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Ajay Bharate et al. (2010) fabricated controlled release Metoprolol succinate tablets by using hydrophilic polymers by wet granulation technique. They have used different granulated fluids like acetone, dichloromethane and isopropyl alcohol and studied the release retardency of the drug form the polymers. HPMC is the most widely used hydrophilic excipient and also it releases the drug through swelling and erosion of the polymer. Prepared granules were subjected to flow and compression characteristics. The compatibility studies have been done between drug and excipients by using FTIR which did not effected any of the physico-chemical properties of the drug. The fabricated formulations tested for dissolution release properties and compared with that of the marketed formulation. HPMC and alginate containing formulations showed better release retardency and can be suggestable for preparing retard releasing tablet formulations of Metoprolol succinate.
Rouslan Moustafine et al. (2008) have reported a study on evaluation of inter polyelectrolyte complexes (IPEC) of chitosan with eudragit-L100 and L-100,55 as potential carriers for oral controlled drug delivery. Main purpose of the study is to characterize the physicochemical properties of IPEC's made up of chitosan and two type's eudragit polymers. The interaction or binding ratio of a unit molecule of chitosan with eudragit L copolymer depends on molecular weight of chitosan and changes from 1:0.85 to 1:1.22 for L-100. The possibility of interaction between these electrolytes was investigated at PH 6. FTIR analysis revealed that the structure of IPEC's can change substantially as a function of PH. Swelling behavior of physical mixtures were studied and potential interactions between the two polyelectrolytes was not observed. Swelling experiments and drug release studies conformed that the drug release not only based on IPEC but also depends on the methacrylic copolymer included. Finally they were accomplished and reported that release of the drug was significantly delayed from tablets made up of IPEC in two ways i) by choosing eudragit L copolymer types and /or ii) changing the molecular weight of chitosan in the IPEC'S composition.
Gummadivelly Sandeep et al. (2009) have been investigated to formulate and characterize matrix tablets of Metoprolol succinate which are having sustained action, using hydrophilic polymers like HPMC k100M, hydroxy propyl cellulose, ethyl cellulose, carbopol-934. By using direct compression method and 96 mm punches the tablets were compressed and coated with indaocaramine for patient compliance sake. Advantages of extended release formulations are ability to maintain Î²-selectivity over 24hours, thus avoiding decreased Î²1-selectivity as seen at high plasma concentration. Compressed tablets were evaluated for various physic-chemical parameters and invitro dissolution tests. ER-20 formulation showed 20hrs of release with zero order kinetics governed by diffusion through swollen matrix and erosion of the matrix or non-fiction transport as the n- values are in the range of 0.45-0.890C. Formulations were found to be stable at 37-450C for a period of one month.
Samanta Mouraw et al. (2010) have been investigated to maximize the bioavailability of conventional drugs like sodium diclofenac and reducing side effects by using matrix systems. The present study mainly aimed to develop three different formulae of drug containing matrix tablets and also to find out the effect of dissolution profiles. Formulations F1, F2 and F3 matrix tablets were of 350mg weight were prepared by using wet granulation along with HPMC(10%, 20%, 30%) , magnesium stearate, PVP, MCC and lactose. In phosphate buffer of PH 6.8 at 370C using type-II apparatus as per USP at 50, 75, and 100rpm to determine the effect of agitation speed dissolution tests was performed. Dissolution efficiency, T50 and T90 were determined . Dissolution efficiency of F2 is more compared with that of the F3 and F1. It showed that increased hypermellose concentration leads to reduced dissolution efficiency values. Determination of T50 and T90 suggests that F1 is less sensitive to variations in agitation speed than F2 and F3. Satisfactory dissolution conditions have been observed at 50rpm. Results showed and conformed that for comparison of dissolution performance of matrix tablets, polymer concentration and agitation speed also must considered.
