Discovery

Abstract

From ancient times, man, by a process of trial and error, has identified a number of plants and other substances which either eaten raw or boiled up will produce certain pharmacological effects. The classic example is probably alcohol which virtually every culture learned to produce independently. Alcohol has a number of well-known effects depending upon the dosage used. In small amounts it causes flushing of the skin (vasodilatation), larger quantities produce a feeling of well-being, and if the dose is further increased, loss of inhibition occurs leading to signs of aggression. Beyond aggression, somnolence occurs and indeed coma can supervene as the central nervous system becomes progressively depressed. This well-known continuum of effects illustrates very neatly the effect of increasing dosage over a period of time with a substance which is metabolised simply and at a fairly constant rate. It further illustrates that where small quantities of a drug are useful, larger quantities are not necessarily better, in fact they are usually harmful.