Pickering emulsions: challenges and opportunities in topical delivery

ABSTRACT

Introduction: Topical drug delivery is a challenging area with many advantages such as avoidance of first passage effect, stabilization of blood concentrations and attainment of local therapeutic effect with fewer side effects. Despite all these advantages, topical drug delivery remains limited to few molecules, since skin acts as a barrier to the delivery of many therapeutic molecules. To overcome this obstacle, a favored strategy relies on selecting suitable vehicles for dermatologic therapy, such as emulsions, gels and, more recently, nanoparticulate systems.

Areas covered: Particle-stabilized emulsions, also known as Pickering emulsions, have garnered interest in recent years. Although most of the investigation on Pickering emulsions has been based on model systems with inorganic or organic solid particles, recent advances have been made regarding the application of nanocarriers, protein-based particles or cyclodextrins for this purpose. This review reports the latest advances in Pickering emulsions technical challenges, and discusses the potential benefits and drawbacks of using these formulations for topical pharmaceutical and cosmetic applications as an alternative to conventional surfactant-based systems.

Expert opinion: Pickering emulsions appear as a multifunctional dosage form with endless advantages. A great deal of progress is expected in this area, which might represent a renewed vision for the pharmaceutical and cosmetic industry.

KEYWORDS:

• Cyclodextrins
• dermal delivery
• pickering emulsions
• silica
• starch
• titanium dioxide

Article highlights

• Pickering emulsions use in topical formulations is only now emerging, mostly due to the consumers’ demand for natural (‘green’) and safer products and to the industry quest for low cost and environment- friendly processes.

• The use of organic and inorganic particles in pharmaceutical and cosmetic products is rising faster with the advantage that their use can modify the drug release and promote better drug penetration.

• The biocompatibility of organic particles on Pickering emulsions and the capacity to promote controlled and sustained drug release are attractive features for formulators.

• The advances in novel mechanisms to stabilize Pickering emulsions result in tailor-made dosage forms, where properties can be shaped and enhanced in order to assure the desired ones.

• New improved vehicles including Pickering emulsions represent a significant challenge to the industry.

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Declaration of interests

The authors gratefully acknowledge the support from Fundação para a Ciência e Tecnologia (Portugal), FEDER (UID/DTP/04138/2013 to iMed.ULisboa and grant SFRH/BDE/51599/2011). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.