Tackiness of acrylic and cellulosic polymer films used in the coating of solid dosage forms

Direct cyclodextrin based powder extrusion 3D printing of budesonide loaded mini-tablets for the treatment of eosinophilic colitis in paediatric patients

The purpose of this study was to combine direct powder extrusion (DPE) 3D printing and fluid bed coating techniques to create a budesonide (BD) loaded solid oral formulations for the treatment of eosinophilic colitis (EC) in paediatric patients. The preferred medication for EC treatment is BD, which has drawbacks due to its poor water solubility and low absorption. Additionally, since commercially available medications for EC treatment are created and approved for adult patients, administering them to children sometimes requires an off-label use and an impromptu handling, which can result in therapeutic ineffectiveness. The DPE 3D approach was investigated to create Mini-Tablets (MTs) to suit the swallowing, palatability, and dose flexibility control requirements needed by paediatric patients. Additionally, DPE 3D and the inclusion of hydroxypropyl-β-cyclodextrin in the initial powder mixture allowed for an improvement in the solubility and rate of BD dissolution in aqueous medium. Then, to accomplish a site-specific drug release at the intestinal level, MTs were coated with a layer of Eudragit FS 30D, an enteric polymer responsive at pH > 7.0 values. In vitro release experiments showed that film-coated MTs were suitable in terms of size and dose, enabling potential therapeutic customization and targeted delivery of BD to the colon.

Impact of nanosizing on the formation and characteristics of polymethacrylate films: micro- versus nano-suspensions

Aqueous-based film coating suspensions are associated with reliance on alkalinising reagents and poor film formation. The impact of particle size in this process and resultant film properties remains unclear. This study offers the first direct comparison of film formation properties between aqueous micro- and nano-suspensions of the enteric polymer Eudragit S100. High-pressure homogenisation was employed to produce nano-suspensions of the enteric polymer. Formed enteric suspensions (micro- and nano-) were evaluated in terms of size, morphology, and ability to form film; with resultant films analysed in terms of; film thickness, mechanical and thermoplastic properties, water uptake, weight loss, and drug permeability in acidic medium. High-pressure homogenisation yielded particles within a submicron range (150-200 nm). Produced nano-suspensions formed significantly thinner films (p < 0.01), at lower plasticiser concentrations, than films cast from micro-suspensions (differences in thickness up to 100 µm); however, exhibited comparative gastro-resistant properties (p > 0.05) in terms of water uptake (∼25% w/w), weight loss (<16% w/w) and drug permeability (<0.1%). Interestingly, nano-suspension-based films exhibited lower glass transition temperatures (Tg) (p < 0.01), when compared to films cast from micro-suspensions (∼7-20 °C difference), indicating enhanced plasticisation. This was reflected in film mechanical properties; where nano-suspension-based films demonstrated significantly lower tensile strength (p < 0.01) and higher percentage elongation (p < 0.05), suggesting high elasticity. Thinner, highly elastic films were formed from nano-suspensions, compared to films cast from micro-suspensions, exhibiting comparative properties; obviating the need for alkalinising agents and high concentrations of plasticiser.

Eudragit RL-based film coatings: How to minimize sticking and adjust drug release using MAS

Polymeric film coatings based on quaternary polymethacrylates (QPMs, e.g. Eudragits®) are frequently used for controlled release applications. However, their considerable sticking tendency is a major drawback in practice. In this study, different amounts of magnesium aluminum silicate (MAS) were added to the film coatings in order to overcome this hurdle. MAS is negatively charged and can electrostatically interact with the positively charged QPM. Different types of tablet cores were coated with aqueous Eudragit® RL 30D dispersions, optionally containing varying amounts of MAS. Dynamic changes in the wet mass of the systems as well as drug release upon exposure to 0.1 M HCl and phosphate buffer pH 6.8 were monitored. Propranolol HCl, acetaminophen, and diclofenac sodium were used as cationic, nonionic and anionic model drugs. The tablets were optionally cured for 12 h at 45 or 60 °C. Importantly, the addition of MAS to aqueous Eudragit® RL 30D dispersion substantially reduced the films' stickiness and led to stable inner coating structures, even without curing. Desired drug release rates can be adjusted by varying the QPM:MAS ratio and coating level.

