A new plant gum, Okra (extracted from the pods of Hibiscus esculentus), has been evaluated as a controlled-release agent in modified release matrices, in comparison with sodium carboxymethyl cellulose (NaCMC) and hydroxypropylmethyl cellulose (HPMC), using Paracetamol as a model drug. Tablets were produced by direct compression and the in-vitro drug release was assessed in conditions mimicking the gastro intestinal system, for 6 h. Okra gum matrices provided a controlled-release of Paracetamol for more than 6 h and the release rates followed time-independent kinetics. The release rates were dependent on the concentration of the drug present in the matrix. The addition of tablet excipients, lactose and Avicel, altered the dissolution profile and the release kinetics. Okra gum compared favourably with NaCMC, and a combination of Okra gum and NaCMC, or on further addition of HPMC resulted in near zeroorder release of paracetamol from the matrix tablet. The results indicate that Okra gum matrices could be useful in the formulation of sustained-release tablets for up to 6 h.
The uptake and specificity of drugs and the bioavailability of poorly soluble drugs has been improved by means of targeted drug delivery using nanoparticles. Many platforms have been used for nanoparticulate drug delivery and these include liposomes, polymer conjugates, metallic nanoparticles, polymeric micelles, dendrimers, nanoshells, and protein and nucleic acid-based nanoparticles. Starch is the 2 nd most abundant natural polymer and has found wide use in drug delivery systems as binder, disintegrant and filler. However, its application is limited by the poor functional properties of native starch. Starch nanocrystals of different shapes and sizes can be obtained based on the starch origin and isolation process involved. Nanocrystals with varying morphology have been reported; from nanocrystals of platelet-like shaped waxy maize starch with 5-7 nm thickness and 15-40 nm diameters, to those with round and grape-like shape from potato starch granules, with sizes ranging from 40 nm to 100 nm. This review describes different methods of obtaining starch nanoparticles, their modification and application in drug delivery. Cite asOdeniyi MA, Omoteso OA, Adepoju OA, Jaiyeoba KT. Starch nanoparticles in drug delivery: A review.
Acha (Digitaria exilis) starches are investigated as nanocrystal carriers for the controlled release of naproxen. Starch nanocrystals (SNC) are prepared by acid hydrolysis using H2SO4 and the modified form (carboxymethylated SNC) is obtained by reaction of the SNC with monochloroacetic acid and sodium hydroxide. Physicochemical properties, degree of substitution, SEM and FTIR analyses, loading and release studies including in vitro release kinetics of the drug‐loaded starch nanocrystals are determined. FTIR analysis confirms the introduction of the hydrophilic carboxylate functional group into the starch molecule of the modified starches with strong peaks in the region 1300–1650 cm−1. SEM images reveal the disruption of the granular structure of the starch particles due to hydrolysis conferring crystallinity on the granules. The drug release kinetics of all the starch polymers follow the Korsemeyer–Peppas model indicating that the drug release was by non‐Fickian diffusion. The native starch, starch nanocrystals, and carboxymethylated nanocrystal forms have drug loading content that are above 50% and loading efficiency above 75% and produce a steady and sustained release of naproxen. The release studies of native Acha starch and the modified SNC show that their formulations can function as carriers/polymers that can achieve sustained and/or delayed drug release of poorly soluble drugs.
A study has been made of the effects of sun and oven drying methods on the physicochemical characteristics and compressibility of Okra powder and the release properties of its metronidazole tablet formulation. Corn starch was used as the reference standard. The mechanical properties of the tablets were evaluated using crushing strength and friability, while the release properties were determined using the disintegration times and dissolution rates. The results obtained showed that sun-dried Okra powder had smaller particle size, exhibited good flow and possessed higher hydration and swelling capacities compared to the oven dried samples. The compressibility of Okra powders assessed by the indices of plasticity from Heckel (Py) and Kawakita plots (Pk) showed that sun dried Okra powders had higher Py but lower Pk values than the oven-dried Okra powder. Metronidazole tablets formulated with oven dried Okra powder formed stronger tablets than tablets containing sun dried Okra powder. Generally, tablets containing sun dried Okra powders had faster disintegration and dissolution than tablets formulated with oven-dried powder. The results suggest that the choice of drying method during the processing of pharmaceutical raw materials is critical to its physicochemical properties and the release properties of its tablet formulations.
Granules have been prepared by a standard method from ternary mixtures of lactose,, boric acid and either sulphanilamide, heavy kaolin or salicylic acid, using an aqueous solution of polyvinylpyrrolidone as binder. The granules were examined for size distribution and for the work required to crush larger granules from each batch. For the same binder volume the mean granule sizes and resistance to crushing of the granules increased as the wettability of the third component increased. The detailed results are discussed in relation to powder wetting and the packing properties of powder mixtures.
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