Aminoalkyl Methacrylate Copolymer Research Articles

Polymer Characteristics for Drug Layering on Particles Using a Novel Melt Granulation Technology, MALCORE®.

MALCORE®, a novel manufacturing technology for drug-containing particles (DCPs), relies on the melt granulation method to produce spherical particles with high drug content. The crucial aspect of particle preparation through MALCORE® involves utilizing polymers that dissolve in the melt component, thereby enhancing viscosity upon heating. However, only aminoalkyl methacrylate copolymer E (AMCE) has been previously utilized. Therefore, this study aims to discover other polymers and comprehend the essential properties these polymers need to possess. The results showed that polyvinylpyrrolidone (PVP) was soluble in the stearic acid (SA) melt component. FTIR examination revealed no interaction between SA and polymer. The phase diagram was used to analyze the state of the SA and polymer mixture during heating. It revealed the mixing ratio and temperature range where the mixture remained in a liquid state. The viscosity of the mixture depended on the quantity and molecular weight of the polymer dissolved in SA. Furthermore, the DCPs prepared using PVP via MALCORE® exhibited similar pharmaceutical properties to those prepared with AMCE. In conclusion, understanding the properties required for polymers in the melt granulation process of MALCORE® allows for the optimization of manufacturing conditions, such as temperature and mixing ratios, for efficient and consistent drug layering.

Design of Ternary Amorphous Solid Dispersions for Enhanced Dissolution of Drug Combinations.

Using sulfamethoxazole (SMZ) and trimethoprim (TMP) as model drugs, we designed amorphous solid dispersions (ASDs) for the simultaneous solubility enhancement of two active pharmaceutical ingredients (APIs) by exploiting the drug-drug and drug-polymer interactions. In order to make this approach broadly applicable and over a wide dose range, a mixture of SMZ and TMP at weight ratios of 5:1 and 1:5 (w/w) were formulated into ternary ASDs. Depending on the dose ratio of the two drugs, the polymer used was either an aminoalkyl methacrylate copolymer (Eudragit, EDE) or polyacrylic acid. The drug-drug and drug-polymer interactions were characterized to be ionic by infrared and solid-state nuclear magnetic resonance spectroscopy. The interactions resulted in a substantial reduction in molecular mobility, evident from the increase in the structural relaxation time determined by dielectric spectroscopy. The drug-drug interaction resulted in ∼3 orders of magnitude reduction in molecular mobility. The addition of a polymer led to a further decrease in molecular mobility of up to 4 orders of magnitude. The strength of intermolecular interactions was also estimated from the glass transition temperatures of the ASDs obtained by differential scanning calorimetry. The strong intermolecular interactions yielded highly stable ASDs with no evidence of crystallization, both at elevated temperatures and under accelerated storage conditions (40 °C/75% relative humidity; 6 weeks). The dissolution performances of the ASDs were evaluated using the area under the curve (AUC) obtained from the concentration-time profiles under the non-sink condition. SMZ and TMP in their ternary ASDs, when compared with their crystalline counterparts, exhibited up to 6.4- and 4.6-fold increases in AUC, respectively. Importantly, the synchronized release of the two drugs was observed, a desirable attribute in synergistic formulations. A single-phase ternary ASD, stabilized by drug-drug and drug-polymer interactions, is likely responsible for the unique release profile.

Testosterone Sustained Release Microspheres for the Treatment of Fecal Incontinence

The objective of this study was to develop a testosterone sustained release formulation for the treatment of fecal incontinence. To suppress the initial burst release of testosterone, which can lead to systemic toxicity, we incorporated a washing step using an aminoalkyl methacrylate copolymer E solution or propylene glycol solution into a typical o/w emulsion method to prepare polylactic-co-glycolic acid microspheres. We used this method to develop a polylactic-co-glycolic acid microsphere formulation that shows sustained release of testosterone for up to one month. Not only did this formulation show a sustained release profile after administration into the intersphincteric groove in minipigs, it also increased both the anal pressure and mass of the external anal sphincter, while keeping systemic testosterone exposure low. Thus, this formulation successfully affected both the internal and external anal sphincters with a sufficient safety profile, deeming it a promising candidate treatment strategy for fecal incontinence.

