Effect of variables in chitosan film formulations on propranolol hydrochloride tablets

Abstract

Chitosan of different molecular weight (L<M<H) in 1% w/w acetic acid solution giving apparent viscosity of 125 mPa.s at concentrations of 2.025, 1.75 and 0.825 respectively were used as coating solution. Propylene glycol, PEG400 and triacetin of 10, 20 and 30% w/w of chitosan were added as plasticizer. They could form glossy yellowish film coating upon propranolol HC1 tablets with pan-spray method. The plasticized coated tablets with the higher M.W. of chitosan H exhibited slower drug release than those coated with plasticized the lower M.W. of chitosan M and L respectively. For plasticized coated tablets with propylene glycol, the coated tablets of plasticized combined chitosan L and H showed slowest drug release except plasticized coated tablets with propylene glycol 10%. For plasticized coated tablets with chitosan L, M and H, as the amount of propylene glycol increased, the drug release was faster, but the result was reversed in coated tablets with PEG400 and triacetin. The weight variation, friability, defects, hardness, disintegration time were also investigated. The physical appearance, IR spectra, X-ray diffraction, film swelling, moisture sorption and tensile properties of free films prepared from coating solutions were used to study the properties of chitosan free films and related to the properties of film on coated tablets. Incompatibility between chitosan and PEG400, and chitosan and triacetin were found in free films and on coated tablets. From IR spectra, they indicated that chitosan acetate might be formed after drying coating solutions. The dominantly slower drug release of coated tablets after kept at room temperature and exposure to accelerated condition might due to the hydrolysis of chitosan acetate.