title: [Preparation of nifidipine pulsatile release tablets].
abstract: OBJECTIVE
  To prepare nifidipine (NFP) bi-layered pulsatile release tablets, to evaluate the effects of the formulation and dissolution medium on drug release behavior, and to elucidate the mechanism of drug release based on the obtained results.
  
  
  METHODS
  Core tablets containing osmotic active agent were prepared by direct compression and spray coated with swelling layer and semipermeable membrane subsequently. Pharmaceutical properties of NFP pulsatile tablets were investigated by dissolution test.
  
  
  RESULTS
  Pulsatile release of NFP from bi-layered tablets was accomplished. The lag-time was prolonged with the increase of coating level of semipermeable membrane, and the steady release rate was increased significantly with the increase of osmotic active agent and swelling layer. It was shown that drug release behaviors were constant and irrespective of various pH values of dissolution medium and rotation speeds. All results indicated that diffusion, swelling and osmotic pumping were involved in the mechanism of drug release.
  
  
  CONCLUSIONS
  Ideal pulsed release behaviors can be achieved by adjusting the coating level and composition of semipermeable membrane to meet the requirement of chronotherapy. The comprehensive mechanism of drug release is suitable for water insoluble drugs.
authors.affiliation: Department of Pharmacy, Daping Hospital, Third Military University of Medical Sciences, Chongqing 400042, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Zhi-rong
authors.initials: ZR
authors.lastname: Zhang
mesh_terms: D002910:Chronology as Topic; D003692:Delayed-Action Preparations; D016503:Drug Delivery Systems; D006801:Humans; D009543:Nifedipine / Q000008:administration & dosage*; D012995:Solubility; D013607:Tablets; D013678:Technology, Pharmaceutical; D014665:Vasodilator Agents / Q000008:administration & dosage*
chemical_list: D003692:Delayed-Action Preparations; D013607:Tablets; D014665:Vasodilator Agents; D009543:Nifedipine