title: Push-pull osmotic pump for zero order delivery of lithium carbonate: development and in vitro characterization.
abstract: Lithium carbonate, a drug with narrow therapeutic index, needs therapeutic drug monitoring and dose adjustment to maintain lithium level within the therapeutic window. Conventional formulations of lithium carbonate exhibit immediate drug release causing swing/fluctuations in the plasma concentration of lithium, consequently leading to unfavorable side-effects and make dose adjustment difficult. The push-pull osmotic pump has been developed for zero order delivery of lithium carbonate for a period of 24 h. The effect of various formulation variables on bilayer core tablet and its semi permeable coating along with orifice diameter have been investigated and optimized for desired drug release profile. Drug release was found to be inversely proportional to the membrane thickness but directly related to the amount of pore formers in the semipermeable membrane. Images from a scanning electron microscope confirmed the presence of pores in the semipermeable membrane which facilitated the required water penetration. No distortion or change in orifice shape was noticed prior to and after the dissolution study. Drug release from the developed formulation was found to be independent of pH, agitation intensity and agitation mode but depended on osmotic pressure of dissolution media.
authors.affiliation: Department of Pharmaceutics, V. Patel PERD Centre, Thaltej, Ahmedabad, Gujarat, India.
authors.forename: Vineetkumar
authors.initials: V
authors.lastname: Patel
authors.forename: Arpan
authors.initials: A
authors.lastname: Chudasama
authors.forename: Manish
authors.initials: M
authors.lastname: Nivsarkar
authors.forename: Kamala
authors.initials: K
authors.lastname: Vasu
authors.forename: Chamanlal
authors.initials: C
authors.lastname: Shishoo
mesh_terms: D018692:Antimanic Agents / Q000008:administration & dosage* / Q000737:chemistry; D002626:Chemistry, Pharmaceutical / Q000379:methods; D003692:Delayed-Action Preparations; D016503:Drug Delivery Systems; D006863:Hydrogen-Ion Concentration; D016651:Lithium Carbonate / Q000008:administration & dosage* / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D009997:Osmotic Pressure; D010539:Permeability; D012995:Solubility; D013607:Tablets; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D018692:Antimanic Agents; D003692:Delayed-Action Preparations; D013607:Tablets; D014867:Water; D016651:Lithium Carbonate