Controlled Release Matrix Tablets Research Articles

Formulation and in vitro evaluation of mucoadhesive controlled release matrix tablets of flurbiprofen using response surface methodology

The objective of the current study was to formulate mucoadhesive controlled release matrix tablets of flurbiprofen and to optimize its drug release profile and bioadhesion using response surface methodology. Tablets were prepared via a direct compression technique and evaluated for in vitro dissolution parameters and bioadhesive strength. A central composite design for two factors at five levels each was employed for the study. Carbopol 934 and sodium carboxymethylcellulose were taken as independent variables. Fourier transform infrared (FTIR) spectroscopy studies were performed to observe the stability of the drug during direct compression and to check for a drug-polymer interaction. Various kinetic models were applied to evaluate drug release from the polymers. Contour and response surface plots were also drawn to portray the relationship between the independent and response variables. Mucoadhesive tablets of flurbiprofen exhibited non-Fickian drug release kinetics extending towards zero-order, with some formulations (F3, F8, and F9) reaching super case II transport, as the value of the release rate exponent (n) varied between 0.584 and 1.104. Polynomial mathematical models, generated for various response variables, were found to be statistically significant (P<0.05). The study also helped to find the drug's optimum formulation with excellent bioadhesive strength. Suitable combinations of two polymers provided adequate release profile, while carbopol 934 produced more bioadhesion.

Comparative Pharmacokinetic Evaluation of Controlled Release Matrix Tablet of Milnacipran Hydrochloride in Rabbit

Comparative Pharmacokinetic Evaluation of Controlled Release Matrix Tablet of Milnacipran Hydrochloride in Rabbit

Formulation Development and In Vitro Evaluation of Controlled Release Matrix Tablet of Etodolac

Formulation Development and In Vitro Evaluation of Controlled Release Matrix Tablet of Etodolac

Role of various natural, synthetic and semi-synthetic polymers on drug release kinetics of losartan potassium oral controlled release tablets.

Objective:The objective of the present work was to formulate and to characterize controlled release matrix tablets of losartan potassium in order to improve bioavailability and to minimize the frequency of administration and increase the patient compliance.Materials and Methods:Losartan potassium controlled release matrix tablets were prepared by direct compression technique by the use of different natural, synthetic and semisynthetic polymers such as gum copal, gum acacia, hydroxypropyl methyl cellulose K100 (HPMC K100), eudragit RL 100 and carboxy methyl ethyl cellulose (CMEC) individually and also in combination. Studies were carried out to study the influence of type of polymer on drug release rate. All the formulations were subjected to physiochemical characterization such as weight variation, hardness, thickness, friability, drug content, and swelling index. In vitro dissolution studies were carried out simulated gastric fluid (pH 1.2) for first 2 h and followed by simulated intestinal fluid (pH 6.8) up to 24 h, and obtained dissolution data were fitted to in vitro release kinetic equations in order to know the order of kinetics and mechanism of drug release.Results and Discussion:Results of physiochemical characterization of losartan potassium matrix tablets were within acceptable limits. Formulation containing HPMC K100 and CMEC achieved the desired drug release profile up to 24 h followed zero order kinetics, release pattern dominated by Korsmeyer — Peppas model and mechanism of drug release by nonfickian diffusion. The good correlation obtained from Hixson-Crowell model indicates that changes in surface area of the tablet also influences the drug release.Conclusion:Based on the results, losartan potassium controlled release matrix tablets prepared by employing HPMC K100 and CMEC can attain the desired drug release up to 24 h, which results in maintaining steady state concentration and improving bioavailability.

Formulation and evaluation of verapamil hydrochloride osmotic controlled release matrix tablets

Formulation and evaluation of verapamil hydrochloride osmotic controlled release matrix tablets

Interaction between fed gastric media (Ensure Plus®) and different hypromellose based caffeine controlled release tablets: Comparison and mechanistic study of caffeine release in fed and fasted media versus water using the USP dissolution apparatus 3

