| HS Code | 775739 |
| Product Name | PURASORB PDL 05 Drug Delivery DL-Lactide Copolymer |
| Chemical Name | Poly(D,L-lactide) |
| Cas Number | 26680-10-4 |
| Molecular Formula | (C3H4O2)n |
| Polymer Type | Amorphous DL-lactide copolymer |
| Inherent Viscosity | 0.45-0.55 dL/g in chloroform at 25°C |
| Molecular Weight | Approximately 40,000-60,000 Da (Mw) |
| Glass Transition Temperature | 50-55°C |
| Appearance | White to off-white powder or granules |
| Solubility | Soluble in chloroform, dichloromethane, and ethyl acetate; insoluble in water |
| Density | 1.25 g/cm³ at 25°C |
| Residual Monomer | Less than 0.5% |
| Water Content | Less than 0.5% |
| Heavy Metals | Less than 10 ppm |
| Biodegradability | Hydrolytically degrades to lactic acid, then to carbon dioxide and water |
| Storage Conditions | Store at -20°C, protected from moisture |
As an accredited PURASORB PDL 05 Drug Delivery DL-Lactide Copolymer factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | PURASORB PDL 05 is supplied as 5 g in a sealed, light-protected glass bottle with desiccant. |
| Container Loading (20′ FCL) | PURASORB PDL 05 Drug Delivery DL-Lactide Copolymer loaded in 20′ FCL, palletized, dry, ventilated, secured, compliant with chemical shipping regulations. |
| Shipping | PURASORB PDL 05 Drug Delivery DL-Lactide Copolymer is shipped as a non-hazardous solid polymer in sealed containers. It is not regulated as dangerous goods for air, sea, or ground transport. No UN number, hazard class, or packing group applies. Store cool and dry; keep away from moisture. Handle per SDS. |
| Storage | Store PURASORB PDL 05 in a tightly sealed, moisture-proof container under cool, dry conditions, preferably at –20°C. Protect from light, heat, moisture, and oxidizing agents. Keep in a dry, well-ventilated area away from ignition sources. Allow to equilibrate to room temperature before opening to prevent condensation; use inert gas blanketing if possible. |
| Shelf Life | PURASORB PDL 05 typically has a two-year shelf life when stored in original packaging under cool, dry conditions, protected from moisture. |
For the preparation of subcutaneous depot microspheres from amorphous poly(DL-lactide), PURASORB PDL 05 is formulated as the matrix polymer at a concentration of 15–25% (w/v) in methylene chloride or ethyl acetate; the active pharmaceutical ingredient is co-dissolved or dispersed at a loading of 10–25% (w/w) relative to total solids. Compliance for in vivo use of the resulting microspheres draws on USP <711> for release-rate testing in Apparatus 4 or 1, ICH Q3C for residual methylene chloride and ethyl acetate, and ISO 10993-1:2018 for biological evaluation of the implant-classified dosage form. The primary emulsion is generated in a rotor-stator homogenizer at 10,000–20,000 rpm, then transferred into an aqueous continuous phase containing 0.5–2.0% polyvinyl alcohol at 35 °C for solvent extraction; after hardening, the microspheres are wet-sieved through a 100 µm mesh and lyophilized with mannitol 3–5% as cryoprotectant. Terminal product types include extended-release depot formulations for GnRH agonists, somatostatin analogues, antipsychotics, and other peptide/oligonucleotide actives where amorphous polymer hydrolysis rates are matched to dosing intervals of 1–6 months. Batch-to-batch particle size is controlled by laser diffraction on a Malvern Mastersizer 3000 with D50 maintained at 40–70 µm; deviation beyond this range after scale-up from 2 L to 50 L reactor is attributed to shear-rate differences at the impeller tip and requires adjustment of continuous-phase viscosity rather than stabilizer concentration alone.