Wurster Fluidised Bed Coating of Microparticles: Towards Scalable Production of Oral Sustained-Release Liquid Medicines for Patients with Swallowing Difficulties

Suspension of microparticles in an easy-to-swallow liquid is one approach to develop sustained-release formulations for children and patients with swallowing difficulties. However, to date production of sustained-release microparticles at the industrial scale has proven to be challenging. The aim of this investigation was to develop an innovative concept in coating sustained-release microparticles using industrial scalable Wurster fluidised bed to produce oral liquid suspensions. Microcrystalline cellulose cores (particle size <150 μm) were coated with Eudragit® NM 30 D and Eudragit® RS/RL 30 D aqueous dispersions using a fluidised bed coater. A novel approach of periodic addition of a small quantity (0.1% w/w) of dry powder glidant, magnesium stearate, to the coating chamber via an external port was applied throughout the coating process. This method significantly increased coating production yield from less than 50% to up to 99% compared to conventional coating process without the dry powder glidant. Powder rheology tests showed that dry powder glidants increased the tapped density and decreased the cohesive index of coated microparticles. Reproducible microencapsulation of a highly water-soluble drug, metoprolol succinate, was achieved, yielding coated microparticles less than 200 μm in size with 20-h sustained drug release, suitable for use in liquid suspensions. The robust, scalable technology presented in this study offers an important solution to the long-standing challenges of formulating sustained-release dosage forms suitable for children and older people with swallowing difficulties.

Influence of relative humidity during coating on polymer deposition and film formation

The influence of relative humidity in the pan during coating on polymer deposition and film formation was investigated. Four tablet substrates, differing in hydrophobicity, porosity, and surface roughness, were prepared and coated with Eudragit(®) RS/RL 30 D (8:2 ratio). The spray rate and atomization air pressure were varied to create two distinct micro-environmental conditions in the coating pan. PyroButton data logging devices placed directly in the pan were found to more accurately reflect the relative humidity to which tablets were exposed in comparison to measurements taken at the exhaust. Polymer deposition was shown to be influenced by the properties of the substrate, rather than the processing conditions used during coating, with higher polymer weight gains observed for the more porous tablets. Differences in the film-tablet interface and in the release performance of the coated products, however, were attributed to both the relative humidity in the pan and tablet porosity. Overall, this study demonstrated that a more humid coating process (86% vs 67%) promoted surface dissolution and physical mixing of the tablet ingredients with the forming film and the extent of this phenomenon was dependent on the tablet porosity.

Application of the design of experiments in optimization of drug layering of pellets with an insight into drug polymer interactions

This study consists of two experimental designs. Within the first one, suitable technique for application of model drug onto inactive pellets was evaluated and formulation and process parameters with greatest impact to process efficency and useful yield were determined. Results of experiments showed that formulation characteristics were the ones with the greatest impact on coating efficiency and that suspension layering technique was significantly better for drug application onto inactive pellets in comparison to solution layering during which pronounced agglomeration of pellets occurred. Analysis of drug-polymer interactions by differential scanning calorimetry was performed to explain the results of experiments. The reason for agglomeration of pellets during solution layering was formation of low Tg amorphous form of model drug. The second set of experiments was performed according to central composite design experimental plan in order to optimize level of binder and concentration of solids in the coating liquid which were found to have greatest positive impact on process efficiency and useful yield in the screening study. Statistically significant models were obtained by response surface methodology and it was possible to use them to define optimal levels of excipients in the formulation.

Effect of Antiadherents on the Physical and Drug Release Properties of Acrylic Polymeric Films

Antiadherents are used to decrease tackiness of a polymer coating during both processing and subsequent storage. Despite being a common excipient in coating formulae, antiadherents may affect mechanical properties of the coating film as well as drug release from film-coated tablets, but how could addition of antiadherents affect these properties and to what extent and is there a relation between the physical characteristics of the tablet coat and the drug release mechanisms? The aim of this study was to evaluate physical characteristics of films containing different amounts of the antiadherents talc, glyceryl monostearate, and PlasACRYL(TM) T20. Eudragit RL30D and Eudragit RS30D as sustained release polymers and Eudragit FS30D as a delayed release material were used. Polymer films were characterized by tensile testing, differential scanning calorimetry (DSC), microscopic examination, and water content as calculated from loss on drying. The effect of antiadherents on in vitro drug release for the model acetylsalicylic acid tablets coated with Eudragit FS30D was also determined. Increasing talc concentration was found to decrease the ability of the polymer films to resist mechanical stress. In contrast, glyceryl monostearate (GMS) and PlasACRYL produced more elastic films. Talc at concentrations higher than 25% caused negative effects, which make 25% concentration recommended to be used with acrylic polymers. All antiadherents delayed the drug release at all coating levels; hence, different tailoring of drug release may be achieved by adjusting antiadherent concentration with coating level.

Formulation development and evaluation of zolmitriptan oral soluble films using 22 factorial designs

Objective:

The present investigation involves the development of zolmitriptan oral soluble film (OSF) formulations and optimization with quality by design (QBD) using natural polymers and evaluation.

Materials and Methods:

Initially, various natural polymers such as sodium alginate, pectin, and gelatin were screened by casting films using solvent casting technique and the prepared films were evaluated. Based on the physical and mechanical properties, sodium alginate was selected as best film former and zolmitriptan-loaded films were casted. The formulation was optimized with the help of 2² factorial experimental designs (QBD) in which sodium alginate concentration and plasticizer concentrations were used as factors and at two levels. The drug-loaded films were evaluated for various mechanical, physicochemical properties, and in vitro drug release properties. Factor effects were interpreted by calculating the main factor effects and by plotting the interaction plots.

