Abstract
Some pH responsive polymeric matrix of Linseed (Linum usitatissimum), L. hydrogel (LSH) was prepared by free radical polymerization using potassium persulfate (KPS) as an initiator, N,N-methylene bisacrylamide (MBA) as a crosslinker, acrylic acid (AA) and methacrylic acid (MAA) as monomers; while ketoprofen was used as a model drug. Different formulations of LSH-co-AA and LSH-co-MAA were formulated by varying the concentration of crosslinker and monomers. Structures obtained were thoroughly characterized using Fourier transforms infrared (FTIR) spectroscopy, XRD analysis and Scanning electron microscopy. Sol-gel fractions, porosity of the materials and ketoprofen loading capacity were also measured. Swelling and in vitro drug release studies were conducted at simulated gastric fluids, i.e., pH 1.2 and 7.4. FTIR evaluation confirmed successful grafting of AA and MAA to LSH backbone. XRD studies showed retention of crystalline structure of ketoprofen in LSH-co-AA and its amorphous dispersion in LSH-co-MAA. Gel content was increased by increasing MBA and monomer content; whereas porosity of hydrogel was increased by increasing monomer concentration and decreased by increasing MBA content. Swelling of copolymer hydrogels was high at pH 7.4 and low at pH 1.2. Ketoprofen release showed an increasing trend by increasing monomer content; however it was decreased with increasing MBA content. Sustained release of ketoprofen was noted from copolymers and release followed Korsmeyer-Peppas model.
Highlights
In order to deliver a drug through the oral route, it is important to consider physiological pH of the gastrointestinal tract [1,2,3]
Linseed hydrogel (LSH)-co-methacrylic acid (MAA) hydrogels were prepared by same method as of LSH-co-AA, except that instead of acrylic acid, MAA was used [16,19]
It was found that the optimum concentration of LSH for LSH-co-AA and LSH-co-MAA formulations was 1 and 2.5% respectively
Summary
In order to deliver a drug through the oral route, it is important to consider physiological pH of the gastrointestinal tract [1,2,3]. Hydrogels isolated from plant materials are mainly cross-linked polysaccharides that absorb high amounts of water and generally swells at intestinal pH and shrink at stomach’s pH [5]. Cross-linked network structure, stimuli responsive nature make water swellable polysaccharides as smart materials or intelligent drug delivery system. Such polysaccharides generally have ionic pendant groups able to accept and/or donate protons as a response to change in physiological pH which is an integral factor of pH responsive hydrogels [6,9,10,11]. By grafting the natural polysaccharides with synthetic polymers, one may get benefit of the properties of both entities.
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