Eudragit RSPO Research Articles

Formulation optimization of solid dispersion of mosapride hydrochloride

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

Formulation and optimization of rifampicin microparticles by Box-Behnken statistical design

The objective of the present study was to optimize and evaluate in vitro gastroretentive performance of rifampicin microparticles. Formulations were optimized using design of experiments by employing a 4-factor, 3-level Box-Behnken statistical design. Independent variables studied were the ratio of polymers (Eudragit RSPO: ethyl cellulose), inert drug dispersing agent (talc), surfactant (sodium dodecyl sulfate) and stirring speed. The dependent variables were particle size and entrapment efficiency. Response surface plots were drawn, statistical validity of the polynomials was validated and the optimized formulation was characterized by Fourier Transform-InfraRed spectroscopy (FT-IR) and differential scanning calorimetry (DSC). Entrapment efficiency and particle size were determined. The designed microparticles have average particle size from 14.10 μm to 45.63 μm and entrapment efficiency from 38.14% to 94.81%. Optimized microparticles showed particle size and drug entrapment, 51.53 μm and 83.43%, respectively with sustained drug release behavior up to 12 h. In the present study, rifampicin microspheres were successfully prepared by a quasi-emulsion solvent diffusion technique for prolonged drug release. FT-IR and DSC studies did not reveal any significant drug interactions. The drug release was found to be controlled for more than 12 h by following zero order release pattern.

Design and Evaluation of Sustained Release Solid Dispersions of Verapamil Hydrochloride

The Purpose of this study was to prepare and characterize solid dispersions of this antiarrhythmic drug Verapamil hydrochloride (VPH) with HPMCK4M, EudragitRSPO and their combination with a view to sustain its dissolution properties. Investigation of the properties of the prepared solid dispersions were performed using release studies and Fourier transform infrared (FT-IR). The results obtained showed that the rate of dissolution of Verapamil hydrochloride was considerably more sustained when formulated in solid dispersions with HPMCK4M and Eudragit RSPO as compared with pure drug and physical mixtures. FT-IR studies confirmed absence of any possible solid state drug and polymer interactions. In order to establish the mechanism and kinetics of drug release, the experimental data was fitted to different kinetic models likes zero order, first order, Higuchi’s model, korsmeyer peppa’s model. From the above research it may be concluded that HPMCK4M acts as a better release retardant for the model drug.

Formulation and Evaluation of Sustained Release Matrix Tablets of Metformin Hydrochloride Using pH Dependent and pH Independent Methacrylate Polymers

Metformin hydrochloride is recommended globally as first line therapy due to its favorable profile on morbidity and mortality associated with type-2 diabetes mellitus. However, limitations of multiple dosing and risk of triggering gastrointestinal symptoms make its dose optimization difficult. Extended-release metformin matrix tablets were prepared by direct compression of drug and different pH-dependent (Eudragit L-100 and S-100) and pH-independent (Eudragit RLPO and RSPO) polymer combinations. The influence of varying the polymer/polymer (w/w) ratio was evaluated. Among the different examined polymer blends, matrix tablets based on S-100/RLPO and S-100/RSPO mixtures gave the more sustained release pattern. The excipients used in this study did not alter physicochemical properties of the drug, as tested by Fourier transform Infrared Spectroscopy and the thermal analysis using differential scanning calorimetry. All the batches were evaluated for thickness, weight variation, hardness, and drug content uniformity. The in vitro drug dissolution study was carried out using USP 22 apparatus II, paddle method and the release mechanisms were explored. Mean dissolution time is used to characterize drug release rate from a dosage form and indicates the drug release retarding efficiency of polymer. Kinetic modeling of in vitro dissolution profiles revealed the drug release mechanism ranges from diffusion controlled to anomalous type. Fitting the data to Korsmeyer equation indicated that diffusion along with erosion could be the mechanism of drug release. Research Article

Formulation and evaluation of a sustained-release tablets of metformin hydrochloride using hydrophilic synthetic and hydrophobic natural polymers.