Results:

Thickness of the films, disintegration time, and percent drug loading efficiency were in the range of 0.698 ± 0.13–1.318 ± 0.22 mm, 175 ± 3.1–280 ± 1.7 s, and 68.34 ± 0.5–94.70 ± 0.7% w/v, respectively. Cumulative percent drug released was 61.8 ± 2.6–94.7 ± 4.1% after 30 min. Polymer concentration at two levels of plasticizer had statistically significant effect on drug loading efficiency and in vitro drug release rate. X₂ formulation was found to be excellent in drug loading efficiency and in vitro drug release profiles; hence, drug excipient compatibility studies using Fourier transform infrared spectroscopy and stability studies for 60 days were carried out for X₂ formulation and found to be stable.

Conclusion:

Sodium alginate OSFs containing zolmitriptan was successfully prepared, optimized, and evaluated.

Impact of anti-tacking agents on properties of gas-entrapped membrane and effervescent floating tablets

Tackiness caused by the gas-entrapped membrane (Eudragit(®)RL 30D) was usually observed during storage of the effervescent floating tablets, leading to failure in floatation and sustained release. In this work, common anti-tacking agents (glyceryl monostearate (GMS) and talc) were used to solve this tackiness problem. The impact of anti-tacking agent on the properties of free films and corresponding floating tablets was investigated. GMS was more effective than talc in reducing tackiness of the film. Addition and increasing amount of anti-tacking agents lowered the film mechanical strength, but the coating films were still strong and flexible enough to resist the generated gas pressure inside the floating tablet. Wettability and water vapor permeability of the film decreased with increasing level of anti-tacking agents as a result of their hydrophobicity. No interaction between anti-tacking agents and polymer was observed as confirmed by Fourier transform infrared spectroscopy, powder X-ray diffractometry, and differential scanning calorimetry studies. Increasing amount of anti-tacking agents decreased time to float and tended to retard drug release of the floating tablets. Floating properties and drug release were also influenced by type of anti-tacking agents. The obtained floating tablets still possessed good floating properties and controlled drug release even though anti-tacking agent had some effects. The results demonstrated that the tackiness problem of the floating tablets could be solved by incorporating anti-tacking agent into the gas-entrapped membrane.

Use of Proteins to Minimize the Physical Aging of EUDRAGIT® Sustained Release Films

The objective of this study was to investigate the influence of two proteins, albumin and type B gelatin, on the physical aging of EUDRAGIT RS 30 D and RL 30 D coated theophylline pellets. The physicomechanical properties of sprayed films, thermal properties of cast films, influence of proteins on the zeta potential and particle size of the dispersion, and the release of proteins from cast films under simulated dissolution conditions were investigated. The release rate of theophylline decreased significantly over time from pellets coated with an acrylic dispersion containing 10% albumin when there was no acidification of the acrylic dispersion; however, when pellets were coated with an acidified EUDRAGIT/albumin dispersion, the theophylline release rate was stable for dosage forms stored in the absence of humidity. The drug release rate was faster for pellets coated with acrylic dispersions containing 10% gelatin compared to the albumin-containing formulations. When sprayed films were stored at 40 degrees C/75% RH, the water vapor permeability decreased significantly for both EUDRAGIT films and those containing EUDRAGIT and albumin; however, there was no significant change in this parameter when 10% gelatin was present. Albumin was released from the acrylic films when the pH of the dissolution media was below the isoelectric point of the protein while no quantitative release of gelatin was observed in pH 1.2 or 7.4 media. The effect of gelatin to prevent the decrease in drug release rate was due to stabilization in water vapor permeability of the film. Acidification of the polymeric dispersion resulted in electrostatic repulsive forces between albumin and the acrylic polymer, which stabilized the drug release rate when the dosage forms were stored in aluminum induction sealed containers at both 40 degrees C/75% RH and 25 degrees C/60% RH.

Investigation of PEGylated derivatives of rosin as sustained release film formers

The purpose of the present study was to investigate the potential use of two PEGylated derivatives of rosin (PD) as sustained release film forming materials. The derivatives differed chemically by their acid numbers--PD-1 with 120.93 and PD-2 with 88.19. The derivative films were characterized for surface morphology, water uptake-weight loss, angle of contact, water vapor transmission rate, mechanical properties and permeability study. Dissolution of diclofenac sodium (DS) and propranolol hydrochloride (PHL) as model drugs was studied from coated pellets. The films of derivatives with and without plasticizers were smooth and continuous. PD-2 films developed greater numbers of pores when in contact with phosphate buffer pH 6.8. The low weight loss, low angles of contact and high water vapor transmission rate of PD-2 films were related to presence of higher concentration of PEG esters. Higher tensile strength and percent elongation of PD-2 films was due to greater degree of internal plasticization of the derivative. The permeability of films to model drugs propranolol hydrochloride and diclofenac sodium was inversely proportional to the film thickness and dibutyl phthalate concentration in them; the permeability being greatest in PD-2 films containing 10% PEG 200. Dissolution rate of propranolol hydrochloride was higher from the coated pellets. The dissolution data followed zero order, Baker-Lonsdale equation and Hixon-Crowell equation of release kinetics with high correlation coefficients. The mechanism of drug release from these coated systems however followed class II transport (n > 1.0). The derivatives investigated could successfully retard release of the model drugs and offers an alternative to the conventionally used polymers.