Nanostructure and Molecular-Level Characterization of Aminoalkyl Methacrylate Copolymer and the Impact on Drug Solubilization Ability.

The effects of pH changes and saccharin (SAC) addition on the nanostructure and mobility of the cationic aminoalkyl methacrylate copolymer Eudragit E PO (EUD-E) and its drug solubilization ability were investigated. Small-angle X-ray scattering performed using synchrotron radiation and atomic force microscopy showed that the EUD-E nanostructure, which has a size of approximately several nanometers, changed from a random coil structure at low pH (pH 4.0-5.0) to a partially folded structure at high pH (pH 5.5-6.5). The EUD-E also formed a partially folded structure in a wide pH range of 4.5-6.5 when SAC was present, and the coil-to-globule transition was moderate with pH increase, compared with that when SAC was absent. The equilibrium solubility of the neutral drug naringenin (NAR) was enhanced in the EUD-E solution and further increased as the pH increased. The enlargement of the hydrophobic region of EUD-E in association with the coil-to-globule transition led to efficient solubilization of NAR. The interaction with SAC enhanced the mobility of the EUD-E chains in the hydrophobic region of EUD-E, resulting in changes in the drug-solubilizing ability. 1H high-resolution magic-angle spinning NMR measurements revealed that the solubilized NAR in the partially folded structure of EUD-E showed higher molecular mobility in the presence of SAC than in the absence of SAC. This study highlighted that solution pH and the presence of SAC significantly changed the drug solubilization ability of EUD-E, followed by changes in the EUD-E nanostructure, including its hydrophobic region.

Optimized Taste-Masked Microparticles for Orally Disintegrating Tablets as a Promising Dosage Form for Alzheimer's Disease Patients.

The objective of this research was to optimize the tasted-masked microparticles for orally disintegrating tablets containing donepezil hydrochloride using quality risk assessment and design of experiment approaches. The double emulsion solvent evaporation technique using aminoalkyl methacrylate copolymer (AMC) was used to prepare taste-masked microparticles. Factors affecting the quality of the taste-masked microparticles were analyzed using an Ishikawa diagram. A risk-ranking approach was used to rank the formulation and process risks. Furthermore, the effect of AMC quantity, stirring time, and volume of outer water phase on various responses, such as particle size, the amount of drug dissolved at 5 min (Q5) in simulated saliva fluid, and mean dissolution time (MDT) in simulated gastric fluid, was investigated using the Box-Behnken design. The optimized microparticles were then used to prepare orally disintegrating tablets (ODTs) and evaluated by in vitro and in vivo testing. The results demonstrated that particle size was influenced by the AMC amount and stirring time. Q5 was significantly affected by the amount of AMC and the volume of the outer water phase. On the other hand, these two factors had a positive effect on MDT. The optimized microparticles had a particle size of 174.45 ± 18.19 µm, Q5 of 5.04%, and MDT of 5.97 min. The ODTs with taste-masked microparticles showed acceptable in vitro dissolution with an MDT of 5 min. According to the results of a panel of six human volunteers, they greatly improved palatability.

Intermolecular Interactions between Drugs and Aminoalkyl Methacrylate Copolymer in Solution to Enhance the Concentration of Poorly Water-Soluble Drugs.

