Smart Drug Delivery Systems Learned from Nature

Introduction When transdermal drug delivery systems were first introduced clinically about 25 years ago, the purpose of controlled release technologies was the constant-rate, long-term release of active agents; a major objective of CR technologies was to develop dosage forms which, with one dose, release active agents at a constant rate effective over a long time period, There were two major underlying reasons, First, the optimum tissue concentration and optimum release characteristics of drug molecules were not fully understood for treating diseases, and second, owing to the large individual differences in pharmacokinetics within the body, the accurate control of concentrations in blood and tissue did not make sense. Of course even today, long term constant-release systems are effective in gaining patient compliance and treating many diseases. However timed-drug delivery systems are increasingly necesary. The active agents in pharmaceuticals are bioinformation molecules that control bodily functions by acting as signal or false-signal molecules. These are frequently produced in the body and released for the maximum effect and without waste. Recently research has started to learn about not only drug molecules but also how plants and insect economically and effectively use their bioinformation molecules. This science is called biomimicry and considered as a valuable new field in the 21 biotech century [1]. For example, the chemical reactions, and the processes of release and movement of information molecules within our body, are the most efficient functions achieved by living creatures through the long course of evolution. Biomimicry, or the imitation of these biological functions, will likely play an essential role in developing sustainable CR technologies. However, it is certainly not easy to correctly understanding the ingenious functions of the living creatures and exactly mimic them. Hence at this stage of research the main purpose of biomimicry would be to develop novel CR and drug delivery systems with the inspiration gained in the course of learning from nature. This paper examines biomimicry in CR technologies in relation to three items: (1) mimicking elements, (2) mimicking mechanisms, and (3) utilizing mechanisms. Mimicking elements means discovering drug molecules produced when necessary in the body, which has been the main stream of pharmaceutical research and development to date. Mimicking mechanisms means understanding the mechanisms that use bioinformation molecules, and using them in DDS technologies, thus making them similar to what nature dose. Utilizing mechanisms on the other hand, means using biological functions as is to develop highly economical DDS.