Influence of processing parameters and formulation factors on the drug release from tablets powder-coated with Eudragit® L 100-55

The aim of this study was to develop a dry powder coating process for chlorpheniramine maleate (CPM) tablets using Eudragit L 100-55 as the delayed release polymer. Powder coating, a water and organic solvent-free process, was investigated as a method to prevent the migration of an ionizable, highly water soluble model drug into the polymeric film during the coating process. Eudragit L 100-55 was pre-plasticized with triethyl citrate (TEC) using hot-melt extrusion at levels of 20%, 30%, and 40%, based on the polymer weight. The extrudate was subsequently cut into pellets and cryogenically ground into a fine powder. Talc was incorporated into the coating powder as an anti-tack agent. PEG 3350 was used as a primer for the powder coating of tablets with pre-plasticized Eudragit L 100-55. The addition of polyethylene glycol 3350 (PEG 3350) to the pre-plasticized Eudragit L 100-55 was necessary to enhance the adhesion of the coating powder to the tablet cores. PEG 3350 also improved film formation and coalescence of the polymeric particles due to its plasticization effects on the acrylic polymer. For comparison, theophylline tablets were also coated with pre-plasticized Eudragit L 100-55. Theophylline was selected as a less water soluble model drug. The powder coating process was performed in a modified laboratory scale spheronizer. The drug release rate was dependent both on TEC content and the coating level. The stability of the powder-coated CPM tablets was confirmed at 25 degrees C/60% RH over a storage time of 12 weeks.

Quinine sulphate pellets for flexible pediatric drug dosing: Formulation development and evaluation of taste-masking efficiency using the electronic tongue

The purpose of this study was to develop a taste-masked quinine sulphate dosage form as a flexible pediatric formulation tool. Pellets were produced as they offer more flexibility to body weight dose adaptation and therefore represent an alternative to tablet breaking in pediatrics. Quinine sulphate pellets were produced via extrusion-spheronisation. Next pellets were coated using Eudragit E PO to obtain a taste-masked formulation. Using 15% dibutyl sebacate (based on polymer weight) as a plasticizer in the formulation caused rapid pellet agglomeration during storage at 40 degrees C and 75% relative humidity. Using stearic acid (15% based on polymer weight) as plasticizer yielded pellets which were less sensitive to sticking. Quinine sulphate release in water within the first 5 min of dissolution testing: 9.2%, 5.9% and 2.1% of the drug dose was released from pellets coated with 10%, 20% and 30% (w/w) Eudragit E PO, respectively. These observations correlated well with the bitterness score of the formulations determined via the Astree electronic tongue and its Bitterness Prediction Module, showing that 20% (w/w) Eudragit E PO was required to obtain a homogeneous film and to delay quinine sulphate release sufficiently to mask the bitterness after drug administration. In acid medium immediate quinine sulphate release was obtained.

Development and in vitro evaluation of Chitosan-Eudragit RS 30D composite wound dressings

The purpose of this research was to design and evaluate chitosan-based films intended for wound dressing application. Required properties for successful wound dressing, such as liquid uptake, vapor and oxygen penetration, bioadhesiveness, and film elasticity, were examined. Water uptake and vapor penetration of the films were determined gravimetrically, while oxygen penetration was determined by Winkler's method. The bioadhesive properties were determined with an in-house pulley system instrument using a pig gut model. Film elasticity was determined with a stretch test using an Instron apparatus. The results showed that pure chitosan films exhibited relatively high liquid uptake and the adsorption tended to decrease with the addition of Eudragit RS 30D. Moisture vapor and oxygen were found to be able to penetrate through all film formulations in comparable amounts. The bioadhesiveness test tended to show lower bioadhesive properties with the addition of Eudragit RS 30D. The formulation containing only chitosan exhibited low elongation of the film at 2 N, but the film elasticity increased with the addition of Eudragit RS 30D. In conclusion, the addition of Eudragit RS 30D could improve a film's mechanical properties but lower its bioadhesiveness.

