Kollidon SR Research Articles

Investigation of polymeric excipients for dutasteride solid dispersion and its physicochemical characterization

To investigate the effects of polymeric excipients for dutasteride solid dispersion, experimental approaches together with physical interactions at molecular level were evaluated. The drug and various polymers (anionic, amphiphilic, and hydrophilic) were mixed physically into different ratios and their thermodynamic and physical properties were analyzed by differential scanning calorimetry and Fourier transform-infrared spectroscopy, respectively. The enhanced equilibrium solubility of dutasteride was also investigated. Dutasteride is non-ionic and showed low solubility in the tested pH ranges (lower than the detection limit of 20ng/mL). Kollidon(®) MAE 100P, an anionic polymer, showed enhanced dutasteride solubility in aqueous solution followed by hydrophilic Kollidon(®) SR and the amphiphilic polymer, Soluplus(®). Melting point (T m ) of dutasteride was 249.7°C and was decreased to 229.84°C when mixed evenly with Kollidon(®) MAE 100P. However, the melting point was not detected at a ratio of 1:4 since it fully dissolved or dispersed in the polymer. Glass transition temperature (T g ) of different compositions exhibited strong interaction of polymer and drug. The result was supported by spectra evidence that Kollidon(®) MAE 100P forms hydrogen bonds with dutasteride presenting strong physical interaction with the primary amine group of dutasteride. This study supports a convenient method that together with microscopic observation can perform polymer selection and characterize solid dispersions.

Effects of release modifier on Carvedilol release from Kollidon SR based matrix

Sustained release Carvedilol matrix tablets constituting Kollidon SR were developed in this study in an attempt to investigate the effect of release modifiers on the release profile of Carvedilol from matrix. Three matrix tablet formulations were prepared by direct compression of Kollidon SR in combination with release modifier (HPMC and Microcrystalline Cellulose) and magnesium stearate. Tablets containing only Kollidon SR with the active ingredient demonstrated a rapid rate of drug release. Incorporation of HPMC in the matrix tablet prolonged the release of drug but incorporation of Microcrystalline Cellulose showed superimposable release pattern with an initial burst effect as confirmed by mean dissolution time and Higuchi release rate data. After 7 hours of dissolution, Carvedilol release from the matrix systems were 91.42%, 83.41%, from formulation F1 and F2 respectively. Formulation F3 exhibited 100 % release at 4 hours. All the tablet formulations showed acceptable pharmaco-technical properties and complied with the in-house specifications for tablet weight variation, friability, hardness, thickness, and diameter. Prepared tablets also showed sustained release property for carvedilol. The drug release mechanism from the matrix tablets of F1 and F2 was found to be followed by Fickian and F3 by Non-Fickian mechanism.DOI: http://dx.doi.org/10.3329/icpj.v1i8.11248 International Current Pharmaceutical Journal 2012, 1(8): 186-192

Effects of release modifier on Carvedilol release from Kollidon SR based matrix

<p>Sustained release Carvedilol matrix tablets constituting Kollidon SR were developed in this study in an attempt to investigate the effect of release modifiers on the release profile of Carvedilol from matrix. Three matrix tablet formulations were prepared by direct compression of Kollidon SR in combination with release modifier (HPMC and Microcrystalline Cellulose) and magnesium stearate. Tablets containing only Kollidon SR with the active ingredient demonstrated a rapid rate of drug release. Incorporation of HPMC in the matrix tablet prolonged the release of drug but incorporation of Microcrystalline Cellulose showed superimposable release pattern with an initial burst effect as confirmed by mean dissolution time and Higuchi release rate data. After 7 hours of dissolution, Carvedilol release from the matrix systems were 91.42%, 83.41%, from formulation F1 and F2 respectively. Formulation F3 exhibited 100 % release at 4 hours. All the tablet formulations showed acceptable pharmaco-technical properties and complied with the in-house specifications for tablet weight variation, friability, hardness, thickness, and diameter. Prepared tablets also showed sustained release property for carvedilol. The drug release mechanism from the matrix tablets of F1 and F2 was found to be followed by Fickian and F3 by Non-Fickian mechanism.</p><p>DOI: <a href="http://dx.doi.org/10.3329/icpj.v1i8.11095">http://dx.doi.org/10.3329/icpj.v1i8.11095</a></p> <p>International Current Pharmaceutical Journal 2012, 1(8): 186-192</p>

