Investigating extraction methods of coconut oil in Metronidazole-Loaded topical microsized-emulsions for management of Rosacea

Metronidazole-Loaded topical microsized-emulsions for management of Rosacea

Abstract

Emulsions for topical application are promising for the delivery and stability of poorly watersoluble drugs and those with challenging oral delivery. Coconut oil (oil from Cocos nucifera Linne, CNO) is used for cosmetic purposes, but there is limited published literature on its use in the delivery of drug-loaded preparations for topical or transdermal applications. The aim of this study was to formulate and evaluate metronidazole-loaded topical emulsions using CNO obtained from three different extraction methods. CNO was obtained using maceration in warm water and n-Hexane of the coconut meat to obtain hot method extract- HME, cold method extract- COE, and the chemical method extract- CME, respectively. The HME, COE, and CME were used to formulate corresponding metronidazole-loaded microsized emulsions (HMEE, COEE, and CMEE, respectively) at a predetermined oil-to-surfactant ratio of 1.5:1 using a homogenizer. The surfactant mix was composed of triethanolamine to stearic acid in the ratio of 1:10. The formulated drug-loaded emulsions were evaluated for physicochemical properties, stability, and antimicrobial activity. The chemical extraction method produced the highest CNO yield (72%), while the cold extraction method produced the lowest (32%). Drug-loaded emulsion COEE had the lowest viscosity of 4.29 Pas when compared with CMEE (4.82 Pas) and HMEE (4.6 Pas), had the least stability as reflected in its largest globule size of 28.46 μm, whereas globule size for CMEE and HMEE were 9.78 and 25.95 μm, respectively. Overall, metronidazole-loaded emulsions reduced the drug activity against the test organisms as determined by the measured zones of inhibition. These findings highlight the potential of a coconut oil-based emulsion for the topical delivery of drugs (e.g., metronidazole); however, for biocompatibility and to achieve the intended therapeutic outcome, careful selection of the drug of choice incorporated into the formulation for the target organism is needed. Also, while the chemical method of extraction for coconut oil would be a good choice to achieve a higher yield, the emulsion prepared from CNO using the hot extraction method showed adequate stability.