It is the study of drugs - what they are, how they work and what they do. It includes the study of the manner in which the function of living tissues and organisms is modified by chemical substances and the study of the effect of chemical agents on living processes. Pharmacology is commonly subdivided into pharmacodynamics (the biological effects of drugs) and pharmacokinetics (absorption, distribution, metabolism and excretion), also expressed as, respectively, the effects of drugs on the body and the effect of the body on drugs. (from A Dictionary of Pharmacology and Clinical Drug Evaluation, by Desmond Lawrence and John Carpenter). Pharmacology should not be confused with Pharmacy, which is a quite different area of study involving the scientific legal and managerial aspects of dispensing medicines. It is important to realise the difference between pharmacology and pharmacy because these subjects lead to quite different careers.