Abstract
Several water-in-oil in water multiple emulsions carrying calcium thioglycolate in the inner aqueous phase were prepared as models for depilatory products. Rheology steady-state flow experiments revealed the multiple systems to be adequately stable after 3-month storage. The effective multiplicity of the emulsions was assessed by optical microscopy and confirmed by thioglycolic acid release experiments. The stability of thioglycolic acid against oxidative degradation at 25°C was far higher in the W/O/W emulsion than in an O/W reference emulsion, while at 45°C the degradation rate was quite similar in both systems.
ACKNOWLEDGMENTS
This work was supported by Progetto Nazionale Tecnologie Farmaceutiche.