Prodrugs and soft drugs.

This review focuses on a new approach to the development of drugs, namely on prodrugs and soft drugs. Nowadays, we try to design drugs that heal sick people having the best acceptance of patients. They must be efficient and selective on their site of action and must be metabolized to non-toxic derivatives. Both, prodrugs and soft drugs should have good distributive properties to enhance their quality. They are designed to maximize the amount of an active drug that reaches its target, through changing the physicochemical, biopharmaceutical or pharmacokinetic properties of drugs. Prodrugs are changed into the active drug within the body through enzymatic or non-enzymatic reactions. Soft drugs are novel and active analogues of already known therapeutic agents. It is expected that continued studies will improve drug properties so as to achieve the best drug delivery system.