| HS Code | 746718 |
| Product Name | RESOMER RG 752 S Bioresorbable PLGA Drug Delivery Grade |
| Manufacturer | Evonik Industries |
| Polymer Type | Poly(D,L-lactide-co-glycolide) (PLGA) |
| Lactide To Glycolide Molar Ratio | 75:25 |
| Polymer Architecture | Amorphous random copolymer |
| End Group | Ester-terminated (uncapped) |
| Bioresorbable | Yes |
| Biodegradable | Yes |
| Drug Delivery Grade | Yes |
| Appearance | White to off-white powder or granules |
| Inherent Viscosity | 0.16-0.24 dL/g (0.1% in chloroform at 25°C) |
| Molecular Weight Range | Approximately 10,000-25,000 Da |
| Glass Transition Temperature | Approximately 45-55°C |
| Residual Monomers | Typically less than 0.5% |
| Water Content | Typically less than 0.5% |
| Heavy Metals | Typically less than 10 ppm |
| Solubility | Soluble in dichloromethane, chloroform, and ethyl acetate; insoluble in water |
| Storage Conditions | Store at -20°C, protected from moisture |
| Typical Applications | Sustained-release microparticles, implants, and parenteral drug delivery systems |
As an accredited RESOMER RG 752 S Bioresorbable PLGA Drug Delivery Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in moisture-barrier, heat-sealed aluminum foil bags under nitrogen with desiccant; 1 kg, 5 kg, and 10 kg quantities. |
| Container Loading (20′ FCL) | 20′ FCL loading for RESOMER RG 752 S Bioresorbable PLGA Drug Delivery Grade: palletized, desiccant-protected, sealed for controlled pharmaceutical transport. |
| Shipping | RESOMER RG 752 S is shipped as a non-hazardous, moisture-sensitive solid in sealed, desiccated, light-resistant packaging under inert gas. It is transported at ambient temperature with no special dangerous-goods classification. Upon receipt, store at -20°C, protected from humidity, heat, and light to preserve drug-delivery-grade polymer stability. |
| Storage | Store RESOMER RG 752 S in a tightly sealed, moisture-proof container in a cool, dry, well-ventilated area, preferably refrigerated at 2–8°C. Protect from heat, light, moisture, and oxidizing agents. Keep away from incompatible materials. Allow to equilibrate to room temperature before opening to prevent condensation. Follow the supplier’s SDS and local regulations. |
| Shelf Life | Shelf life is approximately two years when stored at -20°C, protected from moisture and light in a tightly sealed container. |
RESOMER RG 752 S is pre-dried at 25 °C under 0.1 mbar vacuum for 24 h before dissolution in N-methyl-2-pyrrolidone at 30–50% w/w polymer solids under dry nitrogen. The poly(D,L-lactide-co-glycolide) 75:25 grade has an inherent viscosity of 0.16–0.24 dL/g (0.1% in chloroform, 25 °C), which permits filtration through 0.2 μm PVDF membranes and injection through 21-gauge needles at 25 °C. After subcutaneous administration, water ingress and NMP efflux induce polymer precipitation and form a porous depot; the phase inversion rate and the polymer-rich front determine the initial release burst. Raising polymer loading from 30% to 50% w/w reduces 24 h burst release but increases solution viscosity from approximately 200 mPa·s to above 800 mPa·s at 25 °C. The depot retains leuprolide acetate in a sustained-release implant; the same process configuration is applied to other peptide-loaded in situ forming depots where the 75:25 lactide:glycolide ratio provides a degradation window intermediate between 50:50 and 85:15 grades. Sterility is maintained by aseptic filtration; terminal gamma irradiation at 25 kGy is avoided because chain scission accelerates molecular weight loss and shifts release kinetics. In vitro release is measured by USP <711> apparatus 4 flow-through cells; endotoxin and sterility tests follow USP <85> and USP <71>. Residual NMP is controlled under ICH Q3C Class 2 limits with a permitted daily exposure of 5.3 mg/day and a concentration limit of 530 ppm. Biological safety assessment follows ISO 10993-1:2018.
