Transparent oil-water gels

Synopsis The present article reviews both the cosmetic and the pharmaceutical literature concerning transparent oil-water gels. We propose the term 'transparent oil-water gel' for semisolid systems that consist mainly of water, oil and an emulsifying agent or agents and that are characterized by a jelly-like consistency, transparency, homogeneity, optical isotropy, thermodynamic stability, and the occurrence of a 'ring' or resonance when a containerful is tapped. The literature reflects a rather remarkable degree of confusion, not only with regard to terminology, but also with regard to the basic concept of the formation of transparent oil-water gels. After a brief discussion justifying our selection of the term, the advantages specifically attributed to these gels are summarized, and the raw materials used in their formation as well as factors affecting their formulation are described. Finally, their applications as cosmetic and as pharmaceutical vehicles are reviewed.