pH-independent Polymer Research Articles

Formulation and Evaluation of Taste Masked Chewable Tablet containing Curcumin, Acetaminophen, and Ascorbic acid to treat sore throat

Objective: This study was intended to investigate the formulation and characterization of Mesalamine or 5-Aminosalicylic acid (5-ASA) pellets using novel excipient and formulated as matrix spheres to controlled the drug release extended period of time. Uniformly distributed throughout the gastrointestinal tract and Avoid dose dumping of drug. Methods: Mesalamine's active pharmaceutical component was characterised, and investigations were conducted prior to formulation to ensure a physical combination of the drug and excipients was achieved. Formulation of mesalamine as matrix pellets by using fluid bed processor and mesalamine loaded into seal coated sugar spheres and extended-release coating with Ethyl cellulose. Ethyl cellulose is pH independent polymer and retarder the drug release throughout the gastrointestinal tract and site-specific action in colon. Hypromellose also act as pore former and drug release based on diffusion mechanism. In drug layering, core pellets contain stearic acid and hydrogenated castor oil internally forming a matrix. Developed mesalamine pellets are characterized such as drug content, invitro drug release and appearances and particle size distribution. Results: Development of Mesalamine pellets based on five strategy From MEZ 1 to MEZ 5 are formulated and Characterization are performed. Based on the invitro drug release studies, we concluded that the formulation MEZ-IV was best formulation. Invitro drug release is consistence throughout 12hours.(1hrs-23%, 2nd hrs 41%, 4hrs-73, 6hrs-86, 8hrs-99% and 12hrs-10.

Compression Coating Technique and its Formulation in Circadian Rhythm Activity with Chronotherapeutic Drug Delivery System

Background: Circadian rhythms is a natural process that regulates the sleep wake cycle which is associated with several physiological, biochemical, endocrine, behavioural processes in humans and entrainment to light-dark cycle. The activity of Ramelteon is believed to contribute to its sleep-promoting properties and thought to be involved in the maintenance of the circadian rhythm underlying the normal sleep-wake cycle. A tablet can be given before 2 hr of bed time, so the Ramelteon drug shows its effect throughout the night by releasing the active content with lag time followed by sustained action to promote the sleep. Materials and Methods: Chronotherapeutic drug delivery system were prepared by compression coating technology using pH independent, hydrophilic and hydrophobic polymers. Results: Drug excipient compatibility indicated that the Ramelteon Active pharmaceutical ingredient (API) is compatibility with the excipients proposed. The X-ray Diffraction (XRD) studies indicated that the crystalline form of the Ramelteon API existed in the finished formulation. Conclusion: The core tablets containing Eudragit RSPO 10mg/tablet and ratio of Ethyl cellulose: Hydroxy propyl methyl cellulose (HPMC) of 70:30 in the outer coating material yielded a desired lag time of 2 hr and drug release for a period of 4 hr to achieve a chronotherapeutic drug delivery system. Ramelteon is an excellent candidate in designing chronotherapeutic drug delivery systems and further in vivo studies can be explored in the treatment of circadian rhythm with sleep wake cycle disorders.

The Effect of pH dependent and pH independent polymers on the drug release of anti-ischemic agent :

The objective of current study is to study the effects of combination of pH independent (HPMCK100M) and dependent (partially neutralized; Eudragit L 100-55) polymers on the drug release of Ranolazine form extended release tablet formulation. Ranolazine, an anti-ischemic or anginal agent. Mainly used for treating exercise induced; variant and stable chronic angina pectoris along with myocardial infarction. Anti-ischemic effect exhibited by Ranolazine is independent of haemodynamic effects, due to this benefit; it was useful for treating patients, who were not responded to other anti-anginals. Extended release tablets of Ranolazine were prepared using various proportions of Eudragit L 100-55,HPMCK100M in by direct compression technique. 9 formulations were developed and characterized for pharmacopoeial limits. Data obtained from the dissolution study fitted well to kinetic modeling, kinetic parameters were determined. EHR5 containing 31.25 mg of Eudragit L 100-55& 31.25 mg of HPMCK100M, is the best formulation showing similarity f2=85.77, f1= 2.31 with the marketed product (RANOLAZ). Formulation EHR5 follow zero order, whereas release mechanism found to be nonfickian type (n= 0.653).