Goyal et al. (2009) were studied the factors influencing that influencing the release characteristics of drug substances from hydrophilic polymer matrix tablet using different hydrophilic polymers like polyethylene oxide, hydroxyethylcellulose and xanthan gum. The work also investigates the effects of PH, proportion of polymer, diluents and drug solubility on dissolution characteristics. The tablets were fabricated by direct compression and evaluated for physical characteristics. The swelling studies were conducted for 6hrs in 0.1N HCl and phosphate buffer respectively. Release rate studies performed by using buffer change method for 8hours. The process of drug release from hydrophilic polymeric matrices mainly involves solvent penetration, hydration and swelling of the polymer, diffusion of the dissolved drug in the matrix and erosion of layer. Results showed that drug release from polymer matrix tablet follows higuchi square root time kinetics with r2 value 0.9880 which releases the drug through diffusion and relaxation
Vueba et al. (2004) have been aimed and investigated on ketoprofen release to determine the effect of polymer substitution and type of diluents on drug release mechanism. In recent years hydrophilic polymers particularly cellulose derivatives were chosen to develop controlled release technology because of their ability to form gels in aqueous medium. The present study mainly aims to evaluate the effect of polymers on the kinetics of the drug release using distinct formulations. Distinct test formulations were prepared by using methyl cellulose, hydroxy propyl cellulose and HPMC as polymers while lactose monohydrate and Î²-cyclodextrin were tested as diluents. Different evaluation tests including release rate were performed as per official monographs. Polymers MC25 and hydroxy propyl cellulose were found to be in appropriate for the preparation of modified release ketoprofen hydrophilic matrix tablets. Application of release data to various kinetic models was done and found that type of polymer did not influence the release the mechanism of the drug. Mean dissolution time was performed and was found maximum for HPMC formulation. Also the drug release process was slightly influenced by the type of diluents either lactose or Î²-cyclodextrin. Differential scanning colorimetry thermograms showed no interactions between the drug and polymer or diluents.
Carla Lopes et al. (2006) investigated on compressed mini-tablets as a bi-phasic delivery system designed to study zero-order sustained drug release. Development of mini-matrices is a promising area in pharmaceutical research concerned with a high control over the release rate of the drug combined with a high flexibility on the adjustment of both dose and release of a drug or drugs. They have the diameter equal to or smaller than 2-3mm. This study also aimed to study the formulation parameters affecting invitro performance and also evaluate compressed mini-tablet systems. Prolonged-release component and fast release components were combined through direct compression and compressed mini-tablet system was prepared. Dissolution studies were performed according to USP paddle method and showed that fast release component dissolves in 2min. , where as the % release from prolonged release component were different and depends upon the nature of the polymer component with maximum release rate of 8hrs. F21 and F10 compressed HPMC min-tablets showed good release profile. Also the r2 values for F20 and F10 were found to be 0.9947 and 0.9932 and for HPMC 0.9980 and 0.9930 for showing the zero-order release through diffusion. Finally the results showed that release profile is strongly dependent on the number or composition of sub-units, making up the drug sustained dose.
Pornsak Sribornsak et al. (2007) made a study on swelling and erosion pattern of hydrophilic matrix tablets with pectin and its effect on drug release. In this study pectin a structural component of plant cell walls was selected because of its non -toxicity, low production etc. Direct compression was employed for punching of matrix tablets with various types of pectin. Swelling and erosion studies of these tablets were performed in various media. In pectin matrices the swelling action was found to be controlled by rate of its hydration in the medium. Gel structure analysis and morphology of the swollen tablets was performed. In-vitro drug dissolution studies revealed that swelling and erosion of matrices influences the drug release pattern. It was found that release in SGF (120), but slow in SIF. The dissolution data showed best fit into power law or Korsmeyer-peppas equation showed the common effect of diffusion and erosion mechanism of drug release. The PH of the release medium showed some effect on drug release from the matrix tablets.
