Properties of pH‐dependent tertiary amine‐based gels as potential drug delivery matrices

The rheological and morphological properties and in vitro theophylline release of tertiary amine‐based microgels were evaluated. The testing of such a formulation through in vitro diffusion experiments revealed that the release of theophylline from the microgels was pH‐dependent and differs significantly with respect to a nonresponsive gel like scleroglucan (Scl). The microgels were obtained from 2‐(diethyl amino) ethylmethacrylate (DEA) in the presence of a bifunctional crosslinker at pH 8–9. As the resulting microgels are pH‐responsive and an increase in viscosity from high to low pH range is exhibited, the in vitro release of theophylline as model drug was studied at different pHs of both the matrix and the receptor medium. The release behaviors of PDEA‐based microgels were compared to nonresponsive natural gel Scl, studied previously. For microgels, diverse release patterns were found at different acidity conditions. This observation seems to be related to complex diffusion phenomena and the different gel structure obtained for samples prepared at dissimilar pH. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4035–4040, 2007     

Preparation and characterization of PVA films with magnetic nanoparticles: The effect of particle loading on drug release behavior

This article deals with the drug release behavior of theophylline (Th) from poly(vinyl alcohol) (PVA) hydrogels, prepared with magnetic nanoparticles at different particle loadings. These biocompatible matrices were obtained by incorporating different amounts of an aqueous ferrofluid into PVA hydrogels, loaded with Th as a marker for drug‐delivery studies. PVA films with magnetic particles proved to be magnetic field‐responsive materials as the drug release decreased through the application of a relative low and uniform magnetic field for particle concentrations of 0.9% w/w or higher. Moreover, the percentage of restriction of drug release is found to be correlated with particle loading. The in vitro release profiles were analyzed by applying a semiempirical power law to obtain the kinetic parameters. The value of the release exponent was found to be in the range 0.54–0.56 in all experiments, which thus indicates a predominant diffusional mechanism for drug release from these smart magnetic hydrogels. This effect suggests the possibility of modulating the release behavior by controlling the particle content in the preparation of the composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Composites of polymeric gels and magnetic nanoparticles: Preparation and drug release behavior

The article is concerned with the preparation of polymer–iron oxide nanocomposites and the study as drug‐delivery matrices under the influence of applied magnetic field. Biocompatible materials were prepared by incorporating an aqueous ferrofluid in poly(vinyl alcohol) and scleroglucan (SCL) hydrogels, loaded with theophylline as model drug for release studies. The in vitro release profile was obtained using a flat Franz cell and the kinetic parameters were derived applying a semiempirical power law. A magnetic characterization of nanoparticles contained in the ferrofluid was performed by obtaining the magnetization curve. For both systems, the observed drug release profiles decreased when a uniform external magnetic field is applied suggesting they can be used as environmental responsive matrices for biomedical applications. Dynamic rheological measurements show that a higher storage modulus and a more compact structure are obtained by incorporating the ferrofluid into the hydrogels. These rheological results and environmental electron scanning microscopy micrographs point to an understanding of release behavior once the magnetic field is applied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

A novel gastric release PEG‐enclatherated polymethacrylate‐based memblet system

A novel polymethacrylate‐based membranous system referred to as a “memblet” was developed for potential application in controlled gastric drug delivery. A polymethacrylate‐based latex, Eudragit® E100, was enclatherated with a 60% w/v and a 30% w/v solution of polyethylene glycol 4000 to form hydrogel formulations A and B, respectively. The hydrogels were subsequently compressed into memblets that were characterized for thermal, rheological, morphological, mechano‐chemical properties, and in vitro gastric drug release analysis. Molecular mechanics (MM) simulations were performed to corroborate the experimental findings. Critical yield values of 15.39 and 5.239 Pa were obtained for hydrogel A and B, respectively. The viscoelastic region was found to be <10.67 and 2.542 Pa for hydrogels A and B, respectively. The storage modulus was greater than the loss modulus for hydrogel A while the inverse was true for hydrogel B. Thermal, mechanical, and surface morphology evaluation revealed that the converse was true for the dried membrane structure with hydrogel B having superior characterization profiles than hydrogel A. Notably, the lower PEG concentration (30% w/v) displayed better characterization profiles than a higher concentration (60% w/v). Through MM simulations, desirable agreement between the theoretical and experimental results was achieved over the given concentration range of PEG. Based on the gastric drug release analysis, memblets formulated with hydrogel B displayed superior control of drug release. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Magnetic nanoparticles embedded in pectin‐based hydrogel for the sustained release of diclofenac sodium