Metformin hydrochloride has relatively short plasma half-life, low absolute bioavailability. The need for the administration two to three times a day when larger doses are required can decrease patient compliance. Sustained release formulation that would maintain plasma level for 8-12 h might be sufficient for daily dosing of metformin. Sustained release products are needed for metformin to prolong its duration of action and to improve patient compliances. The overall objective of this study was to develop an oral sustained release metformin hydrochloride tablet by using hydrophilic Eudragit RSPO alone or its combination with hydrophobic natural polymers Gum copal and gum damar as rate controlling factor. The tablets were prepared by wet granulation method. The in vitro dissolution study was carried out using USP 22 apparatus I, paddle method and the data was analysed using zero order, first order, Higuchi, Korsmeyer and Hixson-Crowell equations. The drug release study revealed that Eudragit RSPO alone was unable to sustain the drug release. Combining Eudragit with gum Copal and gum Damar sustained the drug release for more than 12 h. Kinetic modeling of in vitro dissolution profiles revealed the drug release mechanism ranges from diffusion controlled or Fickian transport to anomalous type or non-Fickian transport. Fitting the in vitro drug release data to Korsmeyer equation indicated that diffusion along with erosion could be the mechanism of drug release.

Development and characterization of gastroretentive mucoadhesive tablets of venlafaxine hydrochloride.

The present study was undertaken with an aim to formulation development and evaluation of gastroretentive mucoadhesive sustained release tablet of Venlafaxine hydrochloride which releases the drug in a sustained manner over a period of 12 hours, by using Carbopol 971P in combination with eudragit RS-PO and ethyl cellulose as a mucoadhesive and release retardant respectively. Preformulation study was done initially and results directed for the further course of formulation. Based on Preformulation studies different batches of Venlafaxine hydrochloride were prepared using Carbopol 971P, Eudragit RS-PO and ethyl cellulose chosen for their different hydrophilic properties to calculate the sustained release properties. Sustained release tablets were prepared by direct compression and were evaluated for bioadhesion time, swelling index and matrix erosion, and in vitro drug release. The tablets of batch F3 and F6 had high swelling behaviors but release of drug is very less. And batch F2 having considerable swelling index and in vitro drug release (99.85%). Batch F2 can be taken as an ideal or optimized formulation of sustained release tablets for 12 hour release as it fulfills all the requirements for sustained release tablet. From the discussion it is concluded that use of carbopol as a release retardant and adhesive polymer is very effective; and also it act as strong release retardant in combination with hydrophobic polymers. Keywords: Gastroretentive; Mucoadhesive; Venlafaxine hydrochloride; Tablet.

Molecular dynamics simulation of drug uptake by polymer

Drug uptake by polymer was modeled using a molecular dynamics (MD) simulation technique. Three drugs--doxorubicin (water soluble), silymarin (sparingly water soluble) and gliclazide (water insoluble)--and six polymers with varied functional groups--alginic acid, sodium alginate, chitosan, Gantrez AN119 (methyl-vinyl-ether-co-malic acid based), Eudragit L100 and Eudragit RSPO (both acrylic acid based)--were selected for the study. The structures were modeled and minimized using molecular mechanics force field (MM+). MD simulation (Gromacs-forcefield, 300 ps, 300 K) of the drug in the vicinity of the polymer molecule in the presence of water molecules was performed, and the interaction energy (IE) between them was calculated. This energy was evaluated with respect to electric-dipole, van der Waals and hydrogen bond forces. A good linear correlation was observed between IE and our own previous data on drug uptake(*) [R² = 0.65, R²adj = 0:65; R²pre = 0:56 and a F ratio of 30.25, P < 0.001; Devarajan et al. (2005) J Biomed Nanotechnol 1:1-9]. Maximum drug uptake by the polymeric nanoparticles (NP) was achieved in water as the solvent environment. Hydrophilic interaction between NP and water was inversely correlated with drug uptake. The MD simulation method provides a reasonable approximation of drug uptake that will be useful in developing polymer-based drug delivery systems.

