Document Detail

Release behavior and photo-image of nifedipine tablet coated with high viscosity grade hydroxypropylmethylcellulose: effect of coating conditions.
MedLine Citation:
PMID:  15072787     Owner:  NLM     Status:  MEDLINE    
An orally applicable nifedipine-loaded core tablets was coated using high viscosity grade HPMC (100,000 cps) in ethanol/water cosolvent. The release of coated tablet was evaluated using USP paddle method in 900 ml of simulated gastric fluid (pH 1.2) for 2 h followed by intestinal fluid (pH 6.8) for 10 h. The surface morphologies using scanning electron microscope and photo-images using digital camera of coated tablet during the release test were also visualized, respectively. The viscosity of hydro-alcoholic HPMC solution largely decreased as the amount of ethanol increased. There was no significant difference in viscosity among plasticizers used. The distinct and continuous coated layer was observed using scanning electron microscope. However, the surface morphologies were highly dependent on HPMC concentration and ratio of coating solvents. The higher ratio of ethanol/water gave a longer lag time prior to drug release. Lag time also increased as a function of the coating levels based on weight gains due to increased thickness of coated layer. Lag time is inversely correlated with HPMC concentration in ethanol/water (5:1) cosolvent. As the HPMC concentration slightly decreased from 3.8 to 3.2% in hydroalcoholic coating solution, a large increase of lag time was observed. As the swelling (mixing) time of high viscosity grade HPMC in ethanol/water cosolvent increased from 1 to 5 h, the release rate was decreased due to enough plasticization of polymer. Based on photo-imaging analysis, the coated tablet was initially swelled and gelled without erosion and disintegration over 5 h. The disintegration of the coated tablet was occurred approximately 7 h after dissolution, resulting in pulsed release of drug. The high viscosity grade HPMC can be applicable for polymeric coating after careful selection of solvent systems. The release behavior and lag time could be controlled by coating conditions such as HPMC concentration, ethanol/water ratio as a coating solvent, coating level and swelling (mixing) time of coating solution. The current time-controlled release tablet coated with high viscosity grade HPMC with a designated lag time followed by a rapid release may provide an alternative to site specific or colonic delivery of drugs. In addition, the release behavior can be matched with body's circadian rhythm pattern in chronotherapy.
Qing-Ri Cao; Han-Gon Choi; Dong-Chool Kim; Beom-Jin Lee
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  International journal of pharmaceutics     Volume:  274     ISSN:  0378-5173     ISO Abbreviation:  Int J Pharm     Publication Date:  2004 Apr 
Date Detail:
Created Date:  2004-04-09     Completed Date:  2004-08-05     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7804127     Medline TA:  Int J Pharm     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  107-17     Citation Subset:  IM    
National Research Laboratory for Bioavailability Control, College of Pharmacy, Kangwon National University, Chuncheon, South Korea.
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MeSH Terms
Methylcellulose / analogs & derivatives,  chemistry,  pharmacokinetics*
Microscopy, Electron, Scanning / methods
Nifedipine / chemistry,  pharmacokinetics*
Surface Properties
Tablets, Enteric-Coated
Reg. No./Substance:
0/Tablets, Enteric-Coated; 21829-25-4/Nifedipine; 8063-82-9/hypromellose; 9004-67-5/Methylcellulose

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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