Diethylene glycol monoethyl ether: an emerging solvent in topical dermatology products

Background The solvent diethylene glycol monoethyl ether (DEGEE) is currently used in over 500 cosmetic products and has enabled the formulation of a topical 5% dapsone gel for the treatment of acne. It is anticipated that this common cosmetic ingredient will be a component in numerous future prescription topical products approved for the US market. Dermatologists are already treating patients that apply products containing 5-40% of this solvent multiple times each day. Aims To provide dermatologists a review of this solvent's safety and tolerance in addition to describing how it interacts with the stratum corneum, sebum, and resident microflora. Methods To critically review technical and patent literature that provides insight into this novel solvent. Results Diethylene glycol monoethyl ether when used in a 99.9+% pure pharmaceutical grade is safe and well tolerated. Up to half of the applied solvent crosses the skin's barrier and becomes systemic. For certain drug actives, this solvent provides for an intracutaneous depot. This solvent has not demonstrated any inherent antimicrobial properties but was found to be mildly inhibitory toward Propionibacterium acnes. Conclusions This safe, well-tolerated solvent is already used in many cosmetics and will become an ingredient in an increasing number of prescription products. Its ability to modify the skin delivery of actives it is formulated with (or formulation components that are applied just shortly before or after) make it important for dermatologists to have an understanding of this emerging solvent.