Preparation and evaluation of cross-linked anchote (coccinia abyssinica) starch for sustained release tablet formulation
No Thumbnail Available
Date
2018-05
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa Universty
Abstract
Starch is a natural polysaccharide, inexpensive, renewable, biodegradable polymer and is one of the most abundant organic compounds in nature. Modification of starch is carried out to enhance the positive attributes and to eliminate the shortcomings of the native starches. Starch modification offers numerous possibilities to generate novel starches which includes new functional and value added properties as demanded by the industry. Chemical modification via cross-linking is possible due to the ubiquitous hydroxyl groups in starches that have been exploited for over a century, principally in the preparation of starch esters and ethers, in order to tune the structure of starches for specific applications. It is apparent that synthetic and semi-synthetic polymers used for sustained release preparations have got biodegradability and biocompatibility problems. In addition, cross-linked anchote starch (CLAS) has not yet explored in order to use as an alternative excipient for sustained release in the preparations of oral drug delivery system. Thus the aim of the present study was to extract starch from anchote (Coccinia abyssinica), to cross-link, characterize and explore its potential as a sustained release pharmaceutical excipient. Anchote native starch (NS) was cross-linked with different concentration of sodium hexametaphosphate at 550C for 8h. Three types of CLASs with varying degrees of cross-linking (DCL) were prepared and labeled as CLAS-5, CLAS-10, and CLAS-15. Powder mixtures of ten ibuprofen (IBP) formulations were compressed by direct compression technique. Among these 9 of them were prepared by varying the type of cross-linked starches and the amount incorporated in each formulation. In addition formulation with NS (FNS) was prepared.
Swelling power (SP) and solubility of the CLASs decreased as concentration of SHMP increased and the water uptake decreased. Powder flowability of the CLASs was improved as compared with the NS. Tablet properties were also improved with CLASs than NS. In-vitro dissolution testing were performed in 0.1N HCl for the first 2h and in phosphate buffer (pH 7.2) for another 10h for all the formulations (F1-F9) since these formulations passed relevant tests like disintegration time, friability, and hardness. The release of IBP from the matrix tablets prepared with different drug to polymer ratios was investigated in an effort to develop sustained release tablet formulations. Formulation F1 and F2 was prepared from CLAS-5 as matrix forming polymer with the lowest DCL among the modified starches, and prepared by incorporating 20%
ii
and 25% of the polymer respectively released greater than 90% of the drug content in nearly 6h. But formulation F3 was prepared from the same matrix forming polymer and yet prepared with 30% of the polymer released greater than 90% of the drug content in nearly 8h. Formulations F4, F5, and F6 were prepared from CLAS-10 as a matrix forming polymer and had medium DCL and prepared with 20%, 25%, and 30% of polymer, respectively released greater than 90% of the drug in nearly 10h due to the complete disintegration of the matrix tablets within this period of time. However, formulations F7, F8 and F9 were prepared from the other polymer CLAS-15 having the highest DCL and prepared with 20%, 25%, and 30% of polymer, respectively released greater than 90% of the drug slowly at the end of 12h. The in-vitro dissolution data were subjected to the various drug release kinetic models and the data best fitted the Higuchi’s model. The mechanisms of drug release were anomalous or non-Fickian diffusion category due to the fact that the diffusional release exponent, n ranges between 0.6902 and 0.7699 thus all underwent both diffusion and polymer relaxation. FT-IR spectra indicated no interaction between ibuprofen and the drug release sustaining agent. In conclusion, CLASs can serve as sustained release excipient in matrix tablets.
Description
Keywords
Coccinia abyssinica starch, cross-linking, sodium hexametaphosphate, sustained release, ibuprofen, matrix tablet