MODULATORY EFFECT OF POLYMER TYPE AND CONCENTRATION ON DRUG RELEASE FROM SUSTAINED RELEASE MATRIX TABLETS OF RANOLAZINE: A COMPARATIVE RELEASE KINETIC STUDY

Objective: Ranolazine (RZ), antianginal drug indicated for the treatment of chronic stable angina pectoris, was formulated into sustained-release matrix tablets and optimized to improve patient compliance and achieve controlled release over a certain period.
 Methods: Different formulations were prepared by wet- and melt-granulation techniques. Excipients at different ratios as Eudragit® L100-55, Methocel™ E5, Avicel® PH-101, and carnauba wax powder were used to develop a ternary polymeric matrix system for the controlled delivery of RZ. The prepared formulations were subjected to granulometric and characteristic studies. Comparative dissolution and release kinetic studies of the selected formulation and the reference product, Ranexa® extended-release film-coated tablets, Gilead Sciences, Inc., USA, were further carried out to ensure product similarity.
 Results: The optimum pH-dependent to pH-independent polymers ratio was 1:1.3 (w/w). Extragranular carnauba wax in a concentration of 32.50 mg/tablet (2.50 gm% w/w) was the key excipient in controlling drug release kinetics by forming waxy matrix granules which prevent rapid dissolution. Modulation of the microenvironmental pH using a potent alkalinizing agent was very effective for controlling drug release patterns in different dissolution media from pH 1.2–6.8.
 Conclusion: The release of RZ from the matrix tablets was controlled for a period of 24 h, and thereby expected to provide patient compliance with minimal side effects.

DESIGN AND EVALUATION OF GUANFACINE EXTENDED RELEASE FORMULATION

Objective: The present study was aimed to develop of the Guanfacine Hydrochloride Extended-release tablets for the treatment of Attention Deficit Hyperactivity Disorder (ADHD). The dosage regimen of Guanfacine Hydrochloride is 4 mg at every 6 h. The concentration of Guanfacine in plasma is fluctuating. Hence, to control the plasma fluctuation and to avoid toxicity problem, Guanfacine Hydrochloride was chosen as a drug with an aim to develop an extended release system for 20 to 24 h.
 Methods: The design of the system was based on the use of pH-dependent polymer (Hydroxypropyl Methyl Cellulose), pH-independent polymer (Eudragit L 100-55), along with microenvironment modifiers such as organic acid (Fumaric acid) were used in the formulation. Drug-excipient compatibility was studied by FTIR. Before compression, the granules were evaluated for precompression parameters such as bulk density, tapped density, an angle of repose, compressibility index and Hausner’s ratio. After compression, evaluation tests of tablets such as general appearance, hardness, thickness, weight variation, friability, content uniformity, in vitro release studies and stability studies were performed.
 Results: Out of 9 formulations, the drug release was found to be within the innovator formulation F9. The stability study of formulation F9 revealed there was no significant change in physical and chemical properties of drug stored at 40 °C/75 % RH, 30 °C/65 % RH, 25 °C/60 % RH for 2 mo.
 Conclusion: Optimized formulation batch F9 showed highest F2 value which indicates similarity with innovator product. The study indicates that Guanfacine Hydrochloride Extended-release tablet was successfully developed.

Mesalamine-loaded mucoadhesive microsphere for colon drug delivery system: Effect of process variables and in vitro characterization

Objective: The main objective of this study is to formulate mucoadhesive microspheres for colon drug delivery with sodium alginate (ALG) core enriched with drug. Methods: The core microspheres of ALG were prepared by modified emulsification method followed by cross-linking with different concentration of CaCl2 at different stirring speed with constant drug-to-polymer ratio (1:3). The core microspheres were further coated with Eudragit S-100 using the solvent evaporation technique. Results: The microspheres (core and coated) were characterized by shape, size, surface morphology, size distribution, entrapment efficiency, and in vitro drug release studies. In vitro drug release showed that the optimized batch of core microsphere and coated microspheres exhibited 99.53% ± 0.39% and 89.22% ± 0.26%, respectively. The drug release from all formulations of mesalamine microsphere followed Higuchian Kinetics. Moreover, drug release from core and Eudragit S-100-coated microspheres followed Korsmeyer–Peppas equation with anomalous and Fickian kinetics mechanism, respectively. Stability study suggests that the degradation rate constant of mesalamine from Eudragit S-100-coated microsphere was found to be minimum 2 years shelf life of the formulation. On the basis of scanning electron microscopy, the core microspheres were formed slightly irregular in shape due to surface-attached crystals of the drug and coated mesalamine microspheres showed smooth surface and a smaller number of pores due to coating. Conclusions: It can be concluded that the appropriate combination of a pH-dependent polymer (Eudragit S-100) with a pH-independent polymer sodium ALG) was suitably adequately sustained the drug release from mesalamine microspheres.

