Pharmacology is the study of the properties of drugs and their actions on living tissue.
In the broadest sense a drug is any chemical which modifies the function of living tissue. The main focus of attention is on those drugs which maintain and restore health. The science of pharmacology is closely linked with chemistry, physiology, molecular biology, toxicology, and microbiology. Pharmacologists are involved in drug development and evaluation. This begins with the design and chemical synthesis or extraction of new drugs.