pH-sensitive and mucoadhesive microspheres for duodenum-specific drug delivery system

Particulate systems that could deliver drug specifically to duodenum have not yet been reported. The aim of this study was to develop a novel duodenum-specific drug delivery system based on thiolated chitosan and hydroxypropyl methylcellulose acetate maleate (HPMCAM) for the duodenal ulcer application. Berberine hydrochloride was used as model drug. Thiolated chitosan was synthesized and further used for the preparation of mucoadhesive microspheres. HPMCAM, which is insoluble below pH 3.0 was synthesized and used for the coating of thiolated chitosan microspheres (TCM). The resulting thiolated chitosan immobilized on chitosan was 268.21?±?18 μmol/g. In vitro mucoadhesion study showed that the mucoadhesion property of TCM was better than that of chitosan microspheres. Morphological observation showed that the HPMCAM coating would maintain its integrity in simulated gastric fluid (SGF) for 2?h and dissolved quickly in simulated pathological duodenal fluid (SPDF; pH 3.3). In vitro drug release studies showed that only 4.75% of the drug was released in SGF for 2?h, while nearly 90% of the drug was released within 6?h after transferring into SPDF.     

pH-Sensitive and mucoadhesive microspheres for duodenum-specific drug delivery system

Particulate systems that could deliver drug specifically to duodenum have not yet been reported. The aim of this study was to develop a novel duodenum-specific drug delivery system based on thiolated chitosan and hydroxypropyl methylcellulose acetate maleate (HPMCAM) for the duodenal ulcer application. Berberine hydrochloride was used as model drug. Thiolated chitosan was synthesized and further used for the preparation of mucoadhesive microspheres. HPMCAM, which is insoluble below pH 3.0 was synthesized and used for the coating of thiolated chitosan microspheres (TCM). The resulting thiolated chitosan immobilized on chitosan was 268.21?±?18 μmol/g. In vitro mucoadhesion study showed that the mucoadhesion property of TCM was better than that of chitosan microspheres. Morphological observation showed that the HPMCAM coating would maintain its integrity in simulated gastric fluid (SGF) for 2?h and dissolved quickly in simulated pathological duodenal fluid (SPDF; pH 3.3). In vitro drug release studies showed that only 4.75% of the drug was released in SGF for 2?h, while nearly 90% of the drug was released within 6?h after transferring into SPDF.     

Design and Evaluation of a Two-Layer Floating Tablet for Gastric Retention Using Cisapride as a Model Drug

A new kind of two-layer floating tablet for gastric retention (TFTGR) with cisapride as a model drug was developed. The in vitro drug release was determined, and the resultant buoyancy and the time-buoyancy curve were plotted. Because of the sodium bicarbonate added to the floating layer, when immersed in simulated gastric fluid (SGF) the tablet expands and rises to the surface, where the drug is gradually released. The in vitro drug release of this kind of two-layer dosage was controlled by the amount of hydroxypropylmethylcellulose (HPMC) in the drug-loading layer. Generally, the more HPMC, the slower the drug releases. Because cisapride has greater solubility in SGF than simulated intestinal fluid (SIF), its in vitro drug dissolution in SGF is faster than in SIF. One of the distinguishing characteristics of this kind of tablet is the separate regulation of buoyancy and drug release. The idea developed in this experiment can be used as a general model for the design of other tablets for gastric retention.     

Design and Evaluation of a Two-Layer Floating Tablet for Gastric Retention Using Cisapride as a Model Drug

A new kind of two-layer floating tablet for gastric retention (TFTGR) with cisapride as a model drug was developed. The in vitro drug release was determined, and the resultant buoyancy and the time-buoyancy curve were plotted. Because of the sodium bicarbonate added to the floating layer, when immersed in simulated gastric fluid (SGF) the tablet expands and rises to the surface, where the drug is gradually released. The in vitro drug release of this kind of two-layer dosage was controlled by the amount of hydroxypropylmethylcellulose (HPMC) in the drug-loading layer. Generally, the more HPMC, the slower the drug releases. Because cisapride has greater solubility in SGF than simulated intestinal fluid (SIF), its in vitro drug dissolution in SGF is faster than in SIF. One of the distinguishing characteristics of this kind of tablet is the separate regulation of buoyancy and drug release. The idea developed in this experiment can be used as a general model for the design of other tablets for gastric retention.     