A supermagnetic polysaccharide‐based nanocomposite gel has been developed as a potential drug delivery system. The gel was made via graft copolymerization of 2‐acrylamido‐2‐methylpropanesulfonic acid on pectin using ammonium peroxodisulfate as an initiator and N,N‐methylenebisacrylamide as a crosslinker under microwave irradiation. The magnetic nanoparticles (MNPs) were incorporated within the gel network via an in situ method of diffusion of Fe²⁺/Fe³⁺ followed by reduction with ammonia solution. The graft copolymer gel and its nanocomposite were characterized using attenuated total reflection Fourier transform infrared spectroscopy, thermogravimetric analysis, powder X‐ray diffraction, field‐emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy and transmission electron microscopy. The magnetic properties of the nanocomposite were measured using a vibrating sample magnetometer and mechanical properties using a tensile compressive tester. The gel was evaluated for adsorption and release of the drug diclofenac sodium. The presence of MNPs is observed to enhance significantly the mechanical properties, swelling capacity, drug loading and release ability of the graft polymer gel. The increased porosity of the gel network and higher surface area of MNPs allowed for 20% higher adsorption of diclofenac sodium molecules compared to the parent nonmagnetic gel. About 95% of the loaded drug was released from the MNP‐containing gel. The drug release pattern followed first‐order kinetic model and the Higuchi square root model, indicating swelling‐controlled diffusion to be the mode of drug release. © 2018 Society of Chemical Industry     

β‐cyclodextrin‐conjugated hyaluronan hydrogel as a potential drug sustained delivery carrier for wound healing

In order to develop a potential drug sustained delivery carrier suitable for wound healing, a series of β‐cyclodextrin conjugated hyaluronan hydrogels (β‐CD‐HA) with adjustable crosslink densities were synthesized and characterized, meanwhile the delivery kinetics and mechanism of diclofenac as a model anti‐inflammatory drug from these hydrogels were investigated. By controlling the feeding molar ratio of β‐CD/HA, a β‐CD substitution degree of 4.65% was obtained by ¹H‐NMR analysis. The incorporation of β‐CD modification had little effect on the internal porous structure, water swelling ratio, and rheological property of HA hydrogel, which however were influenced by the crosslink density. Although the crosslink density had an influence on the drug loading and release profile by altering the water swelling property, the interaction between β‐CD and drug was the primary factor for the high loading capacity and long‐term sustained delivery of diclofenac. The semiempirical equation fit showed that the release of diclofenac from HA‐based hydrogels followed a pseudo‐Fickian diffusion mechanism. By the aid of β‐CD and controlled crosslink density, a β‐CD‐HA hydrogel with a diclofenac sustained delivery period of over 28 days and desirable physicochemical properties was achieved, which will be a promising drug sustained delivery carrier for wound healing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43072.     

基质型经皮给药缓释贴片的体外释放研究

研究了基质中雌二醇 (E2 )的质量分数wE 对透皮贴片的释放影响。实验结果表明E2 的释放度在wE 为 1 5 %～ 3%是相近的 ,不受wE 的影响 ;wE 提高 1倍 ,累计释药量平均提高 80 %。动力学研究表明 ,前 12h内 ,释放度满足Higuchi公式 ,即与t1/2 成线性关系 ;12h后与t0 .7成线性关系 ,为非Fick扩散     

Self‐assembled micelles prepared from poly(ɛ‐caprolactone)–poly(ethylene glycol) and poly(ɛ‐caprolactone/glycolide)–poly(ethylene glycol) block copolymers for sustained drug delivery

