 20′ FCL container loading for RESOMER LG 857 S bioresorbable PLGA medical grade: sealed drums, palletized, secured, clean, dry transport. |
| Shipping | RESOMER LG 857 S is typically shipped at ambient temperature in sealed, moisture-barrier packaging with desiccant. It is non-hazardous for transport and not UN-regulated. Protect from heat, humidity, and contamination; refrigeration may be advised for long-term storage. CoA and traceability documents accompany shipment. |
| Storage | Store RESOMER LG 857 S in its original, tightly closed container in a cool, dry, well-ventilated area. Protect from moisture, heat, light, and repeated temperature cycling. Recommended storage is 2–8 °C; use −20 °C for long-term storage. Equilibrate to room temperature before opening to prevent condensation and hydrolysis. Use desiccant after opening. |
| Shelf Life | Typically 24 months when stored unopened at −20°C, protected from moisture; confirm exact expiry on supplier certificate of analysis. |
In anterior cruciate ligament reconstruction, interference screws and fixation pins molded from high-molar-mass 85:15 L-lactide/glycolide copolymer require a melt-processing window that avoids autocatalytic hydrolysis. The resin is first vacuum-dried at 35–45 °C under <100 mbar for 48 h to reduce residual moisture below 0.05 wt%; when residual moisture exceeds 0.1 wt%, melt viscosity drops within the barrel and screw dimensions drift from cavity geometry. A twin-screw extruder with L/D 25–30 and low-shear screw elements is used for optional compounding; neat resin or compounds containing 10–15 wt% β-tricalcium phosphate are then fed to an injection molding machine with barrel zones set from 160 °C to 185 °C, nozzle temperature not exceeding 190 °C, and mold temperature held at 25–40 °C to prevent crystallinity-induced shrinkage anisotropy. Clamp force and injection speed must be configured for thin-wall thread profiles; flow length and gate design should be validated by short-shot studies because high-volatility monomers formed by local over-heating reduce molecular weight at the gate-freeze zone. Compliance for finished interference screws is referenced to ISO 13781:2017, ASTM F2502-17, and the biological evaluation series ISO 10993-1:2018, with degradation testing run according to ASTM F1635-16. Terminal product types are tibial and femoral interference screws, cruciate ligament fixation pins, and small bone anchor tacks.
For long-acting peptide and small-molecule depot microspheres, the dispersed phase is typically prepared by dissolving RESOMER LG 857 S in dichloromethane at 10–20 wt% polymer, with active pharmaceutical ingredient added to achieve a polymer-to-drug ratio between 5:1 and 30:1 depending on dose and target release interval. The continuous phase contains 0.5–2.0 wt% poly(vinyl alcohol) with a hydrolysis degree of 87–89 mol% and sodium chloride or phosphate buffer to control osmotic mass transfer. Homogenization is performed in a rotor-stator mixer at 5,000–15,000 rpm; higher shear reduces mean particle size but raises the fraction of sub-10 µm particles, which increases initial burst and complicates terminal filtration. Solvent extraction is carried out in an aqueous quench vessel maintained at 15–25 °C for 2–4 h, followed by hardening in water at 25–30 °C for 12–24 h and freeze-drying with mannitol or trehalose as cryoprotectant. Residual dichloromethane must meet ICH Q3C limits, release testing is performed with USP <711> dissolution apparatus, and injectable particulate matter must conform to USP <729>. Aseptic manufacture is governed by ISO 13485:2016, with sterility tested using USP <71>. Terminal product types include antipsychotic, GnRH agonist, and somatostatin analogue depot microspheres packaged as sterile lyophilized powder.
