Grades Of Hydroxypropyl Methylcellulose Research Articles

Preparation and Evaluation of Rebamipide Film using Casting Technique for Local Action

Abstract
 The aim of this study was to prepare rebamipide ocular inserts in order to extend its release on the ocular surface for dry eye treatment. Solubility study was applied to the drug with or without l-arginine using different solvents. Solvent casting technique was used to prepare the inserts; l-arginine was used to solubilize the drug, hydroxypropyl methylcellulose grades (E5 and K15M) and poly ethylene glycol 200 were used as excipients. The inserts were evaluated for their physical and mechanical properties, moisture loss% and absorption %, surface pH, and in-vitro drug release. The use l-arginine exhibited an enhancement of rebamipide solubility in both deionized water and phosphate buffer (pH 7.4) by approximately 250 times and 3 times, respectively. The formulations showed uniform weight and thickness except for F1, and all showed uniform drug content. The absence of plasticizer in F1 caused haziness in its appearance and brittleness of the inserts. F3 which contain hydroxypropyl methylcellulose K15M showed good physical and mechanical properties thus was selected for in vitro release and was compared to the marketed brand Mucosta® suspension eye drop; F3 showed significant enhancement in extending the release of rebamipide compared to the reference marketed brand.
 Keywords: Rebamipide, L-arginine, Ocular insert, Solvent casting technique
 
 
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Micro-scale solubility assessments and prediction models for active pharmaceutical ingredients in polymeric matrices

The number of models for assessing the solubility of active pharmaceutical ingredients (APIs) in polymeric matrices on the one hand and the extent of available associated data on the other hand has been rising steadily in the past few years. However, according to our knowledge an overview on the methods used for prediction and the respective experimental data is missing. Therefore, we compiled experimental data, the techniques used for their determination and the models used for estimating the solubility. Our focus was on polymers commonly used in spray drying and hot-melt extrusion to form amorphous solid dispersions (ASDs), namely polyvinylpyrrolidone grades (PVP), polyvinyl acetate (PVAc), vinylpyrrolidone-vinyl acetate copolymer (copovidone, COP), polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft polymer (Soluplus®, SOL), different types of methacrylate copolymers (PMMA), polyethylene glycol grades (PEG) and hydroxypropyl-methylcellulose grades (HPMC). The literature data were further supplemented by our own results. The final data set included 37 APIs and two sugar derivatives. The majority of the prediction models was constituted by the melting point depression method, dissolution endpoint measurements, indirect solubility determination by Tg and the use of low molecular weight analogues. We observed that the API solubility depended more on the working group which conducted the experiments than on the measuring technique used. Furthermore, this compilation should assist researchers in choosing a prediction method suited for their investigations.Furthermore, a statistical assessment using recursive feature elimination was performed to identify descriptors of molecules, which are connected to the API solubility in polymeric matrices. It is capable of predicting the criterium 20% API soluble at 100 °C (Yes/No) for an unknown compound with a balanced accuracy of 71%. The identified 8 descriptors to be connected to API solubility in polymeric matrices were the number of hydrogen bonding donors, three descriptors related to the hydrophobicity of the molecule, glass transition temperature, fractional negative polar van der Waals surface area, out-of-plane potential energy and the fraction of rotatable bonds. Finally, in addition to our own model, the data set should help researchers in training their own solubility prediction models.

Development and radiographical evaluation of floating tablets with combination of Amoxicillin Trihydrate and Ranitidine Hydrochloride

Stomach Specific Floating Tablets (SSFT) with a combination of Amoxicillin-Trihydrate (AT) and Ranitidine Hydrochloride (RH) were developed by using different grades of Hydroxypropylmethylcellulose (HPMCK) (i.e.HPMCK 100M, HPMCK4M and HPMCK15M), to treat patients with H. pylori-infected duodenal ulcer. Floating tablets were prepared by direct compression method, developed formulations were evaluated for different pre-compression and post-compression parameters like angle of repose, compressibility index, hardness, weight variation, floating lag time, content uniformity, and in-vitro drug release. In-Vitro release of two drugs (Amoxicillin-Trihydrate and Ranitidine hydrochloride) from the developed formulation was estimated by the Simultaneous Estimation method (Vierordt's Method). The optimized formulation was subjected to Radio graphical evaluation by incorporating the BaSO4, a radio-opaque substance by replacing a part of the drug from the optimized formulation of into the formulation and then it was administered to the healthy human volunteers to find out the in-vivo residence time. In-vivo X-ray studies were conducted both in fed condition, as well as fasted condition the optimized formulation showed a gastric residence time of more in fed state than that of fasting state. From these studies it was clearly observed that the floating tablets should be given to patients after a standard food and with frequent intake of water.

