●Use of drugs 3
●Adverse effects and risk/benefit 3
●Drug history and therapeutic plan 4●Formularies and restricted lists 4
●Scientific basis of use of drugs in humans 4CHAPTER 1
INTRODUCTION TO THERAPEUTICS
USE OF DRUGS
People consult a doctor to find out what (if anything) is wrong
(the diagnosis), and what should be done about it (the treat-
ment). If they are well, they may nevertheless want to know
how future problems can be prevented. Depending on the diag-
nosis, treatment may consist of reassurance, surgery or other
interventions. Drugs are very often either the primary therapy
or an adjunct to another modality (e.g. the use of anaesthetics
in patients undergoing surgery). Sometimes contact with the
doctor is initiated because of a public health measure (e.g.
through a screening programme). Again, drug treatment is
sometimes needed. Consequently, doctors of nearly all special-
ties use drugs extensively, and need to understand the scien-
tific basis on which therapeutic use is founded.
A century ago, physicians had only a handful of effective
drugs (e.g. morphia, quinine, ether, aspirin and digitalis leaf)
at their disposal. Thousands of potent drugs have since been
introduced, and pharmaceutical chemists continue to discover
new and better drugs. With advances in genetics, cellular and
molecular science, it is likely that progress will accelerate and
huge changes in therapeutics are inevitable. Medical students
and doctors in training therefore need to learn something
of the principles of therapeutics, in order to prepare them-
selves to adapt to such change. General principles are dis-
cussed in the first part of this book, while current approaches
to treatment are dealt with in subsequent parts.
ADVERSE EFFECTS AND RISK/BENEFIT
Medicinal chemistry has contributed immeasurably to human
health, but this has been achieved at a price, necessitating a
new philosophy. A physician in Sir William Osler’s day in the
nineteenth century could safely adhere to the Hippocratic
principle ‘first do no harm’, because the opportunities for
doing good were so limited. The discovery of effective drugs
has transformed this situation, at the expense of very real risks
of doing harm. For example, cures of leukaemias, Hodgkin’s
disease and testicular carcinomas have been achieved through
a preparedness to accept a degree of containable harm. Similar
considerations apply in other disease areas.
All effective drugs have adverse effects, and therapeutic
judgements based on risk/benefit ratio permeate all fields of
medicine. Drugs are the physician’s prime therapeutic tools,
and just as a misplaced scalpel can spell disaster, so can a
thoughtless prescription. Some of the more dramatic instances
make for gruesome reading in the annual reports of the med-
ical defence societies, but perhaps as important is the morbid-
ity and expense caused by less dramatic but more common
errors.
How are prescribing errors to be minimized? By combining
a general knowledge of the pathogenesis of the disease to be
treated and of the drugs that may be effective for that disease
with specific knowledge about the particular patient. Dukes
and Swartz, in their valuable work Responsibility for drug-
induced injury,list eight basic duties of prescribers:- restrictive use– is drug therapy warranted?
2.careful choiceof an appropriate drug and dose regimen
with due regard to the likely risk/benefit ratio, available
alternatives, and the patient’s needs, susceptibilities and
preferences;
3.consultation and consent;
4.prescription and recording;
5.explanation;
6.supervision(including monitoring); - termination, as appropriate;
8.conformitywith the law relating to prescribing.
As a minimum, the following should be considered when
deciding on a therapeutic plan:- age;
2.coexisting disease, especially renal and or hepatic
impairment;
3.the possibility of pregnancy;
4.drug history;