Chen Bin et al. (2009) have made a study on biofluid uptake and release of indomethacin of directly compressed HPMC tablets. For this three different grades of HPMC with different viscosities are selected and directly compressed without any additive or binder. The swelling behavior was monitored in water, simulated gastric fluid(SGF) and simulated intestinal fluid (SIF) without and with an active ingredient. The role played by salts present in the media and the properties of HPMC matrix in these processes was assessed. The amount of fluid uptake by the tablets followed a power law relationship with time for all three media. The controlling parameters for the swelling polymers were found to be viscosity and molecular weight of HPMC. By taking indomethacin as a model drug, drug releasing properties of HPMC tablets have been elucidated. Finally they concluded that similar to the fluid uptake process, drug release was also controlled by size and density of the gel network. HPMC-B grade showed a maximum release for 25hrs.
Caillard et al. (2009) have been investigated succinylated soya protein tablets as delayed drug delivery systems in gastro intestinal tract(GIT). At PH above 4.5, succinylation showed reduced protein charge density and protein solubility at PH 1.2 and increased PH solubility and zeta potential. Soy protein secondary structure was studied using FTIR spectroscopy which showed that polypeptide chain unfolding because of succinylation. Soy protein tablets (900mg) were formulated by direct compression with riboflavin or rifampicin as active tracers and for erosion experiments, tablets were prepared with protein alone. At PH 1.2 and at PH 7.5 the swelling and erosion of the tablets were decreased and increased respectively. Tablets having succinylated protein at 50% or 100% released a lesser amount than 10% loaded riboflavin or rifampicin in 2hours at gastric PH in presence of pepsin but released the same compounds hastily at intestinal PH. Succinylated soy protein tablets were thus gastro resistant suggesting the potential of proteins as pharmaceutical excipients for the design of controlled release tablets.
Al-Saidan et al. (2004) have made a study on the pharmacokinetic evaluation of oral controlled extremely soluble metoprolol tartrate as a model drug and guar-gum as a polymer. The main aim of the current study is to prepare and evaluate three-layer matrix tablets of water soluble metoprolol tartrate as oral controlled delivery. Wet granulation method was used for the preparation of the matrix tablets. In-vitro drug release studies were performed by using Reverse-phase HPLC. For pharmacokinetic study, six healthy volunteers were participated and a two-way cross over design was followed. Plasma concentration of drug was estimated by reverse-phase HPLC and the pharmacokinetic parameters were estimated by utilizing the plasma concentration vs time data. The delayed tmax lower Cmax, decreased Ka, unaltered bioavailability and prolonged t1/2 showed a slow and sustained release of metoprolol tartrate from guar gum tablets when compared with that of the instant/conventional release tablet dosage forms. The results of the tests showed that guar gum three layer tablets can give oral controlled delivery for highly water soluble drug like metoprolol tartrate in humans.
Hirufumi Takeuchi et al. (1998) were investigated the use of sodium alginate and spray dried composite particles of lactose for direct tableting and controlled releasing. Spray dried particles had an excellent flowing property due to their spherical shape and sharp particle size distribution. This paper reports preparation of a novel modified lactose particle containing a gel forming polymer for controlling the drug release rate from the resultant matrix tablets. The composite particles of sodium alginate and lactose were fabricated by using spray drying method and the micromeritic and controlled releasing properties were evaluated. The spray dried particles along with acetaminophen were compressed at 100-400Mpa pressure and the tensile strength of compacts was much higher than commercial lactose. Thermal stability of amorphous form of lactose in the spray dried particles determined by differential scanning colorimetry and it was enhanced in presence of sodium alginate. The drug release from the matrix tablets prepared with spray dried particles and acetaminophen in PH 1.2 was more prolonged than that of a physically mixed tablet of lactose, sodium alginate and drug , because of improved gel forming property of sodium alginate formulated in spray dried. The drug releasing properties were found to be due to dispersal state of sodium alginate in the paricles. Finally the results suggested the inclusion of lactose in a particle could confer more favourable characteristics as an excipients to the resultant composite particle.