Physicochemical and release properties of pellets coated with Kollicoat® SR 30 D, a new aqueous polyvinyl acetate dispersion for extended release

Kollicoat SR 30 D is a new aqueous colloidal polyvinyl acetate dispersion used for extended release coatings. Kollicoat SR 30 D is stable against sedimentation, has a low viscosity (54 mPas) and a negative zeta potential of -23.2 mV because of the presence of the anionic surfactant, sodium dodecyl sulfate. Because of its low minimum film formation temperature (MFT = 18 degrees C), plasticizer addition and a thermal after-treatment (curing) of coated pellets was not required. Coated pellets showed no aging or curing effect. The rate of release could be easily adjusted by varying the coating level. A subcoating layer of the hydrophilic polymer, polyvinyl alcohol, between an ibuprofen-containing core and the Kollicoat SR coating prevented the diffusion of the lipophilic, low melting ibuprofen into the polymer coating during storage. The drug release from Kollicoat SR 30 D coated pellets was almost independent of the pH and ionic strength of release medium.

Eudragit NE40–Drug Mixed Coating System for Controlling Drug Release of Core Pellets

This study was aimed at developing a controlled-release coating system around core pellets with aqueous dispersion, along with some water channeling agents. Core pellets of diltiazem were prepared using the extrusion-spheronization technique and subsequently coated with aqueous dispersion of Eudragit NE40 alone, or drug-polymer mixtures using bottom-spray fluidized bed coater. The lag time in drug release profiles increased as the coating levels of Eudragit NE40 were increased, whereas no lag time was observed in core pellets coated with drug-polymer mixtures. Mixed coating at the 7% level exhibited comparatively better release profiles and provided desirable release rates during the 12-hour testing interval. Diltiazem HCl release from mixed coating was fairly independent of pH and drug loading. Curing of coated pellets was found to be an essential step for stable drug release profiles. The selection of core size range had remarkable effect on drug release rate and was considerably reduced by using greater core size.

Influence of selected surfactants on the tackiness of acrylic polymer films

Anti-tacking agents are always necessary in polymeric film coating formulations in order to prevent substrate agglomeration. The objective of this study was to investigate the abilities of certain nonionic surfactants in a group of sorbitan ester in reducing the tackiness of the films obtained from aqueous acrylic polymer dispersions (Eudragit), compared with those of talc and glyceryl monostearate (GMS). The results from the peel tests demonstrated that GMS, Span 60 and Span 40 could significantly reduce the tackiness of both Eudragit NE 30D and Eudragit RS 30D films. The mechanisms in reducing the film tackiness were investigated by analyzing the film compositions, using attenuated total internal reflectance infrared spectroscopy (ATR-IR) and optical microscopy. The storage modulus of the films was also examined. The results indicated that GMS, Span 60, and Span 40 could reduce the film tackiness by decreasing the polymer contents at the film surfaces, resulting in a notable reduction in the contact area of the polymers between the surfaces. The use of only 5% (w/w) of either GMS, Span 60 or Span 40 in the coating formulations is enough to prevent pellet agglomeration without adverse effects on film flexibility. The pellets coated with Eudragit RS 30D/RL 30D (9:1, w/w) did not exhibit any difference in the drug release profiles when either 100% (w/w) talc or 5% (w/w) GMS was used, whereas the formulations containing Span 60 or Span 40 gave a slightly faster release rate.

Determination of tackiness of chitosan film-coated pellets exploiting minimum fluidization velocity

The tackiness of aqueous chitosan film coatings and effects of anti-sticking agents on sticking tendency, were evaluated. A novel rapid method exploiting minimum fluidization velocity to determine tackiness was introduced and tested. The pressure difference over the miniaturized fluidized-bed was precisely recorded as a function of velocity of fluidization air. High molecular weight chitosan plasticized with glycerol was used as a film-forming agent. Magnesium stearate, titanium dioxide, colloidal silicon dioxide and glyceryl-1-monostearate (GMS) were studied as anti-sticking agents. Film coatings were performed in a miniaturized top-spray coater. The incorporation of anti-sticking agents led to a clear decrease in tackiness of the chitosan films, and magnesium stearate and GMS were shown the most effective. Film-coated pellets containing magnesium stearate and GMS as an anti-sticking agent were very easily fluidized (showing very low values of minimum fluidization velocity) and were thus classified as the best flowing and the least sticking samples. Both these additives were found anti-sticking agents of choice for aqueous chitosan film coatings. Determination of the experimental minimum fluidization velocity in a fluidized bed, is a useful and sensitive method of measuring the tackiness tendency of film-coated pellets.

Characteristics of erythritol and formulation of a novel coating with erythritol termed thin-layer sugarless coating

The purpose of this study was to clarify the characteristics of erythritol and to develop the optimum basic formulation of a novel coating with erythritol termed thin-layer sugarless coating. Characteristics of erythritol were investigated compared with maltitol, mannitol, sorbitol, xylitol, and sucrose. Furthermore, the optimum basic formulation of thin-layer sugarless coating with erythritol was determined by coating glass beads. We selected a continuous spray mist method for thin-layer sugarless coating due to the formation of a thin sugarless coating layer by a simple method. We demonstrated that erythritol is a suitable coating material for thin-layer sugarless coating compared with maltitol, mannitol, sorbitol, xylitol, and sucrose because of its high water solubility, low hygroscopicity, instant crystallization, and low tackiness. We also demonstrated that thin-layer sugarless coating with erythritol can reduce coating time compared with the coating with maltitol or sucrose due to its characteristics. We developed the optimum basic formulation of thin-layer sugarless coating consists of erythritol, powdered acacia, and talc. We confirmed that a smooth coating layer and high coating efficiency were achieved using the formulation.

