Drug delivery vehicles with improved encapsulation efficiency: taking advantage of specific drug–carrier interactions

INTRODUCTION: Drug encapsulation strategies are vital for the delivery of poorly soluble, fragile or toxic compounds. Increasing a drug's encapsulation efficiency in drug carrier particles can achieve a stronger therapeutic effect along with minimized side effects. For these reasons, new encapsulation methods are developed by using new materials and various types of drug-carrier interaction. AREAS COVERED: Strategies used for drug encapsulation are discussed in this review, focusing particularly on approaches leading to high encapsulation ratios resulting from specific interactions between the drug and the carrier. In the first part, classical encapsulation by hydrophobic self-assembly, its limitations and improvements are briefly discussed. Following this, encapsulation strategies for specific drugs are reviewed, where particular kinds of interaction play a role between the drug and the encapsulating material, which can lead to dramatically increased entrapment. Such specific approaches can be utilized more generically for various classes of molecules with similar properties, with regard to their ability to participate in a given kind of interaction. EXPERT OPINION: With the focus on delivering a high drug dose precisely to the site of action, high encapsulation efficiency is the first thing to consider in drug development. Academic research shows considerable interest in specific encapsulation, and it seems to be an established trend now to design drug delivery particles to achieve the most favorable properties. The authors believe the research in this area will focus on material properties and interactions between the drug and the carrier to ensure high drug loading into particles.