Antisolvent precipitation of PURASORB PDL 05 for poorly water-soluble actives begins with a polymer concentration of 1.0–5.0% (w/v) in tetrahydrofuran or acetone, with drug-to-polymer ratios fixed between 1:5 and 1:10 and a stabilizer selected from poloxamer 188 or polysorbate 80 at 0.1–0.5% (w/v) in the aqueous antisolvent. Because the amorphous copolymer has a glass transition temperature near 45–55 °C, precipitation under 4–10 °C antisolvent conditions avoids particle coalescence above Tg. Compliance testing centers on ISO 10993-5:2009 for cytotoxicity, ICH Q3C for residual THF and acetone, and ASTM E2490-08(2020) for intensity-weighted particle size distribution by dynamic light scattering. The downstream process uses a confined impinging jet mixer with a 100 µm nozzle; organic and aqueous streams are pumped at 10 mL/min and 40 mL/min respectively to achieve mixing times shorter than 10 ms, followed by immediate dilution into 10 volumes of cold water. Solvent is removed by rotary evaporation at 30 °C under reduced pressure, and the nanosuspension is lyophilized with sucrose 5–10% (w/v) as cryoprotectant. Terminal product types include sterile nanoparticle lyophilisates for oncology, ocular delivery, and long-circulating injectable preparations; published data for this specific polymer configuration at commercial scale is limited, and pilot-scale runs require particle size characterization at each batch due to sensitivity of the organic-to-water ratio to nozzle fouling.
When a drug-eluting stent requires a conformal bioresorbable coating that remains amorphous at body temperature, PURASORB PDL 05 is applied as a spray solution at 0.5–2.0% (w/v) total solids in ethyl acetate/THF 70:30 (v/v), with an antiproliferative agent such as sirolimus or tacrolimus co-dissolved at a drug-to-polymer ratio of 25:75 to 50:50. The coating is deposited by an ultrasonic atomizer operating at 20–40 kHz and 0.05–0.10 mL/min per nozzle onto the stent fixture; a target dried coating thickness of 2–5 µm is measured by scanning electron microscopy on witness coupons. Compliance requires ISO 10993-4:2017 for hemocompatibility, ISO 10993-6:2016 for local implantation reactions, and ISO 1133-1:2022 for melt-flow characterization of any compression-molded reference plaques used to verify polymer degradation after e-beam sterilization. The downstream process includes a drying step at 40 °C under vacuum for 24 h to reduce residual ethyl acetate below ICH Q3C limits before crimping onto balloon catheters. Terminal product types include coronary and peripheral drug-eluting stents, with the amorphous DL-lactide matrix selected where mechanical flexibility after expansion must be maintained without brittle fracture of the coating; delamination and cracking at crimp strains above 20% are monitored by optical microscopy after balloon expansion in simulated vessel fixtures. Published data for this specific PURASORB PDL 05 coating configuration is limited, so expansion testing should be repeated on each lot of spray-coated stents rather than assuming transferability from bench-top dip-coating trials.
In situ depot formation from PURASORB PDL 05 requires dissolution in N-methyl-2-pyrrolidone at 35–45% (w/w), with the active added at 2–10% (w/w) and the balance composed of NMP; the resulting solution has sufficiently low viscosity to pass through a 21-gauge needle at 25 °C. Upon contact with aqueous physiological fluid, solvent diffusion drives phase inversion and forms an amorphous depot whose drug release is governed by the polymer-rich membrane and bulk hydrolysis. Compliance for clinical use includes ISO 10993-11:2017 for systemic toxicity, ISO 10993-6:2016 for implantation, and ICH Q3C for residual NMP, which carries a permitted daily exposure of 5.3 mg/day as a Class 2 solvent. The downstream process is aseptic compounding under an isolator because terminal filtration through sterilizing-grade membranes is not feasible at 45% polymer concentration; the final solution is filled into pre-sterilized vials or dual-chamber syringes and may be terminally gamma-irradiated at 25 kGy only after confirming that inherent viscosity loss remains below 10% by capillary viscometry. Terminal product types include subcutaneous depots for antipsychotics, analgesia, and veterinary contraceptive or antiparasitic applications; comparisons with PLGA in situ gels indicate the absence of glycolide units in PURASORB PDL 05 alters acid-buffer capacity and should be addressed by dissolution testing in USP <711> Apparatus 4 rather than a simple paddle method. Because the polymer-rich depot is not a pre-formed implant, the injectable solution must be characterized by droplet-free appearance and syringeability force below 25 N at 1 mL/min on a texture analyzer fitted with a 21-gauge needle.