Injectable depot systems based on RESOMER LG 857 S are formulated by dissolving the polymer in N-methyl-2-pyrrolidone at 30–45 wt%, with dimethyl sulfoxide or triacetin used as co-solvent in some formulations to adjust initial precipitation rate. The active compound is either dissolved in the same solvent phase or dispersed as a micronized suspension at 1–30 wt% of the polymer mass. Phase inversion after subcutaneous or periodontal injection is driven by water influx and solvent efflux; polymer concentration and solvent composition set the depot porosity and burst release, but for LG 857 S the high inherent viscosity requires warming to 35–40 °C during mixing and filling to reduce solution viscosity below 5–10 Pa·s for 21G needle administration. Terminal depots are generally filled into single-use syringes using aseptic processing because terminal gamma irradiation can reduce inherent viscosity and shift release kinetics; if terminal sterilization is unavoidable, electron-beam or low-dose gamma must be bracketed with USP <711> release data. Compliance includes USP <71> sterility, USP <85> bacterial endotoxins, ICH Q3C residual solvent thresholds for NMP, and local implantation testing per ISO 10993-6:2016. Finished product types include subcutaneous leuprolide depots, periodontal in situ implants, and veterinary gastro-protective depots.
Patient-specific cranio-maxillofacial scaffold fabrication using RESOMER LG 857 S starts with filament extrusion because the high molar mass prevents solvent-based binder jetting and limits ink jetting throughput. The resin is dried to <0.05 wt% moisture and compounded with 5–10 wt% β-tricalcium phosphate or 5 wt% barium sulfate if radiopacity is required; filler content above 15 wt% causes irregular filament diameter and nozzle clogging. Filament is extruded on a single-screw extruder with L/D 15–20 at 160–180 °C into a water trough at 20–25 °C, then pulled through a laser diameter gauge to maintain 1.75 ± 0.05 mm. Fused filament fabrication is conducted with a hardened nozzle of 0.2–0.4 mm, nozzle temperature 180–200 °C, build plate 55–70 °C, and print speed 20–40 mm/s; interlayer adhesion is the main mechanical limitation, and tensile properties measured from printed coupons are typically lower than injection-molded equivalents when tested per ASTM D638-14. If previously published strength retention data specific to LG 857 S printed coupons are not available, mechanical evaluation should be generated under ASTM D638-14 and ASTM F1635-16. Compliance for finished scaffolds follows ISO 10993-1:2018, in vitro degradation by ASTM F1635-16, and where applicable, additive manufacturing process validation under ISO/ASTM 52900. Terminal products are patient-specific bone regeneration scaffolds, research-scale osteochondral constructs, and containment cages for bone void fillers.
Coating of titanium, stainless steel, or β-tricalcium phosphate implant surfaces with RESOMER LG 857 S commonly uses a 2–8 wt% polymer solution in ethyl acetate or a 3:1 ethyl acetate/2-butanone mixture; the selected solvent must be anhydrous because residual water promotes phase separation and pinhole formation. Drug substances such as rifampicin, vancomycin, or sirolimus are added at 10–30 wt% relative to polymer, producing a barrier film that modulates local delivery without serving as a structural matrix. The coating is applied in a low-humidity environment at 20–30% RH using an ultrasonic atomizer operating at 40–60 kHz; higher humidity causes surface whitening and loss of adhesion. Coated implants are dried under vacuum at 35–40 °C for 24–48 h to remove residual solvent to ICH Q3C limits, and adhesion is verified by pull-off testing according to ASTM D4541 or cross-cut methods listed in ISO 2409. Compliance for drug-eluting implant coatings includes hemocompatibility testing under ISO 10993-4 when blood contact is indicated, cytotoxicity under ISO 10993-5, and particulate matter limits under USP <788> for injectable or implantable systems where coating fragments may be generated during deployment. Finished device types include antibiotic-coated fracture fixation pins, sirolimus-eluting bioabsorbable stent coatings, and barrier-coated ceramic bone void fillers.
Dental and craniofacial barrier membranes are produced by compression molding RESOMER LG 857 S into films of 200–800 µm thickness. The resin is dried, then pre-compressed in a heated press at 160–175 °C for 2–4 min and fully pressed at 10–20 MPa, followed by quenching to a platen temperature below 30 °C to limit shrinkage after demolding. No plasticizer is required in most membrane constructions, but up to 5 wt% triethyl citrate may be incorporated when a softer handling profile is specified; addition above 10 wt% reduces yield stress and creates tack. Tensile properties are evaluated according to ASTM D882-18 for thin film, and degradation behavior is assessed with ASTM F1635-16. Compliance for clinical membrane use is based on ISO 10993-1:2018 and ISO 7405 for dental applications; when the membrane is delivered sterile, USP <71> applies. Terminal products are resorbable guided tissue regeneration membranes, exposed orthopedic barrier sleeves, and temporary adhesion barrier sheets.
