Pharmacognosy is a branch of pharmacy which deals with the identification and analysis of the plant and animal tissues from which drugs may be extracted. The pharmacodynamicist, or pharmacologist, identifies the effects produced by drugs, and determines the sites and mechanisms of their action in the body. The pharmacologist studies the physiological or biochemical mechanisms by which drug actions are produced. The pharmacologist also investigates those factors which modify the effects of drugs, i.e. the routes of administration, influence of rates of absorption, differential distribution, and the body's mechanisms of excretion and detoxification, on the total effect of a drug. Pharmacotherapeutics is the study of the use of drugs in the diagnosis, prevention, and treatment of disease states.
Toxicology is the study of drug effects which are inimical to health.
Experimental pharmacology, in the broadest sense, deals with the reactions of living organisms to chemical agents, or, to put the matter in another way, the behavior of organisms to changes in the chemical environment in which they live. Pharmacology is a part of biology. . . . Of all the vast number of pharmacologic reactions, those which the physician attempts to use for curative purposes are of the greatest interest and most deserved of study. A medicine or preparation with no inherent pertinent pharmacologic activity which is effective only by virtue of the factor of suggestion attendant upon its administration. A drug preparation incorporated into an experiment with the intention that it have effects on the experimental system qualitatively similar to those expected of the independent variable.