English

Objective of the present study was to develop hydrophilic polymer and hydrophobic polymer based matrix Losartan potassium sustained release tablet which can release the drug up to time of 24 hrs in predetermined rate. Formulation of Losartan potassium matrix tablet was prepared by the polymer combination in order to get required theoretical release profile. Influence of hydrophilic and hydrophobic polymer on Losartan potassium was studied. Formulated tablet were also characterized by physical and chemical parameters. In vitro release profile was check for 24 hrs to evaluate the SR matrix tablet of Losartan potassium. Losartan potassium (LP) is a potent, highly specific Angiotensin II type 1 (AT1) receptor antagonist with antihypertensive activity. It is readily absorbed from the gastrointestinal tract with oral bioavailability of about 33% and a plasma elimination half-life ranging from 1.5 to 2.5 hr. Administration of LP in a sustained release dosage would be more desirable for anti- hypertensive effects by maintaining the plasma concentrations of the drug well above the therapeutic concentration. From in vitro dissolution profile, Batch B4 was prepared with blend of HPMC K4M (67.2 mg), HPMC K200M(90mg) and Eudragit RSPO(112.5 mg), where drug release was about 94-98%. Batch B4 showed highest similarity factor values (f 2 = 67.76). KEYWORDS: Losartan potassium, HPMC K4M, HPMC K200M, Eudragit RSPO, Sustained release, Matrix tablets.

Development and evaluation of controlled release ibuprofen matrix tablets by direct compression technique

This investigation reports the development and evaluation of controlled release ibuprofen matrix tablets. Matrix tablets weighing 400 mg were fabricated by directly compressing ibuprofen (100 mg) with Eudragit RSPO and Avicel PH 101. The release of ibuprofen was dependant on concentration of Eudragit in the formulation. Varying Eudragit concentration from 10–50% of the formulation (in increments of 5%) revealed that in 4 h, tablets containing 50% Eudragit released about 40% ibuprofen compared to 100% released from tablets containing 10% Eudragit. Following analysis of release mechanism using various models available in literature, release of ibuprofen from matrix tablets was dominated by polymer diffusion-controlled mechanism at least for first 4 h. Thereafter, the release mechanism became more complicated and lost controlled release by diffusion due to change of tablet integrity, such as erosion of polymer matrix. In conclusion, controlled release ibuprofen matrix tablets with desired drug release rate can be fabricated by various formulation variables with direct compression technique.

Citric acid as a solid-state plasticizer for Eudragit RS PO

The use of solid-state plasticizers for the hot-melt extrusion of pharmaceutical dosage forms has been shown to be beneficial compared with liquid plasticizers. The purpose of this study was to determine the suitability of citric acid (CA) as a solid plasticizer for the preparation of Eudragit RS PO extended-release matrix systems by a melt extrusion technique. The influence of increasing levels of CA monohydrate (CA MH) or anhydrous CA in the powder blend on the extrusion process parameters (screw speed and motor load) was determined as a function of temperature. The solubility of CA MH in extruded tablets was studied by means of modulated differential scanning calorimetry (MDSC) and powder X-ray diffraction (PXRD). Films were cast from organic solutions to demonstrate the plasticizing effect of CA MH as a change in physico-mechanical properties (tensile strength, elastic modulus and elongation). The CA release from extruded tablets was studied over 12 h. The monohydrate form was found to distinctly facilitate the extrusion of Eudragit RS PO, whereas the addition of anhydrous CA to the polymer powder was less effective. This divergent behaviour in plasticization of Eudragit RS PO was attributed to the higher solubility of the monohydrate in the acrylic polymer. The plasticizing effect of the CA MH reached a plateau at 25% during hot-melt extrusion, which coincided with the solubility limit of the organic acid in the polymer as shown by MDSC and PXRD results. The CA MH increased the flexibility of Eudragit RS PO films, as demonstrated by a decrease in tensile strength and elastic modulus and an increase in elongation as a function of CA MH concentration. The dissolution of CA from the matrix tablets followed an extended-release profile, with CA MH exhibiting a faster dissolution rate than the anhydrous form. In conclusion, CA MH was found to be an effective plasticizer for Eudragit RS PO that facilitates the production of controlled-release matrix systems by hot-melt extrusion.