DEVELOPMENT AND IN VITRO–IN VIVO EVALUATION OF GASTRORETENTIVE FLOATING TABLETS OF AN ANTIRETROVIRAL AGENT RITONAVIR

Objective: The present research work concerns the development of the extended release of Ritonavir floating matrix tablets, designed to prolong the gastric residence time, increase the drug bioavailability, and diminish the side effects of irritating drugs.
 Methods: The floating tablets of Ritonavir were prepared by direct compression method using different grades of hydroxypropyl methylcellulose (HPMC), crospovidone, Polyox WSR 303, and sodium bicarbonate, as gas generating agent. Evaluation parameters and in vivo radiographic studies were conducted in suitable model.
 Results: Among all formulations, F21 was chosen as optimized formulation based on evaluation parameters such as floating lag time (33 s), total floating time (>24 h), and in vitro dissolution studies. From in vitro dissolution studies, the optimized formulation F21 and marketed product were shown 98.67% and 91.46±5.02% of drug release, respectively. The main appliance of medication discharge follows zero-order kinetics and non- Fickian transport by coupled diffusion and erosion. In vivo experiments maintained the potentials in extending the gastric residence time in the fasted state in beagle dogs. The mean gastric residence time of the optimized formulation found to be 330 min±40 in the stomach, where longer gastric residence time is an important condition for prolonged or controlled drug release and also for enhanced bioavailability.
 Conclusion: From in vitro and in vivo radiographic studies, Ritonavir floating tablets estimated to provide novel choice for harmless, inexpensive, and extended release for the effective management of AIDS.

NOVEL APPROACH OF EXTRACTION AND CHARACTERIZATION OF OKRA GUM AS A BINDER FOR TABLET FORMULATION

Objective: The major objective of the present investigation was to extract a natural polymer (okra gum) with its characterization as pharmaceutical binder and to formulate, develop, and evaluate the compression-coated tablet using okra as binder along with synthetic hydrophilic polymers like various grades of hydroxypropyl methylcellulose (HPMC).Methods: A novel extraction method was carried out using fresh unripe pods of okra (ladies finger) with the aid of organic solvents and its characterization was done. The core tablets were prepared by direct compression method which was compression coated with okra gum and HPMC.Results: After the extraction of the okra gum was carried out, the yield of mucilage obtained was 10%. It is considered as a proof for the purity of the mucilage extract. The above study reveals that the polymers were subjected to the Fourier transform infrared and differential scanning calorimetry thermogram had no significant interactions between the drug and the polymers. The characterization of the new polymer okra showed that it has swelling properties, and in spite of being a hydrophilic polymer, it can be successfully used in pharmaceutical formulation as a good binder.Conclusion: In the present aspect of the study was to evaluate the efficacy of okra gum that has been used as a tablet binder. It is easily available and inexpensive. Okra gum as a binder produces tablet formulations with good physicochemical properties and good candidate for sustained release formulations.

NOVEL APPROACH OF EXTRACTION AND CHARACTERIZATION OF OKRA GUM AS A BINDER FOR TABLET FORMULATION

Objective: The major objective of the present investigation was to extract a natural polymer (okra gum) with its characterization as pharmaceutical binder and to formulate, develop, and evaluate the compression-coated tablet using okra as binder along with synthetic hydrophilic polymers like various grades of hydroxypropyl methylcellulose (HPMC).Methods: A novel extraction method was carried out using fresh unripe pods of okra (ladies finger) with the aid of organic solvents and its characterization was done. The core tablets were prepared by direct compression method which was compression coated with okra gum and HPMC.Results: After the extraction of the okra gum was carried out, the yield of mucilage obtained was 10%. It is considered as a proof for the purity of the mucilage extract. The above study reveals that the polymers were subjected to the Fourier transform infrared and differential scanning calorimetry thermogram had no significant interactions between the drug and the polymers. The characterization of the new polymer okra showed that it has swelling properties, and in spite of being a hydrophilic polymer, it can be successfully used in pharmaceutical formulation as a good binder.Conclusion: In the present aspect of the study was to evaluate the efficacy of okra gum that has been used as a tablet binder. It is easily available and inexpensive. Okra gum as a binder produces tablet formulations with good physicochemical properties and good candidate for sustained release formulations.