An aminoalkyl methacrylate copolymer, Eudragit® E (EUD-E), has gained tremendous attention as a solid dispersion carrier because it efficiently stabilizes drugs in the amorphous state. Furthermore, EUD-E remarkably enhances drug dissolution in water. This review focuses on the interaction between drugs and EUD-E in solution, which contributes to the enhancement of drug concentration. Studies examining interactions between acidic drugs and EUD-E in organic solvents have revealed that the interaction occurs predominantly by electrostatic interaction, including hydrogen bonding and dipolar interactions. Other studies on interactions in aqueous solution found evidence for strong electrostatic interactions between acidic drugs and EUD-E in ion exchange experiments. 1H-NMR studies using high-resolution magic-angle spinning, nuclear Overhauser effect spectroscopy, diffusion, and relaxation time measurements successfully identified the interaction site and strength in aqueous solution. Hydrophobic and ionic interactions occurred between drugs and EUD-E. The conformation of EUD-E, which was affected by the ionic strength and pH of the aqueous media, also influenced the interaction. The knowledge discussed in this review will be helpful in designing solid dispersion formulations with EUD-E, which will efficiently enhance drug concentration and subsequent absorption into the body.

Synthesis and application of aqueous stomach aminoalkyl methacrylate copolymer

A series of stomach cationic aminoalkyl methacrylate copolymer emulsions containing large number of tertiary amino groups in molecular side chain were prepared throughl emulsion polymerization, which take dimethylaminoethyl methacrylate, methyl methacrylate and butyl methacrylate as main raw materials. The The properties of the emulsions were characterized by Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). And effects of monomer mass ratio and emulsifier system on the properties of emulsions polymerization were also discussed. The results showed that the emulsion performance was stable when the amount of emulsifier was 4.5wt% taking cationic and non-ionic composite emulsifier as emulsifying system. At the same time, it has excellent moisture resistance and stable performance when used in pharmaceutical coating materials.

FORMULATION AND EVALUATION OF MICROSPHERE BASED ORO DISPERSIBLE TABLETS OF SUMATRIPTAN SUCCINATE

Sumatriptan succinate (SS) is a drug used in the treatment of migraine headaches, but suffers from low patient compliance due to its unpalatable bitter taste. The purpose of the present work was to prepare taste-masked oro dispersible tablets (ODTs) of SS by incorporating drug loaded microspheres into tablets for use in patients experiencing difficulty in swallowing. Microspheres loaded with SS were prepared by solvent evaporation technique. Eudragit EPO, a pH-sensitive aminoalkylmethacrylate copolymer, was used for coating the drug particles, acetone as solvent for the polymer and light liquid paraffin as an encapsulating medium. Drug : polymer ratio of 1:1 was considered to be optimized formulation with a yield of 99.96%, entrapment efficiency of 61.55%, particle size ranging from 30.32 – 90.96μm and in vitro drug release of 85.06% within an hour. FTIR studies suggested absence of drug-excipient interaction. Tablets prepared by direct compression containing microspheres and effervescent agents were evaluated for pre-compression and post-compression parameters. The wetting time, in vitro dispersion time and in vitro disintegration time of the tablets were found to be 39 sec, 35 sec and 32 sec, respectively. The drug release from the tablet was about 85.44% within an hour. The SEM of final ODTs revealed that the microspheres remained intact even after compression. Stability studies indicated that the selected formulation was stable. The results obtained suggested that effective taste-masking was achieved for SS using the technique of microencapsulation and ODTs of acceptable characteristics were obtained by adding effervescent agents followed by direct compression.

Application of water-insoluble polymers to orally disintegrating tablets treated by high-pressure carbon dioxide gas

The phase transition of pharmaceutical excipients that can be induced by humidifying or heating is well-known to increase the hardness of orally disintegrating tablets (ODTs). However, these conditions are not applicable to drug substances that are chemically unstable against such stressors. Here, we describe a system which enhances the hardness of tablets containing water-insoluble polymers by using high-pressure carbon dioxide (CO2). On screening of 26 polymeric excipients, aminoalkyl methacrylate copolymer E (AMCE) markedly increased tablet hardness (+155N) when maintained in a high-pressure CO2 environment. ODTs containing 10% AMCE were prepared and treatment with 4.0MPa CO2 gas at 25°C for 10min increased the hardness to +30N, whose level corresponded to heating at 70°C for 720min. In addition, we confirmed the effects of CO2 pressure, temperature, treatment time, and AMCE content on the physical properties of ODTs. Optimal pressure of CO2 gas was considered to be approximately 3.5MPa for an AMCE formula, as excessive pressure delayed the disintegration of ODTs. Combination of high-pressure CO2 gas and AMCE is a prospective approach for increasing the tablet hardness for ODTs, and can be conducted without additional heat or moisture stress using a simple apparatus.

