According to the Medical dictionary the definition of “Pharmacokinetics is, sometimes abbreviated as PK, the word coming from Ancient Greek pharmakon "drug" and kinetikos "to do with motion,” is a branch of pharmacology dedicated to the determination of the fate of substances administered externally to a living organism. The substances of interest include pharmaceutical agents, hormones, nutrients, and toxins.” Pharmacokinetics is the study of the rate of drug absorption and disposition in the body. So, differential calculus is an important part in the development of many of the equations used. There are four pharmacokinetic processes to which every drug is subject in the body: Absorption, Distribution, Metabolism, and Excretion Absorption is the process by which a drug is made available to the fluids of distribution of the body. (i.e. blood or plasma) Most orally-administered drugs reach a maximum or peak level blood concentration within 1-2 hours. Once a drug has been absorbed from the stomach and/or intestines into the blood, it is circulated to some degree to all areas of the body to which there is blood flow and that is the process of distribution. Metabolism is the complex of physical and chemical processes occurring within a living cell or organism that are necessary for the maintenance of life. In metabolism some substances are broken down to yield energy for vital processes while other substances, necessary for life, are produced. Drugs are often eliminated by biotransformation, the alteration of a substance within the body, or excretion into the urine or the fluid that is made by the liver, also known as bile. The liver is the major location for drug metabolism, but specific drugs may experience biotransformation in other tissues. The metabolic transformation of drugs is catalyzed by enzymes, and most of the reactions obey Michaelis-Menten kinetics (a method of...