Pharmacology is the study of drugs which is concerned with the uses, effects, and modes of action of drugs. It emerged as a major area in American medicine largely due to the efforts of John Jacob Abel (1857- 1938) who stressed the importance of chemistry in medicine, did research on the endocrine glands, first isolated epinephrine (adrenaline), crystallized insulin (1926), and became the first pharmacology professor in the U.S.
This field of study can be broken down into two smaller pieces: pharmacokinetics and pharmacodynamics. These are the two main areas of pharmacology dedicated to providing a comprehensive picture of the safety and action of a medication.
Pharmacokinetics is concerned with what your body does with a drug. Think about what happens when you eat food. The food travels from your mouth to your stomach and then to your intestines. Along each step of the process, the food is broken down, nutrients are absorbed, and waste is removed. A similar process occurs with drugs. Determining how the drug is absorbed, distributed throughout the body, broken down, and then eliminated is what constitutes pharmacokinetics. Pharmacokinetics is based on ADME: absorption, distribution, metabolism, and elimination.
The term pharmacodynamics comes from the ancient Greek word dynamikós, which means 'force or power.' Pharmacodynamics is the force, or power, the drug has on the body. Most drugs bind to specific receptor sites within the body to exert their force. Pharmacodynamics concepts include affinity, efficacy and potency, and whether the drug is an agonist or antagonist. Pharmacodynamics includes both the desired effect of the drug as well as the undesired, or side, effects.