A co-rotating twin-screw extruder with an L/D ratio of 40:1 and a 1.5 mm strand die melt-compounds PURASORB PDL 05 with thermostable small-molecule actives at 20–40% (w/w) drug loading; processing-zone temperatures are held between 110 °C and 140 °C, and screw speed is set at 100 rpm. Because the initial inherent viscosity midpoint of 0.5 dL/g in chloroform at 25 °C is already relatively low, the residence time during extrusion is limited to 2–4 min to avoid hydrolytic chain scission and a resulting drop in strand integrity. Downstream processing includes water-bath quenching at 10 °C, pelletization to 2–3 mm granules, and compression molding at 120 °C and 10 MPa to form cylindrical subcutaneous rods or flat biodegradable wafers. Compliance for the finished implant requires ISO 10993-1:2018 evaluation endpoints, ISO 10993-6:2016 local tissue response, and ISO 13485:2016 controls for the extrusion and packaging line; residual monomer content is measured by gas chromatography against the polymer manufacturer’s monograph. Automated vision inspection rejects strands with diameter variability exceeding ±10%, a common failure mode when moisture content before extrusion rises above 0.1%; therefore pre-drying at 40 °C under vacuum for 12 h is mandatory when ambient relative humidity exceeds 60%. Terminal product types include hormonal implant rods, analgesic wafers, and veterinary subcutaneous pellets; the formulation should avoid combination with amine-based additives at processing temperature because base-catalyzed ester hydrolysis accelerates chain scission. Published data for melt-extruded PURASORB PDL 05 at production scale is limited, so pilot batches should include intrinsic-viscosity sampling at the die exit to establish lot-specific boundaries for degradation.
To form tip-sharp dissolvable microneedles, PURASORB PDL 05 is cast from a 10–15% (w/v) solution in dichloromethane or acetone, with a water-soluble plasticizer such as glycerol at 1–3% (w/w) and a vaccine or small-molecule antigen at 5–15% (w/w) relative to polymer. The solution is transferred into polydimethylsiloxane negative molds and centrifuged at 2,000 × g for 10 min to fill pyramidal or conical microcavities of 500–800 µm height; residual solvent is evaporated at 25 °C for 48 h, then vacuum-dried at 1 mbar to comply with ICH Q3C residual-methylene chloride limits. Compliance testing includes ISO 10993-10:2010 for skin sensitization and irritation, ISO 10993-5:2009 for cytotoxicity of extracts, and ISO 10993-23:2021 for skin irritation if the array breaches the stratum corneum. The downstream process includes demolding under a stereomicroscope to reject tip-fracture defects, then inkjet or manual loading of the active if a backing-layer approach is preferred; a 2 cm² array typically contains 50–100 needles, each with a tip radius below 5 µm. Terminal product types include intradermal vaccine patches, lidocaine fast-dissolving arrays, and cosmetic peptide delivery systems; process control focuses on polymer-solution viscosity at 25 °C below 500 mPa·s, because higher values prevent complete tip filling and generate measurable loss of payload in the upper mold cavity.
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PURASORB PDL 05 Drug Delivery is a bioresorbable poly(D,L-lactide) copolymer in which D-lactide and L-lactide repeat units are arranged in a random sequence. The product is supplied as white to off-white granules and is manufactured under a drug delivery quality system intended for parenteral controlled-release matrices, microparticle systems, and combination products. The nominal inherent viscosity is 0.4–0.6 dL/g, measured in chloroform at 25 °C at a concentration of 0.1 g/dL. This places the grade in the low-to-mid molecular weight band of the PURASORB PDL series. Because the D,L configuration suppresses stereoregularity, PURASORB PDL 05 is amorphous under normal processing conditions and exhibits a glass transition temperature of 50–55 °C by ISO 11357-2:2020, with no detectable crystalline melting point. The polymer is acid-terminated rather than ester-endcapped, a specification that influences hydration kinetics, degradation autocatalysis, and interaction with weakly basic active pharmaceutical ingredients.
| Parameter | Specification / Typical Value | Reference Method |
|---|---|---|
| Appearance | White to off-white granules | Visual inspection |
| Inherent viscosity | 0.4–0.6 dL/g | Chloroform, 25 °C, 0.1 g/dL |
| Glass transition temperature | 50–55 °C | ISO 11357-2:2020 |
| Residual lactide monomer | ≤0.5 wt% | High-performance liquid chromatography |
| Water content | ≤0.5 wt% | Karl Fischer titration |
| Tin catalyst residue | ≤200 ppm | Inductively coupled plasma mass spectrometry |
| Residual solvents | Complies with ICH Q3C Option 1 limits | Headspace gas chromatography |
| Heavy metals | ≤10 ppm | USP 232/USP 233 |
The specification set imposes storage and handling constraints. Because the polyester backbone hydrolyzes in the presence of moisture, unopened containers should be kept at -15 °C or below and allowed to equilibrate to room temperature in sealed packaging before opening. Bulk granules exposed to relative humidity above 60% for extended periods can adsorb sufficient water to reduce molecular weight during subsequent melt or solvent processing. Vacuum drying at 40 °C for 24 h to a water content of ≤0.1 wt% is a common pre-processing requirement when melt extrusion or moisture-sensitive formulations are used.