Hydration,Erosion, and Release Behavior of Guar-Based Hydrophilic Matrix Tablets Containing Total Alkaloids of Sophora alopecuroides

It is a challenge to deliver water-soluble drug based on hydrophilic matrix to colon because of swelling and erosion of polysaccharides in contact with media. In our study, guar-based hydrophilic matrix tablets containing water-soluble total alkaloids of Sophora alopecuroides prepared by wet granulation technique were evaluated. A novel method was established to investigate the changes of swelling and volume for guar-based tablets in undynamic state, which generally showed a rapid swelling and volume change in the first 9 h, then the hydrated speed slowed down. On the other hand, the influence of different pH of the media on water uptake and erosion of various guar-based formulations in dynamic state indicated that the hydrated constants in simulated gastric fluid (SGF) was higher than that in SIF, which followed varied mechanism of water penetration by fitting Davidson and Peppas model. The extent of erosion was between 22.4 and 32.6% in SIF within 360 min. In vitro sophoridine release studies in successive different mimicking media showed that the guar matrix tablets released 13.5–25.6% of sophoridine in the first 6 h; therefore it was necessary to develop the bilayer matrix tablet by direct-compressing coating 100 mg guar granula on core tablet. The initial release of coated tablet was retarded and the bilayer matrix tablet was suitable for colon target.     

Formulation development and in-vitro/in-vivo correlation for a novel sterculia gum-based oral colon-targeted drug delivery system of azathioprine

The present study was aimed at designing a microflora triggered colon-targeted drug delivery system (MCDDS) based on swellable polysaccharide, sterculia gum in combination with biodegradable polymers with a view to target azathioprine (AZA) in the colon for the treatment of IBD with reduced systemic toxicity. The microflora degradation study of gum was investigated in rat cecal medium. The polysaccharide tablet was coated to different film thicknesses with blends of chitosan/Eudragit RLPO and over coated with Eudragit L00 to provide acid and intestinal resistance. Swelling and drug release studies were carried out in simulated gastric fluid (SGF) (pH 1.2), simulated intestinal fluid (SIF) (pH 6.8) and simulated colonic fluid (SCF) (pH 7.4 under anaerobic environment), respectively. Drug release study in SCF revealed that swelling force of the gum could concurrently drive the drug out of the polysaccharide core due to the rupture of the chitosan/Eudragit coating in microflora-activated environment. Chitosan in the mixed film coat was found to be degraded by enzymatic action of the microflora in the colon. Release kinetic data revealed that, the optimized MCDDS was fitted well into first order model and apparent lag time was found to be 6?h, followed by Higuchi spherical matrix release. The degradation of chitosan was the rate-limiting factor for drug release in the colon. In-vivo study in rabbit shows delayed T_max, prolonged absorption time, decreased C_max and absorption rate constant (K_a) indicating reduced systemic toxicity of the drug as compared to other dosage forms.     

Chitosan-alginate multilayer beads for gastric passage and controlled intestinal release of protein