Sung In Hong et al. (2008) made an attempt to study the dissolution kinetics and physical characteristics of three layered tablet with polyetheylene oxide core matrix capped by carbopol. Solid-dispersed nifidipine was prepared using PEG-4000. Then it was punched along with polyetheylene oxide matrix as core and carbopol on both sides through direct compression. The differential scanning colorimetry, X-ray diffraction pattern obtained after 4weeks of storage showed that crystallinity of polyethylene glycol-4000 in solid dispersions is increased to some extent upon aging during its storage period. Formation of crystalline domain of nifidipine and polyetheylene oxide or sodium dodecyl sulfate was not observed. Various factors such as molecular weight of polyetheylene oxide, ionic strength, buffer concentration and PH of the dissolution medium were investigated for their effect on dissolution rate. Dissolution studies revealed that carbopol layers minimized the surface area that has been available to dissolution medium and they also covered the exposed side area of the tablet, after swelling. The dominating mechanism for the release of drug was found to be diffusional release. To understand the release mechanism, the data obtained for capped and blended tablets were fitted into the power law equation. These results gave some valuable information on parameters that can be used in the design of a controlled release dosage form of nifidipine.
Quan Liu et al. (2008) attempted to study zero order delivery of a extremely soluble, low dose drug alfuzosin HCl via gastro retentive system. Two systems containing polyetheylene oxide , HPMC, sodium bicarbonate, citric acid and PVP were dry blended and compressed into bilayer and triple layer composite matrices. The prepared tablets were subjected to dissolution study under sink conditions. Both the dosage forms were found to be effective in prolonged flotation with zero order release, complete disentanglement and erosion. The composite design approach and the proposed matrix evaluation may offer formulation scientists with greater opportunity to successfully develop and evaluate variety of swelling and floating systems for highly soluble drugs.
Udaya Toti et al. (2004) studied the effect of modified guar gum on controlled release of Diltiazem HCl. Poly acrylamide-grafted guar gum was prepared by taking three different ratios of guar gum to acrylamide (1:2,1:3.5 & 1:5). Amide groups of these grafted copolymers were converted into carboxylic functional groups. FTIR and differential scanning colorimetry were performed to characterize the copolymers. Tablets were prepared by incorporating an antihypertensive drug. To understand the release kinetics, in-vitro release studies were performed in simulated gastric and intestinal conditions for 2 and 10hours respectively, using USP paddle type at 100rpm. Release continued upto 8 and 12hours respectively for grafted copolymer of guar gum and hydrolyzed guar gum polymers. Nature of the drug transport from the polymers was determined by applying dissolution release data into higuchi, hixson crowell and kopcha equations. Drug release was found to be dissolution controlled in case of unhydrolyzed copolymer and for hydrolyzed one, initially swelling controlled but became dissolution controlled in PH 7.4. Parameters of kopcha equation revealed the predominance of diffusion on drug release for both type of matrices. Hence this study indicates that hydrolyzed polyacryl amide grafted guar gum matrices are PH sensitive and can be used for intestinal drug delivery.
Gothi et al. (2009) investigated to minimize the rate of dose administration, to avoid nocturnal heart attack and to improve the patient compliance by developing extended release matrix tablet of Metoprolol succinate. They studied the effect of concentration of hydrophilic polymers like HPMCK100M, xanthan gum through wet granulation and evaluated for various parameters. In-vitro dissolution studies were performed as per USP specifications and observed that drug release kinetics was found to be dependent on type and amount of polymer in matrix system. Higher the polymeric content in the matrix decrease the release rate of drug and vice-versa. Finally they concluded that the drug release can be modulated by varying the concentration of polymer. F9 was the best matched formulation with respect to marketed product. Optimized formulation was found to be stable for accelerated stability study for 3months at 400C and 75% RH.