FORMULATION AND IN VITRO EVALUATION OF AMLODIPINE GASTRORETENTIVE FLOATING TABLETS USING A COMBINATION OF HYDROPHILIC AND HYDROPHOBIC POLYMERS

Objective: The aim of this study was to formulate a developed floating tablet of amlodipine using different concentrations and types of hydrophilic and hydrophobic polymers to be conserved in the stomach for modulating solubility and bioavailability, diminishes drug waste and decline side effects.Methods: Through this study, eleven innovative formulations of amlodipine floating tablets were prepared [mixture of amlodipine, sodium bicarbonate (NaHCO3), hydroxypropyl methylcellulose (HPMC) E50, HPMC K100M, ethylcellulose (EC) 5 mp. a. s.] by direct compression method. The pre-compressed mixtures were then evaluated for numerous parameters such as angle of repose, bulk density, tapped density, Carr's compressibility index and Hausner's ratio. After compression, tablets were subjected to several tests like; floating behavior of tablets, tablet thickness, hardness test, friability test, weight variation, in vitro dissolution test. In addition, the optimum formulation was evaluated for Fourier transform-infrared (FT-IR) and differential scanning calorimetry (DSC) tests. Results: From in vitro dissolution tests and kinetic assessments; F8 was selected as an optimum formula, depending on the R2 value of zero order kinetics (0.9915) and (n) value of Korsmeyer-Peppas (0.9635) which indicate purely relaxation zero order kinetic with good delaying in drug release that was reached to 14 h.Conclusion: It can be concluded that the developed formulation of a certain combination of low viscosity grades of HPMC and EC was considered an efficient floating tablet.

Formulation and Evaluation of Nelfinavir Extended Release Trilayer Matrix Tablets by Design of Experiment

The present study was aimed to develop once-daily controlled release trilayer matrix tablets of nelfinavir to achieve zero-order drug release for sustained plasma concentration. Nelfinavir trilayer matrix tablets were prepared by direct compression method and consisted of middle active layer with different grades of hydroxypropyl methylcellulose (HPMC), PVP (Polyvinyl Pyrrolidine) K-30 and MCC (Micro Crystalline Cellulose). Barrier layers were prepared with Polyox WSR-303, Xanthan gum, microcrystalline cellulose and magnesium stearate. Based on the evaluation parameters, drug dissolution profile and release drug kinetics DF8 were found to be optimized formulation. The developed drug delivery system provided prolonged drug release rates over a period of 24 h. The release profile of the optimized formulation (DF8) was described by the zero-order and best fitted to Higuchi model. FT-IR studies confirmed that there were no chemical interactions between drug and excipients used in the formulation. These results indicate that the approach used could lead to a successful development of a controlled release formulation of nelfinavir in the management of AIDS.

DESIGN AND IN VIVO EVALUATION OF CONTROLLED RELEASE GLICLAZIDE TRILAYER MATRIX TABLETS IN THE MANAGEMENT OF DIABETES MELLITUS