Chitosan-alginate beads loaded with a model protein, bovine serum albumin (BSA) were investigated to explore the temporary protection of protein against acidic and enzymatic degradation during gastric passage. Optimum conditions were established for preparation of homogenous, spherical, and smooth chitosan-alginate beads loaded with BSA. Multilayer beads were prepared by additional treatment with either chitosan or alginate or both. The presence of chitosan in the coagulation bath during bead preparation resulted in increased entrapment of BSA. During incubation in simulated gastric fluid (SGF pH 1.2), the beads showed swelling and started to float but did not show any sign of erosion. Inclusion of pepsin in the gastric fluid did not show a further effect on the properties of the beads. Release studies were done in simulated gastric fluid (SGF pH 1.2) and subsequently in simulated intestinal fluid (SIF pH 7.5) to mimic the physiological gastrointestinal conditions. After transfer to intestinal fluid, the beads were found to erode, burst, and release the protein. Microscopic and macroscopic observations confirmed that the release of protein was brought about by the burst of beads. Chitosan-reinforced calcium-alginate beads showed delay in the release of BSA. The multilayer beads disintegrated very slowly. The enzymes pepsin and pancreatin did not change the characteristics of BSA-loaded chitosan-alginate beads. Single layer chitosan-alginate beads released 80-90% of the model protein within 12 h while multilayer beads released only 40-50% in the same period of time. The release from chitosan-alginate beads and multilayer beads in SIF was further delayed without prior incubation in SGF. It is concluded that alginate beads reinforced with chitosan offer an excellent perspective for controlled gastrointestinal passage of protein drugs.     

Development of polysaccharide-based colon targeted drug delivery systems for the treatment of amoebiasis

The main focus of this study is to develop colon targeted drug delivery systems for metronidazole (MTZ). Tablets were prepared using various polysaccharides or indigenously developed graft copolymer of methacrylic acid with guar gum (GG) as a carrier. Various polysaccharides such as GG, xanthan gum, pectin, carrageenan, β-cyclodextrin (CD) or methacrylic acid-g-guar (MAA-g-GG) gum have been selected and evaluated. The prepared tablets were tested in vitro for their suitability as colon-specific drug delivery systems. To further improve the colon specificity, some selected tablet formulations were enteric coated with Eudragit-L 100 to give protection in an acidic environment. Drug release studies were performed in simulated gastric fluid (SGF) for 2 hr followed by simulated intestinal fluid (SIF) at pH 7.4. The dissolution data demonstrate that the rate of drug release is dependent upon the nature and concentration of polysaccharide/polymer used in the formulations. Uncoated tablets containing xanthan gum or mixture of xanthan gum with graft copolymer showed 30-40% drug release during the initial 4-5 hr, whereas for tablets containing GG with the graft copolymer, it was 70%. After enteric coating, the release was drastically reduced to 18-24%. The other polysaccharides were unable to protect drug release under similar conditions. Preparations with xanthan gum as a matrix showed the time-dependent release behavior. Further, in vitro release was performed in the dissolution media with rat caecal contents. Results indicated an enhanced release when compared to formulations studied in dissolution media without rat caecal contents, because of microbial degradation or polymer solubilization. The nature of drug transport was found to be non-Fickian in case of uncoated formulations, whereas for the coated formulations, it was found to be super-Case-II. Statistical analyses of release data indicated that MTZ release is significantly affected by the nature of the polysaccharide used and enteric coating of the tablet. Differential scanning calorimetry indicated the presence of crystalline nature of drug in the formulations.     

Development of Polysaccharide-Based Colon Targeted Drug Delivery Systems for the Treatment of Amoebiasis

ABSTRACT

The main focus of this study is to develop colon targeted drug delivery systems for metronidazole (MTZ). Tablets were prepared using various polysaccharides or indigenously developed graft copolymer of methacrylic acid with guar gum (GG) as a carrier. Various polysaccharides such as GG, xanthan gum, pectin, carrageenan, β-cyclodextrin (CD) or methacrylic acid-g-guar (MAA-g-GG) gum have been selected and evaluated. The prepared tablets were tested in vitro for their suitability as colon-specific drug delivery systems. To further improve the colon specificity, some selected tablet formulations were enteric coated with Eudragit-L 100 to give protection in an acidic environment. Drug release studies were performed in simulated gastric fluid (SGF) for 2 hr followed by simulated intestinal fluid (SIF) at pH 7.4. The dissolution data demonstrate that the rate of drug release is dependent upon the nature and concentration of polysaccharide/polymer used in the formulations. Uncoated tablets containing xanthan gum or mixture of xanthan gum with graft copolymer showed 30–40% drug release during the initial 4–5 hr, whereas for tablets containing GG with the graft copolymer, it was 70%. After enteric coating, the release was drastically reduced to 18–24%. The other polysaccharides were unable to protect drug release under similar conditions. Preparations with xanthan gum as a matrix showed the time-dependent release behavior. Further, in vitro release was performed in the dissolution media with rat caecal contents. Results indicated an enhanced release when compared to formulations studied in dissolution media without rat caecal contents, because of microbial degradation or polymer solubilization. The nature of drug transport was found to be non-Fickian in case of uncoated formulations, whereas for the coated formulations, it was found to be super-Case-II. Statistical analyses of release data indicated that MTZ release is significantly affected by the nature of the polysaccharide used and enteric coating of the tablet. Differential scanning calorimetry indicated the presence of crystalline nature of drug in the formulations.     

