Stability Studies of Nano-Scaled Emulsions Containing Ibuprofen for Topical Delivery

Biphasic systems, like emulsions and nano-scaled emulsions, are naturally unstable. The extent and rate of the destabilization process differ from system to another. The stability of such systems upon storage is an important aspect to ensure their abilities to exert the expected effects and consequently render them pharmaceutically acceptable. In the present study, the stability of the nano-scaled emulsion containing newly synthesized palm oil esters (POEs) was assessed under different storage conditions and over specified durations. Three nano-scaled emulsion formulae were chosen for this investigation. They basically comprised ibuprofen as the active ingredient, triethanolamine aqueous solution pH 7.4 as the external phase, POEs as the oil phase, Tween 80 as an emulsifier, Carbopol® 940 as the rheology modifier and menthol or limonene as penetration promoters. The evaluation processes were carried out at several temperatures (4, 25 and 40 °C) with factors, such as droplets size, electrical conductivity, drug content, pH and flow properties were relatively held constant. The data collectively showed that all formulations were stable over an observation period of three months. Keywords: Ibuprofen, nano-scaled emulsion, palm oil esters, stability