DRUG
Wet
drowning
Types of drowning
In four-fifths of deaths due to drowning, the victim
has inhaled liquid into his or her lungs. In the
other fifth, no liquid is present in the lungs; this
condition is called dry drowning. In both cases,
death is by suffocation.
drug
A chemical substance that alters the
function of one or more body organs or
the process of a disease. Drugs include
prescribed medicines, over-the-counter
remedies, and various substances (such
as alcohol, tobacco, and drugs of abuse)
that are used for nonmedical purposes.
CLASSIFICATION AND LICENSING
Drugs normally have a chemical name,
an officially approved generic name
(see
generic drug
) ,
and often a brand
name. Drugs for medical use are either
licensed for prescription by a doctor
only or can be bought over the counter
at a chemist’s or supermarket.
Most drugs are artificially produced
to ensure a pure preparation with a pre-
dictable potency (strength). Some drugs
are genetically engineered. A drug is
classified
according
to
its
chemical
make-up, or the disorder it treats, or
according to its specific effect on the
body. All new drugs are tested for their
efficiency and safety. In the UK, drugs
are
licensed
by
the
Medicines
and
Healthcare products Regulatory Agency
(MHRA). A licence may be withdrawn
if toxic effects are reported or if the
drug causes serious illness.
USES
Drugs can be used to relieve physical
or mental symptoms, to replace a nat-
ural substance that is deficient, or to
stop the excessive production of a
hor-
mone
or other chemical by the body.
Some drugs are given to destroy for-
eign organisms, such as bacteria or
fungi. Others, w hich are known as
vac-
cines
,
are given to stimulate the body’s
immune system
to form
antibodies
.
METHODS OF ADMINISTRATION
Drugs are given by mouth or injection,
or are applied directly or indirectly to
the affected site via transdermal, nasal,
and other direct routes (for example, to
the lungs through an inhaler). Drugs that
are injected take effect more rapidly than
those taken by mouth because they enter
the bloodstream directly, without pass-
ing first through the digestive system.
There are different routes for injection.
The fastest is intravenous; intramuscular
is also fast because muscles have a good
blood supply; subcutaneous injection is
the slowest method, but is easier for
self-administration of drugs.
ELIMINATION
Unabsorbed drugs are broken down in
the liver. Those taken orally are excreted
in faeces; those that have entered the
bloodstream are eliminated in urine.
ADVERSE EFFECTS
Most drugs can produce adverse effects.
These effects may wear off as the body
adapts to the drug. Adverse effects are
more likely if there is a change in the
absorption, breakdown, or elimination
of a drug (caused, for example, by liver
disease). Unexpected reactions some-
times occur due to a genetic disorder,
an allergic reaction, or the formation of
antibodies that damage body tissues.
Some drugs interact with food, alcohol,
or other drugs.
Many drugs can cross the placenta;
some affect the growth and develop-
ment of the fetus if taken by a pregnant
woman. Most drugs can pass into the
breast m ilk of a nursing mother, and
some have adverse effects on the baby.
drug abuse
Use of a drug for a purpose other than
that for w hich it is normally prescribed
or recommended. Commonly abused
drugs include
stimulant drugs
,
such as
cocaine
and
amphetamine drugs
;
central
nervous system
depressants,
such as
alcohol
and
barbiturate drugs
;
hallucino-
genic drugs
,
such as
LSD
;
and narcotics
(see
opioid drugs
) ,
such as
heroin
.
Some
drugs are abused in order to improve
performance in sports (see
sports, drugs
and
;
steroids, anabolic
) .
Problems resulting from drug abuse
may arise from the adverse effects of
the drug, accidents that occur during
intoxication, or from the habit-forming
potential of many drugs, w hich may
lead to
drug dependence
.
drug addiction
Physical or psychological dependence
on a drug (see
drug dependence
) .
drug dependence
The compulsion to continue taking a
drug, either to prevent the ill effects
that occur when it is not taken, or to
produce the desired effects of taking it.
TYPES
Drug dependence can be psychological
or physical, or more commonly both. A
person is psychologically dependent if
he or she experiences craving or distress
when the drug is withdrawn. In physical
drug dependence, the body has adapted
to the drug, causing the symptoms and
signs of
withdrawal syndrome
when the
drug is stopped. These symptoms are
relieved if the drug is taken again.
CAUSE
Dependence develops as a result of reg-
ular
or
excessive
drug
use,
and
it
develops most frequently with drugs
that alter mood or behaviour.
SYMPTOMS AND SIGNS
Drug dependence may cause physical
problems, for example lung and heart
disease from smoking and liver disease
from
excessive
alcohol
consumption.
Mental problems, such as anxiety and
depression, are common during drug
withdrawal. Dependence may also be
linked with drug tolerance, in w hich
increasing doses of the substance are
needed to produce the same effect.
COMPLICATIONS
Complications such as
hepatitis
or
AIDS
are a particular risk for people who
abuse drugs by injection. Death may
occur as a result of taking a contami-
nated drug, or be due to accidental
overdose from taking a purer, more
potent preparation than usual.
TREATMENT AND OUTLOOK
Controlled withdrawal programmes are
available in special centres and hospitals,
w hich usually offer gradual, supervised
reductions
in
dose.
Alternative,
less
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