A new process control strategy for aqueous film coating of pellets in fluidised bed

The parameters with effect on maximum spray rate and maximum relative outlet air humidity when coating pellets in a fluidised bed were investigated. The tested variables include type of water based modified release film coating (Eudragit NE 30D, Eudragit RS 30D, Aquacoat ECD) coating principle (top spray, bottom spray), inlet air humidity and type of pellets (sugar spheres, microcrystalline cellulose pellets). The maximum spray rate was not influenced by the coating principles. The highest spray rate was obtained for the film polymer with the lowest tackiness which is assumed to be the controlling factor. The type of pellets affected the maximum spray rate. A thermodynamic model for the coating process is employed throughout the process and not just during steady state. The thermodynamic model is incorporated into a new process control strategy. The process control strategy is based on in-process calculation of degree of utilisation of the potential evaporation energy (DUE) of the outlet air and the relative outlet air humidity (RH). The spray rate is maximised using set points of DUE and RH as control parameters. The product temperature is controlled simultaneously by regulating the inlet air temperature.

Influence of an enteric polymer on drug release rates of theophylline from pellets coated with Eudragit RS 30D

The purpose of this research study was to investigate the influence of an enteric polymer on the drug release properties of theophylline pellets coated with Eudragit RS 30D. Theophylline pellets were coated with aqueous colloidal dispersions of Eudragit RS 30D containing various amounts of Eudragit L 100-55. The effect of storage conditions on the release of drug from coated pellets was determined as a function of the pH of the dissolution medium. The results from the dissolution study showed significant changes in the dissolution rate of theophylline from pellets coated with Eudragit RS 30D when cured at 40 degrees C for 4 days. No change in the drug release rate was observed when Eudragit L100-55 was present in the Eudragit RS 30D dispersion. Increasing the ratio of Eudragit L100-55 to Eudragit RS 30D resulted in faster drug release rates from the coated pellets. An increase in the pH of the dissolution medium was found to enhance drug release from the pellets coated with Eudragit RS 30D containing Eudragit L 100-55. Theophylline pellets when coated with Eudragit RS 30D containing the enteric polymer Eudragit L100-55 demonstrated no aging effects when stored at elevated temperatures. The overcoating of the pellets with Eudragit RD 100 did not affect the drug release profiles and prevented the particles from agglomerating during curing and storage.

Studies on modifying the tackiness and drug release of Kollicoat EMM 30 D coatings

In the search for antitack additives for Kollicoat EMM 30 D (ethyl acrylate-methyl methacrylate 30% dispersion, Ph. Eur.) film coatings, various possibilities were investigated. The best results were obtained using a combination of simethicone and talc. This mixture was tested on propranolol, theophylline, and verapamil HCl blank pellets in a previously developed Kollicoat EMM 30 D basic formulation. Almost any desired drug release rate can be obtained with all three pellet formulations by varying the two pore formers hypromellose 3mPas and microcrystalline cellulose type 105. A thin application of colloidal silica onto the coated pellets additionally prevents them from sticking together during storage.

Influence of Eudragit NE 30 D blended with Eudragit L 30 D-55 on the release of phenylpropanolamine hydrochloride from coated pellets

The objective of this study was to investigate the influence of Eudragit NE 30 D blended with Eudragit L 30 D-55 on the release of phenylpropanolamine hydrochloride (PPA x HCl) from coated pellets. The miscibility of Eudragit NE 30 D/L 30 D-55 blends at different ratios was studied by using differential scanning calorimetry. The release of PPA x HCl from pellets coated with Eudragit NE 30 D alone and a Eudragit NE 30 D/L 30 D-55 blend, when stored at 40 degrees C and 60 degrees C, was determined by UV spectroscopy. Eudragit NE 30 D and Eudragit L 30 D-55 were miscible in ratios greater than 4:1. The curing time that was required to reach an equilibrium state decreased with the addition of Eudragit L 30 D-55. The presence of Eudragit L 30 D-55 also produced a film coating that was less tacky, and a dispersion of Eudragit NE 30 D containing Eudragit L 30 D-55 (5:1) was shown to prevent agglomeration of the pellets during coating and storage.

