Extended-release oral drug delivery technologies: monolithic matrix systems

Fabrication, optimization and characterization of an osmotic push-pull drug delivery system for paliperidone

Objectives

Paliperidone is a BCS class II drug with low solubility and high permeability. It has 28% absolute oral bioavailability and an elimination half-life of 23 h. An osmotic push-pull trilayer tablet currently available on the market has achieved controlled release of a low dose over an extended time period, while avoiding the need for a loading dose. However, this trilayer tablet has several disadvantages, such as complicated processing, high production costs and difficulty in achieving uniformity of the contents. Thus, the objective of this study was to overcome the above difficulties associated with paliperidone and to formulate a bilayer tablet with a similar drug profile to that of the reference listed drug Invega®.

Methods

The bilayer tablets were prepared by optimization of the core and semi-permeable membrane. Effects of the curing time, and the size and number of orifices on the prepared tablets' dissolution profile were analyzed. Two different grades of polyethylene oxide were used in the core and push layer as pore formers.

Results

The weight variation, friability and hardness values of the prepared tablets were well within compendium limits. The optimized bilayer parameters for the prepared tablets were curing time, 5 h; seal coat, 7% w/w; ER coat, 13% w/w; orifice size, 0.6 mm; and orifice number, 2. Further tablet formulation resulted in an F2 value of 75.67, indicating a dissolution profile similar to that of Invega®.

Conclusion

Bi-layer tablets of paliperidone overcoming the drawbacks of the marketed formulation were successfully prepared, and offer advantages such as a simpler preparation process, cost effectiveness and faster preparation of the tablet core.

INVESTIGATION OF THE ABILITY TO BIODEGRADABILITY OF POLYURETHANE FOAM COMPOSITE MATERIALS WITH ALBUCID AND THE DYNAMICS OF ALBUCID RELEASE IN VITRO

Studies of biodegradability of polyurethane foam (PUF) composite materials with albucid under the influence of biological medium 199 (BM 199) and saline solution for 2 weeks, 1, 3 and 6 months were conducted. IR spectroscopy, physical-mechanical tests, DSC and TGA before and after incubation in model mediums were investigated. It was found that the influence of BM 199 and saline solution on the structure and properties of composite materials with albucid is similar. According to the results of physical-mechanical studies under the influence of model mediums there are processes of biodegradation which are confirmed by a decrease in adhesive strength after incubation in BM 199 and saline solution. According to IR spectroscopy, biodegradation is accompanied by redistribution of hydrogen bonds of NH groups of the polymer matrix. The results of studies by the DSC method indicate a decrease of Tg and increase of ΔСР of PUF composites with albucid compared to the control, which is associated with increasing of segmental mobility of macromolecules under the influence of model mediums and due to the albucid release from polymer matrix. It was found that PUF and PUF composites with albucid in vitro remain heat-resistant materials, because after incubation in BM 199 and a saline solution there is an increase in T0 and Tmax by the TGA method. Studies of the dynamics of albucid release from the PUF matrix were carried out. It was found that the composite materials are capable to the prolonged release of the drug. The amount of released albucid is 36.0 % on the 60th day of the experiment, which does not exceed the therapeutic dose and has no toxic effects. Therefore, polyurethane foam composite materials with albucid can be proposed as promising materials for use as implants with prolonged action of albucid in ophthalmological surgery.

