Pharmacology can be defined as a discipline of paramedical sciences that teaches how the use of drugs can bring about changes from pathological states to physiological conditions. Whereas mediator pharmacology is a subdivision pharmacology which teaches the functions of molecules released in the body and produces profound pharmacological effects. Also, their sustained release may results in pathological conditions. The agonists or antagonists of these mediators may offer novel therapeutic agents for clinical benefits. This book provides necessary scientific developments in mediator pharmacology.