Abstract
Polymethylmethacrylate (PMMA) coated microcapsules of diclofenac sodium (DFS) were prepared by a modified wa-ter-in-oil-in-water (W1/O/W2) emulsion solvent evaporation method using sodium alginate (SAL) as a matrix material in the internal aqueous phase (W1).Their performance with respect to controlled release of the drug in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) were evaluated, and compared with non-matrix microcapsules prepared by the conventional W1/O/W2 emulsion solvent evaporation method. Scanning electron micrographs (SEM) revealed that all the microcapsules were discrete and spherical in shape; however, the surface porosity of the matrix microcap-sules appeared to be less than that of the non-matrix microcapsules. In case of non-matrix microcapsules, an increase in the volume of water in W1 phase resulted in decrease in the drug entrapment efficiency (DEE) along with increase in release of the drug in both SGF and SIF. While in case of matrix microcapsules increase in the amount of SAL in W1 phase and concentration of the coating polymer in organic phase led to increase in DEE of the matrix microcapsules and considerable decrease in the drug release in both SGF and SIF. No interaction between the drug and any of the polymers used to prepare microcapsules was evident from Fourier transform infra-red (FTIR) analysis. The matrix microcapsules prepared using higher concentration of SAL and PMMA released the drug following zero order or Case-II transport model. The matrix microcapsules appeared to be suitable for releasing lesser amounts of DFS in SGF and providing extended release in SIF.
Highlights
Diclofenac Sodium (DFS), a non steroidal anti-inflammatory drug, is widely used in rheumatoid arthritis, severe osteoarthritis and in ankylosing spondilities [1]
While in case of matrix microcapsules increase in the amount of sodium alginate (SAL) in W1 phase and concentration of the coating polymer in organic phase led to increase in drug entrapment efficiency (DEE) of the matrix microcapsules and considerable decrease in the drug release in both simulated gastric fluid (SGF) and simulated intestinal fluid (SIF)
Initial experiments revealed that higher volume of organic phase and external aqueous phase as well as processing temperature considerably reduced DEE of the non-matrix microcapsules
Summary
Diclofenac Sodium (DFS), a non steroidal anti-inflammatory drug, is widely used in rheumatoid arthritis, severe osteoarthritis and in ankylosing spondilities [1]. A controlled release dosage form maintains adequate therapeutic plasma level of drug avoiding peak-and-valley effect and thereby, minimizes the emergence of adverse effects, prolongs the release of drug over extended period of time, reduces frequency of administration and improves patient compliance, provides therapeutic action during night time no-dosing period and is suitable for better drug therapy [3,4]. Among the various methods of preparing microcapsules, water-in-oil-in-water (W1/O/W2) emulsion solvent evaporation technique has been widely investigated. In this method, an aqueous solution or suspension of the drug (internal aqueous phase, W1) is emulsified in a solution of polymer in organic solvent.
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