2 An Introduction to Drugs and their Action
2.1 Introduction
The primary objective of medicinal chemistry is the design and discovery of
new compounds that are suitable for use as drugs. The discovery of a new
drug requires not only its design and synthesis but also the development
of testing methods and procedures, which are needed to establish how a
substance operates in the body and its suitability for use as a drug. Drug
discovery may also require fundamental research into the biological and
chemical nature of the diseased state. This and other aspects of drug design
and discovery require input from specialists in other fields, such as biology,
biochemistry, pharmacology, mathematics, computing and medicine amongst
others, and the medicinal chemist to have an outline knowledge of these
fields.
This chapter seeks to give a broad overview of medicinal chemistry. It
attempts to provide a framework for the topics discussed in greater depth in
the succeeding chapters. In addition, it includes some topics of general interest
to medicinal chemists.
2.2 What are drugs and why do we need new ones?
Drugs are strictly defined as chemical substances that are used to prevent or cure
diseases in humans, animals and plants. Theactivityof a drug is its pharmaco-
logical effect on the subject, for example, its analgesic orb-blocker action.
Drugs act by interfering with biological processes, so no drug is completely
Fundamentals of Medicinal Chemistry, Edited by Gareth Thomas
#2003 John Wiley & Sons, Ltd
ISBN 0 470 84306 3 (Hbk), ISBN 0 470 84307 1 (pbk)