Chitosan-Alginate Multilayer Beads for Gastric Passage and Controlled Intestinal Release of Protein

Abstract

Chitosan-alginate beads loaded with a model protein, bovine serum albumin (BSA) were investigated to explore the temporary protection of protein against acidic and enzymatic degradation during gastric passage. Optimum conditions were established for preparation of homogenous, spherical, and smooth chitosan-alginate beads loaded with BSA. Multilayer beads were prepared by additional treatment with either chitosan or alginate or both. The presence of chitosan in the coagulation bath during bead preparation resulted in increased entrapment of BSA. During incubation in simulated gastric fluid (SGF pH 1.2), the beads showed swelling and started to float but did not show any sign of erosion. Inclusion of pepsin in the gastric fluid did not show a further effect on the properties of the beads. Release studies were done in simulated gastric fluid (SGF pH 1.2) and subsequently in simulated intestinal fluid (SIF pH 7.5) to mimic the physiological gastrointestinal conditions. After transfer to intestinal fluid, the beads were found to erode, burst, and release the protein. Microscopic and macroscopic observations confirmed that the release of protein was brought about by the burst of beads. Chitosan-reinforced calcium-alginate beads showed delay in the release of BSA. The multilayer beads disintegrated very slowly. The enzymes pepsin and pancreatin did not change the characteristics of BSA-loaded chitosan-alginate beads. Single layer chitosan-alginate beads released 80–90% of the model protein within 12 h while multilayer beads released only 40–50% in the same period of time. The release from chitosan-alginate beads and multilayer beads in SIF was further delayed without prior incubation in SGF. It is concluded that alginate beads reinforced with chitosan offer an excellent perspective for controlled gastrointestinal passage of protein drugs.     

Preparation and Evaluation of Sustained Release Ibuprofen Beads

Sustained release beads of ibuprofen were prepared by a capillary method using cellulose acetate phthalate, surfactants (Tween 80 and Span 80), and polymers (K 100 M Methocel and K 100 LV Methocel). These beads were formulated into capsule and tablet dosage forms. The beads did not disintegrate in simulated gastric fluid; however, they disintegrated in simulated intestinal fluid. The dissolution profiles of ibuprofen beads and dosage forms of beads (tablets and capsules) were conducted in phosphate buffer (pH 7.2) at 37°C. The beads containing Span 80 and K 100 M Methocel resulted in prolonged drug release. The preparation containing Span 80 and equal quantities of both the polymers (K 100 M Methocel and K 100 LV Methocel), also showed good sustained release properties. The formulations prepared with Tween 80 and K 100 LV Methocel released over 90% of the drug in 2 hours indicating no sustained release properties. The beads in tablet dosage form yielded slower dissolution profiles compared to the beads in capsule form which, in turn, had slower release profiles compared to the beads alone. Release of ibuprofen was much slower from tablets after one year of storage compared to tablets immediately after their manufacture.     

