Reviewing the use of ethylcellulose, methylcellulose and hypromellose in microencapsulation. Part 1: materials used to formulate microcapsules

Abstract

This review highlights references where ethylcellulose, methylcellulose and hypromellose were used to make microcapsules. The review has been divided into three parts. This first part discusses various materials used to formulate microcapsules, such as the three encapsulating polymers as well as protective colloids, plasticizers and surfactants. The second part covers the various techniques used to make microcapsules, such as temperature-induced phase separation, emulsion solvent evaporation, solvent evaporation, film coating, and others. The third part covers the various applications for which microcapsules are used, such as modified release, improved efficacy and safety, taste- and odor-masking, and others. It is hoped that formulators can use Part 1 as a guide to the literature documenting formulation of microcapsules made from these encapsulating polymers. SciFinder was utilized to identify the pertinent literature. SciFinder leverages literature databases, such as Chemical Abstracts Service Registry and Medline. A total of 379 references were identified during the review. The need for a three-part review reflects the extensive amount of literature identified concerning these three encapsulating polymers.

Keywords::

• Encapsulation
• microcapsule
• microsphere
• microparticle
• multiparticulate
• hydroxypropylmethylcellulose
• HPMC

Acknowledgment

The authors gratefully acknowledge Roland Adden for providing helpful insight regarding cellulose ether chemistries.

Declaration of interest

The authors are employed by The Dow Chemical Company.