Preparation of prospective plant oil derived micro-emulsion vehicles for drug delivery

Biocompatible oil-in-water (o/w) micro-emulsions can be prospective drug delivery vehicles for their capability to solubilize lipophilic (oil soluble) drugs in the dispersed oil. Plant oils are considered suitable for such a purpose. In this study, we have attempted to examine the dispersion of corn, cottonseed, clove, orange and peppermint oils, as well as isopropyl myristate (IPM) in water continuum in presence of surfactants Tween-20, Brij-30 and Brij-92 and co-surfactants ethanol (EtOH) and isopropyl alcohol (iPrOH). Both ternary (oil/surfactant/water) and psedoternary (oil/surfactant + co-surfactant/water) phase diagrams were constructed. The ternary systems produced larger micro-emulsion forming zones than the psedo-ternary systems. The combinations peppermint oil/iPrOH/water, IPM/iPrOH/water and 1:1 (v/v) peppermint oil + IPM/iPrOH/water were found to form fair proportion of single-phase surfactant-less micro-emulsion. The surfactant-aided ternary systems produced larger clear microemulsion zones, compared to pseudo-ternary systems, while the behaviour of surfactant-less systems was intermediate. The prepared systems had shelf life of 1 year and they withstood temperature variations in the range of 4-40 degrees C.