The purpose of the present study was to develop and optimize multi-layered matrix tablets of Gliclazide trilayer tablets to achieve zero-order drug release for sustained plasma concentration. Gliclazide tablets were prepared by direct compression and consist of middle active layer with different grades of hydroxypropyl methylcellulose (HPMC K 4M, K 15M and K100M), Guar gum and Eudragit L 100. The tablets were also evaluated for physicochemical characteristics and release kinetics. The physicochemical characteristics of the prepared tablets were satisfactory. The developed drug delivery systems showed prolonged drug release rates over a period of 24 h. In vivo bioavailability studies were carried out on the optimized formulation (EF14), mean time to attain peak drug concentration (Tmax) was 6.00 ± 0.14 and 4.02 ± 0.12 h for the optimized and marketed product respectively, while mean maximum drug concentration (Cmax) was 124.80 ± 1.02 ng/ml and 95.12 ± 1.05 ng/ml respectively. AUC0-α and AUC0-t for optimized formulation was significantly higher (p<0.05) as compared to marketed product. A fair correlation between the dissolution profile and bioavailability for the optimized formulation was observed. The results indicate that the approach used could lead to a successful development of a controlled release formulation of the drug. The EF14 was shown significant plasma concentration with controlled release and maintained for 24 hours with patient compliance by reducing the dosage frequency, when compared with marketed product in the efficient management of Diabetes mellitus.

GASTRO-FLOATING TABLETS OF REPAGLINIDE: PREPARATION AND IN VIVO EVALUATION

Objective: Current research concerns the expansion of repaglinide matrix floating tablets, which are designed to prolong the gastric residence time, increase the drug bioavailability, and diminish the side effects.Methods: Different formulations of repaglinide floating tablets were prepared with different grades of hydroxypropyl methylcellulose (HPMC) and other agents. Evaluation parameters and in vivo bioavailability studies were conducted in the suitable model.Results: Among all the formulations, F21 containing HPMC K1500 PH PRM, Polyox WSR 303, and sodium bicarbonate, as gas generating agent was selected as optimized formulation based on physicochemical properties, floating lag time (36 s), and total floating time (>24 h). From in vitro dissolution studies, the optimized formulation F21 showed drug release of 98.92±5.19% within 24 h whereas 95.09±5.01% of the drug was released from the marketed product within 1 h.Conclusion: From in vitro and in vivo bioavailability studies repaglinide floating tablets expected to give a new choice for safe, economical, and increased bioavailability for effective management of diabetes mellitus.

DEVELOPMENT AND IN VIVO EVALUATION OF NELFINAVIR EXTENDED RELEASE TRILAYER MATRIX TABLETS IN THE MANAGEMENT OF AIDS

The purpose of this investigation was to design and develop trilayer matrix tablets of Nelfinavir prepared by direct compression method and consisted of middle active layer with different grades of hydroxypropyl methylcellulose (HPMC), PVK K 30 and MCC. Barrier layers are prepared with Polyox WSR 303, Xanthan gum, microcrystalline cellulose and magnesium stearate. Based on the evaluation parameters, drug dissolution profile and release drug kinetics DF8 was found to be optimized formulation. The developed drug delivery system provided prolonged drug release rates over a period of 24 h. The release profile of the optimized formulation (DF8) was described by the Zero-order and best fitted to Higuchi model. From in vivo bioavailability studies the extended release of Nelfinavir from trilayer matrix tablets also provides for higher plasma drug content and improved bioavailability. The results indicate that the approach used could lead to a successful development of low biological half life Nelfinavir with controlled drug release in the effective management of AIDS.

FORMULATION AND IN VITRO EVALUATION OF BILAYER TABLET OF ATENOLOL FOR BIPHASIC DRUG RELEASE

Objective: In the present research work, the aim was to prepare the bilayer tablet of atenolol for biphasic drug release to improve its bioavailability and absorption in the lower gastrointestinal tract. Methods: In the formulation of immediate release crospovidone, croscarmellose sodium, and sodium starch glycolate was used as super disintegrate and was directly compressed. For a sustained release portion different grade hydroxypropyl methylcellulose (HPMC) K4M, HPMC K15M, gum tragacanth, gum acacia, guar gum, and ethyl cellulose. Preformulation studies were performed before compression. The compressed bilayer tablets were evaluated for weight variation, dimension, hardness, friability, drug content, disintegration time, and in vitro drug release using USP dissolution apparatus type 2 (paddle). Results: The formulation IR3 showed 95% drug release in 30 min, and regression coefficient value (r2) value was found to be 0.994 suggesting first-order drug release kinetics. The F9 formulation using HPMC K15M and gum acacia (1:1) showed 91.20% drug release at the end of 12 h, and regression coefficient value (r2) was 0.992 suggesting zero-order drug release kinetics. Formulation IR3F9 showed faster drug release for bilayer tablet containing 5%w/w crospovidone in immediate release layer and HPMC and guar gum (1:1) in sustained release. Formulation IR3F9 showed swelling index 206%, floating lag time was found to be 2 min and total floating time up to 12 h. Conclusion: The formulation IR3F9 showed a faster drug release profile among the others in the preparation of the atenolol bilayer tablet. Hence, it was considered as an optimized formulation.

