Getting a chemical at a certain spot whether it is on a plant or inside the human body comes at a cost because of the spraying effort and pill consumption. If the desired effect is to last, administering the chemical has to be repeated over and over again. Supplying a large single dose reduces that frequency but is not always an option because the large dose is toxic or has adverse side effects compared to a small dose. Slow release combines the beneficial effects of applying a single large dose distributed over a long time in small quantities. Slow-release systems work by reducing the diffusion of a chemical into the system. The practical technology behind slow release can be found in Micro-encapsulation or inclusion compounds.
Slow-release tablet systems are presently used to maintain steady levels of drugs in the blood.