Prof.Gebre-Mariam, TsigeDr.Birhanu, Gebre-mariamTeshome, Melaku2022-05-092023-11-062022-05-092023-11-062021-11http://etd.aau.edu.et/handle/123456789/31571Cotton linter (CL) is a by-product of the garment industry that is good raw material for cellulose preparation. The aim of this study was to extract and characterize native cellulose and cellulose acetate (CA) from CL and evaluates CA as a sustained release excipient in tablet formulation. In this study, cellulose was extracted by steam explosion method and CA was prepared from the extracted cellulose by using acetic anhydride as acetylating agent and sulphuric acid as a catalyst. Physico-chemical properties of cellulose and CA were characterized. Mechanical properties of plain CA tablets and release profile of theophylline as a model drug were investigated from CA matrix. The cellulose yield from CL on dry weight basis was found to be 78.06%+1.70, while CA yield from cotton linter cellulose (CLC) was 112.4%+1.28. The degree of polymerization (DP) of CLC was 472.52+3.64, while DP of cotton linter cellulose acetate (CLCA) preparations ranged from 148.24+1.80 - 234.09+4.12 based on their degree of substitution (DS). The identification of CLCA was confirmed by Fourier transform infrared (FTIR) spectra, while CLC was identified by using chemical test in addition to FTIR. The degree of crystallinity of CLC was 81.59% and those of CLCA with DS 0.83 and DS 2.46 were 57.92% and 33.78%, respectively. Scanning electron microscopy (SEM) of CLC showed fibrous morphology while SEM of CLCA revealed aggregated particles. The CLCA with DS 2.46 exhibited better heat stability than CLC and comparable result with commercial cellulose acetate (CCA). However, CLC exhibited better thermal stability than CLCA having DS 0.83. The CLCA with DS 2.46 exhibited good flow properties making it suitable for direct compression. The release study showed that, matrix tablets of CLCA with DS 2.46 preparations exhibited prolonged disintegration times and retarded in-vitro dissolution than tablets prepared with CLCA DS 0.83 and comparable result with CCA. However, CLCA had higher % release of drug as compared to ethyl cellulose (EC) containing formulation. The drug release rate was also prolonged as the percentage of CLCA DS 2.46 increased from 59.5% to 79.5% (w/w). The kinetic study showed that, the formulations are best fitted to the Higuchi‟s square root kinetic model (R 2 = 0.9862 to 0.9976) indicating the release of drug from the matrix was diffusion based. Therefore, CL could be a potential local source of cellulose while CLCA could be a potential candidate as a sustained release excipient.en-USCellulose, Cellulose acetate, Cotton linter, Degree of substitution, Sustained releaseThesis