INVESTIGATION OF BIODEGRADATION AND PROPERTIES OF POLYURETHANE FOAM COMPOSITE MATERIALS WITH LYSOZYME IN VITRO

The study of biodegradation ability of polyurethane foams composite materials with lysozyme under the influence of saline solution for 2 weeks, 1, 3 and 6 months by IR spectroscopy, DSC, TGA was conducted. According to the results of IR spectroscopy under the influence of model medium there are processes of biodegradation, which are confirmed by a decrease in the intensity of the absorption band νС=О. Along with biodegradation there is a redistribution of hydrogen bonds of NH and CO groups of polymer matrix. According to DSC after incubation in saline solution there is an increase in Tg and ΔCp at the glass-transition (for polyurethane foams and composites with lysozyme in the amount of 5 wt. %), an increase in Tg and decrease in ΔCp (for composites with lysozyme in the amount of 1 and 3 wt. %), which indicates the redistribution of hydrogen bonds under the influence of saline solution and due to lysozyme release. It was found that after incubation in saline solution there is an increase in T0 and Tmax for both polyurethane foams and composite materials with lysozyme by the method of TGA. Thus, composites with lysozyme in vitro are heat-resistant materials. According to the study results of the dynamics of lysozyme release composites are capable to the prolonged release of enzyme for 5 days, the amount of which varies depending on the lysozyme content (43.85-61.97 % of the total amount of the introduced drug) and is sufficient for the manifestation of antimicrobial activity. The tissue culture method has established the biocompatibility of investigated materials. For polyurethane foam composite materials with lysozyme more active growth of fibroblastic elements than in the control and polyurethane foam and slowing down the process of cell degeneration was observed. The obtained results indicate that polyurethane foam composite materials with lysozyme are promising materials that due to the presence of the enzyme will have antimicrobial action and can be used in medical practice as polymer composites for the treatment of wounds and burns.

Design of experiments and multivariate analysis approach to study dissolution stability of a modified-release drug product to support lean design strategies

OBJECTIVE

The purpose of this paper is to present the use of Design of Experiments and multivariate analysis for evaluation of a modified-release drug product stability to support post-approval lean stability approaches. The focus of the paper was to investigate potential root-causes for acceleration of dissolution upon stability.

METHODS

For statistical evaluation of stability data, multiple linear regression statistics was used. The design space of the stability study was modeled using MODDE 12.1 software. For experimental set-up, parameters such as Temperature, Time, Packaging, Batch, and Active Pharmaceutical Ingredient supplier were selected.

RESULTS

With multiple linear regression modeling of the all generated stability data until six months, we were able to identify or confirm the Stability-related quality attributes and Shelf life limiting attributes. From the multiple linear regression correlation coefficients, we have evaluated that decrease of an antioxidant upon stability could cause potential shift in dissolution. However, main factors for accelerated dissolution can be attributed to other material and process variables. In the last part of the study, we have shown the usefulness of these methodologies for supporting lean stability approaches. With enhanced drug product knowledge, we designed two reduced long-term stability studies and showed that with 'One-half' reduced design, we would still be able to confirm 24-month shelf life.

CONCLUSIONS

Implementing Quality by design approaches on stability studies could reduce the need for excessive analytical testing, help to evaluate meaningfulness of the data and set a risk-based stability testing strategy.

Budding Multi-matrix Technology-a Retrospective Approach, Deep Insights, and Future Perspectives

The human race is consistently striving for achieving good health and eliminate disease-causing factors. For the last few decades, scientists have been endeavoring to invent and innovate technologies that can substitute the conventional dosage forms and enable targeted and prolonged drug release at a particular site. The novel multi-matrix technology is a type of matrix formulation where the formulation is embraced to have a matrix system with multiple number of matrices. The MMX technology embraces with a combination of outer hydrophilic layer and amphiphilic/lipophilic core layer, within which drug is encapsulated followed by enteric coating for extended/targeted release at the required site. In comparison to conventional oral drug delivery systems and other drug delivery systems, multi-matrix (MMX) technology formulations afford many advantages. Additionally, it attributes for targeting strategy aimed at the colon and offers modified prolonged drug release. Thus, it has emerged rapidly as a potential alternative option in targeted oral drug delivery. However, the development of this MMX technology formulations is a exigent task and also has its own set of limitations. Due to its promising advantages and colon targeting strategy over the other colon targeted drug delivery systems, premier global companies are exploiting its potential. This article review deep insights into the formulation procedures, drug delivery mechanism, advantages, limitations, safety and efficacy studies of various marketed drug formulations of MMX technology including regulatory perspectives and future perspectives.