Dual-controlled oral colon-targeted delivery of bovine insulin based on mesoporous phosphonate

The time- and pH-controlled oral colon-targeted delivery system for bovine insulin was developed by dip-coating lag-time films on tablet comprising bovine insulin-loaded pH-sensitive mesoporous phosphonate (ZrBPMP-3) as tablet core and absorption enhancer of insulin, sodium glycocholate, in outer layer, in which the lag time can be controlled via adjusting coating times of lag-time films and the release of bovine insulin in the colon can be triggered by pH-sensitive ZrBPMP-3. The pH transition release experiments show that the tablet with four times lag-time films coating can carry bovine insulin passing through the stomach and small intestine with a minimum release and trigger off the release of loaded bovine insulin in the colon under dual control, time control and pH value control. Furthermore, the released bovine insulin can still retain its native conformation, as evidenced by circular dichroism spectroscopy, indicating that bovine insulin cannot denature and lose its bioactive conformation during the loading, lag-time films coating, delivery and release. In addition, it is worth mentioning that ZrBPMP-3 almost exhibits non-cytotoxicity at low concentration in MTT assays. Thus, ZrBPMP-3 as a new kind of carrier and based on which developing controllable colon-targeted delivery system have potential application in oral delivery of insulin and even other therapeutic peptides and proteins.     

Oral controlled release formulation for highly water-soluble drugs: drug--sodium alginate--xanthan gum--zinc acetate matrix

An oral controlled release formulation matrix for highly water-soluble drugs was designed and developed to achieve a 24-hour release profile. Using ranitidine HCl as a model drug, sodium alginate formulation matrices containing xanthan gum or zinc acetate or both were investigated. The caplets for these formulations were prepared by direct compression and the in vitro release tests were carried out in simulated intestinal fluid (SIF, pH7.5) and simulated gastric fluid (SGF, pH1.2). The release of the drug in the sodium alginate formulation containing only xanthan gum completed within 12 hours in the SIF, while the drug release in the sodium alginate formulation containing only zinc acetate finished almost within 2 hours in the same medium. Only the sodium alginate formulation containing both xanthan gum and zinc acetate achieved a 24-hour release profile, either in the SIF or in the pH change medium. In the latter case, the caplet released in the SGF for 2 hours was immediately transferred into the SIF to continue the release test. The results showed that the presence of both xanthan gum and zinc acetate in sodium alginate matrix played a key role in controlling the drug release for 24 hours. The helical structure and high viscosity of xanthan gum might prevent zinc ions from diffusing out of the ranitidine HCl-sodium alginate-xanthan gum-zinc acetate matrix so that zinc ions could react with sodium alginate to form zinc alginate precipitate with a cross-linking structure. The cross-linking structure might control a highly water-soluble drug to release for 24 hours. Evaluation of the release data showed the release mechanism for the novel formulation might be attributed to the diffusion of the drug.     

Enteric-coated epichlorohydrin crosslinked dextran microspheres for site-specific delivery to colon

Abstract

Enteric-coated epichlorohydrin crosslinked dextran microspheres containing 5-Fluorouracil (5-FU) for colon drug delivery was prepared by emulsification-crosslinking method. The formulation variables studied includes different molecular weights of dextran, volume of crosslinking agent, stirring speed, time and temperature. Dextran microspheres showed mean entrapment efficiencies ranging between 77 and 87% and mean particle size ranging between 10 and 25?µm. About 90% of drug was released from uncoated dextran microspheres within 8?h, suggesting the fast release and indicated the drug loaded in uncoated microspheres, released before they reached colon. Enteric coating (Eudragit-S-100 and Eudragit-L-100) of dextran microspheres was performed by oil-in-oil solvent evaporation method. The release study of 5-FU from coated dextran microspheres was complete retardation in simulated gastric fluid (pH 1.2) and once the coating layer of enteric polymer was dissolved at higher pH (7.4 and 6.8), a controlled release of the drug from the microspheres was observed. Further, the release of drug was found to be higher in the presence of dextranase and rat caecal contents, indicating the susceptibility of dextran microspheres to colonic enzymes. Organ distribution and pharmacokinetic study in albino rats was performed to establish the targeting potential of optimized formulation in the colon.     