Sustained-release solid dispersion of pelubiprofen using the blended mixture of aminoclay and pH independent polymers: preparation and in vitro/in vivo characterization

The present study aimed to develop the sustained-release oral dosage form of pelubiprofen (PEL) by using the blended mixture of 3-aminopropyl functionalized-magnesium phyllosilicate (aminoclay) and pH-independent polymers. The sustained-release solid dispersion (SRSD) was prepared by the solvent evaporation method and the optimal composition of SRSD was determined as the weight ratio of drug: Eudragit® RL PO: Eudragit® RS PO of 1:1:2 in the presence of 1% of aminoclay (SRSD(F6)). The dissolution profiles of SRSD(F6) were examined at different pHs and in the simulated intestinal fluids. The drug release from SRSD(F6) was limited at pH 1.2 and gradually increased at pH 6.8, resulting in the best fit to Higuchi equation. The sustained drug release from SRSD(F6) was also maintained in simulated intestinal fluid at fasted-state (FaSSIF) and fed-state (FeSSIF). The structural characteristics of SRSD(F6) were examined by using powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR), indicating the change of drug crystallinity to an amorphous form. After oral administration in rats, SRSD(F6) exhibited the prolonged drug exposure in plasma. For both PEL and PEL-transOH (active metabolite), once a day dosing of SRSD(F6) achieved oral exposure (AUC) comparable to those from the multiple dosing (3 times a day) of untreated drug. In addition, the in vivo absorption of SRSD(F6) was well-correlated with the in vitro dissolution data, establishing a good level A in vitro/in vivo correlation. These results suggest that SRSD(F6) should be promising for the sustained-release of PEL, thereby reducing the dosing frequency.

Design and development of controlled release floating matrix tablet of Nicorandil using hydrophilic cellulose and pH-independent acrylic polymer: in-vitro and in-vivo evaluations

Objectives: The purpose of the study was to develop a floating matrix tablet of Nicorandil using blends of hydrophilic cellulose and pH-independent acrylic polymer to improve the therapeutic effectiveness of the drug in cardiovascular disease.Methods: Nicorandil tablets were prepared by direct compression and evaluated for drug-excipients compatibility, in-vitro buoyancy and in-vivo γ-scintigraphy study. The selected formulation (FT5) was also evaluated for stability study and the in-vivo absorption in rabbits to compare the pharmacokinetic parameters with the commercially available immediate release tablet of Nicorandil.Results: DSC and FT-IR studies confirmed the absence of incompatibility and were found stable at refrigerator temperature (2-8°C) and at 25ºC/60% RH. The in-vivo γ-scintigraphy studies revealed that the system was floated for a period of 6 -7 h in the stomach and in-vivo absorption study showed a significant difference (p < 0.05) in the pharmacokinetic parameters (AUC increased by 3 fold and MRT by 2.5 fold) as compared to the marketed formulation.Conclusion: In conclusion, the developed Nicorandil floating matrix tablet improved the pharmacokinetics parameters (AUC and MRT) in rabbit plasma with expected lowering in side effects potential.

Formulation, characterization and evaluation of the effect of polymer concentration on the release behavior of insulin-loaded Eudragit(®)-entrapped mucoadhesive microspheres.

Introduction:The aim of this study was to use Eudragit® RL 100 (pH-independent polymer) and magnesium stearate (a hydrophobic droplet stabilizer) in combination to improve the controlled release effect of insulin-loaded Eudragit® entrapped microspheres prepared by the emulsification-coacervation technique.Materials and Methods:Mucoadhesive insulin-loaded microspheres containing magnesium stearate and varying proportions of Eudragit® RL 100 were prepared by the emulsification-coacervation technique and evaluated for thermal properties, physicochemical performance, and in vitro dissolution in acidic and subsequently basic media.Results:Stable, spherical, brownish, discrete, free-flowing and mucoadhesive insulin-loaded microspheres with size range of 14.20 ± 0.30-19.80 ± 0.60 μm and loading efficiency of 74.55 ± 1.05-75.90 ± 1.94% were formed. After 3 h, microspheres prepared with insulin: Eudragit® RL 100 ratios of 1:4, 1:6, and 1:8 released 73.40 ± 1.38, 66.20 ± 1.59, and 71.30 ± 1.27 (%) of insulin, respectively.Conclusion:The physicochemical and physico-technical properties of the microspheres developed in this study demonstrated the effectiveness of the Eudragit® RL entrapped mucoadhesive microspheres (prepared by the emulsification-coacervation technique using varying polymer concentration) as a carrier system for oral insulin delivery.

