Formulation and Evaluation of Sustained Release Extrudes Prepared via Novel Hot Melt Extrusion Technique

The purpose of the present investigation is to emphasize the application of hot-melt extrusion technique (HMET) for the preparation of sustained release matrix formulation of highly dosed, freely soluble drugs. In this study, sustained release multiple unit dosage of venlafaxine hydrochloride (VH) was prepared by HMET. Custom design was used to screen the effect of four factors-type of polymer (ethylcellulose and eudragit RSPO) (X ₁), amount of polymer (X ₂), type of plasticizer (DBS, ATBC, TEC, and PEG) (X ₃), and plasticizer concentration (X ₄), on the drug release at 8 h (Y1) and machine torque (Y2). The experiments were carried out according to a four-factor 16-run statistical model and subjected to 12-h dissolution study in purified water. The significance of the model was indicated by ANOVA. Results of in vitro release study indicate that formulations prepared with higher amount of ethylcellulose and DBC show significant retardation at 8 h. The result shows that increase in concentration of polymer with the combination of water insoluble plasticizer (DBS and ATBC) has better sustained release while increasing concentration of TEC and PEG results faster in vitro release. Besides that increase in plasticizer concentration helps in reducing the melt temperature and machine torque. The in vivo study was performed, and formulations were compared using area under the plasma concentration-time curve (AUC_0-∞), time to reach peak plasma concentration (T_max), and peak plasma concentration (C_max). The drug release profiles of extrudes were found to fit both diffusion and surface erosion models. Further to this, scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction analysis of the hot-melt extrudates demonstrated that VH remained crystalline and was homogeneously dispersed throughout the polymer matrix.     

Reduced Myocardial Flow Reserve Is Associated With Diastolic Dysfunction and Decreased Left Atrial Strain in Patients With Normal Ejection Fraction and Epicardial Perfusion

Introduction

Coronary microvascular dysfunction (MVD) may contribute to the pathogenesis of heart failure with preserved ejection fraction (HFpEF). Using myocardial flow reserve (MFR) measured by positron emission tomography (PET) as an assessment of microvascular function, we hypothesized that abnormal MFR is associated with LV diastolic dysfunction (DD) and reduced LV and LA strain in patients with risk factors for HFpEF and normal epicardial perfusion on cardiac PET.

Performance of opus immunoassays for thyroxine and beta-human chorionic gonadotrophin in serum

Two representative immunoassays for measuring thyroxine and β-subunit of human chorionic gonadotrophin in serum, using the Opus immunoassay analyzer, were evaluated by comparing them to the reference RIA for T4 and β-HCG enzyme immunoassay. Both assays were superior in accuracy and precision than the reference methods and exhibited good linearity throughout the concentration range needed for discriminating abnormally low and elevated concentrations from the established reference ranges of thyroxine and β-human chorionic gonadotrophin in serum. Correlation between the results of the Opus immunoassays and the reference assays for T4 and β-HCG was very good with correlation coefficients of 0.92 and 0.98, respectively. © 1996 Wiley-Liss, Inc.     

One-stage repair of cardiac and arch anomalies without circumlatory arrest

Indian Journal of Thoracic and Cardiovascular Surgery -