The aim of the study was to investigate caffeine release in fed and fasted state media from three controlled release matrix tablets containing different HPMC viscosity grades. The biorelevant in vitro dissolution methods utilize the USP 3 dissolution apparatus and biorelevant media to simulate fed and fasted gastro-intestinal dissolution conditions. The effect of tablet reciprocation rate (dip speed) in dissolution media (10 and 15 dips per minute) and media (water, fed and fasted) on caffeine release rate from - and erosion rate of - 100, 4000 and 15,000 mPa s HPMC viscosity tablets was investigated using factorial designed experiments. Furthermore, the mechanism of release in Ensure Plus(®), a nutrition drink similar in composition to the FDA standard meal, was investigated by studying tablet swelling using texture analysis. Altering dip speed has negligible effect on release and erosion rates. Using fasted media instead of water slightly decreases caffeine release from 100 and 4000 mPa s HPMC viscosity tablets as well as erosion rates, while 15,000 mPa s tablets remain unaffected. Fed compared to fasted media decreases caffeine release rate, and the food effect is greater for the 100 mPa s viscosity tablets compared to the 4000 and 15,000 mPa s viscosity tablets. The investigation using texture analysis indicates that Ensure Plus(®) becomes rate-limiting for caffeine release from HPMC tablets by forming a hydrophobic barrier around the tablets. The barrier decreases tablet water permeation, which decreases erosion rate in 100 mPa s viscosity tablets, swelling in 15,000 mPa s viscosity tablets and caffeine release from both tablets. This observed interaction between Ensure Plus(®) and the HPMC tablets may translate into decreased drug release rate in the fed stomach, which may decrease the amount of drug available for absorption in the small intestine and thus reduce systemic drug exposure and maximum plasma concentration.

EFFECT OF HPMC/CARBOPOL ON THE RELEASE OF CHLORPHENIRAMINE MALEATE FROM MATRIX TABLETS

Chlorpheniramine maleate is widely used in treatment for allergic disorder and cold. The controlled release matrix tablets of chlorpheniramine maleate were prepared using HPMC K15M, HPMC K100M and carbopol and studied their effect on drug release. Prepared tablets were evaluated for various physical parameters. In vitro drug release study shows that slow release in HPMC K100M than other two polymers. If concentration of polymer increases than the drug release is decreases due to formation of polymeric matrix. Zero order, first order, Higuchi’s and Korsmeyer’s equations applied to know the mechanism of drug release from prepared tablets. The similarity and dissimilarity factor found to be 77.88 and 4.14, respectively for drug release in stability study which shows there was no significant difference in drug release. Key words: Chlorpheniramine maleate, matrix tablet, HPMC K15M, HPMC K100M, carbopol and swelling index

Study the effect of formulation variables on drug release from hydrophilic matrix tablets of milnacipran and prediction of in-vivo plasma profile

The objective of this study was to design oral controlled release (CR) matrix tablets of Milnacipran using hydroxypropyl methylcellulose (HPMC) as the retardant polymer and to study the effect of various formulation factors such as polymer proportion, polymer viscosity, compression force and also the pH of dissolution medium on the in-vitro release of drug. Two viscosity grade of HPMC (15 K and 100 K) were used in the proportion of 50, 100, 150 and 200 mg per CR tablet. In-vitro release rate was characterized using various model dependent approaches and model independent dissolution parameters [T50% and T80% dissolution time, mean dissolution time (MDT), mean residence time (MRT), dissolution efficiency (DE)]. The statistical analysis was performed on all the model independent approaches using student t test and ANOVA. Results were found that as polymer concentration (50 mg to 200 mg) and viscosity (15 K to 100 K) increases, the MDT, MRT, T50% and T80% extended significantly. Drug release rate was found to be significantly different at different hardness. In-vivo human plasma concentration--time profile was predicted from in-vitro release data using convolution method. Predicted human pharmacokinetic parameters shows that the design CR formulation has capability to sustained the plasma drug level of milnacipran.

Microwave assisted synthesis of acrylamide grafted locust bean gum and its application in drug delivery

Acrylamide grafted copolymer of locust bean gum was prepared by microwave irradiation using ceric ammonium nitrate as redox initiator. The grafting process was optimized in terms of irradiation time, amount of initiator and acrylamide by using constant amount of native locust bean gum. The grafted gum was characterized by Fourier transform infrared spectroscopy (FT-IR), 13C nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), X-ray diffraction study (XRD), differential scanning calorimetry (DSC), elemental analysis, contact angle, viscosity, molecular weight, swelling and biodegradability studies. The grafted gum was found to be biodegradable and non-toxic. It was further used to prepare controlled-release matrix tablet of buflomedil hydrochloride. The in vitro release profile of the tablet showed the rate controlling property of acrylamide grafted locust bean gum was similar to that of hydroxypropyl methylcellulose (HPMC-K15M).

