Controlled drug delivery systems： the next 30 years

The drag delivery scientists need to reexamine the advances made during the past 60 years, analyze our current abilities, and design the future technologies that will propel us to achieve the next level of drug delivery technologies. History shows that the first generation （1G） of drag delivery research during 1950-1980 was quite productive, while the second generation （2G） technologies developed during 1980 2010 were not as prolific. The ultimate goal of drug delivery research is to develop clinically useful formulations to treat various diseases. Effective drug delivery systems can be developed by overcoming formulation barriers and/or biological barriers. The engineering approach has a limit in solving the problem, if biological difficulties are not clearly identified and understood. The third generation （3G） drug delivery systems will have to focus on understanding the biological barriers so that they can be overcome by engineering manipulation of the drug delivery systems. Advances in the next 30 years will be most accelerated by starting open dialogues without any preconceived ideas on drug delivery technologies. The new generation of drug delivery scientists needs to be aware of the successes and limitations of the existing technologies to design the new technologies for meaningful advances in the future.