Oral delivery of metformin by chitosan nanoparticles for polycystic kidney disease

Nanoparticle drug delivery has many advantages over small molecule therapeutics, including reducing off-target side effects and increasing drug potency. However, many nanoparticles are administered parenterally, which is challenging for chronic diseases such as polycystic kidney disease (PKD), the most common hereditary disease worldwide in which patients need continuous treatment over decades. To address this clinical need, we present the development of nanoparticles synthesized from chitosan, a widely available polymer chosen for its ability to improve oral bioavailability. Specifically, we optimized the synthesis parameters of chitosan nanoparticles and demonstrate mucoadhesion and permeation across an intestinal barrier model in vitro. Furthermore, when administered orally to mice, ex vivo imaging of rhodamine-loaded chitosan nanoparticles showed significantly higher accumulation in the intestines compared to the free model drug, as well as 1.3 times higher serum area under the curve (AUC), demonstrating controlled release and improved serum delivery over 24 h. To test its utility for chronic diseases such as PKD, we loaded the candidate PKD drug, metformin, into chitosan nanoparticles, and upon oral administration to a PKD murine model (Pkd1fl/fl;Pax8-rtTA;Tet-O cre), a lower cyst burden was observed compared to free metformin, and was well tolerated upon repeated dosages. Blood urea nitrogen (BUN) and creatinine levels were similar to untreated mice, demonstrating kidney and biocompatibility health. Our study builds upon previous chitosan-based drug delivery approaches, and demonstrates a novel, oral nanoformulation for PKD.

Polyethylene oxide and its controlled release properties in hydrophilic matrix tablets for oral administration

Polymers are excipients that modify the rate of drug release from pharmaceutical dosage forms. Hydrophilic polymer-based controlled drug delivery system is more advantageous as compared to the conventional delivery system as it reduces the dosing frequency, improves therapeutic efficacy, reduces side-effects, and probably enhances patient compliance. Polyethylene oxide (PEO), a nonionic hydrophilic polymer, is one of the most widely used polymers for extending the drug release. This review mainly focuses on the PEO marketed by, but not limited to, The Dow Chemical Company under the trade name of POLYOX^TM. It is commercially available polyethylene oxide polymer existing in various molecular weight and viscosity grades depending upon the application. This study essentially discusses chemistry, physicochemical properties, and the impact of formulation and processing variables on the release of drug from hydrophilic PEO matrix tablets. Moreover, it also summarizes the stability, patents, and regulatory perspectives of POLYOX that can further influence the future developments of controlled release dosage forms.

Hypromellose - A traditional pharmaceutical excipient with modern applications in oral and oromucosal drug delivery

Hydroxypropylmethylcellulose (HPMC), also known as Hypromellose, is a traditional pharmaceutical excipient widely exploited in oral sustained drug release matrix systems. The choice of numerous viscosity grades and molecular weights available from different manufacturers provides a great variability in its physical-chemical properties and is a basis for its broad successful application in pharmaceutical research, development, and manufacturing. The excellent mucoadhesive properties of HPMC predetermine its use in oromucosal delivery systems including mucoadhesive tablets and films. HPMC also possesses desirable properties for formulating amorphous solid dispersions increasing the oral bioavailability of poorly soluble drugs. Printability and electrospinnability of HPMC are promising features for its application in 3D printed drug products and nanofiber-based drug delivery systems. Nanoparticle-based formulations are extensively explored as antigen and protein carriers for the formulation of oral vaccines, and oral delivery of biologicals including insulin, respectively. HPMC, being a traditional pharmaceutical excipient, has an irreplaceable role in the development of new pharmaceutical technologies, and new drug products leading to continuous manufacturing processes, and personalized medicine. This review firstly provides information on the physical-chemical properties of HPMC and a comprehensive overview of its application in traditional oral drug formulations. Secondly, this review focuses on the application of HPMC in modern pharmaceutical technologies including spray drying, hot-melt extrusion, 3D printing, nanoprecipitation and electrospinning leading to the formulation of printlets, nanoparticle-, microparticle-, and nanofiber-based delivery systems for oral and oromucosal application. Hypromellose is an excellent excipient for formulation of classical dosage forms and advanced drug delivery systems. New methods of hypromellose processing include spray draying, hot-melt extrusion, 3D printing, and electrospinning.