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RESOMER LG 857 S is a medical-grade bioresorbable poly(L-lactide-co-glycolide) with a 85:15 molar ratio of L-lactide to glycolide and an ester-terminated chain architecture. The product is manufactured under ISO 13485:2016 quality system controls and is specified for implantable applications that require a high inherent viscosity, typically 5.0–7.0 dL/g measured as a 0.1% solution in chloroform at 25°C per DIN EN ISO 1628-1. The glass transition temperature is typically 60–65°C when determined by differential scanning calorimetry according to ASTM D3418-15. The high lactide content and high molecular weight distinguish this grade from lower-viscosity PLGA systems and acid-terminated PLGA variants. Typical intended use includes long-term resorbable implants such as orthopedic fixation devices, suture anchors, craniomaxillofacial implants, and depot-forming drug delivery platforms where extended mechanical integrity or slow mass loss is required. The grade is supplied as white to off-white granules and is not intended for direct clinical use until the finished device has been validated under the relevant medical device regulation.
In an 85:15 PLGA backbone, the methyl group on the lactide repeat unit restricts water penetration and sterically shields the ester carbonyl. This reduces the hydrolytic chain-scission rate relative to 50:50 PLGA under identical in vitro conditions at 37°C in phosphate-buffered saline at pH 7.4 following ASTM F1635-16. The degradation mechanism remains bulk erosion, but the latency phase before mass loss is extended because oligomeric fragments do not readily diffuse until the number-average molecular weight falls below approximately 10,000 Da. The high initial molecular weight of RESOMER LG 857 S therefore delays the onset of significant mass loss and mechanical collapse compared with lower-viscosity grades of the same lactide-glycolide ratio.
Mechanical property retention is geometry-dependent. Thin films, porous scaffolds, and highly oriented injection-molded parts degrade at different rates even when cut from the same lot. Published strength-retention curves for this specific high-viscosity configuration are limited, and device-level testing under simulated physiological load remains necessary. In general, the grade is selected when a device must retain tensile or flexural modulus for multiple months rather than for only a few weeks. The ester-terminated architecture further reduces the initial concentration of free carboxylic acid end groups, which lowers the initial autocatalytic acceleration observed in acid-terminated PLGA grades.
The table below summarizes representative specification parameters and analytical methods associated with the product. Lot-specific certificates of analysis should be consulted for release values and acceptance limits.
| Parameter | Method | Specification or Typical Range |
|---|---|---|
| Appearance | Visual inspection | White to off-white granules |
| L-lactide:glycolide molar ratio | Proton nuclear magnetic resonance | 85:15 |
| Inherent viscosity | DIN EN ISO 1628-1 | 5.0–7.0 dL/g (0.1% in chloroform, 25°C) |
| Glass transition temperature | ASTM D3418-15 | 60–65°C |
| Residual monomers | High-performance liquid chromatography | <0.5% w/w |
| Residual solvent | Gas chromatography | <0.1% w/w |
| Sulfated ash | Pharmacopoeial method | <0.1% w/w |
| Heavy metals | Pharmacopoeial method | <10 ppm |
Compliance with ISO 13485:2016 addresses manufacturing control, not biological safety of a finished device. Finished-device biocompatibility must be evaluated under ISO 10993-1:2018 and applicable regional medical device regulations. The polymer itself does not confer regulatory clearance, and batch-specific documentation should include residual monomer, residual solvent, and viscosity data to support process validation.
