ABSTRACT
This chapter presents some basic principles of drug release from microcapsules and to give an overview of ensemble release properties of microencapsulated drugs. Drug release from microcapsules has been extensively investigated on several levels. From the onset of interest in sustained or controlled drug delivery, release of encapsulated substances has been treated as a function of the mean product character. The intention of this chapter is to present some basic principles of drug release from microcapsules and to give an overview of ensemble release properties of microencapsulated drugs. Models proposed are listed with the most common equations used to describe release of the core material from microcapsules and microspheres. The main system variables that govern drug release from microcapsules and microspheres are not exclusively limited to the field of microparticles. The release rate from gelatin microcapsules or micropellets was reduced when formaldehyde was used as a cross-linking agent.