Generalized regression neural networks in prediction of drug stability

This study had two aims. Firstly, we wanted to model the effects of the percentage of Eudragit RS PO and compression pressure as the most important process and formulation variables on the time course of drug release from extended-release matrix aspirin tablets. Secondly, we investigated the possibility of predicting drug stability and shelf-life using an artificial neural network (ANN). Ten types of matrix aspirin tablets were prepared as model formulations and were stored in stability chambers at 60 degrees C, 50 degrees C, 40 degrees C and 30 degrees C and controlled humidity. Samples were removed at predefined time points and analysed for acetylsalicylic acid (ASA) and salicylic acid (SA) content using stability-indicating HPLC. The decrease in aspirin content followed apparent zero-order kinetics. The amount of Eudragit RS PO and compression pressure were selected as causal factors. The apparent zero-order rate constants for each temperature were chosen as output variables for the ANN. A set of output parameters and causal factors were used as training data for the generalized regression neural network (GRNN). For two additional test formulations, Arrhenius plots were constructed from the experimentally observed and GRNN-predicted results. The slopes of experimentally observed and predicted Arrhenius plots were tested for significance using Student's t-test. For test formulations, the shelf life (t(95%)) was then calculated from experimentally observed values (t(95%) 82.90 weeks), as well as from GRNN-predicted values (t(95%) 81.88 weeks). These results demonstrate that GRNN networks can be used to predict ASA content and shelf life without stability testing for formulations in which the amount of polymer and tablet hardness are within the investigated range.

Investigation of In vitro Release Kinetics of Carbamazepine from Eudragit® RS PO and RL PO Matrix Tablets

Purpose: The objective of this research work was to prepare and evaluate the effect of Eudragit RS PO and Eudragit RL PO polymers on the physical property and release characteristics of carbamazepine matrix tablets. Methods: Matrix tablets containing carbamazepine were prepared with Eudragit® RS PO alone as the rate-retarding polymer (coded batch series ‘A’) and also with a combination of Eudragit® RS PO and RL PO (coded batch series ‘B’). The tablets were characterized for hardness as well as for carbamazepine release. The release data were subjected to different models in order to evaluate their release kinetics and mechanisms. Results: The hardness of batch series ‘A’ matrix tablet was >160 kg/cm2 while for batch series ‘B’, it was >170 kg/cm2. Carbamazepine tablets containing only Eudragit RS PO showed very slow release (less than 6% in 8 h) but when Eudragit RL PO was blended with Eudragit RS PO, the release rate improved significantly to 44% in 24 h (p Conclusion: Carbamazepine matrix tablets of satisfactory hardness were produced. Furthermore, by blending Eudragit RS PO with Eudragit RL PO in the matrix, tablets of varying release characteristics can be prepared.

Preparation and evaluation of polymeric carbamazepin spherical crystals by emulsion solvent diffusion technique

In this study, a significant effect of different polymers on improving the solubility, dissolution rate, and physicochemical properties of carbamazepine (CBZ) has been demonstareted by emulsion solvent diffusion technique, with ethanol– chloroform–water as the solvent system. The hydrophilic polymers like polyethylene glycol, chitosan, and hydrophobic polymer Eudragit RSPO were used in the recrystallization process. The pure drug CBZ and the prepared spherical crystals of CBZ with different polymers were characterized in terms of morphology (microscopical photograph), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), drug contents, solubility, dissolution rate, crushing strength, wettability, flowability, and packability. The FTIR spectra of the prepared spherical crystals showed that changes in the chemical nature occur and do not present great fingerprint difference. The XRD also revealed a characteristic decrease in crystallinity. The solubility and dissolution studies demonstrated a marked increase in solubility and dissolution rate in comparison with the pure drug. The prepared spherical crystals with different polymers exhibited excellent physicochemical properties like flowability, packability, and wettability compared with the pure drug. The spherical crystals with polyethylene glycol and chitosan showed higher crushing strength when compared with the hydrophobic polymer (Eudragit RSPO).

Effects of process parameters on the properties of biocompatible Ibuprofen-loaded microcapsules

The objective of this study was to obtain an optimum formulation for microencapsulating Ibuprofen. This was achieved by investigating various factors which influenced the microcapsule size. Considering Ibuprofen as a lipophilic model drug, biocompatible Ibuprofen-loaded microcapsules in the size range of 20–60 μm were prepared by the water in oil emulsion-solvent evaporation method. An aqueous surfactant phase was used as the continuous external phase (W), a biocompatible organic solvent dissolving Ibuprofen was used as oil phase (O), in addition with a low boiling solvent. The biocompatible polymeric microcapsule membrane was composed of Eudragit RSPO or Ethylcellulose. The influence of various process parameters, such as the volatile organic solvent, the oily core, the stirring rate, on the characteristics of microcapsules was investigated. The encapsulation yield of Ibuprofen close to 100%, whatever the polymer type, was determined by UV–vis experiments, in accordance with the results obtained by 13C NMR spectroscopy. An innovative technique, DSC-based thermoporosimetry, was used for the estimation of the loading rate of Ibuprofen. The results indicated that this developed analytical method had to be improved since DSC-transitions accounted to free and enclosed Ibuprofen were observed and altered the accuracy of the results.