For microsphere fabrication, RESOMER RG 752 S is dissolved in dichloromethane or ethyl acetate at 10–20% w/w polymer. The aqueous continuous phase contains 1–3% w/w polyvinyl alcohol and 0.5–1.0% w/w sodium chloride; the emulsification step uses a rotor-stator homogenizer at tip speed 5–25 m/s followed by solvent extraction at 20–25 °C. This yields microspheres with a median diameter of 20–90 μm. For hydrophilic peptide payloads, a water-in-oil-in-water double emulsion is generated; encapsulation efficiency is limited by outward diffusion of the internal aqueous phase during solvent removal and by early polymer shell hardening at the oil/water interface. Core loading above 10–15% w/w drug for highly water-soluble molecules often causes surface pores and a 24 h burst exceeding 40% of labeled content. Residual dichloromethane is reduced below 600 ppm in accordance with ICH Q3C Class 2 PDE of 6.0 mg/day; ethyl acetate is monitored against the Class 3 concentration limit of 5000 ppm and PDE of 50 mg/day. Particle size distribution is controlled by sieving through 25–125 μm screens before vial filling. Injectability and particulate load are assessed by USP <788> with small-volume parenteral limits of not more than 2000 particles ≥10 μm and 200 particles ≥25 μm per container. The terminal product is a lyophilized microsphere depot for risperidone or equivalent hydrophobic small molecules. In vitro release testing is carried out in phosphate-buffered saline pH 7.4 at 37 °C ± 0.5 °C with gentle agitation. Hydrolytic degradation testing follows ASTM F1635-16.
| Solvent | Class | PDE (mg/day) | Concentration limit (ppm) |
|---|---|---|---|
| Dichloromethane | 2 | 6.0 | 600 |
| N-Methyl-2-pyrrolidone | 2 | 5.3 | 530 |
| Acetone | 3 | 50 | 5000 |
| Ethyl acetate | 3 | 50 | 5000 |
At 5–10 mg/mL RESOMER RG 752 S in acetone, rapid injection into an aqueous antisolvent containing 0.1–0.5% w/w poloxamer 188 under controlled mixing produces nanoparticles with mean diameter 120–220 nm as measured by dynamic light scattering according to ISO 22412:2017. Acetone is removed by rotary evaporation at 30 °C; residual solvent is held below the ICH Q3C Class 3 limit of 5000 ppm. The low molecular weight PLGA 75:25 grade delivers a short degradation half-life suitable for intracellular and peritumoral nanocarrier applications; however, burst release of weakly associated hydrophobic drug can exceed 50% in 24 h when drug–polymer miscibility is insufficient. Wet-milling and high-pressure homogenization at 500–1500 bar are alternative processing routes that reduce organic solvent use but increase polymer hydrolysis risk due to cavitation heating. For small-molecule payloads, drug is pre-dissolved with the polymer at 1–5% w/w relative to polymer before nanoprecipitation to improve encapsulation uniformity. Terminal dosage forms are sterile-filtered nanodispersions for injection; filter validation uses 0.2 μm membranes and inline pressure drop is maintained below 2.0 bar to prevent filter clogging. Sterility and endotoxin tests follow USP <71> and USP <85>.
Twin-screw extrusion of RESOMER RG 752 S is conducted on a co-rotating 16 mm twin-screw extruder with L/D 25:1; barrel temperature zones are set at 70/90/100/105 °C, screw speed at 100–200 rpm, and residence time at 120–300 seconds. The polymer is pre-dried at 25 °C under 0.1 mbar vacuum for 24 h to moisture below 0.2% w/w; moisture above 0.5% w/w in the feed section causes hydrolytic molecular weight loss during extrusion, visible as melt viscosity drift and torque fluctuation. The glass transition temperature of the extruded matrix remains between 45 °C and 50 °C as measured by differential scanning calorimetry per ASTM D3418-15. Extruded rods are cut into 5–20 mm lengths and inserted through 12-gauge or larger trocars for subcutaneous placement; for intratumoral placement, the rod may be cut to 5 mm segments. In vitro mass loss follows the bulk erosion protocol of ASTM F1635-16; release is measured in phosphate-buffered saline pH 7.4 at 37 °C ± 0.5 °C using USP <711> apparatus 7 reciprocating holders. Melt processing eliminates residual organic solvent, but the low melt viscosity of this grade limits the use of high-molecular-weight drug dispersions; phase separation is controlled by limiting drug loading to 10–20% w/w depending on drug melting point and polymer miscibility.
