Consideration on the Formulation of Benzoyl Peroxide at Ambient Temperature: Choice of Non-Polar Solvent and Preparation of Submicron Emulsion Gels

Abstract

The aim of this study performed at ambient temperature was first to determine the solubility of benzoyl peroxide in various solvents with a large range of polarity. All these solvents can be used in the dermatological field. Then, using the most suitable solvent, a new drug vehicle submicron oil-in-water emulsion was formulated. Correlation between dielectric constant (epsilon) and drug solubility in various solvents and different binary mixtures was verified. An original ternary diagram with surfactant-co-surfactant/oil/water was performed at low temperature to determine the regions of submicron emulsions. A dramatic change in the magnitude of benzoyl peroxide solubility occurred above a dielectric constant value of about 20. The solubility of this drug can be enhanced by the replacement of polar solvent by a vehicle of lower dielectric constant. A stable submicron emulsion gel was made with cremophor EL, glycerol, caprilic-capric triglycerides, and water in the proportion of 20-20/35/25, respectively; 1.5% benzoyl peroxide was also added. This submicron emulsion vehicle consisted of oil droplets, with a mean diameter of approximately 100-150 nm, dispersed in a continuous water phase. These studies confirm the potential of benzoyl peroxide incorporation into submicron emulsion gel and the stability of this formulation.

Electric fields drive bond homolysis

“…without a field or exposure to Au) do not show a strong correlation with the solvent dielectric, although overall an increased background reactivity in more polar solvents is observed, in line with published reports. 29,30 In TD, a clear peak for 4,4'-bis(methylthio)biphenyl was observed in situ by STM-BJ conductance measurements (Figure S5) while it yields no conversion by ex-situ HPLC analysis even upon prolonged EEF exposure (up to 24 hrs). We find that the background rate is highest in DMSO, and NMR analysis shows 1 converts rapidly to 2 via an intermediate, possibly a peracid, sulfone, or both.…”

Electric fields drive bond homolysis

“…without a eld or exposure to Au) do not show such a strong correlation with the solvent dielectric (R 2 = 0.82 excluding DMSO data), although overall an increased background reactivity in more polar solvents is observed, in line with published reports. 32,33 The background rate is the highest in dimethylsulfoxide (DMSO), and NMR analysis shows that 1 converts rapidly to 2 via an intermediate, possibly a peracid, sulfone, or both. We observe some background reactivity in dimethylformamide (DMF) and NMF, while none is observed in TD or PC.…”

Electric fields drive bond homolysis

“…without a field or exposure to Au) do not show such a strong correlation with the solvent dielectric (R 2 = 0.82 excluding DMSO data), although overall an increased background reactivity in more polar solvents is observed, in line with published reports. 32,33 The background rate is highest in dimethylsulfoxide (DMSO), and NMR analysis shows 1 converts rapidly to 2 via an intermediate, possibly a peracid, sulfone, or both. We observe some background reactivity in dimethylformamide (DMF) and NMF, while none is observed in TD or PC.…”