Mechanical evaluation of matrix type transdermal therapeutic systems containing captopril

The objective of this study was to evaluate the mechanical properties of transdermal therapeutic systems (TTS) containing captopril together with synthetic and pH independent polymers, Eudragit RL 100 and RS 100. The formulations were characterized in terms of their adhesiveness and bioadhesiveness by using texture analyser. These optimum formulations were chosen according to the results of our previous study regarding in vitro dissolution and ex vivo diffusion rate studies through excised human skin by using Franz Diffusion Cell. Results indicated that the mechanical properties of the formulations were suitable to be used as a transdermal patch. Keywords: captopril, transdermal therapeutic system, patch adhesiveness, patch bioadhesiveness, texture analyser

Design and optimization of self-microemulsifying drug delivery system (SMEDDS) of felodipine for chronotherapeutic application

The objective of this research work was to design, develop and optimize the self micro-emulsifying drug delivery system (SMEDDS) of Felodipine (FL) filled in hard gelatine capsule coated with polymer in order to achieve rapid drug release after a desired time lag in the management of hypertension. Microemulsion is composed of a FL, Lauroglycol FCC, Transcutol P and Cremophor EL. The optimum surfactant to co-surfactant ratio was found to be 2:1. The resultant microemulsions have a particle size in the range of 65-85 nm and zeta potential value of -13.71 mV. FL release was adequately adjusted by using pH independent polymer i.e. ethyl cellulose along with dibutyl phthalate as plasticizer. Influence of formulation variables like viscosity of polymer, type of plasticizer and percent coating weight gain was investigated to characterize the time lag. The developed formulation of FL SMEDDS capsules coated with ethyl cellulose showed time lag of 5-7 h which is desirable for chronotherapeutic application.

A Novel Approach to Extended Release Clopidogrel: Differentially Coated Mini-Tablets Filled In Hard Gelatin Capsules

The main objective of the present study is to formulate an extended release formulation of clopidogrel bisulphate into mini-tablets coated with a combination of pH dependent polymer, pH independent polymer and pore former. Clopidogrel is extensively absorbed and 50% of drug is eliminated in urine in unchanged form. To improve the bioavailability of clopidogrel, the extended release formulation was formulated with an in-situ solubility enhancer, and barrier coated with moisture protective layer. The barrier coated minitablets are coated with the combination of pH dependant polymer (Hypromellose phthalate HP 50), pH independent polymer (Ethyl cellulose 7cps) and pore former (Hypromellose 5cps) at different ratio, with a weight build up of 10%w/w. In-vitro dissolution was studied in pH 1.2 HCl for 1 hour, followed by pH 6.5 phosphate buffer for 11 hrs, using USP dissolution test apparatus 1 at 100 RPM. The formulation (F37), coated with the ratio of 60:25:15 (Ethocel 7cps: Hypromellose phthalate 50: Hypromellose 5cps), shown the better release of 32% in acid for 1hr, to achieve the loading dose, and the extent of 100% release at 12hr, in pH 6.5 phosphate buffer. Zero-order, first-order, Higuchi, Hixson-Crowell and Korsmeyer peppas models were used to estimate the kinetics of drug release. Drug release kinetics indicated that the drug release was best explained by Higuchi’s equation, as these plots showed the highest linearity (R 2 = 0.9902) indicating the release of drug from matrix as a square root of time dependent process.