The acid-terminated architecture of PURASORB PDL 05 provides one terminal carboxylic acid group per polymer chain. In aqueous media, ester hydrolysis proceeds by random scission of the backbone and by autocatalytic chain-end reactions involving carboxylic acid groups. The result is that an acid-terminated poly(D,L-lactide) of a given inherent viscosity displays earlier mass loss and a more pronounced internal pH depression than an ester-endcapped analogue of equivalent chain length when tested in low-buffer-capacity environments such as 0.01 M phosphate-buffered saline at 37 °C and pH 7.4.
For monolithic implants and large microspheres, the degradation front is controlled by the competing rates of water diffusion and water-soluble oligomer clearance. If the characteristic diffusion path is long and the surrounding buffer capacity is low, acidic degradation products accumulate inside the matrix. This creates an autocatalytic core-accelerated degradation pattern rather than a uniform surface erosion process. The effect is relevant when formulators compare PDL 05 with ester-terminated DL-lactide grades of the same inherent viscosity. Published in vitro data for racemic poly(D,L-lactide) of similar inherent viscosity show degradation half-times ranging from several weeks to several months depending on sample geometry, porosity, and buffer exchange rate; direct extrapolation to PURASORB PDL 05 requires geometry-specific testing because of the acid-terminated end-group contribution.
The acid functionality also affects drug-polymer interactions. Weakly basic drugs can form reversible ionic complexes with surface carboxylic acid groups, altering burst release and encapsulation efficiency in emulsion-based processes. This interaction is not observed to the same extent with ester-terminated grades. When a therapeutic agent contains primary or tertiary amine substituents, a compatibility assessment should be performed by differential scanning calorimetry and HPLC recovery from stressed mixtures at 40 °C and 75% RH for 4 weeks. Isothermal microcalorimetry is an alternative technique for detecting incompatibility before committing to scale-up.
Solvent-based microencapsulation of PURASORB PDL 05 is typically performed by dissolving the granules in dichloromethane at 10–20 wt%. The active ingredient is either dissolved in the polymer solution or dispersed as a micronized solid. The organic phase is emulsified into a continuous aqueous phase containing 1–5% w/v partially hydrolyzed poly(vinyl alcohol) using a high-shear mixer such as a Silverson L5M-A fitted with a square-hole high-shear screen. Rotor speeds between 3,000 rpm and 10,000 rpm generate emulsion droplets with volume moment mean diameters in the 20–120 µm range, measured by laser diffraction according to ISO 13320:2020. Solvent removal proceeds in a stirred hardening bath with 0.5–2.0% w/v PVA at 25 °C, followed by vacuum drying at 30–40 °C for 24–48 h. The powder bed temperature must remain below the glass transition to prevent particle sintering; jacketed vacuum tumble dryers with controlled ramp rates are preferred over static ovens because crust formation can trap residual solvent. Dichloromethane must be driven below 600 ppm to meet the ICH Q3C Class 2 residual solvent limit for parenteral products. In practice, residual solvent removal is often the rate-limiting unit operation rather than particle formation. High residual dichloromethane plasticizes the amorphous matrix, lowers the glass transition, and can cause particle aggregation during terminal sterilization or accelerated stability storage.
Conversion of PURASORB PDL 05 from solvent-based to melt-based processing is constrained by the thermal degradation window. Melt extrusion of amorphous poly(D,L-lactide) requires barrel temperatures between 100 °C and 140 °C, typically on a 16 mm or 18 mm co-rotating twin-screw extruder with an L/D ratio from 25:1 to 40:1. The feed throat should be jacketed below 30 °C to prevent pellet bridging as the temperature approaches the glass transition. Residence time at 120 °C should remain below 5 min, and melt pressure should be monitored continuously because viscosity reduction can indicate hydrolytic or thermal chain scission. Vacuum drying to ≤0.1 wt% water is required before extrusion; moisture in the melt produces bubbles and reduces molecular weight retention. Addition of plasticizers such as triethyl citrate at 5–10 wt% can lower processing temperature but may increase release rate by reducing the effective glass transition below 37 °C. Published data on hot-melt extrusion of this specific acid-terminated grade is limited. Process qualification should include melt mass-flow rate measurement according to ISO 1133-1:2022 and gel permeation chromatography before and after extrusion. Melt-processed implants may also exhibit a more homogeneous matrix and lower residual solvent burden than solvent-cast systems, but the thermal history can cause premature molecular weight loss if the screw speed, barrel profile, and die backpressure are not matched to the grade.
