Pharmacodynamics: Mechanism of Drug Action

Pharmacodynamics is the study of mechanisms behind drug actions. It helps us understand the behaviour of drugs inside a body and the way body reacts to the drugs. Every class of drug preserves a unique mechanism of action mostly through different receptor proteins and sometimes involving associated secondary messengers. Pathway or the mechanism a drug follows determines the onset of action, drug interactions, adverse drug reaction, etc. After administration of drugs, showing the pharmacological effects involves many interconnected phases and transportation of drug molecules to the site of action is really crucial and for that our body uses different enzymes, ion exchange pumps, and specialized proteins. On reaching the site of action, drugs are attached as signals or signalling molecule and upon binding to its specific ligand binding site the transducer mechanism takes place. So, in this chapter we have focused on the molecular basis of the drug action which will not only serve as a first-hand guide to pharmaceutical and medical graduates but also to students from biological sciences.