Eudragit®: a technology evaluation

Introduction: Eudragit is the brand name for a diverse range of polymethacrylate-based copolymers. It includes anionic, cationic, and neutral copolymers based on methacrylic acid and methacrylic/acrylic esters or their derivatives.

Areas covered: In this review, the physicochemical characteristics and applications of different grades of Eudragit in colon-specific/enteric-coated/sustained release drug delivery and taste masking have been addressed.

Expert opinion: Eudragits are amorphous polymers having glass transition temperatures between 9 to > 150^oC. Eudragits are non-biodegradable, nonabsorbable, and nontoxic. Anionic Eudragit L dissolves at pH > 6 and is used for enteric coating, while Eudragit S, soluble at pH > 7 is used for colon targeting. Studies in human volunteers have confirmed that pH drops from 7.0 at terminal ileum to 6.0 at ascending colon, and Eudragit S based systems sometimes fail to release the drug. To overcome the shortcoming, combination of Eudragit S and Eudragit L which ensures drug release at pH < 7 has been advocated. Eudragit RL and RS, having quaternary ammonium groups, are water insoluble, but swellable/permeable polymers which are suitable for the sustained release film coating applications. Cationic Eudragit E, insoluble at pH ≥ 5, can prevent drug release in saliva and finds application in taste masking.     

Salmon calcitonin-loaded Eudragit® and Eudragit®-PLGA nanoparticles: in vitro and in vivo evaluation

The main objective of this study was to prepare salmon calcitonin (sCT)-loaded Eudragit®RSPO, Eudragit®L100 and Eudragit®-poly(lactic-co-glycolic acid) blend nanoparticles for in vitro and in vivo evaluation as an oral drug delivery system. The prepared nanoparticles ranged in size from 179.7 to 308.9?nm with a polydispersity index between 0.051 and 2.75, and had surface charges ? ?11 to +6?mV. Efficient sCT encapsulation and release was observed with all the nanoparticle formulations. The polymer type was an important factor that influenced the release characteristics and the in vivo hypocalcemic effect. Nanoparticle formulations were also prepared with sodium taurodeoxycholate (NaTDC) and characterized. No statistically significant difference was noted between the hypocalcemic effect of any of the nanoparticle formulations with and without NaTDC (p?>?0.05). The use of Eudragit®RSPO nanoparticles appears to be a potential approach for the oral delivery of sCT.     

Salmon calcitonin-loaded Eudragit® and Eudragit®-PLGA nanoparticles: in vitro and in vivo evaluation

The main objective of this study was to prepare salmon calcitonin (sCT)-loaded Eudragit?RSPO, Eudragit?L100 and Eudragit?-poly(lactic-co-glycolic acid) blend nanoparticles for in vitro and in vivo evaluation as an oral drug delivery system. The prepared nanoparticles ranged in size from 179.7 to 308.9?nm with a polydispersity index between 0.051 and 2.75, and had surface charges ~ -11 to +6?mV. Efficient sCT encapsulation and release was observed with all the nanoparticle formulations. The polymer type was an important factor that influenced the release characteristics and the in vivo hypocalcemic effect. Nanoparticle formulations were also prepared with sodium taurodeoxycholate (NaTDC) and characterized. No statistically significant difference was noted between the hypocalcemic effect of any of the nanoparticle formulations with and without NaTDC (p?>?0.05). The use of Eudragit?RSPO nanoparticles appears to be a potential approach for the oral delivery of sCT.     

Effect of pH on Diclofenac Release from Eudragit RS100® Microparticles. A Kinetic Study by DSC

The present work is aimed at investigating the release of Diclofenac (DCF) from Eudragit RS100T® (RS) microparticles to a biological model membrane consisting of dimyristoylphosphatidylcholine (DMPC) multilamellar vesicles (MLV). The microparticles were prepared by the Quasi-Emulsion Solvent Diffusion method (QESD). The drug release was monitored by Differential Scanning Calorimetry (DSC) technique, following the effects exerted by DCF on the thermotropic behaviour of DMPC multilamellar vesicles at different temperatures. DCF affects the transition temperature (T_m) of phospholipid vesicles, causing a m shift towards lower values, which is modulated by the drug fraction entering into the lipid bilayer. Calorimetric measurements were performed at two different pH (4.0 and 7.4) on suspensions of blank liposomes added to weighed amounts of unloaded and DCF-loaded microspheres, as well as to the powdered free drug, after incubation at 37°C. The T_m shifts, caused by the drug released from the polymeric system or by the free drug during incubation cycles, were compared to those caused by a chosen molar fractions of the free drug dispersed directly in the membrane. This in vitro study suggests as the kinetic process involved in drug release is influenced by the amount of drug loaded in the microspheres as well as by the pH value, acting on drug solubility and membrane disorder.     