Absorption improvement of sepantronium bromide (YM155) by aminoalkyl methacrylate copolymers in in situ intestinal tracts of mice

Sepantronium bromide (YM155) is a small molecule suppressant of survivin with time-dependent antitumor activity. In Phase II trials, the dosage form is a parenteral solution for continuous intravenous administration for 7 days. Although an oral YM155 formulation is required to improve patient convenience, oral bioavailability is low due to poor membrane permeability. Plasma concentrations of YM155 were significantly increased in intestinal loops pre-washed with phosphate buffered saline (p < 0.05). In addition, plasma concentrations of YM155 significantly decreased in the presence of mucin, which is a typical anionic substance in the intestinal tract (p < 0.05). Freeze-dried powder of aminoalkyl methacrylate copolymer (Eudragit® E) with HCl (E-FD) improved YM155 absorption in mice. In addition, E-FD suppressed the interaction between YM155 and mucin. These results suggest that E-FD improves YM155 absorption by reducing the interaction between YM155 and mucin. E-FD is therefore a promising candidate as an absorption-improving agent for the development of oral formulations of YM155.

Characterization of solid dispersions of Patchouli alcohol with different polymers: effects on the inhibition of reprecipitation and the improvement of dissolution rate

Solid dispersion technique is known to be an effective approach for the polymer to keep drugs stable in the solid state, thereby improving the dissolution rate and oral bioavailability through inhibiting reprecipitation in supersaturated solution. In this study, to evaluate the inhibitory effect of polyethylene glycol-6000 (PEG), Polyvinylpyrrolidone K30 (PVP) and Aminoalkyl methacrylate copolymer (Eudragit), the reprecipitation profiles were observed from supersaturated solutions of Patchouli alcohol (PA) in the presence and absence of the polymers. Furthermore, the dissolution profiles of PA solid dispersions formulated with PEG, PVP or Eudragit were compared for investigating the effect on improving dissolution of each polymer. Solid dispersions formulated with Eudragit were found to result in solution with the highest extent of supersaturation. By contrast, PEG and PVP were less effective. At equivalent supersaturation, all three polymers are capable of mitigating reprecipitation relative to that of PA alone. In addition, in the PA solid dispersion with Eudragit (E-SD (1/3)), the highest concentration of supersaturation of PA was maintained for prolonged time. These results unambiguously indicate that it is imperative to select the appropriate polymer and drug/polymer ratio in addition to considering the stability of the supersaturated solution, which was generated following dissolution of amorphous solid dispersion.

Aminoalkylmethacrylate copolymer E improves oral bioavailability of YM466 by suppressing drug–bile interaction

The aim of this study was to find out polymeric compounds that can inhibit the interaction between YM466, a novel anticoagulant, and bile to improve its oral bioavailability. In vitro ultrafiltration method using extract gall powder was useful to detect the formation of insoluble complex of YM466 with bile and also used to select a polymer that can inhibit the interaction between YM466 and bile. The in vitro studies revealed that aminoalkylmethacrylate (AAM) copolymer E, a polymethacrylate, dose-dependently inhibited the interaction between YM466 and bile and that this polymer could interact with bile salt, but not with YM466, possibly by electrostatic and/or hydrophobic interactions. The coadministration of AAM copolymer E with YM466 to rats dose-dependently increased the plasma concentration of YM466 and it was found that the oral dose of the polymer three times of YM466 (polymer to drug ratio in weight, P–D ratio, 3) significantly increased AUC0–1h of YM466 to 2.6-fold of that of YM466 alone. Considering the condition of therapeutic use of YM466 and the maximum tolerated dose of the polymer, the formulation of P–D ratio 3 would be clinically practical and promising from the viewpoint of safety. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:3128–3135, 2013