Formulation and Evaluation of Bi-layered SustainedRelease Matrix Tablets of Tramadol Hydrochloride

Bi-layer tablets of tramadol hydrochloride were prepared by direct compression technique incorporating an immediate release layer and a sustained release layer. An immediate release layer was successfully designed to release the bolus dose instantaneously. Water soluble Xanthan gum, water insoluble Kollidon SR and Eudragit L 100 were used as carriers in the sustained release layer of the matrix tablet. All the tablets were evaluated for thickness, diameter, weight variation, hardness and friability. The in vitro drug release was studied for eight hour, first two hours dissolution in acidic medium followed by six hour dissolution in buffer medium. Matrix tablet showed a sustained release rate with a controlled fashion as a function of the quantity of polymer used. The in vitro drug release data were fitted with several mathematical models and mean dissolution time along with fractional dissolution time values (T25%, T50% and T80%) were calculated. Xanthan gum was found to be the most effective rate retarding agent compared to Kollidon SR and Eudragit L 100, when used at same ratio in the formulations.

In Vitro Evaluation of Oral Extended Release Drug Delivery System for Metoprolol Succinate Using Kollidon SR

The objective of this study was to develop a sustained release matrix tablet Metoprolol Succinate by cost saving and production efficient process. Among various tablet manufacturing process, direct compression is the simplest and cost saving process. Different trials were formulated and evaluated using different concentrations of directly compressible grade Kollidon SR as release retardant. The formulated tablets were evaluated for physical and dissolution study using buffer medium. The most outstanding aspect of this study is to monitor the influence of different percentage of Kollidon SR on release rate from the matrix tablet. In this study, influence of different ratio of polymer concentration on drug release was evaluated. The release pattern of different batches were evaluated for Zero order, Higuchi, First order, Krosmeyer-Peppas and Hixson-Crowell kinetics and showed that all the batches followed best the Higuchi kinetics. The drug release kinetics was found to be governed by the amount of the polymer in the matrix system. The higher polymeric content in the matrix decrease the release rate of the drug. The nature of the drug release from the matrix tablets was dependent on drug diffusion and polymer relaxation and therefore followed non-Fickian or anomales release. The studies indicated that the drug release can be modulated by varying the concentration of the polymer. Among the four formulations, formulation 1 is the best formulation as it controls the release best and best linearity for zero order plots.

Self nanoprecipitating preconcentrate of tamoxifen citrate for enhanced bioavailability

We disclose a self nanoprecipitating preconcentrate (SNP) of tamoxifen citrate (TMX), which forms TMX loaded polymeric nanoparticles, on dilution with aqueous media. SNP comprised TMX, polymer (Kollidon SR) and surfactant/s dissolved in a pharmaceutically acceptable vehicle. Binary surfactant mixtures of Aerosol OT (AOT) with Tween 80 revealed synergistic reduction in surface tension to enable both high entrapment efficiency (EE) and low particle size (PS). Synergism of the surfactants was confirmed by molecular interaction parameter(βσ). Combination of AOT and Tween 80 resulted in EE (∼85%) and PS (<250nm). Formation of TMX-KSR nanoparticles in situ was reproducible under most experimental conditions and exhibited pH independent behavior. Dilution volume (>80mL) influenced both PS and EE while dilution temperature influenced only PS. Marginal increase in size was evident at the end of 1h nevertheless was not of concern as TMX SNP exhibited near complete release in 1h. DSC and XRD studies revealed amorphous nature of TMX in nanoparticles. FTIR imaging confirmed uniform distribution of TMX in nanoparticles. ESEM and TEM revealed spherical nanoparticles. Biodistribution studies of 99mTc labeled TMX SNP in rats revealed no significant absorption however oral pharmacokinetics revealed enhanced oral bioavailability of TMX (165%) compared to TMX suspension. SNP presents a new in situ approach, for design of drug loaded polymeric nanoparticles.

