Document Detail

A controlled porosity osmotic pump system with biphasic release of theophylline.
MedLine Citation:
PMID:  17978514     Owner:  NLM     Status:  MEDLINE    
A controlled porosity osmotic pump system with biphasic release of theophylline was developed for the nocturnal therapy of asthma. The developed system was composed of a tablet-in-tablet (TNT) core and a controlled porosity coating membrane. Release pattern of the developed system was influenced by amount of pore former (18.2-45.5%, w/w of polymer), weight gain (16-26 mg per tablet) of the coating membrane and osmotic agents used in inner layer of the TNT core. When sodium phosphate and sodium chloride were selected as the osmotic agents in inner and outer layer of the TNT core respectively, target release profile was obtained with coating solution cellulose acetate-polyethylene glycol 400-diethyl phthalate (54.5-36.4-9.1%, w/w) at a weight gain of 16-22 mg per tablet. To examine the mechanism of drug release, release profiles of osmotic agents, micro-environmental osmotic pressure and micro-environmental pH of the formulation during dissolution were studied. Micro-environmental osmotic pressure decreased and micro-environmental pH increased continuously during the whole dissolution process, theophylline release was dominated by the successive dissolution of sodium chloride and sodium phosphate. Theophylline solubility increased as environmental pH exceeded 10.8. At the last stage of the biphasic release, micro-environmental pH in the developed formulation reached 10.9, and theophylline release was promoted by its elevated solubility despite of the decrease of micro-environmental osmotic pressure in the developed formulaiton.
Yueqi Bi; Shengjun Mao; Liangchun Gan; Yuanbo Li; Changguang Wang; Nannan Xu; Yu Zheng; Qiuhong Cheng; Shixiang Hou
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Chemical & pharmaceutical bulletin     Volume:  55     ISSN:  0009-2363     ISO Abbreviation:  Chem. Pharm. Bull.     Publication Date:  2007 Nov 
Date Detail:
Created Date:  2007-11-05     Completed Date:  2008-02-05     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0377775     Medline TA:  Chem Pharm Bull (Tokyo)     Country:  Japan    
Other Details:
Languages:  eng     Pagination:  1574-80     Citation Subset:  IM    
West China Pharmacy School, Sichuan University, Chengdu, China.
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MeSH Terms
Cellulose / analogs & derivatives,  chemistry
Drug Delivery Systems / methods*
Hydrogen-Ion Concentration
Infusion Pumps*
Osmotic Pressure
Phosphates / chemistry
Phthalic Acids / chemistry
Polyethylene Glycols / chemistry
Sodium Chloride / chemistry
Tablets, Enteric-Coated / administration & dosage,  chemistry*,  pharmacokinetics
Theophylline / administration & dosage,  chemistry*,  pharmacokinetics
Vasodilator Agents / administration & dosage,  chemistry*,  pharmacokinetics
Reg. No./Substance:
0/Phosphates; 0/Phthalic Acids; 0/Polyethylene Glycols; 0/Tablets, Enteric-Coated; 0/Vasodilator Agents; 58-55-9/Theophylline; 7632-05-5/sodium phosphate; 7647-14-5/Sodium Chloride; 84-66-2/diethyl phthalate; 9004-34-6/Cellulose; 9004-35-7/acetylcellulose

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