The influence of vitamin E succinate on the stability of polyethylene oxide PEO controlled release matrix tablets

Hydrophilic matrices are a principal technology used for extended release (ER) oral dosage forms and a recent review concluded that their development is currently one of the most important challenges in pharmaceutical research. High molecular weight polyethylene oxides (PEOs) have been proposed as an alternative to hydroxypropylmethylcellulose (HPMC) for the manufacture of controlled release matrix tablets. It is known that PEO's are prone to oxidative degradation which can occur by chain scission and can be catalyzed by metal ions. In this study, we investigated the stability of PEO matrix tablets, of different molecular weight, containing diltiazem hydrochloride, when stored at 40°C. The results show that there were dramatic increases in the release rate of the diltiazem following storage over only a few weeks, resulting in immediate release profiles after eight weeks, even for the highest molecular weight grade. We employed Gel permeation chromatography (GPC), viscosity and differential scanning calorimetry (DSC) techniques to try and determine the underlying causes of these dramatic shifts in dissolution profiles on storage. The results showed that there were significant decreases in the molecular weight of the PEO's during storage. The second part of the study looked at the addition of three different levels of vitamin E succinate to the tablets. The results clearly demonstrate the ability of the added antioxidant to reverse the significant reductions in molecular weight seen using GPC, viscosity and DSC. Importantly the addition of the antioxidant was able to stabilize the release profile of the diltiazem especially when present at a 1% level. Researchers and those working in pharmaceutical development should be aware of the potential stability risks when making matrix tablets containing PEO's and may wish to consider the addition of an antioxidant to the tablet formulation.

Physical properties and in vivo bioavailability in human volunteers of isradipine using controlled release matrix tablet containing self-emulsifying solid dispersion

Poorly water-soluble drug with a short half-life such as isradipine (IDP) offer challenges in the controlled release formulation because of low dissolution rate and poor bioavailability. Self-emulsifying solid dispersions (SESD) of IDP consisted of surfactant and fatty acid in poloxamer 407 (POX 407) as a carrier and were manufactured by the melting method. Then, controlled release HPMC matrix tablet containing SESD were prepared via direct compression. The dissolution behaviors and in vivo bioavailability of controlled release matrix tablet in healthy human volunteers were investigated. The physical properties of solid dispersion were also examined using differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). It was shown that structure of IDP was amorphous in the solid dispersion. The dissolution rate of IDP from SESD was markedly enhanced because of increased solubility and wetting effect. Controlled release HPMC matrix tablets containing SESD released drug in a controlled manner and were stable during storage over 3 months at 40 °C/75% RH. Furthermore, the tablet containing 5mg IDP SESD showed significantly increased oral bioavailability and extended plasma concentration compared with the marketed 5 mg Dynacirc(®) capsule. A combined method of solid dispersion and controlled release technology could provide versatile dosage formulations containing IDP with poor water solubility and short half-life.

EFFECT OF HYDROPHILIC POLYMERS ON CONTROLLED RELEASE MATRIX TABLETS OF ACYCLOVIR

Acyclovir was formulated as oral controlled release matrix tablets using natural and synthetic polymers separately or in combinations. Tablets were prepared by direct compression method. The tablets were evaluated to thickness, weight variation test, drug content, hardness, friability and in vitro release studies.All the formulations showed compliance with pharmacopoeal standards. The tablets prepared with various combination of hydroxy propyl methylcellulose (HPMC K100), locust bean gum (LBG) and karaya gum (KG) failed to produce the desired controlled release. Dissolution studies indicated that formulation F5 was most successful of the study. The formulation F5 exhibited anomalous (non-Fickian) diffusion mechanism. Based on the results of in-vitro studies it was concluded that the hydrophilic polymers canbe used as an effective matrix former to provide controlled release of acyclovir. SEM images of tablet after dissolution showed pore formation. FT-IR and DSC study did not show any possibility of interaction between acyclovir and excipients.

The role of oral controlled release matrix tablets in drug delivery systems.

Formulations that are able to control the release of drug have become an integral part of the pharmaceutical industry. In particular oral drug delivery has been the focus of pharmaceutical research for many years. This type of drug delivery has been at the centre of research due to its many benefits over conventional dosage. The focus of this review is on matrix tablets due to their widely use and simplicity of the formulation. This includes the discussion of various types of matrix tablets and factors affecting the drug release from these formulations. The mechanism of drug release from HPMC matrices is also discussed.

