The grail of the study was to design, develop and characterize sustained release mucoadhesive microspheres of acyclovir and to optimize the drug release profile using response surface methodology by applying Box–Behnken design (BBD) which was equipped with three levels and three factors. Microspheres were prepared from Methocel K15M and Ethocel Standard 45 Premium using the emulsification solvent evaporation technique. The independent factors were the amounts of Methocel K15M (X1), amount of Ethocel Standard 45 Premium (X2), and RPM (X3). The dependent variables were cumulative percentage drug release (CDR) at 8 hour (Y1), bond strength (Y2), and swelling at 4 hour (Y3). To understand the effects of different factor level combinations on the responses, various response surface graphs and contour plots were prepared. Predicted values and experimental values for optimized formulation (X1 = 600 mg, X2 = 500 mg, and X3 = 336.57) was found to be in close agreement. Dhaka Univ. J. Pharm. Sci. 18(1): 1-2, 2019 (June)

The aim of the current study was to formulate Fexofenadine hydrochloride loaded sustained release microspheres using HPMC K100 M CR, a release retardant hydrophilic polymer by solvent evaporation method. The effect of different drug loading on drug content, drug encapsulation efficiency and release of drug was monitored. The studies on in vitro release mechanism were performed using USP paddle method with 900 ml of phosphate buffer (pH 6.8) for 10 h at 100 rpm. The mechanism of the drug release was determined by fitting in vitro release data to various release kinetic models such as the zero order, first order, Higuchi, Hixson Crowell and Korsemeyer–Peppas model and finding R2 values for the release profile corresponding to each model. The results confirm that the release rate of the drug from the microspheres is highly affected by the drug to polymer ratio. The study finds that Higuchi release kinetics, Korsmeyer–Peppas release kinetics and Hixson–Crowell release kinetics were the major release mechanism. The release mechanism was found to be non-Fickian with increase of polymer content. Scanning electron microscopic technique was performed to obtain the morphological changes due to different drug loading. Differential scanning calorimetry and Fourier transform infra-red spectroscopy was performed to determine any interaction of drug with the polymer. A statistically significant variation in release rate was observed for variation in the amount of HPMC K100 M CR. In the present study, a series of sustained release formulations of Fexofenadine hydrochloride were developed with different drug loading so that these formulations could further be evaluated from the in vivo studies. The formulations were found to be stable and reproducible.

The present study deals with the formulation and evaluation of Fexofenadine hydrochloride (HCl) loaded sustained release microspheres by emulsion solvent evaporation method with Eudragit RL 100. The effects of percent drug loading on drug encapsulation efficiency, drug content and drug release rate were assessed. In vitro dissolution study was performed spectrophotometrically according to USP paddle method using phosphate buffer (pH 6.8) for 10 hours. The release rate of Fexofenadine HCl from the microspheres was significantly increased with the increase of drug loading. The drug release patterns were simulated in different kinetic orders such as zero order release kinetics, first order release kinetics, Higuchi release kinetics, Korsmeyer-Peppas release kinetics and Hixson-Crowell release kinetics to assess the release mechanism and Higuchi release kinetics was found to be the predominant release mechanism. Morphological changes due to different drug loading were assessed by scanning electron microscopic (SEM) technique. Differential scanning calorimetry and fourier transform infra-red (FT-IR) spectroscopy was performed to evaluate compatibility of drug with the polymer. A statistically significant variation indrug encapsulation efficiency and release rate was observed for variation in drug loading.

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Metformin HCl microspheres were prepared with the aim of increasing its bioavailability and decreasing gastrointestinal side effects by means of sustained action. Eudragit RSPO and Eudragit RLPO, polymers of different permeability characteristics were used to prepare different microspheres. Emulsification solvent evaporation technique using acetone as the internal phase and liquid paraffin as the external phase was the method of choice. Six formulations were prepared using two polymers. The effect of drug loading and polymeric property on the surface morphology, entrapment efficiency, particle size and release characteristics of the microspheres were examined. FTIR and DSC studies established compatibility of the drug with the polymers. SEM studies clearly revealed the effect of drug loading and polymeric nature on the surface morphology of the microspheres.Entrapment efficiencies were within 77.09-97.11% and particle size of all the batches were in the acceptable range.Release data were treated with different mathematical kinetic models. The drug release profile showed that Eudragit RSPO and Eudragit RLPO have opposite effect on drug release. On the other hand, increase in drug loading results in increased drug release. Kinetic modeling of in vitro dissolution profiles revealed that the drug release mechanism varies from diffusion controlled to anomalous type.