Ketoprofen-loaded Eudragit RSPO microspheres: An influence of sodium carbonate on in vitro drug release and surface topology

Eudragit RSPO microspheres containing ketoprofen as model drug, prepared by solvent evaporation technique using acetone-liquid paraffin (heavy) solvent system were examined. Depending upon polymer concentration in the internal phase, microspheres of particle mean diameter (122.8, 213.6 and 309.5 μm) were obtained. The influence of surface washing of microspheres with n-hexane, i.e. untreated microspheres (UM) on the drug content, drug release and surface topology of microspheres were compared to those of microspheres washed with sodium carbonate, i.e. treated microspheres (TM) in order to make the non-encapsulated surface drug soluble. The significant reduction in encapsulation efficiency (p < 0.001) and drug content (p < 0.001) after treatment, in combination with the small crystalline peaks observed during XRD testing and lack of melting endotherm observed in DSC testing, suggests that the washing process actually removes a significant amount of drug (p < 0.001) from the surface and encapsulated near to the surface of the microsphere polymer matrix. Scanning electron microscopy (SEM) examination revealed that the removal of surface drug did not affect the size of microspheres but the topology of treated smallest microspheres was modified. The ketoprofen release profiles were examined in phosphate buffer pH 7.4, using USPXXIII paddle type dissolution apparatus. In general both UM and TM result in biphasic release patterns, but the initial burst effect (first release phase) of TM was lower than that of UM. The second release phase did not change for the bigger size but increased for the smallest microspheres, probably owing to the modification of matrix porosity

Designing, Optimisation &amp; Characterization of Sustained Release Matrix Pellets Prepared by Extrusion Spheronization Containing Mixture of Proteolytic Enzymes

A method for developing sustained release multiple unit dosage form consisting of pellets of a proteolytic enzyme blend using extrusion spheronization as a process is demonstrated in this paper. Effect of Cellulose and Methacrylate based polymers and plasticizers on stability of the enzyme blend are determined. The effect of type & concentration of the sustained release polymer, spheronization rpm and plasticizer on the yield & sphericity of pellets is studied. The results indicated that the SR pellets could be formulated for this enzyme blend using both HPMC K15 and EUDRAGIT RSPO. The best rpm for spheronization turned out to be 1200 rpm. Use of plasticizer improved yield and sphericity. Triethyl citrate was better over polyethylene glycol 400 and EUDRAGIT RSPO was better over HPMC K15 with respect to yield and sphericity of pellets. The pellets could be suitably enteric coated for protection of enzyme blend in lower pH of GIT. The in vitro release profile indicated release extension could be extended up to 12 hours in intestinal condition postulating to an acceptable bioavailablity in vivo.

Thermal treating as a tool to produce plastic pellets based on Eudragit RS PO and RL PO aimed for tableting

A 3 2 full-factorial design was used for preparation of pellets using extrusion–spheronization technique. Independent variables were %ibuprofen (40, 60, 80) and %Eudragit RS PO/RL PO (0, 50, 100). In all formulations 3% w/w PVP K30 and 10% Avicel PH101 were also used. The pellets were cured in oven at 60 °C for 24 h. The evaluated responses were crushing strength or yield point, elastic modulus and mean dissolution time (MDT) of pellets. The cured pellets were also compressed at 15 kN compaction force and then observed under scanning electron microscope. It was shown that the cured pellets containing 40% or 60% drug exhibited a plastic deformation without any fracture under mechanical tests. The curing process resulted in significant decrease in the elastic modulus of the pellets. The SEM of the compressed pellets were also confirmed the plastic behavior of these pellets. The transition of pellet behavior from brittle to plastic upon curing was due to shift of Eudragit structure from glassy to rubbery state which was supported by DSC studies. However pellets with 80% drug showed brittle properties even after curing due to presence of less amount of Eudragit in their structure. Increasing the ratio of Eudragit RS in the pellets decreased the yield point and elastic modulus of cured pellets containing 40% or 60% drug, indicating more plastic behavior of these pellets. This was attributed to lower Tg of Eudragit RS than Eudragit RL. The curing process also retarded drug release from pellets and increased MDT. Increasing the ratio of Eudragit RS in the pellets increased MDT in cured pellets containing 40% or 60% drug but had no effect in pellets with 80% drug. Overall the results of this study revealed that thermal treating is a proper tool to produce plastic ibuprofen pellets based on Eudragit RS PO and Eudragit RL PO.