Stefania Conti et al (2008) was aimed to study the potential role of solution colorimetry estimations in fabricating the formulation of swellable matrices. The primary aim of this work was to extend the analysis to polymer contacts and to assess its mechanistic information. A mixture of HPMC and sodium CMC were used for this purpose, which shows synergistic effect in their ability to change drug delivery rates. A mixed ratio of 1:1 polymer matrix exhibited significant slow release than either of the polymers alone. To study the system completely solution colorimetry was used. Tablets were prepared by direct compression. Dissolution tests were performed in acetate buffer PH 6.8 at 370C. The dissolution data were fitted to the well-known power-law model to describe drug release behavior of polymeric systems. The measured response of a physical blend was compared with a theoretical one; which helps in detecting the interactions which may explains the synergism. An unfavorable interaction was noted between drug and sodium carboxy methyl cellulose. The trend was mired by the t90 values determined from dissolution testing- sodium carboxy methyl cellulose - 10.8hrs, HPMC - 16.4hrs and mixture - 19.1hrs, shows that solution colorimetry estimations can be used to assist the selection of polymeric excipients in designing controlled drug delivery systems.
Morkhade et al. (2006) studied the natural gum copal and gum damar as novel sustained release matrix forming materials in tablet formulati8on. The physico chemical properties, molecular weight, polydispersity index and glass transition temperature of gum copal and gum damar were performed. By using wet granulation technique and isopropyl alcohol as a granulating fluid matrix tablets were prepared. Diclofenac sodium was used as a active moiety for the current study. Tablets were evaluated for physicochemical properties and in-vitro dissolution studies, release kinetics. Drug release profile on different gum concentrations (10, 20 and 30%w/w with respect to total tablet weight) was observed and reported. The matrix tablets that were produced by both the polymers showed good strength and acceptable pharmacotechnical properties. Tablets with 30% w/w gum copal and gum damar concentrations showed sustained drug delivery for more than 10hr. Gum copal matrix tablets followed zero order kinetic release, where as gum damar (10 and 20%w/w) was found suitable to formulate the insoluble plastic matrix that releases the drug by diffusion. Finally it has been observed and accomplished that both gums possess considerable matrix forming property which may be useful for sustained drug delivery.
Varshosaz et al. (2006) designed sustained-release matrix tablets of extremely water-soluble tramadol HCl by using natural gums(xanthan gum) and guar gum as co effective, nontoxic simply available and appropriate hydrophilic matrix systems compared with the widely investigated hydrophilic matrices and rate of hydration of the polymers. Direct compression method was employed for the preparation of matrix tablets of tramadol. Various ratios of 0:100, 20:80, 60:40, 80:20, 100:0 of guar gum or xanthan gum: HPMC, xanthan gum: guar gum were prepared. Physical characteristics of tablets were evaluated and the dissolution test was performed in the phosphate buffer of PH7.4 upto 8hrs. Tablets that were prepared with xanthan gum showed the maximum mean dissolution time(MDT), the low dissolution efficiency (DE8%), and a zero-order drug release of drug via swelling, diffusion, and erosion mechanisms. Guar gum of its own is not competently control the drug release, where as xanthan gum and all combinations of natural gums along with HPMC could retard tramadol HCl release. But, as per to the similarity factor (f2), pure HPMC and H8G2 were found to be the most similar formulations to Topalgic-LP as the reference standard.
Kuksal et.al (2006) were designed to prepare and characterize extended release matrix tablets of zidovudine with hydrophilic eudragit RPLO and RSPO only or a mixture along with hydrophobic ethyl cellulose. Release kinetics was studied by using USP-22 paddle type apparatus. The effect of dissolution medium on matrix tablet surface was visualized with the help of scanning electron microscopy. Additionally, the in-vitro and in-vivo data of newly formulated sustained release zidovudine tablets was compared with conventional marketed tablet (Zidovir, Cipla ltd, Mumbai,India.). The in-vitro dissolution studies showed that tablets prepared with Eudragit polymer was able to sustain the drug release only for 6hrs (94.3%Â±4.5% release). But a combination of eudragit along with ethyl cellulose prolonging the drug release for 12hours (88.1%Â±4.1% release). Applying kinetics the invitro drug release data showed that diffusion along with erosion could be the possible mechanism of drug release. Invivo studies in rabbits shown sustained release pharmacokinetic profile of zidovudine from the matrix tablets that have been prepared using combination of eudragits and ethyl cellulose. Finally from the results it was concluded that the matrix tablets that were prepared with the polymers showed sustained therapeutic action which was better than conventional dosage forms, because of their improved efficacy and better patient compliance.
