COMPARATIVE IN VITRO DISSOLUTION STUDY ON METFORMIN MARKET PRODUCTS USING DIFFERENT DISSOLUTION APPARATUSES

Objective: This study was proposed to evaluate and compare the in vitro dissolution profiles of six Metformin Hydrochloride (MH) market products. Methods: Different dissolution apparatuses (USP apparatus II, IV and beaker method) were used to evaluate the dissolution profiles (in phosphate buffer, pH 6.8) of two immediate release (IR) generic products of Metformin Hydrochloride (MH): Cidophage® 1000 mg (G1, Egyptian market) and Metformin arrow® 1000 mg (G2, French market) with respect to the reference products named Glucophage® 850 mg (R1, Egyptian market and R2, French market). In addition to a generic controlled-release (CR) product; Cidophage Retard® 850 mg (G3) versus the reference product; Glucophage XR® 1000 mg (R3) (both from Egyptian market). Dissolution efficiency (D. E.) and the similarity factor (f2) were calculated. Weight uniformity, hardness, tablet dimensions and MH content were measured. Results: Results of the three apparatuses showed that MH IR products studied (reference and generics) did not meet the 75% USP 30 specifications for MH dissolved at 30 min. For MH CR products, Glucophage XR® did not fulfill the USP release criteria, while Cidophage Retard® did. USP apparatus IV revealed the highest sensitivity and discriminative capability. Conclusion: Generally, MH IR generics (G1 and G2) might be interchangeable with the innovator product (Glucophage®). However, Cidophage Retard® might not be interchangeable with Glucophage XR®

PREPARATION AND EVALUATION OF METRONIDAZOLE SUSTAINED RELEASE FLOATING TABLETS

Objective: The objective of the present study is the preparation of metronidazole (MZ) floating tablets that are designed to retain in the stomach for a long time for better eradication of Helicobacter Pylori (H. pylori), a main cause of peptic ulcer disease. Methods: Synthetic and natural polymers were studied for their floating potential in the presence of sodium bicarbonate, namely: hydroxypropyl methylcellulose (HPMC), carbopol 974P, sodium alginate{low and medium viscosity (LV & MV) grades}, locust gum and guar gum. Hardness, floating ability, release profiles and kinetics as well as DSC / FT-IR were studied. Results: Results of both DSC and FT-IR spectroscopy revealed that there was no interaction between the drug and any of the proposed polymers. Carbopol 974P based tablets showed an unacceptable floating lag time (2 h) and did not maintain good tablet integrity. All other formulas were able to float after few seconds and showed buoyancy for more than 24 h. Meanwhile, sustained profiles of MZ release were obtained. After 6 h the amount of MZ released were: 75.11 %, 61.26 %, 54.56 %, 54.25 % and 43.42 % from sodium alginate-LV, HPMC-K4M, guar gum, locust gum and sodium alginate-MV based tablets, respectively. Kinetically, among the 5 assessed models, the release pattern of MZ from the tablets fitted best to Zero order and Hixson & Crowell Cube-Root models. Conclusion: These stomach targeted dosage forms could maintain the minimum inhibitory concentration for sufficient time to allow for local eradication and thereby achieve better efficiency of therapy with improved patient compliance, reduced costs and minimized side effects caused by immediate release dosage forms

IN VITRO EVALUATION OF IBUPROFEN HOT-MELT EXTRUDED PELLETS EMPLOYING DIFFERENT DESIGNS OF THE FLOW THROUGH CELL

Objective: Hot-melt extrusion technique (HME) was used to prepare a sustained release (SR) multiparticulate oral dosage form (pellets) containing Ibuprofen (IBU). Prepared IBU-HME pellets were in vitro evaluated by flow-through cell dissolution tester (FTC, USP Apparatus #4) using different flow conditions and FTC designs. Methods: In this study, Sucroester®WE15 was used as the polymeric carrier to prepare two different IBU loadings (60 % and 30 % w/w). In order to optimize the FTC conditions, different cell sizes, pellets loading and hydrodynamic conditions of FTC on IBU release rate from pellets were proposed. Results: The results showed that the IBU release rate was increased in the larger cell than the small cell. In addition, laminar flow showed more reproducible results than turbulent flow. It was found that the large cell with laminar flow rate and homogeneous mixing of the pellets with glass beads was the optimum conditions for in vitro evaluation of these preparations. Conclusion: Improper methods of sample loading as well as cell size may result in confusing or erroneous data if not analyzed carefully. Therefore, it might be critical to choose a specific cell design of the FTC for in vitro evaluation of pellets to obtain reliable and discriminative results reflecting the major as well as minor formulation variables

IN-VITRO DISSOLUTION STUDY OF MELOXICAM IMMEDIATE RELEASE PRODUCTS USING FLOW THROUGH CELL (USP APPARATUS 4) UNDER DIFFERENT OPERATIONAL CONDITIONS

Objective: To evaluate and compare the in-vitro dissolution profiles of five generic immediate release (IR) products of Meloxicam (MX) available in Egyptian market with the innovator reference product (Mobic®, R) using different operational conditions of the flow through dissolution cell (FTC, USP Apparatus 4), in phosphate buffer (pH=7.5). Methods: The comparative in-vitro dissolution studies were performed under different FTC operational conditions such as cell size, tablet position within the cell, open and closed loops setup and type of flow (laminar and turbulent) on MX dissolution rate from different IR products. Results: The study showed that two generic products, out of five, gave similar dissolution profiles with R using a specified well controlled condition of FTC. A selected generic product (Mobitil, G1) was tested versus R under different operational conditions of the FTC such as cell size, type of flow, tablet position and open & closed loops setup. The dissolution profile of MX from R was highly affected by changing the tablet position, slightly affected by the open & closed loops setup and not affected by cell size and type of flow. On the other hand, the dissolution profile of MX from G1 was affected by all the previous operational conditions. Comparing ƒ2 values between G1 against R among the different operational conditions proposed, only one in-vitro dissolution test showed similar dissolution profile of G1 with respect to R. Conclusion: Three generic products of MX might not be interchangeable with the innovator product (Mobic®)

Strength of Concrete Filled Steel Box Columns Incorporating Interaction Buckling

Concrete filled steel columns have seen an increased usage in building structures throughout the world. In Australia, the use of thin-walled steel sections coupled with concrete infill has been used on various building projects with great advantage. The major advantages of the use of thin-walled steel sections are the reduced structural steel costs and the economy in construction that the method provides. This paper presents both an experimental and theoretical treatment of coupled local and global buckling of concrete filled steel columns sometimes termed interaction buckling. The paper then concludes with comparisons of design recommendations for the strength evaluation of slender composite columns with thin-walled steel sections

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