Development and in vitro evaluation of an enteric-coated multiparticulate drug delivery system for the administration of piroxicam to dogs

The aim of the study was to develop enteric-coated pellets for the administration of piroxicam (a poorly water-soluble drug) to small animals in order to avoid local gastrointestinal irritation, one of the major side effects of nonsteroidal anti-inflammatory drugs after oral ingestion. Pellets were made by an extrusion-spheronization process. The influence of several excipients on the in vitro drug release was evaluated. Piroxicam release from the uncoated pellets was measured in phosphate buffer (pH 6.8) using the paddle dissolution method (USP XXIII). The enteric-coated pellets were tested in 0.1 N HCl and phosphate buffer, pH 6.8. The addition of sodium croscarmellose (Ac-Di-Sol) did not influence the piroxicam release from microcrystalline cellulose pellets. Sodium carboxymethyl starch (Explotab) increased the release from 30 to 65% at 45 min. The incorporation of sodium carboxymethyl cellulose on its own or as a co-processed blend with microcrystalline cellulose (Avicel RC 581 and CL 611) enhanced the release of piroxicam at 45 min from 30% (pure Avicel PH 101) to 95% (combination of Avicel PH 101 and CL 611 in a ratio of 1:3). Additional use of cyclodextrins had only a minor influence on the dissolution rate. An Eudragit L 30 D-55 and FS 30 D (6/4) film was applied to the core pellets (containing 2.5% (w/w) piroxicam and a combination of Avicel PH 101 and CL 611 in a ratio of 1:3) in order to obtain gastroresistant properties. The coated pellets retained their dissolution characteristics after compression into fast disintegrating tablets because waxy cushioning beads were added to minimize film damage.

Polysaccharides as excipients for colon-specific coatings. Permeability and swelling properties of casted films

Oligosaccharides such as inulin (In) and polysaccharides such as galactomannans, combined with polymethacrylates on isolated films for film coatings, were obtained from aqueous-based solvents and investigated as potential vehicles for colonic drug delivery. These compositions, which are susceptible to fermentation by colonic microflora, constitute promising excipients for the development of new colon-specific therapeutic systems. The characteristics of several compositions have been demonstrated in permeability and swelling studies on isolated films composed of a polymethacrylate associated with In or galactomannans of mesquite seed gum (MSG). Results reported prove a dependency of the properties of mixed films on the polymethacrylate-polysaccharide concentration ratio and on the composition of the dissolution media. An increase in permeability through the mixed films was observed in a simulated colonic environment for the following compositions: Eudragit RS30D-MSG 70:30 w/w; Eudragit RS30D-In 90:10 w/w; Eudragit RS30D-In 76:24 w/w.

Influence of insoluble excipients on film coating systems

Insoluble excipients are added to polymeric film coating solutions and dispersions to improve the physical appearance of dosage forms, enhance the stability of photolytic drugs, and aid in processing. These insoluble additives, however, may significantly affect the physical, mechanical, adhesive, and drug-release properties of the films. In this review, the theories of the interactions between polymer and insoluble excipient are addressed. This article also discusses the influence of the concentration, particle size, morphology, and surface chemistry of insoluble excipients on the various polymer properties.

Starch acetate--a novel film-forming polymer for pharmaceutical coatings

Starch acetates (SA) have been investigated as novel, multifunctional excipients for the direct compression tableting process. In this study, the film-forming ability of SA (DS 2.8) and the effect of commonly used plasticizers on the physical properties of SA films were evaluated. The results were compared with the properties of ethylcellulose (EC). Free films were prepared by a solvent-cast method. Mechanical studies, water vapor and drug permeability tests, and thermal analysis (DSC) were used to characterize the film-forming ability of SA and efficiency of tested plasticizers. SA films were tougher and stronger than EC films at the same plasticizer concentration. Also, in most cases, the water vapor permeability of SA films was lower than that of EC films. DSC thermograms supported the findings of the tensile test: plasticizers with several small ester groups (e.g., triacetin and triethyl citrate) were the most compatible with SA. Due to the good mechanical properties, low water vapor, and drug permeabilities of the films, SA seems to be a promising film-former for pharmaceutical coatings. The toughness of SA films may result from their dense film structure, which is due to strong interaction forces between adjacent SA molecular chains.

Influence of ibuprofen as a solid-state plasticizer in Eudragit RS 30 D on the physicochemical properties of coated beads

The purpose of this study was to investigate the physicochemical properties of nonpareil beads coated with Eudragit RS 30 D containing ibuprofen as a multifunctional agent. The influence of the concentration of ibuprofen in the film coating and the effect of the coating level on drug release from coated beads was determined in pH 7.2 phosphate buffer solution. The influence of storage time at 23 degrees C and 60 degrees C on the release of ibuprofen from coated beads was also investigated. The thermal properties of the films were determined using a differential scanning calorimeter. Scanning electron microscopy was employed to image the surface morphology of the coated beads. Infrared spectroscopy was used to study the interaction of Eudragit RS 30 D and ibuprofen. Results from the dissolution studies demonstrated that increasing the amount of ibuprofen in the polymeric film reduced the rate of drug release, mainly because of a more complete coalescence of the polymeric particles of the latex dispersion. The glass transition temperature (Tg) of Eudragit RS 30 D films decreased and the surface of the coated beads became smoother as the concentration of ibuprofen was increased. Hydrogen bonding between the polymer and ibuprofen was demonstrated by Fourier transform infrared spectroscopy. No significant differences were found in drug dissolution between the coated beads stored at 23 degrees C for 12 months and those stored at 60 degrees C for 12 hours. The results of this study demonstrated that the ibuprofen plasticized the Eudragit RS 30 D. Furthermore, the dissolution rate of ibuprofen can be controlled and changes in the drug release rate can be minimized by using the drug-induced plasticization technique with this polymer.