Preparation and Characterization of Lidocaine Double Layer Buccal Tablet Using Mucoadhesive Carbopol® Polymers

The present study was intended to develop a new oral mucosal dosage form with a view of solving problems of the topical administration of Lidocaine, a local anesthetic drug, in the oral cavity. The drug was formulated as sustained release mucoadhesive bilayered tablets using mucoadhesive polymers. The first layer, consisting of a drug impermeable backing, was prepared by compression of Kollidon SR, Mg-stearate, Aerosil and talc blend in a hydrolic press at 5 ton pressure for 5 seconds. The second layer, responsible for buccal drug delivery and tablet retention on the mucosa was obtained by compression of a mixture of drug, mucoadhesive polymer and cellulose derivative for 1 min at 5 ton pressure. The tablets were evaluated in terms of swelling and water uptake and in vivo mucoadhesive performance was performed with nonmedicated tablets. In vitro drug release studies were also carried out containing fixed amount of Lidocaine (50mg), different concentrations of mucoadhesive polymer (Carbopol 934P) and hydroxypropyl methyl cellulose (HPMC). Drug release was only 30.9% in 6 hours when Carbopol 934P was used alone and at a higher concentration (240mg). Release was faster when lower concentration of polymer was used. When used in combination with HPMC, drug release was slower. In vivo mucoadhesive performance with nonmedicated tablets showed very good adherence to buccal mucosa for 6 hours and no signs of irritation was reported. Moreover, it adheres well to the gum, is not washed away by salivary fluid and is simple to apply, which indicates a better patient compliance. DOI: http://dx.doi.org/10.3329/dujps.v10i1.10012 DUJPS 2011; 10(1): 29-34

Formulation and in vitro evaluation of theophylline matrix tablets prepared by direct compression: Effect of polymer blends

The deformation mechanism of pharmaceutical powders, used in formulating directly compressed matrix tablets, affects the characteristics of the formed tablets. Three polymers of different deformation mechanisms were tested for their impact on theophylline directly compressed tablets namely Kollidon SR (KL SR, plastic deformation), Ethylcellulose (EC, elastic deformation) and Carnauba wax (CW, brittle deformation) at different compression forces. However, tablets based mainly on KL SR, the plastically deformed polymer (TN1) exhibited the highest hardness values compared to the other formulae which are based on either blends of KL SR with CW, the very brittle deformed polymer. The upper detected force for TN formulae and the lower punch force were found to dependent mainly on the powder deformation. This difference is attributed to the work done during the compression phase as well as the work lost during the decompression phase. Furthermore, the release profiles of TN from formulae TN2 and TN4 that are based on the composition (2KL SR:1EC) and (1KL SR:2EC), respectively, were consistent with different deformation mechanisms of KL SR and EC and on the physicochemical properties like the water absorptive capacity of EC. Upon increasing the weight ratio of KL SR (TN2), the release rate was greatly retarded (39.4%, 37.1%, 35.0% and 33.6% released after 8h at 5, 10, 15 and 20kN.

Hot melt granulation: a facile approach for monolithic osmotic release tablets

The aim of this work was to develop and evaluate an extended release matrix tablet of glipizide (GP), an oral hypoglycemic agent. Matrices of GP were prepared using microcrystalline cellulose Avicel™ PH 112, sodium chloride (SC) and polyethylene glycol 6000 (PEG). The content of Kollidon SR (KR), hydroxypropyl methylcellulose K4M premium CR grade (HM) and polyethylene oxide WSR 303 (PO) and/or magnesium hydroxide (MH) was varied in different formulations. All the formulations were processed by hot melt granulation technique. GP release was observed to be influenced by the amount of SC and MH present in the core formulation. The matrix tablets were coated with a solution containing combination of cellulose acetate 398.10 (CA) and PEG. The release of GP was observed to be inversely proportional to the weight of the coating membrane. Matrices containing PO in combination with SC and MH (14.28:8.56) showed significantly higher degree of hydration and swelling that was evident in the surface texture as visualized by scanning electron microscopy (SEM). Results of SEM studies confirmed the presence of pores in the semi-permeable coating membrane from where the GP release would have occurred. The release of GP from this formulation was similar to that of the marketed extended release tablet as judged from similarity factor (f2) analysis, which yielded a value of 74.7. The optimized formulation was found to be stable when tested according to long term and accelerated storage conditions of ICH guidelines upto 3 months.

