Design of a microemulsion-based drug delivery system for diclofenac sodium

A microemulsion-based drug delivery system has been designed for diclofenac sodium (ds) comprising span 60,1-propanol,water,and lemon oil. the microemulsion system has been characterized by a pseudo-ternary phase diagram using the water titration method. the properties and structure of this system have been studied by the use of refractive index,electrical conductivity,viscosity and uv-visible spectroscopy. the conductivity (σ) and viscosity (kη) measurements have provided evidence for percolation behavior with variation in φ (weight fraction of aqueous phase). this phase transition corresponds to the structural change from water-in-oil to a bicontinuous microemulsion system. the percolation threshold (φc) obtained from conductivity measurements was in accordance with that obtained by viscosity measurements. five microemulsion samples were selected and the changes in microstructure after incorporation of the drug,diclofenac sodium (ds) were examined by centrifugation,conductivity measurements,viscosity measurements and spectroscopic studies. the conductivity measurements showed that ds-loaded samples have higher conductivity values when compared to non-loaded samples. it was also found that ds is interfacially active. in addition,loading of ds had no negative effect on the stability of the system.