Formulation and in vitro Evaluation of Betahistine Dihydrochloride Twice Daily Controlled Release Matrix Tablet

In order to reduce dosing frequency, a sustained release dosage form of betahistine dihydrochloride was developed as a twice daily controlled release tablet formulation that could be used to decrease vertigo resulted in Meniere's disease for a prolonged time. Six formulations were developed by using Methocel K4M CR, Methocel K15M CR and Methocel K 100 LVCR as single and combinations in different percentage. The tablets were prepared by wet granulation method. Physical properties of betahistine dihydrochloride granules and betahistine dihydrochloride matrix tablets were evaluated. The tablets were characterized for Betahistine Dihydrochloride release in both gastric simulated fluid (0.1 N HCl, pH 1.3) and simulated intestinal fluid (buffer solution pH 6.8). The data were subjected to different models in order to evaluate their release kinetics and mechanisms. The results of the in vitro dissolution study indicate that most of the formulations showed above 80% of drug release in 12 hours but formulations (F-2 and F-4) met the official specification of release profile. Dissolution data were fitted to zero order equation, Higuchi square root law, Korsmeyer-Peppas model and Hixson-Crowell cube root law as these plots showed the highest value of linearity to evaluate kinetic data. The release of betahistine dihydrochloride was prolonged for 12 hours indicating the usefulness of the formulations for twice daily dosage forms, leading to improve efficacy, controlling the release and better patient compliance. DOI: http://dx.doi.org/10.3329/dujps.v10i2.11786 Dhaka Univ. J. Pharm. Sci. 10(2): 93-100, 2011 (December)

Design and Optimization of Venlafaxine Hydrochloride Controlled Release Tablets Using HPMC K<SUB>15</SUB>M

Venlafaxine hydrochloride was formulated as oral controlled release matrix tablets using hydrophilic polymer such as hydroxypropyl methyl cellulose (HPMC K 15 M) along with electrolytes. In this work a new attempt was made for in situ interactions between drug and electrolytes were devised to control the release of highly water soluble drugs from oral hydrophilic monolithic systems. Electrolytes such as Calcium carbonate, magnesium trisilicate, sodium bicarbonate were used at different concentrations in various formulations, while drug and polymer concentrations were maintained constantly at 1:1 ratios in all the formulations. These electrolytes were used to monitor matrix swelling and gel properties. These findings indicated that the swelling and gel formation in the presence of ionizable species within the hydrophilic matrices provide an attractive alternative for controlled drug delivery from a simple monolithic system. FTIR studies were carried out for some selected formulations, which indicated that there were no interactions between drug and excipients used.

Albizia procera gum as an excipient for oral controlled release matrix tablet

The purpose of this research was to develop and evaluate controlled release matrix tablets of paracetamol based on natural gum exudates of Albizia procera. Procera gum was characterized of its properties like compressibility index, angle of repose, viscosity and moisture content. The interaction between the gum and paracetamol was also studied through differential scanning calorimetry (DSC) and FTIR spectroscopy. Matrix tablets were then prepared by wet granulation method with different concentrations of procera gum and hydroxypropyl methylcellulose (HPMC) and evaluated for their physical properties like weight variation, hardness, friability and content uniformity. Dissolution study was conducted to characterize release mechanism from the matrix system and data were fitted to various kinetic models. The mechanism of drug release from both types of matrix tablets was found to be anomalous type. Results from various evaluations suggested that A. procera gum could be used as drug release retardant in controlled release matrix systems.

The Development of Eudragit® NM-Based Controlled-Release Matrix Tablets

Eudragit® NM was investigated as a matrix former in combination with microcrystalline cellulose as an insoluble filler for preparing controlled-release tablets containing model drugs with different solubility. Three sets of matrix tablets differing in the drug-to-filler ratio (1:1, 2:1, and 4:1) and polymer amount with diltiazem hydrochloride (freely soluble) or caffeine (sparingly soluble) were prepared. Samples were evaluated by the dissolution test at pH 6.8 corresponding to the upper part of the small intestine; the selected samples were tested at a changing pH level to better simulate in vivo conditions. The prepared matrix tablets fulfilled all the requirements of the European Pharmacopoeia. Tablets with Eudragit® NM showed excellent mechanical characteristics. In vitro studies showed that the set 1:1 was the most suitable for the sustained release of a freely soluble drug concerning the burst effect and the total drug amount released within 12 hours. The significant effect of the drug-to-filler ratio and polymer amount on the dissolution profile was confirmed by similarity factor analysis. A faster drug release was observed during the dissolution test within changing pH levels because of the pH-dependent solubility of diltiazem. A prolonged release of the sparingly soluble drug was not achieved, and a trend for fast disintegration was observed. The combination of Eudragit®NM with microcrystalline cellulose as an insoluble filler seems to be suitable only for freely soluble drugs, when the amount of the drug and the filler is similar.