Formulation optimization of solid dispersion of mosapride hydrochloride

Mosapride citrate (MSP) is a gastroprokinetic agent that acts as a selective 5-HT(4) agonist and accelerates the gastric emptying, and is used for the treatment of acid reflux, irritable bowel syndrome, and functional dyspepsia. The purpose of this study is to investigate the solid dispersion formulations of MSP with controlled release characteristic using various polymers, elucidate the release mechanism, and characterize the interaction patterns between MSP and polymers. Solid dispersions of MSP with different drug-to-polymer ratios were prepared by a solvent evaporation method and characterized in comparison with the simple physical mixtures. Eudragit RSPO, Eudragit RLPO, hydroxypropylmethylcellulose (HPMC) or Kollidon SR was used as a controlled-release polymer along with polyvinylpyrrolidone (PVP) as a carrier. Characterization of MSP solid dispersion was performed using thermal analysis (DSC), powder X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, where the drug was converted from the crystalline state to amorphous state in all polymeric carriers used. In vitro dissolution studies showed that the drug release has been extended up to 24 h by using Eudragit RSPO or HPMC. Moreover, the formulations containing higher polymer content ratio showed better slow-release profile. These results indicate that the solid dispersion formulation containing PVP/Eudragit RSPO or HPMC mixture could serve as a good controlled-release system for MSP.

Development of Prolonged Delivery of Tramadol and Dissolution Translation by Statistical Data Treatment

The present study was carried out to fabricate a prolonged design for tramadol using Kollidon SR (Polyvinyl acetate and povidone based matrix retarding polymer). Matrix tablet formulations were prepared by direct compression of Kollidon SR of a varying proportion with a fixed percentage of tramadol. Tablets containing a 1:0.5 (Drug: Kollidon SR) ratio exhibited a rapid rate of drug release with an initial burst effect. Incorporation of more Kollidon SR in the matrix tablet extended the release of drug with subsequent minimization of the burst effect as confirmed by the mean dissolution time, dissolution efficiency and f2 value. Among the formulation batches, a direct relationship was obtained between release rate and the percentage of Kollidon SR used. The formulation showed close resemblance to the commercial product Contramal and compliance with USP specification. The results were explored and explained by the difference of micromeritic characteristics of the polymers and blend of drug with excipients. Insignificant effects of various factors, e.g. pH of dissolution media, ionic strength, speed of paddle were found on the drug release from Kollidon-SR matrix. The formulation followed the Higuchi kinetic model of drug release. Stability study data indicated stable character of Batch T6 after short-term stability study.

Effect of Kollidon® SR on the release of Albuterol Sulphate from matrix tablets

The objective of this study was to evaluate Kollidon SR for the development of extended release Albuterol Sulphate matrix tablets in comparison with other polymers as Hydroxypropylmethylcellulose K15M, Carbopol 71G NF, and Eudragit L100-55. The mechanical properties of the tablets were improved as concentration of Kollidon SR or other polymers increased. It was found that Kollidon SR 30% (w/w) and HPMC 30% (w/w) tablets have f 2 similarity factor of 83.5 in their Albuterol Sulphate dissolution profile. The marketed product was found to release 99.7% of drug content within 8 h, while Kollidon SR and HPMC tablets with 30% (w/w) polymer concentration level released 92.7% and 92.9% respectively of drug content within 8 h. Kollidon SR has a unique character of maintaining tablets geometric shape until the end of dissolution test, this is mainly due to the water insoluble content, polyvinyl acetate, forming 80% (w/w) of Kollidon SR, while the remaining content 20% (w/w) is the water soluble, polyvinylpyrrolidone, responsible for pore formation causing a diffusion controlled release. Drug release from all previous formulations is best described to be controlled by more than one kinetic mechanism of release. In conclusion, Kollidon SR and HPMC and Carbopol were found to be potential candidates for the development of extended release of Albuterol Sulphate tablets.