Electrospinning of RESOMER RG 752 S from hexafluoroisopropanol at 25–40% w/v uses 18–22 kV applied potential, 0.5–1.5 mL/h feed rate, and 10–15 cm spinneret-to-collector distance to deposit nonwoven drug-eluting fiber mats. Because the low molecular weight grade provides limited chain entanglement, stable jet formation often requires blending 5–10% w/w high-molecular-weight PLGA or polycaprolactone as a rheology modifier; without this addition, bead-on-string morphology is observed and the fiber mat lacks mechanical integrity. Vacuum drying at 40 °C for 48 h removes residual hexafluoroisopropanol; however, published data for this specific configuration with RG 752 S is limited, so residual solvent and degradation endpoints should be confirmed by gas chromatography and ASTM F1635-16 before scale-up. For periodontal guided tissue regeneration, the mat is characterized by an interconnected pore fraction above 80% by liquid displacement and by in vitro cell viability per ISO 10993-5; localized tissue response is assessed by ISO 10993-6 subcutaneous implantation. Drug-loaded fibers containing doxycycline or metronidazole are produced by pre-dissolving the drug in the polymer solution at 1–10% w/w relative to polymer.
Spray-coating of RESOMER RG 752 S on cobalt-chromium coronary stent platforms is performed with 2–5% w/w polymer in ethyl acetate using an ultrasonic nozzle at 0.5–2.0 mL/h and nitrogen atomization pressure 0.5–1.5 bar. Multiple pass deposition builds a coating thickness of 5–15 μm; single-pass thickness above 20 μm increases edge delamination after crimping onto the balloon catheter. Ethyl acetate is removed by vacuum drying at 40 °C for 48 h and is monitored as an ICH Q3C Class 3 solvent with PDE 50 mg/day and concentration limit 5000 ppm. The 75:25 lactide:glycolide ratio degrades more slowly than 50:50 and limits acidic oligomer accumulation at the metal-polymer interface, which is an operational boundary in biodegradable stent coatings because interfacial pH drop can accelerate metal corrosion. Stent coating integrity after expansion and crimping is evaluated according to ASTM F2081; drug release is measured at 37 °C ± 0.5 °C using USP <711> apparatus 7. The terminal product is a biodegradable drug/polymer matrix on a coronary stent; the coating should be stored under nitrogen at −20 °C to minimize hydrolysis before deployment.
| Product form | Apparatus | Medium | Temperature |
|---|---|---|---|
| In situ implant | USP <711> apparatus 4 flow-through | PBS pH 7.4, 0.1% Tween 80 | 37 °C ± 0.5 °C |
| Microspheres | USP <711> apparatus 2 paddle | PBS pH 7.4, 0.1% SDS | 37 °C ± 0.5 °C |
| Extruded rod | USP <711> apparatus 7 reciprocating holder | PBS pH 7.4 | 37 °C ± 0.5 °C |
| Stent coating | USP <711> apparatus 7 | PBS pH 7.4, 0.5% bovine serum albumin | 37 °C ± 0.5 °C |
Compression molding of RESOMER RG 752 S at 50–60 °C and 10–15 kN force for 60–90 seconds forms cylindrical intravitreal pellets with diameter 0.5 mm and length 1.5 mm. The low glass transition temperature permits consolidation below the degradation threshold of heat-labile corticosteroids such as dexamethasone; however, the molded pellet softens above 45 °C, so forced-air cooling of the mold to below 25 °C is required before ejection to prevent dimensional drift and edge chipping. Pellets are filled into 22-gauge intravitreal injectors and terminally inspected for particulate and endotoxin load under ISO 14644-1 class 5 conditions. In vitro release testing is conducted in 10 mL phosphate-buffered saline pH 7.4 at 37 °C ± 0.5 °C using USP <711> apparatus 4 flow-through cells. Because the low molecular weight PLGA 75:25 grade undergoes bulk erosion, release of sparingly water-soluble drugs can be diffusion-limited in the first 14 days and then accelerated by matrix degradation; the degradation profile is tracked by gel permeation chromatography against monodisperse polystyrene standards and by mass loss per ASTM F1635-16. Published data for this specific compression-molded configuration with RG 752 S is limited, so lot-to-lot release consistency should be confirmed by dissolution profile similarity testing.