Application of Multivariate Adaptive Regression Splines (MARSplines) for Predicting Hansen Solubility Parameters Based on 1D and 2D Molecular Descriptors Computed from SMILES String

A new method of Hansen solubility parameters (HSPs) prediction was developed by combining the multivariate adaptive regression splines (MARSplines) methodology with a simple multivariable regression involving 1D and 2D PaDEL molecular descriptors. In order to adopt the MARSplines approach to QSPR/QSAR problems, several optimization procedures were proposed and tested. The effectiveness of the obtained models was checked via standard QSPR/QSAR internal validation procedures provided by the QSARINS software and by predicting the solubility classification of polymers and drug-like solid solutes in collections of solvents. By utilizing information derived only from SMILES strings, the obtained models allow for computing all of the three Hansen solubility parameters including dispersion, polarization, and hydrogen bonding. Although several descriptors are required for proper parameters estimation, the proposed procedure is simple and straightforward and does not require a molecular geometry optimization. The obtained HSP values are highly correlated with experimental data, and their application for solving solubility problems leads to essentially the same quality as for the original parameters. Based on provided models, it is possible to characterize any solvent and liquid solute for which HSP data are unavailable.

Development and Evaluation of Compression Coating Gastro-Floating Tablet of Alfuzosin Hydrochloride for Zero-Order Controlled Release

Alfuzosin hydrochloride is an appropriate candidate drug to prepare a gastro-retention controlled release dosage form since it demonstrates a narrow absorption window in the proximal section of the gastrointestinal tract with a short half-life. The purpose of the present study was to develop and optimize a gastro-floating tablet of alfuzosin hydrochloride by using the compression coating method for controlling drug release in a controlled manner. The floating tablets were developed utilizing hydroxypropyl methylcellulose and carbomer as matrix materials. The impact of formulation factors on buoyancy property and in vitro drug release of the floating tablet was investigated. The "similarity factor" (f₂) was used as the indicator for the optimization of the formulations. Furthermore, in vivo pharmacokinetic study in rabbits and correlation of in vitro/in vivo study were also performed. It was found that the optimized formulation F9 could float immediately less than 2 min and remain lastingly buoyant over 24 h and follow zero-order release kinetics well. In comparison with the commercially available prolonged release tablets XATRAL® XL, the prepared floating tablet exhibited similar pharmacokinetic parameters (C_max, T_max, t_1/2, and AUC_0 - t) and plasma concentration versus time profile. Moreover, it indicated from the correlation of in vitro/in vivo study that the floating tablets exhibited a good correlation of in vitro/in vivo. In summary, the compression coating gastro-floating tablets might be a promising drug delivery system for alfuzosin hydrochloride to control drug release.