Preparation and In Vitro/In Vivo Evaluation of Gliclazide Loaded Eudragit Nanoparticles as a Sustained Release Carriers

ABSTRACTThe aim of this study was to formulate and optimize gliclazide-loaded Eudragit nanoparticles (Eudragit L100 and Eudragit RS) as a sustained release carrier with enhanced efficacy. Eudragit L 100 nanoparticles (ELNP) were prepared by controlled precipitation method whereas Eudragit RSPO nanoparticles (ERSNP) were prepared by solvent evaporation method. The influence of various formulation factors (stirring speed, drug:polymer ratio, homogenization, and addition of surfactants) on particle size, drug loading, and encapsulation efficiency were investigated. The developed Eudragit nanoparticles (L100 and RS) showed high drug loading and encapsulation efficiencies with nanosize. Mean particle size altered by changing the drug:polymer ratio and stirring speed. Addition of surfactants showed a promise to increase drug loading, encapsulation efficiency, and decreased particle size of ELNP as well as ERSNP. Dissolution study revealed sustained release of gliclazide from Eudragit L100 as well as Eudragit RSPO NP. SEM study revealed spherical morphology of the developed Eudragit (L100 and RS) NP. FT-IR and DSC studies showed no interaction of gliclazide with polymers. Stability studies revealed that the gliclazide-loaded nanoparticles were stable at the end of 6 months. Developed Eudragit NPs revealed a decreased tmin (ELNP), and enhanced bioavailability and sustained activity (ELNP and ERSNP) and hence superior activity as compared to plain gliclazide in streptozotocin induced diabetic rat model and glucose-loaded diabetic rat model. The developed Eudragit (L100 and RSPO) NP could reduce dose frequency, decrease side effects, and improve patient compliance.

Design and evaluation of sustained release bilayer tablets of propranolol hydrochloride

The objective of the present research was to develop a bilayer tablet of propranolol hydrochloride using superdisintegrant sodium starch glycolate for the fast release layer and water immiscible polymers such as ethylcellulose, Eudragit RLPO and Eudragit RSPO for the sustaining layer. In vitro dissolution studies were carried out in a USP 24 apparatus I. The formulations gave an initial burst effect to provide the loading dose of the drug followed by sustained release for 12 h from the sustaining layer of matrix embedded tablets. In vitro dissolution kinetics followed the Higuchi model via a non-Fickian diffusion controlled release mechanism after the initial burst release. FT-IR studies revealed that there was no interaction between the drug and polymers used in the study. Statistical analysis (ANOVA) showed no significant difference in the cumulative amount of drug release after 15 min, but significant difference (p < 0.05) in the amount of drug released after 12 h from optimized formulations was observed.

Formulation and in vitro, in vivo evaluation of extended- release matrix tablet of zidovudine: influence of combination of hydrophilic and hydrophobic matrix formers.

The aim of the present study was to prepare and characterize extended-release matrix tablets of zidovudine using hydrophilic Eudragit RLPO and RSPO alone or their combination with hydrophobic ethyl cellulose. Release kinetics was evaluated by using United States Pharmacopeia (USP)-22 type I dissolution apparatus. Scanning electron microscopy was used to visualize the effect of dissolution medium on matrix tablet surface. Furthermore, the in vitro and in vivo newly formulated sustained-release zidovudine tablets were compared with conventional marketed tablet (Zidovir, Cipla Ltd, Mumbai, India). The in-vitro drug release study revealed that either Eudragit preparation was able to sustain the drug release only for 6 hours (94.3% +/- 4.5% release). Combining Eudragit with ethyl cellulose sustained the drug release for 12 hours (88.1% +/- 4.1% release). Fitting the in vitro drug release data to Korsmeyer equation indicated that diffusion along with erosion could be the mechanism of drug release. In vivo investigation in rabbits showed sustained-release pharmacokinetic profile of zidovudine from the matrix tablets formulated using combination of Eudragits and ethylcellulose. In conclusion, the results suggest that the developed sustained-release tablets of zidovudine could perform therapeutically better than conventional dosage forms, leading to improve efficacy and better patient compliance.