A series of poly(?‐caprolactone)–poly(ethylene glycol) (PCL‐PEG) and poly(?‐caprolactone/glycolide)–poly(ethylene glycol) [P(CL/GA)‐PEG] diblock copolymers were prepared by ring‐opening polymerization of ?‐caprolactone or a mixture of ?‐caprolactone and glycolide using monomethoxy PEG (mPEG) as macroinitiator and Sn(Oct)₂ as catalyst. The resulting copolymers were characterized using ¹H‐NMR, gel permeation chromatography, differential scanning calorimetry, and wide‐angle X‐ray diffraction. Copolymer micelles were prepared using the nanoprecipitation method. The morphology of the micelles was spherical or worm‐like as revealed by transmission electron microscopy, depending on the copolymer composition and the length of the hydrophobic block. Introduction of the glycolide component, even in small amounts (CL/GA = 10), disrupted the chain structure and led to the formation of spherical micelles. Interestingly, the micelle size decreased with the encapsulation of paclitaxel. Micelles prepared from mPEG5000‐derived copolymers exhibited better drug loading properties and slower drug release than those from mPEG2000‐derived copolymers. Drug release was faster for copolymers with shorter PCL blocks than for those with longer PCL chains. The introduction of glycolide moieties enhanced drug release, but the overall release rate did not exceed 10% in 30 days. In contrast, drug release was enhanced in acidic media. Therefore, these bioresorbable micelles and especially P(CL/GA)‐PEG micelles with excellent stability, high drug loading content, and prolonged drug release could be promising for applications as drug carriers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45732.     

APPARENT NON-FICKIAN RELEASE FROM A SCLEROGLUCAN GEL MATRIX

Hydrogels, and particularly biopolymeric hydrogels, have recently received tremendous interest as controlled release systems for their peculiar features such as high biocompatibility, biodegradability, bioadhesivity, chemical and thermal resistance and good mechanical properties. Among biopolymers, the exocellular microbial polysaccharide scleroglucan appears to be particularly well suited for the formulation of monolithic hydrogel matrices for controlled drug release. In this work we studied the macroscopic factors influencing the kinetics of a model drug release (theophylline) from a scleroglucan hydrogel matrix (2%w/w) and modeled the relevant experimental results. The evidences for the release experiments indicate that the kinetics of the processes follow an apparently non-Fickian behavior under different active drug concentration, temperature and stirring speed. However, by considering the peculiar nature of the hydrogel matrix and the geometrical features of the experimental setup in the formulation of the appropriate initial and boundary conditions, data can be satisfactorily modeled with the classical Fick's law.     

Poly(L‐histidine)‐chitosan/alginate complex microcapsule as a novel drug delivery agent

Novel poly(L ‐histidine)‐chitosan/alginate complex microcapsules were prepared from biodegradable polymers poly(L ‐histidine) (PLHis) in the presence of chitosan at acetate buffer solution pH 4.6. Microcapsules obtained are spherical and well‐dispersed with a smooth surface and a narrow size distribution. The microcapsules can encapsulate the protein model drug hemoglobin (Hb) efficiently. The results show that the complex microcapsules with low, medium, or high molecular weight of chitosan (0.05%, w/v), the highest encapsulation efficiencies obtained are 91.3%, 85.9%, and 94.2% with loading efficiencies of 47.8%, 44.3%, and 39.7%, respectively. The release profiles indicate that Hb‐loaded microcapsules conform to first‐order release kinetic in whole procedure, and 84.8%, 71.4%, and 87.3% of Hb were released during 72‐h incubation in PBS pH6.8 for microcapsules with low, medium, and high molecular weight chitosan (0.05%, w/v), respectively. The results also indicate that particle size and drug loading efficiency have a significant influence on the release profile and encapsulation efficiency. Our results reveal that the PLHis‐chitosan/alginate complex microcapsules are able to encapsulate and release Hb and are potential carriers for protein drugs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Properties of chitosan/poly(vinyl alcohol) films for drug‐controlled release