Zero-order release of poorly water-soluble drug from polymeric films made via aqueous slurry casting

In spite of significant recent interest in polymeric films containing poorly water-soluble drugs, dissolution mechanism of thicker films has not been investigated. Consequently, release mechanisms of poorly water-soluble drugs from thicker hydroxypropyl methylcellulose (HPMC) films are investigated, including assessing thickness above which they exhibit zero-order drug release. Micronized, surface modified particles of griseofulvin, a model drug of BSC class II, were incorporated into aqueous slurry-cast films of different thicknesses (100, 500, 1000, 1500 and 2000 μm). Films 1000 μm and thicker were formed by either stacking two or more layers of ~500 μm, or forming a monolithic thick film. Compared to monolithic thick films, stacked films required simpler manufacturing process (easier casting, short drying time) and resulted in better critical quality attributes (appearance, uniformity of thickness and drug per unit area). Both the film forming approaches exhibited similar release profiles and followed the semi-empirical power law. As thickness increased from 100 μm to 2000 μm, the release mechanism changed from Fickian diffusion to zero-order release for films ≥1000 μm. The diffusional power law exponent, n, achieved value of 1, confirming zero-order release, whereas the percentage drug release varied linearly with sample surface area, and sample thickness due to fixed sample diameter. Thus, multi-layer hydrophilic polymer aqueous slurry-cast thick films containing poorly water-soluble drug particles provide a convenient dosage form capable of zero-order drug release with release time modulated through number of layers.

Influence of pH Modulation on Dynamic Behavior of Gel Layer and Release of Weakly Basic Drug from HPMC/Wax Matrices, Controlled by Acidic Modifiers Evaluated by Multivariate Data Analysis

The solubility of weakly basic drugs in passage through gastrointestinal tract leads to their pH-dependent release from extended release formulations and to lower drug absorption and bioavailability. The aim of this study was to modulate the micro-environmental pH of hypromellose/montanglycol wax matrices and to observe its influence on the release of weakly basic drug verapamil hydrochloride (VH) with a pH-dependent solubility with respect to gel layer formation and its dynamics. For this study, malic and succinic acids differing in their solubility and pKa were selected as pH modifiers. The dissolution studies were performed by the method of changing pH. Within the same conditions, pH, thickness, and penetration force of the gel layer were measured as well. From the PCA sub-model, it is evident that a higher acid concentration ensured lower gel pH and conditions for higher drug solubility, thus creating larger gel layer with smaller rigidity, resulting in higher VH release during the dissolution test. Incorporation of stronger and more soluble malic acid (100 mg/tablet) created the most acidic and the thickest gel layer through which a total of 74% of VH was released. Despite having lower strength and solubility, matrices containing succinic acid (100 mg/tablet) released a comparable 71% of VH in a manner close to zero-order kinetics. The thinner and less rigid gel layers of the succinic acid matrices allowed an even slightly faster VH release at pH 6.8 than from matrices containing malic acid. Thus acid solubility is more parametrically significant than acid pKa for drug release at pH 6.8.

Micro/nanofabricated platforms for oral drug delivery

The oral route of drug administration is most preferred due to its ease of use, low cost, and high patient compliance. However, the oral uptake of many small molecule drugs and biotherapeutics is limited by various physiological barriers, and, as a result, drugs suffer from issues with low solubility, low permeability, and degradation following oral administration. The flexibility of micro- and nanofabrication techniques has been used to create drug delivery platforms designed to address these barriers to oral drug uptake. Specifically, micro/nanofabricated devices have been designed with planar, asymmetric geometries to promote device adhesion and unidirectional drug release toward epithelial tissue, thereby prolonging drug exposure and increasing drug permeation. Furthermore, surface functionalization, nanotopography, responsive drug release, motion-based responses, and permeation enhancers have been incorporated into such platforms to further enhance drug uptake. This review will outline the application of micro/nanotechnology to specifically address the physiological barriers to oral drug delivery and highlight technologies that may be incorporated into these oral drug delivery systems to further enhance drug uptake.

A smart pill for drug delivery with sensing capabilities

In this paper a novel system for local drug delivery is described. The actuation principle of the micropump used for drug delivery relies on the electrolysis of a water-based solution, which is separated from a drug reservoir by an elastic membrane. The electrolytically produced gases pressurize the electrolytic solution reservoir, causing the deflection of the elastic membrane. Such deflection, in turn, forces the drug out of its reservoir through a nozzle. The proposed system is integrated in a swallowable capsule, equipped with an impedance sensor useful to acquire information on the physiological conditions of the tissue. Such information can be used to control pump activation.