Felodipine β-cyclodextrin complex as an active core for time delayed chronotherapeutic treatment of hypertension

The present research work deals with the development of a time delayed chronotherapeutic formulation of felodipine (FD) aimed at rapid drug release after a desired lag time in the management of hypertension. The developed system comprises a drug core embedded within a swellable layer and coated with an insoluble, water permeable polymeric system. FD cyclodextrin complex was used as an active core while ethyl cellulose was used as an effective coating layer. Dissolution studies of the complex revealed that there was a 3-fold increase in dissolution of the complex compared to plain FD. This dissolution enhancement and rapid drug release resulted from FD amorphisation, as confirmed by XRD, DSC and SEM studies. FTIR and ¹H NMR studies confirmed the complex formation between FD and cyclodextrin based on the observed hydrogen bond interactions. FD release was adequately adjusted by using a pH independent polymer, i.e., ethyl cellulose, along with dibutyl phthalate as plasticizer. Influence of formulation variables like polymer viscosity, plasticizer concentration, super disintegrant concentration in the swellable layer and percent coating weight gain was investigated to characterize the lag time. Upon permeation of water, the core tablet swelled, resulting in the rupture of the coating layer, followed by rapid drug release. The developed formulation of FD showed a lag time of 5-7 h, which is desirable for chronotherapeutic application.

Formulation development and statistical optimization of chronotherapeutic tablets of indometacin

Chronotherapeutic drug delivery offers a new approach in the pharmacologic interventions design for the effective treatment in the diseases which follows circadian rhythm. In the present study chronotherapeutic tablets of indometacin was designed to match the timing of rheumatoid arthritis treatment with the intrinsic illness timing. The developed chronotherapeutic delivery system consists of a core tablet containing the active ingredient along with osmogents and other excipients, which was coated with a swellable polymer, hydroxyl propyl methyl cellulose by compression coating technique. The time controlled release was achieved by coating the entire system with a combination of pH-independent polymer, Eudragit RS 100 and Eudragit RL 100 (1:1). The optimization technique using Box–Behnken design was employed for the selection of the ideal formula. The optimization procedure was validated, and the observed value of the ideal batch was found to be similar with the predicted values within 5% of predicted error. The formulation when administered at bed time starts releasing the drug after a lag time of 4 h and provides sufficient plasma concentration after 6 h of normal sleep. Thus, the tablets can be successfully used for the chronotherapeutic drug delivery of indometacin in the treatment of rheumatoid arthritis.

Formulation and Evaluation of Sustained Release Matrix Tablets of Metformin Hydrochloride Using pH Dependent and pH Independent Methacrylate Polymers

Formulation and Evaluation of Sustained Release Matrix Tablets of Metformin Hydrochloride Using pH Dependent and pH Independent Methacrylate Polymers

Formulation and Evaluation of Sustained Release Matrix Tablets of Metformin Hydrochloride Using pH Dependent and pH Independent Methacrylate Polymers

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Formulation and Evaluation of Sustained Release Matrix Tablets of Metformin Hydrochloride Using pH Dependent and pH Independent Methacrylate Polymers

Metformin hydrochloride is recommended globally as first line therapy due to its favorable profile on morbidity and mortality associated with type-2 diabetes mellitus. However, limitations of multiple dosing and risk of triggering gastrointestinal symptoms make its dose optimization difficult. Extended-release metformin matrix tablets were prepared by direct compression of drug and different pH-dependent (Eudragit L-100 and S-100) and pH-independent (Eudragit RLPO and RSPO) polymer combinations. The influence of varying the polymer/polymer (w/w) ratio was evaluated. Among the different examined polymer blends, matrix tablets based on S-100/RLPO and S-100/RSPO mixtures gave the more sustained release pattern. The excipients used in this study did not alter physicochemical properties of the drug, as tested by Fourier transform Infrared Spectroscopy and the thermal analysis using differential scanning calorimetry. All the batches were evaluated for thickness, weight variation, hardness, and drug content uniformity. The in vitro drug dissolution study was carried out using USP 22 apparatus II, paddle method and the release mechanisms were explored. Mean dissolution time is used to characterize drug release rate from a dosage form and indicates the drug release retarding efficiency of polymer. Kinetic modeling of in vitro dissolution profiles revealed the drug release mechanism ranges from diffusion controlled to anomalous type. Fitting the data to Korsmeyer equation indicated that diffusion along with erosion could be the mechanism of drug release. Research Article

Engineering polymer blend microparticles: An investigation into the influence of polymer blend distribution and interaction