Investigate the effect of solvents on wet granulation of microcrystalline cellulose using hydroxypropyl methylcellulose as a binder and evaluation of rheological and thermal characteristics of granules

Wet granulation is the most commonly used technique in the pharmaceutical industry for delivering oral solid dosage forms. In wet granulation, the binder solvent is one of the critical factors affecting granule properties. In the current study, an attempt was made to investigate the effect of solvents (aqueous and hydro-alcoholic) on thermal and flow properties of Microcrystalline Cellulose (MCC) granules prepared using two different grades of Hydroxypropyl Methylcellulose (HPMC), which served as an effective binder. The granulation endpoint was evaluated using thermal effusivity sensor. Rheometer and Modulated Differential Scanning Calorimetry (mDSC) was used to study the flow and thermal properties of wet and dried granules. Furthermore, physical characterization was carried out by granule strength, particle size distribution and tablet hardness for all granules under the study. Thermal effusivity sensor results indicate 55% w/w concentration of binder solution as the endpoint by measuring thermal effusivity for both binders. Additionally, powder rheometer results show that the wet granules of hydro-alcoholic batches show greater resistance to flow whereas the dried granules display excellent flow characteristics as evident from Basic flowability energy values and specific energy values. Permeability results suggest that the granules formed with hydro-alcoholic binder solvent exhibit better porosity and permeability. Tablet hardness data showed that tablets formulated using hydro-alcoholic solvent granules have greater hardness than tablets formulated using water based solvent granules. The granule strength for water based granules is relatively higher than that of hydro-alcoholic based granules. mDSC thermograms show a sharp rise in enthalpy value at 55% w/w binder solution which is indicative of a more significant amount of solvent being present on the surface of granules and formation of optimal granules. To summarize, we have determined a technique to measure endpoint determination and simultaneously investigate the role of solvent systems on the rheology of MCC granules, which could assist in selecting an appropriate solvent system for granulation.

Physicochemical characterisation and in vitro evaluation of modified release matrix tablets: The role of different grades of hydroxypropylmethyl cellulose

The purpose of this work was to formulate prolonged release matrix tablets with water soluble opioid drug (API) using different types of hydroxypropylmethyl cellulose (Methocel) as controlled release polymers. Methocel K100M was incorporated as intra-granular polymer (sample 1) along with Methocel K4M (sample 2) or Methocel K15M (sample 3) as extra-granular polymers. The final blends and tablets prepared by wet granulation process were fully characterized. Results showed that the polymer used extra-granularly significantly affects the tablet properties. By incorporation of Methocel extra granularly (samples 2 and 3), the hardness and tensile strength of the tablets increased and the total tablet porosity decreased. Sample 1, containing only Methocel K100M (intra granularly) has the lowest index of swelling and the fastest release of API probably due to the cross-linking of the polymer chains during the process of wet granulation. Also, the type of Methocel used extra-granularly (with different viscosity grade) was found to significantly affect the swelling ratio of the designed matrix systems and the drug release behavior. Sample 2 containing Methocel K4M extra-granularly has a lower index of swelling and faster release of API compared to sample 3. Considering the release mechanism, release data showed best fitting to the heuristic model proposed by Korsmeyer-Peppas. Two additional approaches were used for mathematical modeling of the release data in order to make them directly applicable for our experimental results. Keywords: matrix tablet, water soluble opioid drug, prolonged release, HPMC (Methocel)

The effect of pH, buffer capacity and ionic strength on quetiapine fumarate release from matrix tablets prepared using two different polymeric blends