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RESOMER RG 752 S Bioresorbable PLGA Drug Delivery Grade is a poly(D,L-lactide-co-glycolide) copolymer with a nominal lactide-to-glycolide molar ratio of 75:25. The material is produced for parenteral and implantable sustained-release dosage forms and is supplied as a white to off-white powder or granules. The grade is distinguished from general-purpose PLGA by lot-specific control of inherent viscosity, residual lactide and glycolide monomers, residual organic solvents, tin catalyst levels, and bioburden. Inherent viscosity is typically controlled between 0.16 dL/g and 0.24 dL/g when measured as a 0.1% w/v solution in chloroform at 25°C using an Ubbelohde viscometer. Differential scanning calorimetry according to ISO 11357-2 at 10 K/min typically records a glass transition temperature between 42°C and 46°C. The copolymer is soluble in dichloromethane, chloroform, acetone, ethyl acetate, tetrahydrofuran, and N-methyl-2-pyrrolidone and is practically insoluble in water, methanol, ethanol, and aliphatic hydrocarbons.
At the lower end of the inherent-viscosity window, 0.16 dL/g, the resin has low solution viscosity and is easier to filter through 0.22 µm membranes in aseptic manufacturing; at the upper end, 0.24 dL/g, matrix strength is higher and microsphere surfaces are less tacky. This molecular-weight window makes the grade suitable for solvent-evaporation microencapsulation and hot-melt extrusion where low melt viscosity is required. However, the window is narrow: a shift of ±0.02 dL/g can alter the release profile in slow-release microsphere systems, so incoming lot viscosity should be checked before large-scale manufacture. The grade suffix S indicates a defined end-group and molecular-weight window; the certificate reports the acid number. Where carboxylic acid termini are present, the acid number should be reviewed for peptides and acid-labile actives because carboxylic acid end groups can participate in peptide acylation and influence microenvironmental pH during bulk hydrolysis.
Compared with 50:50 PLGA grades such as RESOMER RG 502 or RG 504, the 75:25 copolymer has lower glycolide content and a higher glass transition temperature, which reduces the rate of water uptake and hydrolytic chain scission under physiologic conditions. Compared with high-molecular-weight 75:25 grades such as RESOMER RG 756, RG 752 S has a lower melt viscosity and can be processed at lower temperatures but yields a shorter degradation-controlled release duration in equivalent microsphere geometries.
Hydrolytic degradation of PLGA proceeds by random chain scission of ester bonds. In phosphate-buffered saline at pH 7.4 and 37°C, 50:50 PLGA microspheres typically enter mass loss within 4–8 weeks, while 75:25 PLGA microspheres of comparable diameter may extend mass loss to 3–4 months. The longer degradation window arises from the higher D,L-lactide content, which reduces the number of glycolide-glycolide and glycolide-lactide ester linkages and increases the hydrophobic character of the polymer. Degradation of RG 752 S follows bulk erosion with internal autocatalysis. In particles larger than approximately 10 µm, acidic degradation products accumulate in the core faster than they diffuse out, producing acid-catalyzed chain scission. In nanoparticles and thin films below 10 µm, the diffusion path is short, autocatalysis is less pronounced, and molecular weight loss is more uniform.