With bovine serum albumin (BSA) as a model drug, drug‐loaded films of chitosan (CS) and poly(vinyl alcohol) (PVA) were obtained by a casting/solvent evaporation method and crosslinked by tripolyphosphate (TPP). The films were characterized by FTIR, XRD, and SEM. The influential factors of drug‐loaded films on drug‐controlled release were studied. These factors included, primarily, the component ratio of CS and PVA, the loaded amount of BSA, the pH and ionic strength of the release solution, and the crosslinking time with TPP. The results showed that within 25 h, when the weight ratios of CS to PVA in the drug‐loaded films were 90 : 10, 70 : 30, 50 : 50, and 30 : 50, the cumulative release rates of BSA were 63.3, 72.9, 81.8, and 91.8%, respectively; when the amounts of model drug were 0.1, 0.2, and 0.3 g, the release rates were 100, 81.8, and 59.6%, respectively; when the pH values of the drug release medium were 1.0, 3.8, 5.4, and 7.4, the release rates reached 100, 100, 37.9, and 7.8%, respectively; the cumulative release rates of BSA were 78.4, 82.3, 84.3, and 91.7% when the ionic strengths of the release solution were, respectively, 0.1, 0.2, 0.3, and 0.4M; when the crosslinking times of these drug films in the TPP solution were 0, 5, 15, 30, and 60 min, the release rates attained 100, 100, 81.8, 65, and 43.3%, respectively. All the results indicated that the CS/PVA film was useful in drug delivery systems. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 808–813, 2005     

Ethyl methacrylate grafted on two starches as polymeric matrices for drug delivery

The use of copolymers grafted on starch for controlled‐release technology is an interesting proposal, since a modification of a natural polymer is more suitable than synthetic polymers because of its biocompatibility and biodegradability. The aim of this paper is to synthesize acrylic polymers grafted on carbohydrates to investigate the release kinetic of different solubility drugs from polymeric matrix systems and to observe the effect of grafted copolymers and drug solubility on the release mechanism. Copolymer variables such as carbohydrate content, stereoregularity of grafted chains, particle size, morphology, sensitivity to hydration, and rheological properties are discussed. Tablets were prepared by direct compression of the graft copolymer and drug. The drugs' release in vitro kinetics was studied by dissolution testing. Drug release from tablets depends on polymer matrix, polymer content, drug, and pH. An increase in drug solubility results in an increase in the rate of dissolution, as in the case of a poor hydrophilic matrix. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 523–536, 2005     

Preparation and evaluation of chitosan‐coated polyphosphazene hydrogel beads for drug controlled release

Chitosan‐coated polyphosphazene‐Ca²⁺ hydrogel beads were fabricated by dropping polyphosphazene into CaCl₂/chitosan gelling solution. Polyphosphazene used here was a water‐soluble degradable polyanion (PCPAP), which carried almost two carboxylatophenamino groups on each phosphorus atom of the polymer backbone. Two kinds of turbidimetric titration were applied in this study to reveal the interaction between PCPAP and chitosan within the pH range of 4.57≈7.14. The effect of gelling solution pH on the properties of chitosan‐coated PCPAP beads was especially emphasized. It was found that the PCPAP/chitosan complex prepared at relatively high pH (pH 6.5) dissociated most slowly in pH 7.4 phosphate‐buffered solution (PBS). The erosion of chitosan‐coated beads and the release of model drug (Coomassie brilliant blue and myoglobin) in PBS were both obviously prolonged with the increase of gelling solution pH, exhibiting perfect accordance with the behavior of complex dissociation. In addition, the coating of PCPAP/chitosan complex on the bead surface facilitated the improvement of drug loading efficiency. The higher the gelling solution pH, the more the drug loading efficiency improved. At pH 6.5 (PCPAP 5%, CaCl₂ 7%, chitosan 0.3%), the loading efficiency of myoglobin in beads reached as high as 93.2%. These results indicate that the chitosan‐coated polyphosphazene‐ Ca²⁺ bead is a potential formulation for drug controlled release. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1993–1999, 2004     

Synthesis and characterization of chitosan/cloisite 30B film for controlled release of ofloxacin