The objective of this study was to investigate the effect of the different physiological parameters of the gastrointestinal (GI) fluid (pH, buffer capacity, and ionic strength) on the in vitro release of the weakly basic BCS class II drug quetiapine fumarate (QF) from two once-a-day matrix tablet formulations (F1 and F2) developed as potential generic equivalents to Seroquel® XR. F1 tablets were prepared using blends of high and low viscosity grades of hydroxypropyl methylcellulose (HPMC K4M and K100LV, respectively), while F2 tablets were prepared from HPMC K4M and PEGylated glyceryl behenate (Compritol® HD5 ATO). The two formulations attained release profiles of QF over 24 h similar to that of Seroquel® XR using the dissolution medium published by the Food and Drug Administration (FDA). A series of solubility and in vitro dissolution studies was then carried out using media that simulate the gastric and intestinal fluids and cover the physiological pH, buffer capacity and ionic strength range of the GIT. Solubility studies revealed that QF exhibits a typical weak base pH-dependent solubility profile and that the solubility of QF increases with increasing the buffer capacity and ionic strength of the media. The release profiles of QF from F1, F2 and Seroquel® XR tablets were found to be influenced by the pH, buffer capacity and ionic strength of the dissolution media to varying degrees. Results highlight the importance of studying the physiological variables along the GIT in designing controlled release formulations for more predictive in vitro–in vivo correlations.

FORMULATION AND EVALUATION OF SIMVASTATIN GASTRORETENTIVE DRUG DELIVERY SYSTEM

Objective: The aim of this study was to formulate and evaluate gastro retentive drug delivery system (GRRDS) using an effervescent approach for simvastatin.Methods: Floating tablets were prepared using directly compressible polymers hydroxypropyl methylcellulose (HPMC) K100M, HPMC K4M and carboxymethylcellulose sodium (NaCMC). The prepared tablets were subjected to pre-formulation studies like Compressibility index, Hausner ratio and post compression parameters like buoyancy/floating test and In vitro dissolution study.Results: Drug-excipient compatibility studies performed with the help of FTIR instrument indicated that there were no interactions. The DSC thermogram of the formulations revealed that crystalline form of simvastatin existed in the formulation which was confirmed by X-ray powder diffraction. Dissolution studies indicated that there was a decrease in the drug release with an increase in the polymer viscosity. The tablets prepared with low-viscosity grade HPMC K4M exhibited short Buoyancy Lag Time and floated for a longer duration as compared with formulations containing high viscosity grade HPMC K100M. The ‘n’ value for dissolution studies for all the formulations was found to be in the range of 0.647 to 0.975 indicating non-Fickian or anomalous drug transport. Conclusion: The drug release rate and floating duration of tablets depended on the nature of the polymer and other added excipients. The release rate of the drug can be optimized by using different ratios of polymers and other excipients. The formulation F8 achieved the optimized batch and complied with all the properties of the tablets.

Release Kinetics Study of Azithromycin from Bi-layered Tablets

The objective of this study was to analysis in vitro release kinetics of Azithromycin from bi-layer tablets prepared by direct compression using high viscosity to low viscosity grades of hydroxypropyl methyl cellulose (HPMC K15M, HPMC K4M, HPMC 50 cps), Carbopol 934p and Carbopol 974p. In addition, it also includes evaluating the effect of formulation variables like polymer proportion and polymer viscosity on the release of Azithromycin. In vitro release studies were performed using USP Type-II (Rotating paddle method) at 100 rpm. The dissolution medium consisted of 0.1N HCl (900 ml) for the first 2 hr and the phosphate buffer (pH 6.0) from 3rd to 10th hour. From twenty five different formulations (F-1 to F-25) based on polymer variation, model-dependent and independent methods were used for data analysis and the best results were observed for HPMC 50cps in Korsmeyer- Peppas (R2=0.995 on F-23) kinetic model. The release mechanism of all formulations was Fickian.Bangladesh Pharmaceutical Journal 20(1): 54-63, 2017

Formulation And In Vitro/In Vivo Evaluation Of Olmesartan Medoxomil Solid Dispersions Incorporated E/R Trilayer Matrix Tablets By Geomatrix