Application of a novel symmetrical shape factor to gastroretentive matrices as a measure of swelling synchronization and its impact on drug release kinetics under standard and modified dissolution conditions

Abstract Objectives We have assessed the kinetics of drug release in relation to the full or partial hydration and swelling of matrices under standard and modified United States Pharmacopeia (USP) apparatus II using a novel index, defined as the symmetrical shape factor. The symmetrical shape factor describes the regularity of the hydration rate of the matrix perimeter relative to its central regions. Methods Monolithic and three-layer matrices based on hypromellose, polyethylene oxide, Kollidon SR, theophylline, diltiazem hydrochloride and alfuzosin hydrochloride were subjected to dissolution testing. Key findings Our results indicated that Kollidon SR matrices and the three-layer composite systems with and without effervescing components were not significantly affected by the dissolution conditions. However, in the case of the floating monolithic systems based on hypromellose and polyethylene oxide, both release profiles and swelling dynamics in accordance with the similarity factor (f2) and symmetrical shape factor values were significantly influenced. Conclusions The symmetrical shape factor values were positively impacted. Consequently the drug release kinetics were more predictable and reproducible. The modified USP method resulted in a more synchronized axial and radial swelling with symmetrical shape factor values approaching unity. Data further indicated that the modified USP method provided for complete matrix hydration and swelling as the dosage form remained fully submerged, allowing for more reliable release mimicking the in-vivo conditions.

Application of a novel symmetrical shape factor to gastroretentive matrices as a measure of swelling synchronization and its impact on drug release kinetics under standard and modified dissolution conditions

We have assessed the kinetics of drug release in relation to the full or partial hydration and swelling of matrices under standard and modified United States Pharmacopeia (USP) apparatus II using a novel index, defined as the symmetrical shape factor. The symmetrical shape factor describes the regularity of the hydration rate of the matrix perimeter relative to its central regions. Monolithic and three-layer matrices based on hypromellose, polyethylene oxide, Kollidon SR, theophylline, diltiazem hydrochloride and alfuzosin hydrochloride were subjected to dissolution testing. Our results indicated that Kollidon SR matrices and the three-layer composite systems with and without effervescing components were not significantly affected by the dissolution conditions. However, in the case of the floating monolithic systems based on hypromellose and polyethylene oxide, both release profiles and swelling dynamics in accordance with the similarity factor (f(2)) and symmetrical shape factor values were significantly influenced. The symmetrical shape factor values were positively impacted. Consequently the drug release kinetics were more predictable and reproducible. The modified USP method resulted in a more synchronized axial and radial swelling with symmetrical shape factor values approaching unity. Data further indicated that the modified USP method provided for complete matrix hydration and swelling as the dosage form remained fully submerged, allowing for more reliable release mimicking the in-vivo conditions.

In vitro Release Kinetics Study of Diltiazem Hydrochloride from Wax and Kollidon SR Based Matrix Tablets

Extended-release matrix tablets of diltiazem hydrochloride (DTZ) were prepared using waxy materials alone or in combination with Kollidon SR. Matrix waxy materials were carnauba wax (CW), bees wax (BW), cetyl alcohol (CA) and glyceryl monostearate (GMS). Dissolution studies were carried out by using a six stations USP XXII type 1 apparatus. The in vitro drug release study was done in 1000 ml phosphate buffer of pH 6.8 for 12 h. Initial burst release was observed in case of waxy granules. Tablets prepared in combination of waxy granules and Kollidon SR sustained the drug release for more than 12 h. Addition of ludipress instead of Kollidon SR caused the drug release faster (for less than 12 h). Fitting the in vitro drug release data to Korsmeyer equation indicates that diffusion along with erosion could be the mechanism of drug release. Significant differences were found among the drug release profile from different polymeric matrices.