Combined use of crystalline sodium salt and polymeric precipitation inhibitors to improve pharmacokinetic profile of ibuprofen through supersaturation

To maximize the pharmacological effect of a pain reliever such as ibuprofen, early onset of action is critical. Unfortunately, the acidic nature of ibuprofen minimizes the amount of drug that can be solubilized under gastric conditions and would be available for immediate absorption upon entry into the intestine. Although the sodium salt of ibuprofen has higher solubility, rapid conversion from the salt to the poorly soluble free acid phase occurs under gastric conditions. Therefore, the combination of the highly soluble sodium salt form of ibuprofen with polymers was evaluated as an approach to prolong supersaturation of ibuprofen during the disproportionation of the salt. Binary combinations of ibuprofen sodium with polymers resulted in the identification of several formulations that demonstrated high degrees and extended durations of supersaturation during in vitro dissolution experiments. These formulations included HPMC, polyvinyl pyrrolidone-vinyl acetate copolymer (PVP-VA64), methylcellulose (MC), and hydroxypropyl cellulose (HPC). The in vitro supersaturation observed with these ibuprofen-polymer formulations translated to an increase in Cmax and an earlier Tmax for the PVP-VA64, MC, and HPC formulations relative to ibuprofen only controls when administered orally to rats under fasted conditions. Based on these observations, combining ibuprofen sodium with polymers such as PVP-VA64, MC, or HPC is a viable formulation approach to prolong supersaturation in the stomach and enable an optimized pharmacokinetic profile in vivo where rapid onset of action is desired.

Application of ethylcellulose coating to hydrophilic matrices: a strategy to modulate drug release profile and reduce drug release variability

Hydrophilic matrix tablets are commonly used for extended release dosage forms. For low aqueous-solubility drugs, there may be challenges in modulation of release profiles and achieving consistent release in physiological conditions. To evaluate potential formulation strategies, matrix tablets of a low-soluble drug, hydrochlorothiazide, were developed using hypromellose and two fillers of different solubility, lactose (soluble) or partially pregelatinized maize starch (partially soluble). Additionally, application of an insoluble barrier membrane, aqueous ethylcellulose coating system, and a hydrophilic pore former onto matrix tablets was evaluated. Drug release from uncoated matrix tablets was variable at different agitation rates. Evaluation of tablets in bio-relevant media using physiologically relevant residence time indicated variable and higher initial release rate for uncoated matrices containing lactose but more robust behavior for tablets containing partially pregelatinized starch. Such in vitro behavior may lead to erratic drug release in vivo, when comparing fed versus fasted conditions. Dissolution profiles from barrier membrane-coated tablets showed initial delay, followed by zero-order release kinetics, with reduction or elimination of variability compared to uncoated matrices. Such reduced variability may mitigate mechanical effects of post-prandial stomach. Effects of coating weight gain and inclusion levels of pore former were evaluated and found to be critical in achieving robust and stable release profiles.

Preparation and scale up of extended-release tablets of bromopride

Reproducibility of the tablet manufacturing process and control of its pharmaceutics properties depends on the optimization of formulation aspects and process parameters. Computer simulation such as Design of Experiments (DOE) can be used to scale up the production of this formulation, in particular for obtaining sustained-release tablets. Bromopride formulations are marketed in the form of extended-release pellets, which makes the product more expensive and difficult to manufacture. The aim of this study was to formulate new bromopride sustained release formulations as tablets, and to develop mathematical models to standardize the scale up of this formulation, controlling weight and hardness of the tablets during manufacture according to the USP 34th edition. DOE studies were conducted using Minitab(tm) software. Different excipient combinations were evaluated in order to produce bromopride sustained-release matrix tablets. In the scale-up study, data were collected and variations in tableting machine parameters were measured. Data were processed by Minitab(tm) software, generating mathematical equations used for prediction of powder compaction behavior, according to the settings of the tableting machine suitable for scale-up purposes. Bromopride matrix tablets with appropriate characteristics for sustained release were developed. The scale-up of the formulation with the most suitable sustained release profile was established by using mathematical models, indicating that the formulation can be a substitute for the pellets currently marketed.

