title: [Sandwiched osmotic pump tablet for controlled release of water-insoluble drug].
abstract: OBJECTIVE
  To study sandwiched osmotic pump tablet for delivering water-insoluble drug for 24 hours.
  
  
  METHODS
  Sandwiched osmotic pump tablet was prepared using nifedipine as the model drug. The effects of various formulation variables and orifice size on drug release were studied. The mechanical properties of cellulose acetate membrane were also investigated.
  
  
  RESULTS
  Polyethylene oxide of drug layer and potassium chloride of push layer showed marked positive effects on drug release. In the range of 0.50 mm to 1.40 mm, orifice size hardly affects drug release. Cellulose acetate membrane is strong enough to assure the integrity of osmotic pump tablet and could sustain an internal pressure ranging from 0.34 MPa to 2.85 MPa.
  
  
  CONCLUSIONS
  Sandwiched osmotic pump tablet can deliver water-insoluble drug constantly for 24 hours. Release media and agitation rate scarcely affect drug release. Compared with the commercialized push-pull osmotic pump tablet, sandwiched osmotic pump tablet is easy in preparation with exempting identification of drug layer before drilling.
authors: College of Pharmaceutical Science, Yuquan Campus, Zhejiang University, Hangzhou 310027, China. liulx@zju.edu.cn
authors: Long-xiao
authors: LX
authors: Liu
authors: Gilson
authors: G
authors: Khang
authors: John Moon
authors: JM
authors: Rhee
authors: Hai Bang
authors: HB
authors: Lee
mesh_terms: D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D009543:Nifedipine / Q000008:administration & dosage*; D009995:Osmosis; D011092:Polyethylene Glycols / Q000737:chemistry; D011189:Potassium Chloride / Q000737:chemistry; D012995:Solubility; D013607:Tablets; D013678:Technology, Pharmaceutical / Q000379:methods*
chemical_list: D003692:Delayed-Action Preparations; D004337:Drug Carriers; D013607:Tablets; C005062:acetylcellulose; D011092:Polyethylene Glycols; D011189:Potassium Chloride; D002482:Cellulose; D009543:Nifedipine