Studies on Bio-adhesion of Matrix Tablets: II.Comparison on Bio-adhesion Strength and Release Profiles of Theophylline Anhydrous and Its Sodium Glycinate Salt

Controlled release matrix tablets of Theophylline anhydrous and Theophylline sodium glycinate were prepared with different types of bio-adhesive polymers e.g. HPMC 15 & 50 cps, Gelatin, PVP K-30, Na-CMC and Xanthan gum. Tablets, prepared by direct compression method were subjected to in-vitro drug dissolution for 8 hours in 0.1 N hydrochloric acid (pH 1.2) using a thermal shaker at 50 rpm at 37 ± 0.5ºC. The bio-adhesive property was investigated in terms of retention time following in-vitro wash-off method by Lehr et al. The anhydrous and corresponding salt form was used to investigate whether physical variation of Theophylline molecule can cause any change in release and bio-adhesion property or not. In most of the cases it is found that salt form releases greater percentage of active drug than its corresponding anhydrous form. Irrespective of drug’s physical property and amount of polymer, bio-adhesive strength of Xanthan gum was proved to be maximum followed by HPMC- 50 cps, Na-CMC and HPMC- 15 cps, whereas gelatin and PVP K-30 showed little or poor muco-adhesion. Xanthan gum, Na-CMC and HPMC based formulations showed nearly zero-order release; on the contrary PVP K-30 based formulation showed a burst release within one hour of dissolution.DOI: http://dx.doi.org/10.3329/dujps.v10i1.10008DUJPS 2011; 10(1): 1-7

Toward Biorelevant Dissolution: Application of a Biphasic Dissolution Model as a Discriminating Tool for HPMC Matrices Containing a Model BCS Class II Drug

The potential of a biphasic dissolution system to assist with the analysis of controlled-release (CR), Biopharmaceutics Classification System (BCS) Class II pharmaceutical products has been investigated. Use of a biphasic dissolution medium (aqueous/octanol) provided sink conditions and afforded complete dissolution of nifedipine formulated in a CR matrix tablet while maintaining the dosage form in an aqueous environment. This was not possible in a monophasic (aqueousonly) dissolution medium. Consequently, the biphasic model allowed the discrimination of three formulations containing different HPMC loadings while the monophasic medium did not. The performance of the formulations in conventional dissolution media incorporating the inorganic salt dibasic sodium phosphate, the surfactant sodium dodecyl sulfate (SDS), and ethanol as solubility modifiers was assessed. The addition of the salt and surfactant failed to produce complete discrimination in a predictive manner. The use of a hydroalcoholic medium comprising water and ethanol enabled the statistical discrimination of the three formulations but not as effectively as the biphasic medium.

Regulating drug release behavior and kinetics from matrix tablets based on fine particle-sized ethyl cellulose ether derivatives: an in vitro and in vivo evaluation.

The design and fabrication of sustained/controlled release dosage forms, employing new excipients capable of extending/controlling the release of drugs from the dosage forms over prolonged periods, has worked well in achieving optimally enhanced therapeutic levels of the drugs. In this sense, the objective of this study was to investigate the suitability of selected cellulose ether derivatives for use in direct compression (DC) and as efficient drug release controlling agents. Controlled release matrix tablets of ciprofloxacin were prepared at different drug-to-polymer (D : P) ratios by direct compression using a fine particle sized ethylcellulose ether derivative (ETHOCEL Standard Premium 7FP) as rate controlling polymer. The tablets obtained were evaluated for various physico-chemical characteristics and in-vitro drug release studies were conducted in phosphate buffer (pH 7.4) using PharmaTest dissolution apparatus at constant temperature of 37°C ± 0.1. Similarity factor f 2 was employed to the release profiles of test formulations and were compared with marketed ciprofloxacin conventional tablets. Drug release mechanism and the kinetics involved were investigated by fitting the release profile data to various kinetic models. It was found that with increasing the proportion of ethylcellulose ether derivative in the matrix, the drug release was significantly extended up to 24 hours. The tablets exhibited zero order or nearly zero order drug transport mechanism. In vivo drug release performance of the developed controlled release tablets and reference conventional tablets containing ciprofloxacin were determined in rabbit serum according to randomized two-way crossover study design using High Performance Liquid Chromatography. Several bioavailability parameters of both the test tablets and conventional tablets including C max⁡, T max⁡ and AUC0-t were compared which showed an optimized C max⁡ and T max⁡ (P < 0.05). A good correlation was obtained between in vitro drug release and in vivo drug absorption with correlation value (R 2 = 0.934). Relative bioavailability was found to be 93%. Reproducibility of manufacturing process and accelerated stability of the developed tablets were performed in stability chamber at 40 ± 2°C and 75 ± 5% relative humidity for a period of 6 months and were found to be stable throughout the stability period.