<p>An attempt has been made to develop and optimize an novel anti hypertensive trilayered controlled release matrix tablets incorporated with Olmesartan medoxomil solid dispersion prepared by direct compression and consisted of middle active layer with different grades of hydroxypropylmethylcellulose (HPMC), guar gum, ethyl cellulose. Upper and lower layers are prepared with Carnauba wax, guar gum and sodium CMC. The developed drug delivery system provided prolonged drug release rates over a period of 24 h. The release profile of the optimized formulation (HF14) was described by the Zero-order and Higuchi model. In-vivo bioavailability studies were carried out with the optimized formulation (HF14) and reference standard A fair correlation between the dissolution profile and bioavailability for the optimized formulation was observed. The results indicate that the approach used could lead to a successful development of a trilayer extended release formulation up to 24h. These results also demonstrated that the Olmesartan solid dispersion incorporated trilayer tablets shown more bioavailability because of its conversion from crystalline to amorphous form.</p>

VARIOUS FORMULATION VARIABLES EFFECTING FLOATATION BEHAVIOUR OF SINGLE UNIT GASTRORETENTIVE CAPSULES OF OFLOXACIN

<p><strong>Objective: </strong>Objective of the present study was to prepare simple single unit gastro-retentive capsules of ofloxacin with the aim to have the gastric retention of the system for longer periods of time (12h) and to study the effect of various polymers on floating behaviour of such single unit gastro-retentive capsules of ofloxacin.</p><p><strong>Methods: </strong>The method used for the preparation of gastro-retentive capsules was a simple physical blending of various low-density hydrophilic polymers alone and in combination with hydrophobic polymers and filling into capsules. These capsules were then subjected to <em>in vitro</em> floatation and matrix integrity study in 0.1N HCl using static volume beaker method and the United States pharmacopoeia (USP) type II dissolution apparatus method at 100rpm.</p><p><strong>Results: </strong>Two grades of hydroxypropyl methylcellulose (HPMC) K4M and K15M used were found suitable for the purpose. Results showed that increase in HPMC level increased colloidal gel barrier strength along with matrix integrity with consequently improved buoyancy. Lactose which was added as release rate modifier decreased matrix integrity and buoyancy. Eudragit a hydrophobic polymer was added so as to have intact, the buoyant formulation for 12 h with desired drug release characteristics. The addition of eudragit enhanced matrix integrity and floatation time to certain levels but higher levels showed negative results. Floatation time of more than 16 h was observed in the formulations containing 2:1 ratio of HPMC K15M and eudragit respectively. 3<sup>2</sup> factorial design was used to study the effect of various formulation variables on buoyancy and matrix integrity. Formulations containing zero level of HPMC were found buoyant for more than 12 h with all levels of eudragit S100 (i.e.,-1, 0,+1 level). It was also observed that matrix integrity consequently buoyancy increased with increase in eudragit with all levels of HPMC.</p><p><strong>Conclusion: </strong>The study concludes that eudragit S100 a hydrophobic polymer increased floatation time of the formulated capsules with all the three levels of HPMC K15M, but at the same time eudragit level should not exceed HPMC, while lactose a release rate enhancer decreased matrix integrity/floatation time of the formulated capsules.</p>

In Vitro - In Vivo Evaluation Of E/R Trilayer Matrix Tablets Containing Solid Dispersion Of Atorvastatin

<p>Investigation of <em>in vitro/in vivo</em> behaviour of extended release tablets containing solid dispersions of Atorvastatin is the focus of the present research work. Atorvastatin trilayer matrix tablets were prepared by direct compression method and consisted of middle active layer with different grades of hydroxypropylmethylcellulose (HPMC), ethyl cellulose and Carbopol 934P. Barrier layers are prepared with hydrophobic polymers carnauba wax and xanthan gum. Based on the evaluation parameters, drug dissolution profile and release order kinetics HF16 was found to be optimized formulation. The developed drug delivery system provided prolonged drug release rates over a period of 24 h. The release profile of the optimized formulation (HF16) was described by the Zero-order and best fitted to Higuchi model. FTIR confirmed that there was no chemical interaction between drug and excipients used in the formulation. . In vivo bioavailability studies were conducted for optimized formulation HF16 and reference standard. The optimized formulation of Atorvastatin trilayer matrix tablet was shown significant plasma concentration with extended release and maintained for 24 hrs with patient compliance by reducing the dosage frequency, when compared with reference standard. </p>