Incorporation of benzoyl peroxide nanocrystals into adapalene-loaded solid lipid microparticles: Part II - Solid-in-Oil dispersion of nanoparticulate benzoyl peroxide

Benzoyl peroxide as a monotherapeutic and in combination with adapalene is a cornerstone of current acne therapy, but its unfavourable side effect profile reduces the therapeutic value of this compound. The incorporation into an adapalene-loaded microparticulate lipid matrix, which - via the principle of targeted erosion - allows the targeted release of active substances in the hair follicles, is a promising approach to reduce side effects such as skin redness, increased scaling and allergic reactions. However, there are challenges to the production of such a vehicle which require a galenic solution. That is in particular the redispersion of nanoparticulate benzoyl peroxide in lipids while maintaining its nanodisperse character. In the present work, the lamellar liquid crystalline phase of a binary water/phospholipid system is used to stabilize a nanosuspension during freeze-drying. Both after redispersing in water and after dispersing in nonpolar fat phases, the initial size of the nanosuspension was recovered with only minor deviations. The found cryoprotective effect of purified phospholipid allows the generation of highly concentrated solid-in-oil systems both in fat phases liquid at room temperature and in lipid melts, which after solidification can serve as starting material for the preparation of lipid microparticles loaded with benzoyl peroxide nanocrystals.