Influence of ibuprofen as a solid-state plasticizer in Eudragit RS 30 D on the physicochemical properties of coated beads

The purpose of this study was to investigate the physicochemical properties of nonpareil beads coated with Eudragit RS 30 D containing ibuprofen as a multifunctional agent. The influence of the concentration of ibuprofen in the film coating and the effect of the coating level on drug release from coated beads was determined in pH 7.2 phosphate buffer solution. The influence of storage time at 23 degrees C and 60 degrees C on the release of ibuprofen from coated beads was also investigated. The thermal properties of the films were determined using a differential scanning calorimeter. Scanning electron microscopy was employed to image the surface morphology of the coated beads. Infrared spectroscopy was used to study the interaction of Eudragit RS 30 D and ibuprofen. Results from the dissolution studies demonstrated that increasing the amount of ibuprofen in the polymeric film reduced the rate of drug release, mainly because of a more complete coalescence of the polymeric particles of the latex dispersion. The glass transition temperature (Tg) of Eudragit RS 30 D films decreased and the surface of the coated beads became smoother as the concentration of ibuprofen was increased. Hydrogen bonding between the polymer and ibuprofen was demonstrated by Fourier transform infrared spectroscopy. No significant differences were found in drug dissolution between the coated beads stored at 23 degrees C for 12 months and those stored at 60 degrees C for 12 hours. The results of this study demonstrated that the ibuprofen plasticized the Eudragit RS 30 D. Furthermore, the dissolution rate of ibuprofen can be controlled and changes in the drug release rate can be minimized by using the drug-induced plasticization technique with this polymer.

Influence of film additives on stabilizing drug release rates from pellets coated with acrylic polymers

The objective of this study was to investigate the influence of talc and triethyl citrate (TEC) on stabilizing the drug release rates following curing and storage at elevated temperature of pellets coated with an aqueous acrylic polymeric dispersion. Core pellets containing anhydrous theophylline (20%), microcrystalline cellulose, and polyvinylpyrrolidone were prepared by extrusion-spheronization. The aqueous dispersions were prepared by adding up to 30% TEC as a plasticizer and talc up to 200% as an antiadherent to a mixture of Eudragit RS 30D/RL 30D (95:5). The theophylline pellets were coated in a fluidized-bed coating unit and then cured at elevated temperatures. Theophylline pellets were successfully coated with the Eudragit dispersions that contained up to 200% talc, based on the dry polymer weight, and the coating efficiency was greater than 93%. Our results demonstrated that the polymer, which was plasticized by TEC, was able to function as a film-forming agent for dispersions containing high levels of talc. No sticking of the coated pellets was observed during the coating process or during the curing or equilibrating phase, even with high levels of TEC in the film. The dissolution rate of theophylline from the coated pellets was delayed when the film coating dispersion contained high levels of talc. Additionally, the stability of the drug release profiles from the coated pellets after storage was significantly improved. Furthermore, a modified dissolution testing used to simulate mechanical stresses that may be encountered in vivo showed the film coated pellets would have sufficient strength. The results of this study demonstrated that high levels of film additives in the acrylic dispersion contributed to the stabilization of the drug release rates as well as the reproducibility of the coating process.

Influence of plasticization time, curing conditions, storage time, and core properties on the drug release from Aquacoat-coated pellets

Theophylline or chlorpheniramine maleate pellets were coated with an aqueous ethylcellulose dispersion, Aquacoat. The influence of the plasticization time, curing conditions, storage time, and core properties on the drug release were investigated. The plasticization time (time between plasticizer addition to the polymer dispersion and the spraying process) did not affect the drug release, when the water-soluble plasticizer triethyl citrate, was used because of its rapid uptake by the colloidal polymer particles. In contrast, with the water-insoluble plasticizer acetyltributyl citrate (ATBC), plasticization time (1/2 h vs 24 h) influenced the drug release, the longer plasticization time resulted in a slower drug release because of a more complete plasticizer uptake prior to the coating step. However a thermal aftertreatment of the coated pellets at eleylated temperatures (curing step) reduced/eliminated the effect of the plasticization time with ATBC. In general, curing reduced the drug release and resulted in stable drug release profiles. The time period between the coating and the curing step was not critical when the pellets were cured for a longer time. The structure of the pellet core (high dose matrix vs low dose layered pellet) strongly affected the drug release. A slow, zero-order drug release was obtained with high dose theophylline pellets, while a more rapid, first-order release pattern was obtained with low dose theophylline-layered nonpareil pellets.