FORMULATION AND EVALUATION OF TASTE MASKED ORODISPERSIBLE TABLETS OF AMLODIPINE BESYLATE BY DIRECT COMPRESSION

The purpose of this investigation was undertaken to design a simple, rapid , cost effective and highly efficient process to fabricate intensely bitter taste of Amlodipine Besylate by complexing drug with Aminoalkyl methacrylate copolymer (Eudragit EPO) in different ratios by Hot - Melt Extrusion method. Taste masked complex were an alyzed with FTIR, DSC and XRD. DCP were tested for Hardness, Thickness, Weight Variation, Drug Content, Water absorption and In vitro Dispersion Test in Simulated Salivary Fluid pH 6.8. Taste masked granules were directly compressed into tablets using Koll odion CL and Croscarmellose Sodium (Ac - Di - Sol) as superdisintegrants. Tablets of batch F 6 containing mannitol and 6% wt/wt of Kollodion CL showed faster disintegration with in 24 sec and drug release (t 90 , 180sec) at Phosphate Buffer pH 6.8. The observed p olymer interaction and reduced crystallinity may be reason for increased dissolution rate. Thus results conclusively demonstrate successful masking of taste, disintegration and dissolution of the formulated

Investigation of internal structure of fine granules by microtomography using synchrotron X-ray radiation

Computed tomography (CT) using synchrotron X-ray radiation was evaluated as a non-destructive structural analysis method for fine granules. Two kinds of granules have been investigated: a bromhexine hydrochloride (BHX)-layered Celphere CP-102 granule coated with pH-sensitive polymer Kollicoat Smartseal 30-D, and a wax-matrix granule constructed from acetaminophen (APAP), dibasic calcium phosphate dehydrate, and aminoalkyl methacrylate copolymer E (AMCE) manufactured by melt granulation. The diameters of both granules were 200-300 μm. CT analysis of CP-102 granule could visualize the laminar structures of BHX and Kollicoat layers, and also visualize the high talc-content regions in the Kollicoat layer that could not be detected by scanning electron microscopy. Moreover, CT analysis using X-ray energies above the absorption edge of Br specifically enhanced the contrast in the BHX layer. As for granules manufactured by melt granulation, CT analysis revealed that they had a small inner void space due to a uniform distribution of APAP and other excipients. The distribution of AMCE revealed by CT analysis was also found to involve in the differences of drug dissolution from the granules as described previously. These observations demonstrate that CT analysis using synchrotron X-ray radiation is a powerful method for the detailed internal structure analysis of fine granules.

Effects of dissolved state of aminoalkyl methacrylate copolymer E/HCl on solubility enhancement effect for poorly water-soluble drugs

Eudragit® E/HCl salt (E–SD) displays a good antireprecipitation effect on solid dispersion formulations of poorly water-soluble drugs. To elucidate the mechanism underlying the antireprecipitation effect of E–SD, a study on supersaturation was conducted using a dissolution test method with test fluids at varying pH and ionic strength values. Both pH and ionic strength of the test fluid were shown to influence the antireprecipitation effect of E–SD; a strong antireprecipitation effect was observed at a neutral pH (pH 6∼7) and an ionic strength of 0.1 to 1.0. To investigate E–SD in its dissolved state in each test fluid, fluorescence measurement using pyrene as a probe molecule and dynamic light-scattering (DLS) measurement were conducted. The total fluorescence intensity of pyrene increased with increasing E–SD concentrations. Further, small nanoparticles were observed using DLS measurement. These results suggest that E–SD may form a micelle-like structure in the dissolved test fluid.

