Controlled Release Systems

Drugs are bioactive agents used to treat or prevent diseases and illnesses through chemical action in the body. In order for a drug to be effective, it has to be at the site of the cause of the illness, whether it is an infection, a blockage of an artery, pain, or some other malfunction of the bodily organs or tissues due to genetic causes, trauma, or aging. In order for the drug to reach this target site, it has to be introduced to the body (administration), cross barriers (distribution), modified by the enzymes within the body (metabolism), and removed from the body (elimination or excretion). All these processes affect the rate, dose at the target, efficacy, and fate of the drug. In order for the drug to have prolonged or predetermined period of presence, to be of sufficiently high concentration, and to be localized specifically at the target tissue, “controlled release systems” are designed. All the above-mentioned topics have to be discussed before a controlled release system can be designed.