Release testing should be designed around this kinetic profile. For microspheres, dissolution or in vitro release methods use phosphate-buffered saline pH 7.4 at 37°C in USP apparatus 2 or 4 with sink conditions; sampling may extend to 120 days. For implants, mass loss and molecular weight retention are monitored by gravimetry and gel permeation chromatography with refractive index detection after buffer exposure. Published data for the specific RG 752 S formulation in complex geometries is limited; therefore, the use of intermediate-time-point molecular weight analysis is recommended before setting release specifications. Because the 75:25 ratio degrades more slowly than 50:50 grades, release studies may require time points at 1 day, 3 days, 7 days, 14 days, 28 days, 56 days, 84 days, and 120 days. Molecular weight retention during release is measured by gel permeation chromatography with triple detection rather than single-detector methods because PLGA molecular weight distributions are broad and Mark-Houwink coefficients depend on composition. For composition, 1H NMR at 400 MHz or higher field strength can resolve lactide and glycolide signals. Residual monomer by HPLC-UV requires method validation for specificity because lactide and glycolide elute early and may interfere with formulation components.
The following specification profile is representative of commercial drug delivery documentation for this grade. Values are typical ranges and should not replace the lot certificate.
| Parameter | Method or instrument | Typical control range |
| Inherent viscosity | Ubbelohde viscometer, 0.1% w/v in chloroform, 25°C | 0.16–0.24 dL/g |
| Lactide:glycolide molar ratio | 1H NMR, 400 MHz | 73:27 to 77:23 |
| Glass transition temperature | DSC, ISO 11357-2, 10 K/min | 42–46°C |
| Residual lactide | HPLC-UV, supplier-validated | Typically <1.0% |
| Residual glycolide | HPLC-UV, supplier-validated | Typically <0.5% |
| Tin | ICP-MS, USP <233> | ≤150 ppm typical |
| Residual solvents | Headspace GC, USP <467> | ICH Q3C limits per lot CoA |
| Bioburden | Ph. Eur. 2.6.12 / USP <61> | Manufacturer limit; no universal monograph limit |
Incoming quality control should include appearance, inherent viscosity, and residual monomer at minimum. If the resin is intended for a finished product manufactured under European Pharmacopoeia conditions, the supplier certificate should be mapped to Ph. Eur. 2.6.12 for bioburden and Ph. Eur. 2.4.24 for residual solvents. For US filings, USP <61>, USP <62>, and USP <467> are typical reference methods. The polymer is not a monograph-grade material in all pharmacopoeias; therefore, the finished product specification must justify the chosen limits using process validation data.
Before hot-melt extrusion, RG 752 S should be dried under vacuum at 25–35°C for 12–24 h to a residual moisture below 0.1% by Karl Fischer titration. Exceeding 0.1% moisture during extrusion causes hydrolytic chain scission, a decrease in melt viscosity, an increase in residual monomer, and a loss of molecular weight that shifts drug release. On a co-rotating twin-screw extruder with L/D 25:1 to 40:1, barrel zone temperatures between 90°C and 120°C and screw speeds from 100 rpm to 300 rpm are typical. Die pressure and motor torque should be monitored continuously; a torque rise followed by an abrupt decrease indicates extensive chain scission. Residence time should be kept below 2 min, and the material should not be left in a heated barrel at temperatures above 100°C for more than 5 min during shutdown.
Melt processing of RG 752 S at temperatures above 120°C accelerates degradation. In DSC, the onset of glass transition is 42–46°C, but melt viscosity is sufficiently low for extrusion only above approximately 90°C. The usable thermal window is therefore narrow, and barrel temperature uniformity of ±3°C or better is desirable. Barrel zones should be profiled from 80°C at the feed throat to a maximum of 120°C at the die, with an actual melt temperature measured by an immersion thermocouple below 115°C. Melt rheology of RG 752 S is strongly shear-thinning. Capillary rheometry at 100°C and apparent shear rates between 100 s⁻¹ and 1,000 s⁻¹ can quantify lot-to-lot differences before scale-up. Operators should avoid open hoppers in rooms above 60% relative humidity; if ambient moisture exceeds this threshold, a nitrogen purge on the feed throat is required. Because PLGA is susceptible to amine-catalyzed ester cleavage, the polymer should be kept separated from primary and secondary amines and strong alkaline additives during compounding.
