Ginger essential oil has various biological properties such as antioxidant and anti-inflammatory. However, ginger essential oils has its own weaknesses, such as high volatility, low absorption, and poor water-solubility. Transdermal drug delivery is one of the alternatives to transport ginger essential oil into the body. The transdermal drug delivery system which is a nanoemulsion was introduced to overcome the weakness of essential oil. The droplet size of a nanoemulsion is an important property which determines the stability and ease of penetration. In this research, the nanoemulsions were prepared using a spontaneous emulsification method. The effect of preparation conditions and system composition on particle size of ginger essential oil nanoemulsions were examined. In organic phase, ginger essential oil and surfactants which are Tween 40, 60 and 80 were used. In aqueous phase, distilled water and co-solvent (glycerol) were used. For nanoemulsion formation, the organic phase was slowly added into the aqueous phase while being stirred at 500 rpm. The surfactant type had a major effect on particle size, where the smallest droplets particle size were formed by using Tween 80 (15.40 nm). The surfactant concentration also shows a great impact on particle size, where at surfactantto- emulsion ratio (SER) 25 %, the smallest droplets were formed (11.3 nm). By increasing the temperature of organic phase and stirring speed, the particle size was reduced with the smallest droplets being formed at 90 °C (11.16 nm) and at 800 rpm (11.23 nm). Co-solvent addition also had shown an impact on particle size where at 10 % of co-solvent concentration, the smallest droplets were formed (11.22 nm). For thermodynamic stability, nanoemulsions with SER 15 %, 20 %, 25 % and 30% had shown a great stability with no phase and size separation. For storage stability, the droplets particle size were increased by 23 % throughout the two months of storage. In conclusion, a smaller droplet particle (< 15 nm) can be formed by optimizing the system composition and homogenization conditions of nanoemulsions