Panna Thapa et al. (2005) formulated control release oral delivery system and investigated the influence of different diluents, carbopol934p concentration and granulation technique in the release of poorly water-soluble drug(ibuprofen) from carbopol934P matrix tablets. Matrix tablets were prepared by direct compression, wet granulation and dry granulation method at different polymer concentration using lactose, dibasic calcium phosphate (DCP), Microcrystalline cellulose (MCC) and starch as diluents. Dissolution studies were carried out in 900ml phosphate buffer of PH 7.4using using USP-apparatus I. At 5% carbopol 934P concentration, the t1/2 was found in the rank order of tablets starch<MCC<DCP<lactose. The integrity of tablets and drug release were primarily governed by the properties of diluents at low polymer concentration. At 12.5% carbopol 934P concentration, the t1/2 was found in the rank order of tablets containing MCC<DCP<starch<lactose. The effect of polymer predominated as the polymer concentration increased. Similar release profiles were observed at 20% carbopol 934P concentration with t1/2(>9hrs). Drug release rate decreased with polymer concentration. Granulation technique had appreciable effect on drug release profile which was in the rank order of direct compression < dry granulation < wet granulation(alcohol) < wet granulation (water).There was a considerable outcome of granules preparation, polymer concentration in the rate of drug (ibuprofen) release from carbopol 934P matrix based tablets (ANOVA, p<0.05). Diluents have appreciable effect on drug release rate only at low polymer concentration.
Sreenivasa Rao et al. (2004) developed a simple technique for the preparation of controlled release polymeric systems of rifampicin by using eudragit RL100. At room temperature the drug and polymer powder were mixed and compressed. The compressed matrix tablets were placed in acetone chamber for 1.5, 3 and 4.5hr for sintering. The sintered tablets were tested for physical parameter limits and invitro dissolution studies. The drug release from eudragit RL 100 was markedly affected by the sintering time. It was important that the rate of release of rifampicin from eudragit RL100 matrices was inversely linked to the sintering time. The drug showed first-order release kinetics from the polymeric matrices along with diffusive mechanism.
Basak et al. (2004) developed propanolol HCl matrix tablets with HPMC polymer to control the release of drug with an idea to develop two times daily sustained release dosage form. The resulting matrix tablets prepared with HPMC K4M satisfied all the official necessities of tablet dosage forms. The in-vitro drug release was measured in aqueous solutions for a total period of 12hrs using 1.2 PH buffer for 1st hr and PH 7.5 buffer for the rest of period. The drug release was within the limits of predetermined set vis-à-vis USP requirements. The results provide a method of achieving sustained drug action through uniform drug release.
Rao et al. (2003) developed a new method of preparation of sintered matrix tablets of rifampicin with ethylene-vinyl acetate copolymer is developed for controlling its release rate. At room temperature known quantities of polymer powder (ethylene-vinyl acetate copolymer) and drug were taken and mixed thoroughly, and then compressed. The compressed tablet matrices were set aside at 60, 70 and 80 for 1.5, 3 and 4.5hr for sintering and the sintered tablets were characterized for their physical characteristics and in-vitro dissolution studies were performed. The drug release from the matrices was greatly influenced by the sintering time and is inversely related to the sintering time because of its firmness of sintering. The drug release from the polymeric matrices showed a diffusive mechanism and first order release kinetics.
Babu et al. (2002) prepared a novel matrix system of flurbiprofen as an oral controlled release formulation using gum karaya as release retardant. Lactose or dicalcium phosphate was incorporated to improve the drug release rate. Gum karaya matrices containing lactose showed satisfactory release characteristics. Flurbiprofen-gum karaya matrices showed first order release kinetics following super case II transport, where as matrices with both the co-excipient followed first order kinetics with anomalous diffusion release. The selected experimental formulation showed comparable in-vitro dissolution profile and in-vivo blood level pattern with those of the commercial sustained release formulation. The data support a level a correlation between in-vitro release rate profile and in-vivo absorption for flurbiprofen from both the formulations.