On production-scale twin-screw extrusion lines, the melt viscosity of RESOMER LG 857 S creates a narrow operating window. Pre-drying is required before melt processing; residual moisture above 0.1% w/w can initiate hydrolytic chain scission and produce bubble defects. Vacuum drying below the glass transition temperature is preferred because drying above 65°C can sinter the granules. Co-rotating twin-screw extruders with L/D ratios from 24:1 to 40:1 are commonly used for compounding or direct extrusion. Zone temperatures are typically set between 170°C and 210°C, with melt temperatures above 220°C associated with accelerated thermal degradation and monomer formation. Screw speeds in the range of 100–250 rpm and melt pressures of 30–80 bar are typical starting points, but actual values depend on screw design, die geometry, and lot-specific viscosity. For injection molding of small osteosynthesis plates and similar devices, melt temperatures from 180°C to 205°C and mold temperatures from 20°C to 40°C are practical starting conditions. Clamp force must be calculated from projected cavity area, and machines in the 300–1000 kN range are often sufficient for small high-strength implant components. The high melt viscosity increases torque demand; process validation should monitor screw torque at fixed speed because a shift in inherent viscosity of even 0.5 dL/g can alter melt pressure and downstream part dimensions. Incompatibilities include prolonged contact with alkaline additives, strong nucleophiles, or high-moisture fillers, all of which can accelerate ester hydrolysis. Hygroscopic fillers must be co-dried and fed in a controlled manner. Published data for a specific extruder configuration is limited; the above values are industrial starting points, not validated release parameters.
Gamma sterilization at a reference dose of 25 kGy according to ISO 11137-1:2016 induces dose-dependent chain scission in PLGA. For high-viscosity ester-terminated grades, the molecular weight and inherent viscosity may decrease, and the extent of reduction depends on absorbed dose, temperature, package atmosphere, and residual moisture. Published data across PLGA formulations indicate that inherent-viscosity losses can range from approximately 10% to 40% after terminal irradiation, but lot-specific verification is mandatory because the high initial viscosity of RESOMER LG 857 S can shift the dose-response relationship. Irradiation under nitrogen or vacuum reduces oxidative pathways compared with irradiation in air. Ethylene oxide sterilization per ISO 11135:2014 is an alternative when residual ethylene oxide and ethylene chlorohydrin limits can be met under ISO 10993-7:2008. Dry heat sterilization is not appropriate because the glass transition region and melt-processing limits are close enough to permit distortion and chain degradation. Sterile filtration is also not applicable because of the high molecular weight and melt viscosity of the grade.
When a lower-viscosity PLGA 85:15 grade replaces RESOMER LG 857 S, melt processing becomes easier, but the mechanical load-bearing window shortens. The comparison below shows key differences among the high-IV grade, a lower-IV PLGA 85:15 grade, and a faster-degrading 50:50 PLGA.
| Property | RESOMER LG 857 S | Lower-IV PLGA 85:15 | PLGA 50:50 |
|---|---|---|---|
| L-lactide:glycolide ratio | 85:15 | 85:15 | 50:50 |
| Inherent viscosity | 5.0–7.0 dL/g | 1.4–1.7 dL/g | 0.45–0.55 dL/g |
| Chain termination | Ester terminated | Ester terminated | Ester terminated |
| Degradation rate | Slower | Moderate | Faster |
| Melt processing | Narrow window, high torque | Moderate window | Wide window, low viscosity |
| Typical use | Load-bearing implants, long-term scaffolds | Mid-term drug-eluting implants | Short-term particulate and microparticle systems |
In osteosynthesis applications, devices molded from RESOMER LG 857 S are typically evaluated for initial flexural strength according to ISO 178:2019 and for in vitro degradation according to ASTM F1635-16. The high L-lactide content supports prolonged mechanical retention but also requires attention to residual stresses after injection molding, especially when the part thickness exceeds 2 mm. Annealing or controlled orientation may be necessary to reduce warpage and premature stress cracking. For long-acting implantable drug depots, the ester-terminated surface reduces initial autocatalytic acid generation relative to acid-terminated PLGA, which can be advantageous for acid-labile active pharmaceutical ingredients. However, the high melt viscosity of LG 857 S restricts its use in hot-melt extrusion of thermally labile drugs, and published data for specific active pharmaceutical ingredient compatibility is limited. Device developers should evaluate molecular weight retention, residual monomer, and mechanical integrity after each sterilization and processing step.
