2. INTRODUCTION
โข Biopharmaceutics 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.
โข โBiopharmaceutics is the study of the factors influencing the bioavailability of a drug
in man and animals and the use of this information to optimize pharmacological and
therapeutic activity of drug products
โข Pharmacokinetics is the science of the kinetics of drug absorption, distribution, and
elimination (i.e, metabolism and excretion)
โข Pharmacodynamics is the study of the biochemical and physiological effects of drugs
on the body; this includes the mechanisms of drug action and the relationship
between drug concentration and effect
4. โข Absorption is defined as the process by which a drug proceeds from the site of
administration to the site of measurement (usually blood, plasma or serum).
โข Distribution is the process of reversible transfer of drug to and from the site of
measurement (usually blood or plasma).
โข Metabolism is the process of a conversion of one chemical species to another
chemical species
โข Elimination is the irreversible loss of drug from the site of measurement (blood,
serum, plasma). Elimination of drugs occur by one or both of: ยท metabolism ยท
excretion
โข Excretion is defined as the irreversible loss of a drug in a chemically unchanged or
unaltered form
โข Once a drug is in the systemic circulation, it is distributed simultaneously to all
tissues including the organ responsible for its elimination. The distinction between
elimination and distribution is often difficult. When such a distinction is either not
desired or is difficult to obtain, disposition is the term used.