Investigation of critical core formulation and process parameters for osmotic pump oral drug delivery

Push-pull osmotic pump (PPOP) tablets of a practically insoluble model drug were developed and the effect of various formulation and process parameters on tablet performance was evaluated in order to identify critical factors. The formulation factors such as the viscosity grade of polyethylene oxide as the primary polymer as well as the level and location of osmogen within the bilayer tablets led to a difference in performance of osmotic tablets and hence should be critically evaluated in the design of such dosage forms. Modification of granulation process, i.e., the granulating liquid composition or drying method of granules, did not impact the drug release from the osmotic tablets at the evaluated scale of this study. The influence of varying dose and aqueous solubility of other model drugs (i.e., theophylline, acetaminophen, and verapamil HCl) on the developed PPOP template was also investigated. Results showed that irrespective of the perceived complexity of development and manufacturing of osmotic pumps, the osmotic tablets in this study demonstrated a robust and yet flexible platform in accommodating different types of drug candidates, regardless of solubility, for the dose levels below 25% w/w of the pull layer formulation.

Controlled release of ropinirole hydrochloride from a multiple barrier layer tablet dosage form: effect of polymer type on pharmacokinetics and IVIVC

The purpose of the present study was to control in vitro burst effect of the highly water-soluble drug, ropinirole hydrochloride to reduce in vivo dose dumping and to establish in vitro-in vivo correlation. The pharmacokinetics of two entirely different tablet formulation technologies is also explored in this study. For pharmacokinetics study, FDA recommends at least 10% difference in drug release for formulations to be studied but here a different approach was adopted. The formulations F8A and F9A having similar dissolution profiles among themselves and with Requip® XL™ (f 2 value 72, 77, 71 respectively) were evaluated. The C max of formulation F8A comprising hypromellose 100,000 cP was 1005.16 pg/ml as compared to 973.70 pg/ml of formulation F9A comprising hypromellose 4000 cP irrespective of T max of 5 and 5.75 h, respectively. The difference in release and extent of absorption in vivo was due to synergistic effect of complex RH release mechanism; however, AUC0-t and AUC0-∞ values were comparable. The level A correlation using the Wagner-Nelson method supported the findings where R (2) was 0.7597 and 0.9675 respectively for formulation F8A and F9A. Thus, in vivo studies are required for proving the therapeutic equivalency of different formulation technologies even though f 2 ≥ 50. The technology was demonstrated effectively at industrial manufacturing scale of 200,000 tablets.

Mucoadhesive tablets for controlled release of acyclovir

Mucoadhesive chitosan (CS) and/or hydroxypropyl-methylcellulose (HPMC) tablets for gastric drug delivery of acyclovir (ACV) have been developed in order to improve the ACV oral bioavailability. Swelling, bioadhesive and dissolution studies were carried out in two acidic media (pH 1.5 and 4) in order to determine the tablets behaviour in both fed and fasted states. All the designed tablets showed good mucoadhesive properties on gastric mucosa due to the presence of CS and/or HPMC. In vitro dissolution of ACV from tablets was influenced by the swelling behaviour of each polymer. All data release of the studied tablets fitted to Hopfenberg model, which describes drug release from tablets displaying heterogeneous erosion. HPMC and CS/HPMC tablets revealed a sustained release for 24 h, but a complete dissolution of the tablets was not produced at this time. On the contrary, tablets which contained only CS as polymer were able to release the total amount of ACV for 4 h, due to the CS imbibition and erosion processes in pH 1.5 medium. These results allowed us to conclude that CS is the excipient to be chosen to obtain gastroretentive formulations, due to its demonstrated gastric compatibility.