Development of pH-sensitive pectinate/alginate microspheres for colon drug delivery

The purposes of this study were to develop and evaluate calcium pectinate/alginate microspheres (PAMs) and to exploit their pH-sensitive properties for colon-targeted delivery of encapsulated cisplatin. PAMs were prepared using an electrospraying method. The PAMs, as cores, were then coated with Eudragit S100 using a polyelectrolyte multilayer coating technique in aqueous solution. The morphology of the microspheres was observed under scanning electron microscopy. In vitro drug release studies were performed in simulated gastrointestinal fluid, and the results indicated that approximately 5 % of the cisplatin was released from the Eudragit S100-coated PAMs, and 51 % of the cisplatin was released from the uncoated PAMs at 1 h. The release of cisplatin from the Eudragit S100-coated PAMs was more sustained in simulated gastric fluid than in simulated intestinal fluid due to the increased solubility of the coating polymer in media with pH >7.0. Drug release from the Eudragit S100-coated PAMs was best described by the Higuchi’s square root model. From these results, it was concluded that Eudragit S100-coated PAMs are a potential carrier for delivery of cisplatin to the colon.     

Deposition of transparent conductive mesoporous indium tin oxide thin films by a dip coating process

Cetyltrimethyl ammonium bromide (CTAB) templated mesoporous indium tin oxide (ITO) thin films were deposited on quartz plates by an evaporation-induced self-assembly (EISA) process using a dip coating method. The starting solution was prepared by mixing indium chloride, tin chloride, and CTAB dissolved in ethanol. Five to fifty mole percent Sn-doped ITO films were prepared by heat-treatment at 400 °C for 5 h. The structural, adsorptive, electrical, and optical properties of mesoporous ITO thin films were investigated. Results indicate that the mesoporous ITO thin films have an ordered two-dimensional hexagonal (p6mm) structure, with nanocrystalline domains in the inorganic oxide framework. The continuous thin films have highly ordered pore sizes (>20 Å), high Brunauer-Emmett-Teller (BET) surface area up to 340 m²/g, large pore volume (>0.21 cm³/g), outstanding transparency in the visible range (>80%), and show a minimum resistivity of ρ = 1.2 × 10⁻² Ω cm.     

Inclusion of cefalexin in SBA-15 mesoporus material and release property

SBA-15 (Santa Barbara Amorphous-15) is a high ordered mesoporous material. It has the advantages of a non-toxic property, good hydrothermal stability and thermal stability, etc. Inside inner surface a lot of silanols exist. Pore diameter size is uniform and pore size distribution is narrow. This structural feature makes SBA-15 have a higher loading drug amount and be able to effectively extend the drug release cycle. In this paper, polyethylene glycol-block-polypropylene glycol-block-polyethylene glycol was used as template and tetraethyl orthosilicate was used as silica source to prepare SBA-15 by hydrothermal synthesis method. Cefalexin was included in SBA-15 and the included cefalexin drug content was 158.72 mg/g. The composite materials were characterized by using chemical analysis, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared (IR) spectroscopy, and low temperature nitrogen adsorption–desorption. The results showed that cefalexin had been successfully included in host SBA-15 pore channels. Rational analyses of the release processes of cefalexin drug from the pores of SBA-15 to the simulated body fluid, simulated gastric juice and simulated intestinal fluid were made and sustained-release effects of the drug in complex system were studied. The results showed that in simulated body fluid within 1–5 h cefalexin was fast released and the cumulative release reached 50.00% at 5 h. In 15–20 h, the sustained release speed of cefalexin drug in the composite material decreased and the sustained-release cumulative amount reached 99.87% at 20 h. The release of cefalexin was basically complete. In simulated gastric fluid, composite material sustained-release ended at 4 h, the cumulative sustained release ratio reaching 26.10%. In simulated gastric fluid, the sustained-release was complete at 7 h, the cumulative sustained release ratio reaching 32.46%. The composite material of SBA-15 and cefalexin could improve efficiency of the sustained-release of drug and has a very great potential applicable value.     

