Emulsions with alkyl polyglucosides as carriers for off-label topical spironolactone – safety and stability evaluation

Abstract

Androgens play an important role in the pathogenesis of acne. Being an anti-androgen drug with many side effects, spironolactone has recently been used in dermatology as a topical therapy for acne. Off-label drug use in dermatology is common, although those drugs are basically available as compounded formulations; the choice of a proper vehicle is often neglected in that case. Alkyl polyglucosides (APGs) are a FDA certified class of polyethylene glycol (PEG)-free surfactants produced from the renewable resources. Following the preformulation tests, two different APG emulsifiers were used in this study to stabilize emulsions as carriers for topical spironolactone. Assessment of the physical stability of emulsions per se and after incorporation of 5% of spironolactone was performed using polarization microscopy, electrical conductivity and pH measurements. The skin irritation profile and moisturizing potential was assessed in vivo on human volunteers. APG-based emulsions per se and with 5% of spironolactone showed acceptable skin irritation profiles and significant potential for skin hydration, which is important in acne treatment. Good physical stability and satisfying preliminary safety profile of all investigated samples were also obtained showing that moisturizing APG-based emulsions could be promoted as vehicles for off-label topical spironolactone.