In this research program, chitosan film was prepared by blending chitosan with Cloisite 30 B at different concentrations 0 wt %, 1 wt %, and 2.5 wt %. The blends were characterized by Fourier transmission infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X‐ray diffraction (XRD) analysis. From the FTIR spectra the various groups present in chitosan/C 30 B blend were monitored. The homogeneity, morphology, and crystallinity of the blends were ascertained from SEM and XRD data, respectively. The most suitable form of blend was taken and used as a carrier for the controlled release of ofloxacin. The swelling studies have been carried out at different drug loading. Drug release kinetics was analyzed by plotting the cumulative release data versus time by fitting to an exponential equation which indicated the occurrence of non‐Fickian type of kinetics. The drug release was investigated at different pH medium and it was found that the drug release depends upon the pH medium as well as the nature of matrix. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Robocasting of MgO‐doped alumina using alginic acid slurries

The benefits of MgO doping of alumina for maintaining a homogeneous grain structure have long been established. Therefore in this work a bespoke ink for Robocasting of alumina is developed based on the gelation of alginic acid using magnesium ions, thereby ensuring homogeneous MgO doping of the alumina green body. The shear thinning behavior of alginic acid based solutions was paired with the rheological properties of a partially coagulated colloidal suspension to allow high solid loading inks (up to 50 vol%) with good extrusion behavior. Shear thinning coefficients of n ~ 0.2 were recorded, with yield stresses of 250 Pa and stiffness values in the range 100‐1000 kPa. The printed alumina bars reached densities of >98% and unpolished strengths reached up to 326 ± 16 MPa after sintering at 0.4 mol/L magnesium chloride and 45 vol% alumina.     

Glutaraldehyde‐crosslinked chitosan/hydroxyapatite bone repair scaffold and its application as drug carrier for icariin

Chitosan/hydroxyapatite (CS/HA) bone repair scaffolds crosslinked by glutaraldehyde (GA) were prepared. Characterization of morphology, structure, mechanical property, and porosity of scaffolds were evaluated. The influences of CS viscosity, HA content, and crosslinking degree on properties of scaffolds were discussed. SEM images showed that CS/HA scaffolds were porous with short rod‐like HA particles dispersing evenly in CS substrate. When [η]_CS = 5.75 × 10^?4, HA content = 65%, and crosslinking degree = 10%, the resulting CS/HA scaffolds had a flexural strength of 20 MPa and porosity of 60%, which could meet the requirements of bone repair materials. The scaffolds were used as drug carriers for icariin, and the impacts of loading time and crosslinking degree of scaffolds on drug‐loading dose were discussed. The suitable loading time was 24 h and it would be better to keep crosslinking degree no more than 10%. The drug release behavior demonstrated that the icariin‐loading CS/HA scaffolds could achieve basic drug sustained release effect. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1539–1547, 2013     

Effects of drying process for amorphous waxy maize starch on theophylline release from starch‐based tablets

Physical properties and theophylline‐release profiles of compressed tablets prepared with amorphous waxy maize starches dried using different methods were examined. A gelatinized waxy maize starch paste (10% solids in water) was either freeze‐dried or oven‐dried (40 or 105°C) until the moisture content reached to <5%. To form the tablets, the dried amorphous starch powders, either with or without theophylline (3 : 10, w/w), were remoistened to a water content of (17 ± 0.2)%, and compressed into tablets. The drying process applied to the amorphous starch powders affected both the compactness and swelling behavior of the tablets. Although no crystallinity was detected in all the starches tested, X‐ray diffraction patterns indicated that starch chains dried at the lower temperature (40°C) are allowed more time to re‐associate during the drying process than those dried at the higher temperature (105°C). The freeze‐dried starch powders formed tablets characterized by greater compactness and rigidity than was observed in the oven‐dried starch samples. The drug release of the tablets prepared with the starch dried at the higher temperature (105°C) occurred at a much slower rate than that of the tablets made with the starch dried at the lower temperature (40°C). The drug release characteristics of the freeze‐dried starch tablets were nearly identical to those of the tablets prepared with the starch dried at 105°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Release mechanisms of semipolar solutes from poly(dimethylsiloxane) elastomers: Effect of a hydrophilic additive