The aim of this work was to understand the influence of polymer interaction and distribution on drug release from microparticles fabricated from blends of polymers. Blends of pH dependent polymer (Eudragit S, soluble above pH 7) and pH independent polymer (Eudragit RL, Eudragit RS or ethylcellulose) were incorporated into prednisolone loaded microparticles using a novel emulsion solvent evaporation method. Microparticles fabricated from blends of Eudragit S and Eudragit RL or RS did not modify drug release compared to microparticles fabricated from Eudragit S alone. This can be attributed to the high degree of miscibility of Eudragit S with Eudragit RS or Eudragit RL within the microparticles as confirmed by glass transition temperature measurements and confocal laser scanning microscopy. In contrast, microparticles prepared from blends of Eudragit S (75%) and ethylcellulose (25%) extended the release of prednisolone at pH 7.4 (compared to Eudragit S microparticles). This change in release profile was related to the immiscibility of Eudragit S and ethylcellulose as assessed by thermal analysis, and confirmed by microscopy which showed pores within the microparticle structures following dissolution of the Eudragit S domains. The ability of water insoluble polymers to extend drug release from enteric polymer microparticles is dependent on the miscibility and interaction of the polymers. This knowledge is important in the design of pH responsive microparticles capable of extending drug release in the gastrointestinal tract.

Comparison of Release-Controlling Efficiency of Polymeric Coating Materials Using Matrix-type Casted Films and Diffusion-Controlled Coated Tablet

Polymeric coating materials have been widely used to modify release rate of drug. We compared physical properties and release-controlling efficiency of polymeric coating materials using matrix-type casted film and diffusion-controlled coated tablet. Hydroxypropylmethyl cellulose (HPMC) with low or high viscosity grade, ethylcellulose (EC) and Eudragit(R) RS100 as pH-independent polymers and Eudragit S100 for enteric coatings were chosen to prepare the casted film and coated tablet. Tensile strength and contact angle of matrix-type casted film were invariably in the decreasing order: EC> Eudragit S100> HPMC 100000> Eudragit RS100>HPMC 4000. There was a strong linear correlation between tensile strength and contact angle of the casted films. In contrast, weight loss (film solubility) of the matrix-type casted films in three release media (gastric, intestinal fluid and water) was invariably in the increasing order: EC < HPMC 100000 < Eudragit RS100 < HPMC 4000 with an exception of Eudragit S100. The order of release rate of matrix-type casted films was EC > HPMC 100000 > Eudragit RS100 > HPMC 4000 > Eudragit S100. Interestingly, diffusion-controlled coated tablet also followed this rank order except Eudragit S100 although release profiles and lag time were highly dependent on the coating levels and type of polymeric coating materials. EC and Eudragit RS100 produced sustained release while HPMC and Eudragit S100 produced pulsed release. No molecular interactions occurred between drug and coating materials using (1)H-NMR analysis. The current information on release-controlling power of five different coating materials as matrix carrier or diffusion-controlled film could be applicable in designing oral sustained drug delivery.

Mechanical properties of excipients do not affect polymer matrix formation

Coalescence of polymer particles has been identified as a crucial step in film formation on tablets, pellets and granules. Though the significance of thermal treatment on matrix dosage forms is well established the process of coalescence in matrix formation and the forces driving it remain unexplored. The aim of this study was to investigate whether stresses in tablets, caused by deformation of excipient during compression, provide a driving force for polymer matrix formation. Polymer matrix tablets containing Eudragit-RLPO, a pH independent and permeable polymer at two levels 10 and 40% (w/w) were prepared by direct compression. Either lactose monohydrate (brittle) or mannitol (plastic) was used as a diluent at 80 or 50% (w/w) and indomethacin, a model drug was present at 10% (w/w). Tablets from each formulation type were prepared at two compression pressures either 221 MPa (above the yield pressure of both excipients) or 74 MPa (below the yield pressure of both excipients). Tablets from each formulation type compressed at the two compression pressures were thermally treated at 40 °C (below T g) or 70 °C (above T g) for 24 h. The rotating basket (100 rpm) method was used for the release studies conducted at 37 °C in 900 ml phosphate buffer (0.2 M) pH 7.2 as the dissolution medium. Morphological characteristics of the tablets were observed by scanning electron microscopy. Differences in tablet structure due to the formulation and processing variables were further evaluated by disintegration and tensile strength testing. Data from this factorial study were analysed by analysis of variance. Excipient mechanical properties determine matrix properties only at low polymer level independent of curing temperature and at high polymer level cured at 40 °C only. Though lactose and mannitol have different mechanical properties and therefore different deformation behaviors, this did not influence the properties of tablets containing 40% (w/w) polymer cured at 70 °C, suggesting stresses in these tablets are not a significant driving force for matrix formation.