For implant manufacturing by injection molding, mold temperatures between 20°C and 30°C are used, and clamp force should be selected to prevent flash without overpacking. Low-viscosity PLGA can fill thin cavities but may exhibit high mold shrinkage; holding pressure and cooling time must be mapped for each mold geometry. Residual stress in molded PLGA devices can be observed by polarized light microscopy; annealing below 40°C can reduce stress without significant crystallization because the D,L-lactide sequence is amorphous.
In solvent-evaporation microencapsulation, RG 752 S is dissolved in dichloromethane or ethyl acetate at 10–25% w/v. The organic phase is emulsified into an aqueous poly(vinyl alcohol) continuous phase using a Silverson L5M-A rotor-stator mixer at 5,000–15,000 rpm or a comparable device. Solvent removal is performed by stirred in-vessel evaporation at reduced pressure, and residual solvent is measured by headspace gas chromatography. Dichloromethane levels are typically driven below 600 ppm to meet ICH Q3C, but the final limit depends on the daily dose and route of administration. Drug loading in the microspheres is influenced by the organic-to-aqueous phase ratio, the concentration of poly(vinyl alcohol), and the quenching rate after solvent extraction. Batch-to-batch variability in inherent viscosity at the lower end of 0.16 dL/g can lead to higher initial burst and shorter release; at the upper end of 0.24 dL/g, encapsulation efficiency may decrease and solvent volume may need to be increased.
For nanoprecipitation, the copolymer can be dissolved in acetone at 5–20 mg/mL and added to aqueous surfactant under controlled flow. In microfluidic equipment such as a Dolomite Telos system, the flow-rate ratio and total flow rate control particle size and polydispersity; dynamic light scattering documents the Z-average and polydispersity index. For in-situ forming depots, RG 752 S is dissolved in N-methyl-2-pyrrolidone or dimethyl sulfoxide; upon injection into an aqueous environment, the water-miscible solvent exchanges with water and the PLGA precipitates to form a depot. The viscosity of the polymer solution and the solvent-outflow rate control the initial burst and depot shape.
Comparison with related Resomer grades clarifies the positioning of RG 752 S.
| Grade | Lactide:glycolide ratio | Inherent viscosity | Expected degradation mass-loss window for microspheres of similar size |
| RG 752 S | 75:25 | 0.16–0.24 dL/g | 3–4 months |
| RG 502 | 50:50 | 0.16–0.24 dL/g | 1–2 months |
| RG 504 | 50:50 | 0.45–0.60 dL/g | 2–4 months |
| RG 756 | 75:25 | 0.71–1.0 dL/g | 4–6 months or longer depending on geometry |
These release horizons are general in vitro degradation windows based on published studies of PLGA microspheres; specific formulations, drug-polymer interactions, and particle size shift them substantially. Selection between RG 752 S and an acid-terminated 75:25 grade should be based on the acid number and number-average molecular weight reported on the certificate. For sustained-release systems requiring shorter release, 50:50 PLGA grades are usually more appropriate; for release beyond six months, higher-viscosity lactide-rich grades or polycaprolactone-based systems may be required.
Because RG 752 S is used as an excipient in parenteral products, the finished-product manufacturer is responsible for setting release limits for residual solvent, elemental impurities, and endotoxin. The polymer supplier provides a certificate of analysis covering residual monomers, residual solvents, tin, and bioburden. The manufacturer should also evaluate the polymer under ICH Q3D for elemental impurities and ICH Q3C for residual solvents based on the maximum feasible daily intake. Stability data for the polymer should include appearance, inherent viscosity, and residual monomer; storage under 2–8°C in moisture-tight packaging is standard. After first opening, the material should be equilibrated to room temperature before use to avoid condensation. Processing incompatibilities include strong acids, strong bases, amines, high surface-area metal oxides, and oxidizing agents. Steam sterilization of the dry polymer should be avoided because it triggers rapid hydrolysis. If terminal sterilization of a finished polymer formulation is considered, gamma irradiation dose mapping and post-irradiation molecular weight measurement are required because PLGA undergoes chain scission; published data for this specific configuration is limited.