The release profiles of three xanthine derivatives from matrices of pure poly(dimethylsiloxane) (PDMS), and the effect of incorporating 10% w/w polyethylene glycol (PEG)?3000 in the matrix are presented. Theobromine (TBR), theophylline (TPL), and caffeine (CAF), although structurally very similar, are characterized by different physicochemical properties. In addition, differential scanning calorimetry and scanning electron microscopy measurements indicate different physical interactions with the polymeric matrices. The observed rates of release from pure PDMS matrices loaded at 0.065 g/g with each one of the drugs increase in the order TBR < TPL < CAF. The same order holds for the corresponding permeabilities derived from the release kinetic data. The slopes of the release curves versus the square root of time were linearly correlated to the square root of calculated solubilities in the polymer, as expected by the Higuchi equation for diffusive transport of solutes of the same diffusivity. The incorporation of 10% w/w PEG in the PDMS matrix accelerates the release rate of each drug, because of the concurrent water uptake induced by the hydrophilic additive. The extent of the corresponding permeability enhancement for theophylline was close to that predicted by the Maxwell equation for a composite two‐phase system, consisting of a PDMS continuous phase characterized by a much lower permeability than that of the fully swollen PEG dispersed phase. The corresponding enhancement of permeability was higher for TBR and lower for CAF. Possible reasons for these differences are discussed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40782.     

Effect of hydrophobicity of a drug on its release from hydrogels with different topological structures

The effect of the topological structure; that is, the network heterogeneity, of hydrophobically modified, slightly acidic hydrogels on the binding and release of low molar mass drugs has been studied using ibuprofen and ephedrine as model compounds with varying water solubility. The difference in the heterogeneity of the gels has been produced by the choice of the hydrophobe copolymerized into the polymer network. The effect of the drug loading on the release kinetics has been investigated as well. The release of hydrophobic ibuprofen was slower from a strongly aggregated heterogeneous gel than from a more homogeneous one, because of the strong hydrophobic interaction between ibuprofen and the heterogeneous hydrogel. The release of hydrophilic ephedrine from the homogeneous gel with an initial drug content of 30 wt % of dry polymer showed negative time dependence, indicating that during and after the swelling of the gel, ephedrine started to bind to the polymer. However, the release of ephedrine from a heterogeneous hydrogel increased with time. This shows that the heterogeneous, aggregated polymer binds the hydrophobic substance more strongly than the homogeneous one does, and that the homogeneous network has higher affinity for the basic hydrophilic substance than the heterogeneous one does. The loading contents of ibuprofen and ephedrine affect the release rates in different ways because of the different binding and release mechanisms. The number of binding sites accessible for ephedrine inside the polymer network is assumed to change upon the swelling of the gel. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1031–1039, 1999     

The effect of isopropanol addition on enhancement of transdermal controlled release of ibuprofen from ethylene vinyl acetate copolymer membranes

This work reports the study of the addition of isopropanol on controlled release of ibuprofen from ethylene vinyl acetate (EVAc) copolymer membranes. An EVAc solution in cyclohexane (4% w/v) containing triethyl citrate (7% w/v) as plasticizer was mixed with ibuprofen at three different concentrations of 4, 6, and 8%. Isopropanol was mixed with each of the previous mixtures to form solutions of 1, 3, and 5% isopropanol concentrations. Samples were solvent cast on glass petri‐dishes to form membranes. Home‐made diffusion cells were used for in vitro study. These cells were composed of two compartments, donor (exposed to ambient conditions), and receptor (including buffer solution maintained at 37°C). Each cell was equipped with a sampling port and water in and out system. An ultraviolet spectrometer at 222 nm was used to measure release rates of obtained membranes. The diffusion mechanism for drug release was examined by zero‐order, first‐order, Higuchi and Korsmeyer‐Peppas theories to confirm the obtained membranes follow the matrix‐type system. By increasing the drug concentration from 4 to 8%, drug release (cumulative amount) was improved from 20 (47.5%) to 30 (36%) μg/cm² after 24 h. Addition of 5% isopropanol to the above samples (4 and 8% loading) further increased drug release to 24 and 43 μg/cm². Results were in good agreement with the Korsmeyer‐Peppas theory for samples with 4 (% w/w) of ibuprofen. The highest percentage of drug release after 24 h was 59% for the sample with 4% drug loading compared to 50% for the sample with 8% drug loading, both with 5% isopropanol. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011