Bio pharmaceutics examines the interrelationship of the physical/chemical properties of the drug, the dosage form (drug product) in which the drug is given, and the route of administration on the rate and extent of systemic drug absorption. The importance of the drug substance and the drug formulation on absorption, and in vivo distribution of the drug to the site of action, is described as a sequence of events that precede elicitation of a drug’s therapeutic effect. The study of the chemical and physical properties of drugs and the biological effects they produce.  Bio pharmaceutics as its dosage form as related to the onset, duration, and intensity of its action.Biopharmaceutics is the study which shows how the drug absorption rate is affected by various factors like physical and chemical factors of the drug and the route through which the drug is administered. Bio pharmaceutics includes the stability of the drug, liberation of the API from dosage form, rate of extent of drug release and rate of conversion of drug to solution.