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Title: Mixed polymer coating for modified release from coated spheroids
Authors: Tan, Y.T.F.
Heng, P.W.S. 
Wan, L.S.C. 
Keywords: Drug release kinetics
Mixed polymer coating
Modified release
Sodium carboxymethylcellulose
Issue Date: 1999
Citation: Tan, Y.T.F., Heng, P.W.S., Wan, L.S.C. (1999). Mixed polymer coating for modified release from coated spheroids. Pharmaceutical Development and Technology 4 (4) : 561-570. ScholarBank@NUS Repository.
Abstract: Modified-release drug spheroids coated with an aqueous mixture of high- viscosity hydroxypropylmethylcellulose (HPMC) and sodium carboxymethylcellulose (NaCMC) were formulated. The preparation of core drug spheroids and the coating procedures were performed using the rotary processor and a bottom-spray fluidized bed, respectively. Dissolution studies indicated that incorporation of suitable additives, such as poly(vinylpyrrolidone) (PVP) and poly(ethylene glycol) 400 (PEG) improved the flexibility and integrity of the coat layer by retarding the drug release. An increase in coating levels applied generally retarded the release rate of the drug. However, the ratio of HPMC to NaCMC in the mixed, plasticized polymeric coat played a more dominant role in determining the dissolution T(50%) values. The optimal ratio of HPMC to NaCMC for prolonged drug release was found to be 3:1, whereas an increase in the amount of NaCMC in the mixed polymer coat only increased drug release. The synergistic viscosity effect of HPMC and NaCMC in retarding drug release rate was greater in distilled water than in dissolution media of pH 1 and 7.2. Cross-sectional view of the scanning electron micrograph showed that all of the coated spheroids exhibited a well-fused, continuous, and distinct layer of coating film. The drug release kinetics followed a biexponential first-order kinetic model.
Source Title: Pharmaceutical Development and Technology
ISSN: 10837450
DOI: 10.1081/PDT-100101395
Appears in Collections:Staff Publications

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