Physical characterization of carteolol: Eudragit® L binding interaction

Eudragit® L 30D was used as a carrier to prepare carteolol polymeric complexes in order to obtain controlled release dosage forms. The polyanionic form of the polymer, neutralized at different degrees, reacts readily with carteolol hydrochloride to give water-insoluble complexes. Carteolol complexes were characterized by differential scanning calorimetry, IR, ¹H- and ¹³C-NMR spectroscopy. In fact, results indicated that there were intermolecular associations between the polymer and the drug consisting in ammonium salt interactions. Maximum carteolol content was found to be 22% in the complexes.     

Identification of Phase Separation in Solid Dispersions of Itraconazole and Eudragit® E100 Using Microthermal Analysis

Purpose. To evaluate the phase separation in itraconazole/Eudragit® E100 solid dispersions prepared by hot-stage extrusion. Methods. Extrudates were prepared using a corotating twin-screw extruder at 180°C. Micro-TA was used to evaluate the phase separation, where the AFM mode is used to visualize the different phases and local thermal analysis (LTA) to characterize the different phases Results. Itraconazole formed a homogeneous mixture with Eudragit® E100 with drug concentrations up to approximately 20%. Above this concentration, phase separation was observed. MTDSC revealed two T_gs and the mesophase of free glassy itraconazole. Performing micro-TA on the surface of these dispersions indicated an increase in sample roughness in the z-axis piezo signal, which could be an indication of free glassy itraconazole. However, thermal conductivity did not reveal differences between separate phases. Performing LTA, where only a small area (20 × 20 m) is heated, showed two separate and mixed phases of itraconazole and Eudragit® E100. Tip penetration in itraconazole and Eudragit® E100 occurred at 332K and 383K respectively. The difference in tip penetration was explained in terms of the difference in fragility. Conclusion. Micro-TA makes it possible to characterize separate phases of itraconazole and Eudragit® E100, thereby confirming the MTDSC results on phase separation.     

Optimization of Nanostructured Lipid Carriers of Lurasidone Hydrochloride Using Box-Behnken Design for Brain Targeting: In Vitro and In Vivo Studies

Intranasal nanostructured lipid carrier (NLC) of lurasidone hydrochloride (LRD) for brain delivery was prepared by the solvent evaporation method. The effects of independent variables, X1-lipid concentration, X-2 surfactant, and X-3 sonication times on dependent variables, Y1-particle size, Y-2 polydispersity index, and Y-3% entrapment efficiency were determined using Box-Behnken design. Optimized LRD-NLC was selected from the Box-Behnken design and evaluated for their morphological, physiological, nasal diffusion, and in vivo distribution in the brain after intranasal administration. Particle size, polydispersity index, and entrapment efficiency of optimized LRD-NLC were found to be 207.4 ± 1.5 nm, 0.392 ± 0.15, and 92.12 ± 1.0%, respectively. Transmission electron microscopy and scanning electron microscopy was used to determine the particle size and surface morphology of LRD-NLC. The prepared LRD-NLC follows biphasic in vitro drug release. Prepared NLC showed a 2-fold increase in LRD concentration in the brain when compared with the drug solution following intranasal administration. Results showed that intranasal route can be a good and efficient approach for delivering the drug directly to the brain and enhancing the drug efficacy in the brain for the management of schizophrenia and a good alternative to oral drug delivery.     

Application of a Mixture Experimental Design in the Optimization of a Self‐Emulsifying Formulation with a High Drug Load

Response surface methodology (RSM) was applied to optimize the self‐emulsifying drug delivery system (SEDDS) containing 25% (w/w) Drug A, a model drug with a high lipophilicity and low water solubility. The key objective of this study was to identify an optimal SEDDS formulation that: 1) possesses a minimum concentration of the surfactant and a maximum concentration of lipid and 2) generates a fine emulsion and eliminates large size droplets (≥ 1 µm) upon dilution with an aqueous medium. Three ingredient variables [PEG 400, Cremophor EL, and a mixture of glycerol dioleate (GDO), and glycerol monooleate (GMO)] were included in the experimental design, while keeping the other ingredients at a fixed level (25% Drug A, 6% ethanol, 3% propylene glycol, 4% water, and 2% tromethamine) in the SEDDS formulation. Dispersion performance of these formulations upon dilution with a simulated gastrointestinal fluid was measured, and the population of the large droplets was used as the primary response for statistical modeling. The results of this mixture study revealed significant interactions among the three ingredients, and their individual levels in the formulation collectively dictated the dispersion performance. The fitted response surface model predicted an optimal region of the SEDDS formulation compositions that generate fine emulsions and essentially eliminates large droplets upon dilution. The predicted optimal 25% Drug A–SEDDS formulations with the levels of Cremophor EL ranging from 40–44%, GDO/GMO ranging from 10–13%, and PEG 400 ranging from 2.7–9.0% were selected and prepared. The dispersion experiment results confirmed the prediction of this model and identified potential optimal formulations for further development. This work demonstrates that RSM is an efficient approach for optimization of the SEDDS formulation.     

