Drug loaded essential oil microemulsions enhance photostability and evaluation of in vitro efficacy.

Loss of stability of pharmaceutical APIs (Active Pharmaceutical Ingredient) due to photolytic activity has been a major concern in the pharmaceutical industry as it leads to loss of activity of API and excipients, the formation of toxic by-products, change in color and flavor. Itraconazole (ITZ) bulk drug was exposed to UVC (254 nm) irradiation in an environmental chamber (37 °C, 75 %RH) and its photoprotection by cinnamon, clove, eugenol, and oregano based microemulsion was analyzed. No significant change in the spectra was observed at various time points, confirming the photo-protective activity of microemulsions, unlike the bulk drug. FTIR spectra illustrate the fundamental peaks of the functional groups of ITZ and ITZ loaded MEs. The overlaid spectra showed that there was a minor change in peaks of UV exposed ITZ bulk drug but the ITZ loaded microemulsions were able to protect all the major functional groups. The in vitro anti-microbial assay against C. albicans demonstrated no significant change in the activity of ITZ loaded microemulsion between untreated, 7th day and 15th day while the activity of bulk drug was reduced drastically in the UVC exposed sample. It was concluded that microemulsions can be used as an effective photo-protective drug delivery vehicle for light-sensitive compounds.