Development of a novel osmotically driven drug delivery system for weakly basic drugs

The drug substance SAG/ZK has a short biological half-life and because of its weakly basic nature a strong pH-dependent solubility was observed. The aim of this study was to develop a controlled release (cr) multiple unit pellet formulation for SAG/ZK with pH-independent drug release. Pellets with a drug load of 60% were prepared by extrusion/spheronization followed by cr-film coating with an extended release polyvinyl acetate/polyvinyl pyrrolidone dispersion (Kollidon SR 30 D). To overcome the problem of pH-dependent drug release the pellets were then coated with a second layer of an enteric methacrylic acid and ethyl acrylate copolymer (Kollicoat MAE 30 DP). To increase the drug release rates from the double layered cr-pellets different osmotically active ionic (sodium and potassium chloride) and nonionic (sucrose) additives were incorporated into the pellet core. Drug release studies were performed in media of different osmotic pressure to clarify the main release mechanism. Extended release coated pellets of SAG/ZK demonstrated pH-dependent drug release. Applying a second enteric coat on top of the extended release film coat failed in order to achieve pH-independent drug release. Already low enteric polymer levels on top of the extended release coated pellets decreased drug release rates at pH 1 drastically, thus resulting in a reversal of the pH-dependency (faster release at pH 6.8 than in 0.1 N HCl). The addition of osmotically active ingredients (sodium and potassium chloride, and sucrose) increased the imbibing of aqueous fluids into the pellet cores thus providing a saturated drug solution inside the beads and increasing drug concentration gradients. In addition, for these pellets increased formation of pores and cracks in the polymer coating was observed. Hence drug release rates from double layered beads increased significantly. Therefore, pH-independent osmotically driven SAG/ZK release was achieved from pellets containing osmotically active ingredients and coated with an extended and enteric polymer. In contrast, with increasing osmotic pressure of the dissolution medium the in vitro drug release rates decreased significantly.

Evaluation of Tableting and Tablet Properties of Kollidon SR: The Influence of Moisture and Mixtures with Theophylline Monohydrate

The aim of the study was firstly to investigate the influence of moisture on the tableting and tablet properties of Kollidon SR and secondly to investigate the influence of theophylline monohydrate on the tableting behavior and tablet properties produced from binary mixtures with Kollidon SR. In comparison to Kollidon SR, microcrystalline cellulose (MCC) was used. The glass transition temperature (Tg) of the powder over the whole range of RH (0–90%), and in addition, the Tg of tablets of Kollidon SR were measured. Densities and flowability of the powders were analyzed. The tablets were produced at five different maximum relative densities (ρrel, max) on an instrumented eccentric tableting machine. They were produced at three different relative humidities (RH), 30%, 45%, and 60% RH for the pure substances and binary mixtures with different ratios of drug and excipient were tableted at 45% RH. The tableting properties were analyzed by 3D modeling, force-displacement profiles, and compactibility plots. First, the Tg of the powder decreased with increasing RH and the Tg of the tablet was 4–8 K lower than the powder. The predominant deformation of Kollidon SR is plastic deformation and Kollidon SR showed a higher compactibility than MCC. The parameters of the 3D model showed an extreme change between 45 and 60% RH, and at higher RH more and more particles deformed elastically. This was confirmed by analysis of force-displacement profiles. At 60% RH, the radial tensile strength of the Kollidon SR tablets was half of the radial tensile strength at 45% RH. The reason is a higher relative energy of plastic deformation than for MCC. This results in a better utilization of the energy to deform the powder into a tablet and the exceeding of the glass transition temperature at higher RH. In conclusion, at 60% RH at the same ρrel, max, tableting and tablet properties of Kollidon SR are extremely changed since plasticity is significantly higher. In the second part of the study, the insufficient flowability of theophylline monohydrate can be compensated by using Kollidon SR in a mixture with up to 20% theophylline. Further, pressure plasticity ε of MCC and Kollidon SR was lowered in the mixture with theophylline monohydrate. The same is valid for the compactibility. The influence of theophylline monohydrate on the pressure plasticity e of the mixtures was better compensated in the mixture with MCC than in a mixture with Kollidon SR. This compensation was also visible by analyzing the force-displacement-profiles. However, hardly any influence on the radial tensile strength could be detected. Kollidon SR and Kollidon SR mixtures exhibited a higher compactibility than MCC and MCC mixtures. The differences became smaller with increasing theophylline content.

