Background: The study was aimed to enhance the mucoadhesive potential of Eudragit RS
100 and RL 100 using iron oxide.
Methods: Microspheres of Eudragit RS/RL100, containing cinnarizine, were prepared by emulsification
solvent evaporation technique employing 32 full factorial design. Eudragit RS or RL (X1) and iron
oxide (X2) concentrations were the independent variables. Particle size, entrapment efficiency, mucoadhesion,
zeta potential and t90% were the response variables. Microspheres when characterized by
FTIR-ATR and DSC confirm entrapment of drug.
Results: SEM analysis of microspheres exhibits roughness/micropores responsible for drug release.
Particle size of Eudragit RS and Eudragit RL microspheres was found to increase from 275.60±2.68 to
438.72±22.73 nm and 283.14±1.95 to 475.55±29.66 nm. Incorporation of iron oxide increases zeta potential
from 0.88±0.18 to 10.74±1.78 mV and 1.12±0.11 to 14.44±2.44 mV for Eudragit RS and RL
microspheres, respectively. Highest mucoadhesion and zeta potential were obtained when 4.5% w/v of
X1 and 20% w/v of X2 were used in the formulation of microspheres.
Conclusion: The r2 values were significantly higher (P < 0.01) for the Langmuir equation as compared
to Freundlich equation, indicating the involvement of electrostatic forces in the specific adsorption of
mucin on to Eudragit microspheres. In vivo study indicates 2.5 to 3 times increased bioavailabity of
cinnarizine through mucoadhesive microspheres.