Interaction between Eudragit® E100 and anionic drugs: addition of anionic polyelectrolytes and their influence on drug release performance

In this work, we report results concerning the study of solid complexes compounded by a cationic polymethacrylate (Eudragit® E100, Eu) and mesalazine (M) (Eu–M_x complex). The influence of an anionic polyacrylic acid polymer (carbomer, C) on dissolution behavior of M from the complex was evaluated (Eu–M_xC_y complex). The dissolution profiles and solvent front movements of solid matrices in different media (water, buffer pH 7.4, 0.9% NaCl) were investigated and ionic interactions among Eu, M, and C were determined through Fourier transform infrared (FT‐IR) spectroscopy. For Eu–M_x complexes, the affinity between M and Eu modulated the delivery of free M in solution, with the dissolution media affecting the delivery rate mainly due to an ionic interchange process between M and anionic electrolytes (i.e., Cl^?). FTIR spectroscopy allowed the ionic interaction between Eu and M to be verified. The addition of C (Eu–M_xC_y) influenced the dissolution behavior of these matrices. As the amount of C was increased, the release mechanism changed from diffusion (Eu–M₅₀) or anomalous (Eu–M₁₀₀) to zero order (Eu–M_xC₅₀). This variation in rate delivery was also affected by the dissolution media, as occurred with Eu–M_x complexes. The formation of the gel layer during the dissolution process, as consequence of Eu–M_xC_y matrices hydration, was influenced by C amount and dissolution media. © 2011 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:4664–4673, 2011     

Colon-targeted celecoxib-loaded Eudragit® S100-coated poly-ϵ-caprolactone microparticles: Preparation,characterization and in vivo evaluation in rats

Context: Celecoxib suffers from low and variable bioavailability following oral administration of solutions or capsules. Recent studies proved that chemoprevention of colorectal cancer is possible with celecoxib.

Objective: This work aimed to tailor colon-targeted celecoxib-loaded microparticles using time-dependant and pH-dependant coats. Estimation of drug pharmacokinetics following oral administration to fasted rats was another goal.

Methods: A 2³ factorial design was adopted to develop poly-?-caprolactone (PCL) celecoxib-loaded microparticles (F1–F8). To minimize drug-percentages released before colon, another coat of Eudragit^® S100 was applied. In vitro characterization of microparticles involved topography, determination of particle size and entrapment efficiency (EE %). Time for 50% drug release (t_50%) and drug-percentages released after 2 hours (Q_2h) and 4 hours (Q_4h) were statistically compared. Estimation of drug pharmacokinetics following oral administration of double-coat microparticles (F10) was studied in rats.

Results: PCL-single-coat microparticles were spherical, discrete with a size range of 60.66?±?4.21–277.20?±?6.10 μm. Direct correlations were observed between surfactant concentration and EE%, Q_2h and Q_4h. The PCL M.wt. and drug: PCL ratio had positive influences on EE% and negative impacts on Q_2h and Q_4h. When compared to the best achieved PCL-single-coat microparticles (F2), the double-coat microparticles (F10) showed satisfactory drug protection; Q_2h and Q_4h were significantly (P?<?0.01) decreased from 31.84?±?1.98% and 54.72?±?2.10% to 15.92?±?1.78% and 26.93?±?2.76%, respectively. When compared to celecoxib powder, F10 microparticles enhanced the bioavailability and extended the duration of drug-plasma concentration in rats.

Conclusion: The developed double-coat microparticles could be considered as a promising celecoxib extended-release colon-targeting system.     

Enhancement of felodipine dissolution rate through its incorporation into Eudragit® E-PHB polymeric microparticles: in vitro characterization and investigation of absorption in rats

In this study, felodipine was incorporated into microparticles prepared with Eudragit? E and it blended with poly(3-hydroxybutyrate) (PHB) using the emulsion-solvent evaporation technique, with the aim of improving the dissolution rate of the drug. The formulation prepared with Eudragit? E showed irregular and fragmented microparticles, with a loading efficiency (LE) of 82.6%. When the microparticles were prepared with a blend of Eudragit? E and PHB, they had a spherical form with a LE of 103.9%. X-ray diffraction and differential thermal analysis indicated a reduction in the crystallinity of felodipine after its incorporation into the microparticles, which caused a significant increase in the felodipine dissolution rate. An investigation into the absorption in rats was carried out using high-performance liquid chromatography analysis of the blood collected 20 and 60 min after the animals were administered felodipine [30 mg/Kg, orally (p.o.)] or felodipine microparticles (30 mg/Kg, p.o.). Animals that were given felodipine showed mean plasmatic levels of 0.0125 (±0.00156) and 0.0240 (±0.0069) μg mL(-1) after 20 and 60 min, respectively, whereas animals that received microparticles containing felodipine showed respective mean plasmatic levels of 0.0651 (±0.0120) and 0.0369 (±0.0145) μg mL(-1) . Our data suggest that the incorporation into microparticles significantly enhanced the release of felodipine, improving its absorption in rats.