title: Effect of formulation variables on the floating properties of gastric floating drug delivery system.
abstract: OBJECTIVE
  To evaluate the contribution of formulation variables on the floating properties of a gastric floating drug delivery system (GFDDS) using a continuous floating monitoring system and statistical experimental design.
  
  
  METHODS
  A modified continuous floating monitoring system, which consisted of an electric balance interfacing with a PC, was designed to perform the continuous monitoring of floating kinetics of GFDDS. Several formulation variables, such as different types of hydroxypropyl methylcellulose (HPMC), varying HPMC/Carbopol ratio, and addition of magnesium stearate, were evaluated using Taguchi design, and the effects of these variables were subjected to statistical analysis.
  
  
  RESULTS
  The continuous floating monitoring system developed was validated, using capsules with different density, and a good correlation between theoretical and experimental values was obtained (R2 = 0.9998), indicating the validity of the setup. The statistical analysis indicated that magnesium stearate had a significant effect on the floating property of GFDDS (p < 0.05), and addition of magnesium stearate could significantly improve the floating capacity of the GFDDS. It was found that the HPMC of higher viscosity grade generally exhibited a greater floating capacity, but the effect was not statistically significant. For polymers with the same viscosity, i.e., K4M and E4M, the degree of substitution of the function group did not show any significant contribution. A better floating behavior was achieved at higher HPMC/Carbopol ratio. Carbopol appeared to have a negative effect on the floating behavior of GFDDS.
  
  
  CONCLUSIONS
  It was concluded that by using a validated continuous floating monitoring system, the effect of formulation variables on the floating property of the delivery system and their ranges could be identified. Incorporation of hydrophobic agents, such as magnesium stearate, could significantly improve the floating capacity of the GFDDS.
authors.affiliation: Controlled Drug-Delivery Research Center, College of Pharmacy, Rutgers, State University of New Jersey, Piscataway, New Jersey 08854, USA.
authors.forename: Shoufeng
authors.initials: S
authors.lastname: Li
authors.forename: Senshang
authors.initials: S
authors.lastname: Lin
authors.forename: Bruce P
authors.initials: BP
authors.lastname: Daggy
authors.forename: Haresh L
authors.initials: HL
authors.lastname: Mirchandani
authors.forename: Yie W
authors.initials: YW
authors.lastname: Chien
mesh_terms: D000180:Acrylic Resins; D000704:Analysis of Variance; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D016503:Drug Delivery Systems / Q000295:instrumentation*; D007700:Kinetics; D007785:Lactose / Q000031:analogs & derivatives*; D008747:Methylcellulose / Q000031:analogs & derivatives*; D010078:Oxazines; D011145:Polyvinyls
chemical_list: D000180:Acrylic Resins; D010078:Oxazines; D011145:Polyvinyls; C006912:carboxypolymethylene; D008747:Methylcellulose; C071191:MK 458; D007785:Lactose