Effect of aminoalkyl methacrylate copolymer E/ HCl on in vivo absorption of poorly water-soluble drug

This study aimed to investigate in vivo absorption of tacrolimus formulated as a solid dispersion using Eudragit E®/HCl (E-SD). E-SD is an aminoalkyl methacrylate copolymer that can be dissolved under neutral pH conditions. E-SD was used alone as a solid dispersion carrier and/or was mixed with tacrolimus primarily dispersed with hydroxypropylmethylcellulose (HPMC). Tacrolimus was formulated with E-SD at several different ratios. Formulations with tacrolimus/E-SD ratio of 1/3 showed higher in vivo absorption, compared to tacrolimus dispersed in the excipients (primarily HPMC) found in commercially available tacrolimus capsules, using a rat in situ closed loop method. Good correlation was observed between in vitro drug solubility and in vivo drug absorption. In vitro solubility tests and rat oral absorption studies of tacrolimus/HPMC solid dispersion formulations were also conducted after mixing the HPMC dispersion with several ratios of E-SD. E-SD/tacrolimus/HPMC formulations yielded high in vitro drug solubility but comparatively low in vivo absorption. Dog oral absorption studies were conducted using capsules containing a formulation of tacrolimus/E-SD at a ratio of 1/5. The E-SD formulation-containing capsule showed higher in vivo drug absorption than tacrolimus dispersed in the standard HPMC capsule. These studies report enhancement of the in vivo absorption of a poorly water-soluble drug following dispersion with E-SD when compared to formulation in HPMC.

Preparation and evaluation of granules with pH-dependent release by melt granulation

This study had two objectives: (1) to prepare, by melt granulation in a high-shear mixer, granules containing acetaminophen (APAP) as a model drug and aminoalkyl methacrylate copolymer E (AMCE) as a pH-sensitive polymer that readily dissolves at pH values lower than 5, and (2) to investigate the effects of AMCE loading (5–15%) on granule properties and the in vitro release profile of drug from the granules. Compared with polymer-free granules, the granules containing 5% and 10% AMCE were found to have higher median diameters and wider particle size distributions. For the formulation containing 15% AMCE, on the other hand, the diameters and distribution were similar to those for polymer-free granules. From compression testing, load–displacement curves revealed that AMCE enhanced particle strength at ambient temperature and induced plastic strain, while suppressing fragmentation of the granules. In addition, from dissolution testing using media with pH 4.0 and pH 6.5, granules containing AMCE, except 15% AMCE loading, exhibited drug release with significant pH dependence. When the pH 4.0 and pH 6.5 dissolution profiles were further compared by calculating the difference factor (f1), the 5% AMCE granules showed the strongest pH dependence of drug release among all formulations in this study. Large cracks and breakage were observed on the surface of 10% AMCE granules after they were used in dissolution testing. The obtained results are attributed to the plastic strain properties of AMCE above its glass transition temperature, and to the irregular distribution of AMCE within granules. Hence, this study has demonstrated for the first time that the combination of melt granulation and AMCE incorporation enables the formulation of novel functional granules that exhibit pH-dependent release of the active ingredient.

A novel mathematical model considering change of diffusion coefficient for predicting dissolution behavior of acetaminophen from wax matrix dosage form

