Overcoming hydrolytic degradation challenges in topical delivery: non-aqueous nano-emulsions

ABSTRACT

Introduction

Non-aqueous nano-emulsions (NANEs) are colloidal lipid-based dispersions with nano-sized droplets formed by mixing two immiscible phases, none of which happens to be an aqueous phase. Their ability to incorporate water and oxygen sensitive drugs without any susceptibility to degradation makes them the optimum dosage form for such candidates. In NANEs, polar liquids or polyols replace the aqueous phase while surfactants remain same as used in conventional emulsions. They are a part of the nano-emulsion family albeit with substantial difference in composition and application.

Areas covered

The present review provides a brief insight into the strategies of loading water-sensitive drugs into NANEs. Further advancement in these anhydrous systems with the use of solid particulate surfactants in the form of Pickering emulsions is also discussed.

Expert opinion

NANEs offer a unique platform for delivering water-sensitive drugs by loading them in anhydrous formulation. The biggest advantage of NANEs vis-à-vis the other nano-cargos is that they can also be prepared without using equipment-intensive techniques. However, the use of NANEs in drug delivery is quite limited. Looking at the small number of studies available in this direction, a need for further research in this field is required to explore this delivery system further.

KEYWORDS:

• Non-aqueous nano-emulsions
• water-sensitive drugs
• high-pressure homogenization
• Ostwald ripening
• characterization techniques
• Pickering emulsions

Article highlights

• NANEs are lipid-based dispersions with nano-sized droplets formulated using two non-aqueous immiscible phases and surfactant.

• Rotor-stator stirring, high pressure homogenization, ultrasonic emulsification, micro fluidization, phase inversion emulsification, membrane emulsification, microchannel emulsification, spontaneous emulsification, and solvent evaporation are the widely used methods to formulate NANEs.

• The droplet size, surface charge, droplet distribution, nature, and concentration of emulsifier are the main factors that govern the stability of NANEs.

NANEs have been successfully used to incorporate drugs that are labile towards hydrolytic as well as oxidative degradation such as cholecalciferol, ascorbic acid, astaxanthin, etc.

Declaration of interest

The authors have no 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. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

The article was not funded.