In-situ forming depot systems prepared from PURASORB PDL 05 ordinarily contain 20–40 wt% polymer dissolved in N-methyl-2-pyrrolidone or dimethyl sulfoxide. The solution is injected through a 21–23 G needle into an aqueous subcutaneous or intramuscular environment. Phase inversion occurs as the water-miscible solvent exchanges with water; the polymer precipitates and entrains the active substance. N-methyl-2-pyrrolidone produces a rapid coagulation front due to high mutual miscibility with water, whereas dimethyl sulfoxide slows phase inversion and can reduce initial burst but yields a softer depot. Syringeability is governed by zero-shear viscosity. Solutions above 2,000 cP at 25 °C generally require a 21 G needle or wider, and manual injection force above 50 N is considered unsuitable for routine administration. Residual N-methyl-2-pyrrolidone must be assessed against the ICH Q3C permitted daily exposure of 5.3 mg/day; because the solvent is released systemically during the first 24 h, the total solvent load must be scaled against the intended dose. The acid-terminated polymer is soluble in N-methyl-2-pyrrolidone and dimethyl sulfoxide at room temperature, but dissolution times can exceed 12 h for 40 wt% solutions unless a low-shear roller mixer is used. Filtration of these viscous formulations is not practical through sterilizing-grade membranes, so aseptic processing or terminal sterilization must be justified on a product-specific basis.
PURASORB PDL 05 differs from PLGA 50:50 copolymers primarily by the absence of glycolide. Glycolide repeat units increase hydrophilicity and accelerate hydrolysis; therefore, PLGA 50:50 matrices typically lose mass faster than PDL 05 matrices of comparable molecular weight. The poly(D,L-lactide) backbone is more hydrophobic, has a higher glass transition temperature than many PLGA copolymers, and is selected when longer depot persistence or slower water uptake is required. Compared with PURASORB PDL 02, PDL 05 provides higher solution viscosity and greater matrix integrity at equivalent solvent loading, which is advantageous for larger microspheres and implants but requires higher-torque mixing and longer dissolution times. Compared with PURASORB PDL 06, PDL 05 has lower inherent viscosity and therefore lower solution viscosity at a given concentration, which can improve syringeability in in-situ forming systems and reduce melt pressure in extrusion. The acid-terminated specification distinguishes PDL 05 from ester-terminated analogues of the same inherent viscosity; the acid end-group increases initial chain-end hydrophilicity and contributes to autocatalytic degradation.
| Material | Inherent Viscosity | Monomer System | End-Group | Processing Implication |
|---|---|---|---|---|
| PURASORB PDL 02 | 0.15–0.25 dL/g | DL-lactide | Acid | Low solution viscosity; short matrix persistence |
| PURASORB PDL 05 | 0.40–0.60 dL/g | DL-lactide | Acid | Intermediate viscosity; suitable for solvent-based depots |
| PURASORB PDL 06 | 0.60–0.80 dL/g | DL-lactide | Acid | Higher viscosity; slower hydrolysis; difficult to filter |
| Ester-terminated DL-lactide analogue | Equivalent IV | DL-lactide | Ester | Reduced chain-end hydrophilicity; less autocatalysis |
| PLGA 50:50 reference | Equivalent IV | DL-lactide/glycolide | Acid or ester | Faster water uptake; faster mass loss |
The choice between PDL 05 and related products should be driven by the desired release duration, the selected manufacturing route, and the residual solvent or melt-processing constraints. In solvent-rich processes, PDL 05 offers sufficient chain length to form cohesive matrices without the viscosity penalty of higher-molecular-weight grades. In melt processes, its handling window is narrow because the glass transition is close to ambient temperature and the polyester backbone is thermally sensitive. The material is not suitable for applications requiring an aggressive alkaline environment or prolonged exposure to high-humidity aqueous dispersions without molecular weight monitoring. End users must verify biocompatibility and regulatory compliance for the finished combination product under ISO 10993-1:2018, USP 85 for bacterial endotoxins, and ICH Q3C for residual solvents, as the raw polymer specification alone does not confer finished-product acceptance.