Influence of natural polymer coating on novel colon targeting drug delivery system

A novel colon targeted tablet formulation was developed using natural polysaccharides such as chitosan and guar gum as carriers and diltiazem hydrochloride as model drug. The prepared blend of polymer-drug tablets were coated with two layers, inulin as an inner coat followed by shellac as outer coat and were evaluated for properties such as average weight, hardness and coat thickness. In vitro release studies of prepared tablets were carried out for 2 h in pH 1.2 HCl buffer, 3 h in pH 7.4 phosphate buffer and 6 h in simulated colonic fluid (SCF) in order to mimic the conditions from mouth to colon. It was observed that 4% w/v of rat cecal contents in saline phosphate buffer (SCF) incubated for 24 h provides suitable conditions for in vitro evaluation of the formulations prepared. The drug release from the coated system was monitored using UV/ Visible spectroscopy. In vitro studies revealed that the tablets coated with inulin and shellac have controlled the drug release in stomach and small intestinal environment and released maximum amount of drug in the colonic environment. Among the polymers used, chitosan was found to be the suitable polymer for colon targeting. The study revealed that polysaccharides as carriers and inulin and shellac as coating materials can be used effectively for colon targeting of drugs for treating local as well as systemic disorders.     

Evaluation of hydroxypropyl methylcellulose phthalate 50 as film forming polymer from aqueous dispersion systems

Hydroxypropyl methylcelluose phthalate 50 (HPMCP 50) was evaluated as a film forming polymer from aqueous dispersion systems. The influence of plasticizer type and level on the elasticity of HPMCP 50 free films prepared by the casting method was studied by measuring Young's modulus using an Instron Material Testing System. The release of a water soluble drug in various dissolution media from pellets coated with HPMCP 50 with 30% plasticizer containing various levels of hydroxypropyl cellulose (HPC) or hydroxypropyl methylcellulose (HPMC) was also studied. The influence of coating level on drug release from pellets was also investigated. Results showed that HPMCP 50 alone without a plasticizer does not form a film. However, when a plasticizer was added HPMCP 50 did form a film. Also, as the concentration of the plasticizer triethyl citrate was increased the elasticity of HPMCP 50 films was increased. Similar results were obtained with the plasticizer diethyl phthalate. For pellets a high coating level was required to achieve adequate protection in 0.06 N HCl. Drug release from coated pellets was found to be dependent upon the type and the level of the water soluble polymer incorporated with HPMCP 50. Drug release was increased as the percentage of HPC was increased. Higher release rates were obtained with HPMC compared to HPC. Coating level significantly influenced drug release in 0.06 N HCl; however, less of an effect was observed at pH 5.5.     

Evaluation of hydroxypropyl methylcellulose phthalate 50 as film forming polymer from aqueous dispersion systems

Abstract

Hydroxypropyl methylcelluose phthalate 50 (HPMCP 50) was evaluated as a film forming polymer from aqueous dispersion systems. The influence of plasticizer type and level on the elasticity of HPMCP 50 free films prepared by the casting method was studied by measuring Young's modulus using an Instron Material Testing System. The release of a water soluble drug in various dissolution media from pellets coated with HPMCP 50 with 30% plasticizer containing various levels of hydroxypropyl cellulose (HPC) or hydroxypropyl methylcellulose (HPMC) was also studied. The influence of coating level on drug release from pellets was also investigated. Results showed that HPMCP 50 alone without a plasticizer does not form a film. However, when a plasticizer was added HPMCP 50 did form a film. Also, as the concentration of the plasticizer triethyl citrate was increased the elasticity of HPMCP 50 films was increased. Similar results were obtained with the plasticizer diethyl phthalate. For pellets a high coating level was required to achieve adequate protection in 0.06 N HCl. Drug release from coated pellets was found to be dependent upon the type and the level of the water soluble polymer incorporated with HPMCP 50. Drug release was increased as the percentage of HPC was increased. Higher release rates were obtained with HPMC compared to HPC. Coating level significantly influenced drug release in 0.06 N HCl; however, less of an effect was observed at pH 5.5.