18 Drug discovery and development
K. WILSON
18.1 Human disease and drug therapy
18.2 Drug discovery
18.3 Drug development
18.4 Suggestions for further reading
18.1 HUMAN DISEASE AND DRUG THERAPY
18.1.1 Human disease
The wide range of diseases to which humans are exposed have in common the fact that
each is the result of either some physiological dysfunction caused by a gene mutation
or incorrect expression of the related protein, or of the exposure of the individual to an
environmental factor, such as pesticides, diet, or bacterial, fungal or viral infection. The
dysfunction gives rise to characteristic medical symptoms that enable the condition to be
diagnosed, commonly by diagnostic tests of the type described in Chapter 16, and an
evaluation made of the severity of the condition and the future prospects of the patient
makinga full recovery fromit. Underlying manyof the conditionsat a molecular levelis a
change in the amount, function or activity of one or more proteins that in turn trigger
changes in cellular, tissue or organ function. A large part of current worldwide medical
research is aimed at the elucidation of the molecular mechanisms underlying diseases
such as the various forms of cancer and neurological conditions such as Parkinson’s
disease, motor neurone disease and multiple sclerosis, in order to identify key proteins
involved in the disease process with a view to selecting one of the proteins as a target for
the development of a new drug and thereby to minimise or eliminate the symptoms.
18.1.2 The nature of drugs and their target proteins
At the present time there are just over 800 drugs in current use worldwide. The
majority are organic molecules with a molecular weight of less than 500. However,
other possibilities for the nature of the drug are receiving increasing attention.
One such option is to develop a monoclonal antibody as the drug to target the protein.
Thus an increasing number of monoclonal antibodies are being developed for the
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