From wax matrix dosage forms, drug and water-soluble polymer are released into the external solvent over time. As a consequence, the pore volume inside the wax matrix particles is increased and the diffusion coefficient of the drug is altered. In the present study, we attempted to derive a novel empirical mathematical model, namely, a time-dependent diffusivity (TDD) model, that assumes the change in the drug's diffusion coefficient can be used to predict the drug release from spherical wax matrix particles. Wax matrix particles were prepared by using acetaminophen (APAP), a model drug; glyceryl monostearate (GM), a wax base; and aminoalkyl methacrylate copolymer E (AMCE), a functional polymer that dissolves below pH 5.0 and swells over pH 5.0. A three-factor, three-level (33) Box–Behnken design was used to evaluate the effects of several of the variables in the model formulation, and the release of APAP from wax matrix particles was evaluated by the paddle method at pH 4.0 and pH 6.5. When comparing the goodness of fit to the experimental data between the proposed TDD model and the conventional pure diffusion model, a better correspondence was observed for the TDD model in all cases. Multiple regression analysis revealed that an increase in AMCE loading enhanced the diffusion coefficient with time, and that this increase also had a significant effect on drug release behavior. Furthermore, from the results of the multiple regression analysis, a formulation with desired drug release behavior was found to satisfy the criteria of the bitter taste masking of APAP without lowering the bioavailability. That is to say, the amount of APAP released remains below 15% for 10min at pH 6.5 and exceeds 90% within 30min at pH 4.0. The predicted formulation was 15% APAP loading, 8.25% AMCE loading, and 400μm mean particle diameter. When wax matrix dosage forms were prepared accordingly, the predicted drug release behavior agreed well with experimental values at each pH level. Therefore, the proposed model is feasible as a useful tool for predicting drug release behavior, as well as for designing the formulation of wax matrix dosage forms.

A theoretical approach to evaluate the release rate of acetaminophen from erosive wax matrix dosage forms

To predict drug dissolution and understand the mechanisms of drug release from wax matrix dosage forms containing glyceryl monostearate (GM; a wax base), aminoalkyl methacrylate copolymer E (AMCE; a pH-dependent functional polymer), and acetaminophen (APAP; a model drug), we tried to derive a novel mathematical model with respect to erosion and diffusion theory. Our model exhibited good agreement with the whole set of experimentally obtained values pertaining to APAP release at pH 4.0 and pH 6.5. In addition, this model revealed that the eroding speed of wax matrices was strongly influenced by the loading content of AMCE, but not that of APAP, and that the diffusion coefficient increased as APAP loading decreased and AMCE loading increased, thus directly defining the physicochemical properties of erosion and diffusion. Therefore, this model might prove a useful equation for the precise prediction of dissolution and for understanding the mechanisms of drug release from wax matrix dosage forms.

Optimization of a novel wax matrix system using aminoalkyl methacrylate copolymer E and ethylcellulose to suppress the bitter taste of acetaminophen

The purpose of the present study was to design and evaluate a novel wax matrix system containing various ratios of aminoalkyl methacrylate copolymer E (AMCE) and ethylcellulose (EC) as functional polymers in order to achieve the optimal acetaminophen (APAP) release rate for taste masking. A two factor, three level (3 2) full factorial study design was used to optimize the ratios of AMCE and EC, and the release of APAP from the wax matrix was evaluated using a stationary disk in accordance with the paddle method. The disk was prepared by congealing glyceryl monostearate (GM), a wax with a low melting point, with various ratios of polymers and APAP. The criteria for release rate of APAP from the disk at pH 4.0 and pH 6.5 were calculated to be more than 0.5017 μg/(ml·min) and less than 0.1414 μg/(ml·min), respectively, under the assumption that the particle size of spherical matrix should be 100 μm. In multiple regression analysis, the release of APAP at pH 4.0 was found to increase markedly as the concentration of AMCE increased, whereas the release of APAP at pH 6.5 decreased as the EC concentration increased, even when a high level of AMCE was incorporated. Using principle component analysis, it was found that the viscosity of the matrix affects the pH-dependent release of APAP at pH 4.0 and pH 6.5. Furthermore, using multiple regression analysis, the optimum ratio of APAP:AMCE:EC:GM was found to be 30:7:10:53, and the release pattern of APAP from the optimum wax formulation nearly complied with the desired criteria. Therefore, the present study demonstrated that the incorporation of AMCE and EC into a wax matrix system enabled the appropriate release of APAP as a means of taste masking.