Development of Near Zero-Order Release Dosage Forms Using Three-Dimensional Printing (3-DP™) Technology

ABSTRACTThree near zero-order controlled-release pseudoephedrine hydrochloride (PEH) formulations demonstrating proportional release rates were developed using 3-Dimensional Printing (3-DP™) technology. Mixtures of Kollidon SR and hydroxypropylmethyl cellulose (HPMC) were used as drug carriers. The release rates were adjusted by varying the Kollidon SR-HPMC ratio while keeping fabrication parameters constant. The dosage forms were composed of an immediate release core and a release rate regulating shell, fabricated with an aqueous PEH and an ethanolic triethyl citrate (TEC) binder, respectively. The dosage form design called for the drug to be released via diffusional pathways formed by HPMC in the shell matrix. The release rate was shown to increase correspondingly with the fraction of HPMC contained in the polymer blend. The designed formulations resulted in dosage forms that were insensitive to changes in pH of the dissolution medium, paddle stirring rate, and the presence/absence of a sinker. The near zero-order release properties were unchanged regardless of the dissolution test being performed on either single cubes or on a group of eight cubes encased within a gelatin capsule shell. The chemical and dissolution properties of the three formulations remained unchanged following 1 month's exposure to 25°C/60% RH or 40°C/75% RH environment under open container condition. The in vivo performance of the three formulations was evaluated using a single-dose, randomized, open-label, four-way crossover clinical study composed of 10 fasted healthy volunteers. The pharmacokinetic parameters were analyzed using a noncompartmental model. Qualitative rank order linear correlations between in vivo absorption profiles and in vitro dissolution parameters (with slope and intercept close to unity and origin, respectively) were obtained for all three formulations, indicating good support for a Level A in vivo/in vitro correlation.

Temperature/Humidity Sensitivity of Sustained‐Release Formulations Containing Kollidon® SR

The effects of temperature and humidity on tablets containing Kollidon® SR have been evaluated using diphenhydramine HCl as a model drug. Exposure of tablets to ICH accelerated stability condition (40°C/75%RH) in an open dish resulted in rapid increases in tablet hardness, accompanied by step‐wise decreases in dissolution rate. Such a change can be observed as fast as an hour upon exposure. The tablet matrix appears to rapidly absorb atmospheric moisture, as demonstrated by tablet weight gain and moisture adsorption isotherms. Exposure to 25°C/60%RH similarly resulted in increases in tablet hardness, although with minimal impact on dissolution. Potential implications of such rapid moisture uptake during aqueous film‐coating were further evaluated by spraying either water or an Opadry solution in a coating pan. Exposure of Kollidon SR tablets to the aqueous coating process indeed resulted in noticeable changes in both hardness and dissolution. Application of the Opadry solution appears to affect tablet behavior to a lesser degree, compared to water, most likely due to protection via formed barrier film. Attention needs to be paid to the extreme sensitivity of Kollidon SR matrix tablets to temperature and moisture during product development.

Effects of Formulation Variables and Post-compression Curing on Drug Release from a New Sustained-Release Matrix Material: Polyvinylacetate-Povidone

A new commercially available sustained-release matrix material, Kollidon® SR, composed of polyvinylacetate and povidone, was evaluated with respect to its ability to modulate the in vitro release of a highly water-soluble model compound, diphenhydramine HCl. Kollidon SR was found to provide a sustained-release effect for the model compound, with certain formulation and processing variables playing an important role in controlling its release kinetics. Formulation variables affecting the release include the level of the polymeric material in the matrix, excipient level, as well as the nature of the excipients (water soluble vs. water insoluble). Increasing the ratio of a water-insoluble excipient, Emcompress®, to Kollidon SR enhanced drug release. The incorporation of a water-soluble excipient, lactose, accelerated its release rate in a more pronounced manner. Stability studies conducted at 40°C/75%RH revealed a slow-down in dissolution rate for the drug-Kollidon SR formulation, as a result of polyvinylacetate relaxation. Further studies demonstrated that a post-compression curing step effectively stabilized the release pattern of formulations containing ≥47% Kollidon SR. The release mechanism of Kollidon-drug and drug-Kollidon-Emcompress formulations appears to be diffusion controlled, while that of the drug-Kollidon-lactose formulation appears to be controlled predominantly by diffusion along with erosion.