A horse of a different color: how formulation influences medication effects

A medication's pharmacokinetic properties can be as important as its efficacy in determining how successful a treatment is. Formulation plays a critical role in absorption, distribution, and elimination of a drug, which in turn can influence the clinical profile of a medication, including onset and duration of action, consistency of plasma levels, ability to cross the blood-brain barrier, and other factors. Advances in drug delivery technology mean that formulation is now an integral component in the development of a drug. Likewise, formulation is one of the factors that may influence selection of a medication to suit the needs of a particular patient. This article briefly reviews the technologies commonly applied in the development of psychotropic medications, with emphasis on the various oral modified-release formulations, and discusses how formulation can be used to optimize the efficacy and tolerability of psychotropic drugs.

The influence of sodium carboxymethylcellulose on drug release from polyethylene oxide extended release matrices

Anionic polymer sodium carboxymethylcellulose (CELLOGEN® HP-HS and/or HP-12HS) was investigated for its ability to influence the release of three model drugs propranolol hydrochloride, theophylline and ibuprofen from polyethylene oxide (POLYOX™ WSR 1105 and/or Coagulant) hydrophilic matrices. For anionic ibuprofen and non-ionic theophylline, no unusual/unexpected release profiles were obtained from tablets containing a mixture of two polymers. However, for cationic propranolol HCl, a combination of polyethylene oxide (PEO) with sodium carboxymethylcellulose (NaCMC) produced a significantly slower drug release compared to the matrices with single polymers. The potential use of this synergistic interaction can be a design of new extended release pharmaceutical dosage forms with a more prolonged release (beyond 12 h) using lower polymer amount, which could be particularly beneficial for freely water-soluble drugs, preferably for once daily oral administration. In order to explain changes in the obtained drug release profiles, Fourier transform infrared absorption spectroscopy was performed. A possible explanation for the more prolonged propranolol HCl release from matrices based on both PEO and NaCMC may be due to a chemical bond (i.e. ionic/electrostatic intermolecular interaction) between amine group of the cationic drug and carboxyl group of the anionic polymer, leading to a formation of a new type/form of the active (i.e. salt) with sustained release pattern.

Development of sustained release capsules containing "coated matrix granules of metoprolol tartrate"

The objective of this investigation was to prepare sustained release capsule containing coated matrix granules of metoprolol tartrate and to study its in vitro release and in vivo absorption. The design of dosage form was performed by choosing hydrophilic hydroxypropyl methyl cellulose (HPMC K100M) and hydrophobic ethyl cellulose (EC) polymers as matrix builders and Eudragit® RL/RS as coating polymers. Granules were prepared by composing drug with HPMC K100M, EC, dicalcium phosphate by wet granulation method with subsequent coating. Optimized formulation of metoprolol tartrate was formed by using 30% HPMC K100M, 20% EC, and ratio of Eudragit® RS/RL as 97.5:2.5 at 25% coating level. Capsules were filled with free flowing optimized granules of uniform drug content. This extended the release period upto 12 h in vitro study. Similarity factor and mean dissolution time were also reported to compare various dissolution profiles. The network formed by HPMC and EC had been coupled satisfactorily with the controlled resistance offered by Eudragit® RS. The release mechanism of capsules followed Korsemeyer-Peppas model that indicated significant contribution of erosion effect of hydrophilic polymer. Biopharmaceutical study of this optimized dosage form in rabbit model showed 10 h prolonged drug release in vivo. A close correlation (R(2) = 0.9434) was established between the in vitro release and the in vivo absorption of drug. The results suggested that wet granulation with subsequent coating by fluidized bed technique, is a suitable method to formulate sustained release capsules of metoprolol tartrate and it can perform therapeutically better than conventional immediate release dosage form.