ANTIDIARRHOEAL DRUGS
A
stimulates release of insulin from the
pancreas.
Rosiglitazone
reduces
resis-
tance to the effects of insulin in the
tissues and may be used together with
other hypoglycaemics.
SIDE EFFECTS
Certain antidiabetics may lower
the
blood glucose level too much, leading
to
hypoglycaemia
(low blood glucose
levels). Rarely, these drugs may also
cause a decreased blood cell count, a
rash, or intestinal or liver disturbances.
Metformin
does not cause hypogly-
caemia, although treatment with this
drug may result in nausea, appetite loss,
abdominal distension, and diarrhoea. It
should not be taken by people with
liver, kidney, or heart problems.
antidiarrhoeal drugs
COMMON DRUGS
an tispasm o d ics
•Atropine •Dicycloverine
• Hyoscine
o pio id s
•Codeine •Diphenoxylate
• Loperamide
BULK-FORMING AGENTS AND ADSORBENTS
• Ispaghula •Kaolin •Methylcellulose
Drugs that are used to reduce or stop
diarrhoea and to help regulate bowel
action in people who have had a
colos-
tomy
or
ileostomy.
In most acute (of
sudden onset) cases of diarrhoea, the
only treatment recommended is
oral
rehydration therapy.
Antidiarrhoeal drugs
are not suitable for children.
HOW THEY WORK
Antidiarrhoeal drugs include adsorbents
(such as kaolin), which can absorb the
toxic substances that cause diarrhoea;
bulk-forming agents (such as ispagh-
ula), which absorb water from the
faeces thereby making them
firmer;
and antimotility drugs (including the
opioid drugs,
morphine
and
codeine,
and
loperamide, which is chemically similar
to opioids but does not have an opioid
effect), which slow movement through
the intestine.
SIDE EFFECTS
Antidiarrhoeal drugs may cause consti-
pation. In cases of diarrhoea that has
resulted from an infection, antidiar-
rhoeals may delay recovery by slowing
down the elimination of the causative
microorganisms.
Bulk-forming
agents
may
cause
intestinal obstruction if taken without
sufficient drinking water or if the bowel
is narrowed.
Prolonged use
of opioid antidiar-
rhoeals may lead to physical dependence
(see
drug dependence
), producing nau-
sea, abdominal pain, and diarrhoea if
the drug is stopped suddenly.
WARNING
Antidiarrhoeals should not be taken regu-
larly except on medical advice since they
may mask a serious underlying disorder.
antidiuretic hormone
See
ADH.
antidote
A substance that neutralizes or counter-
acts the effects of a poison.
A chemical antidote works by com-
bining
with
a
poison
to
form
an
innocuous substance or by, in some
way, blocking or diverting the action of
the poison. A mechanical antidote pre-
vents the absorption of poison into the
blood from the stomach and intestine.
anti-D(Rh0) immunoglobulin
An
antiserum
that contains antibodies
(see
antibody
), proteins that are manu-
factured by the immune system against
Rhesus (Rh) D factor, a substance pre-
sent on the red blood cells of people
with Rh-positive blood.
Anti-D(Rh0) immunoglobulin is given
to all Rh-negative women routinely at
intervals during normal pregnancy and
at delivery. A dose is also given after an
amniocentesis,
miscarriage, or any event
in which the baby’s blood may enter the
mother’s circulation. The injected anti-
bodies destroy any red blood cells from
the fetus that have entered the woman’s
bloodstream. This helps to prevent the
woman from forming her own anti-
bodies against Rh-positive blood, which
might adversely affect a subsequent
pregnancy. (See also
haemolytic disease of
the newborn; Rhesus incompatibility.)
antiemetic drugs
COMMON DRUGS
an ticho lin ergics
•Hyoscine hydrobromide
an tihistam in es
• Cinnarizine •Cyclizine
• Dimenhydrinate •Meclozine •Promethazine
butyrophenones
•Haloperidol
phenothiazines
•Chlorpromazine
• Perphenazine •Prochlorperazine
serotonin antagonists
•Granisetron
• Ondansetron •Tropisetron
motility stim ulan ts
•Domperidone
• Metoclopramide
others
•Betahistine •Nabilone
A group of drugs used in the treatment
of the
nausea
and
vomiting
that are asso-
ciated
with
motion sickness
,
vertigo
,
Meniere’s disease, radiotherapy,
and cer-
tain drugs. Antiemetics are not normally
used in the treatment of food poisoning
because the body needs to rid itself of
harmful substances.
HOW THEY WORK
Antihistamines
and
anticholinergic drugs
reduce vomiting associated with vert-
igo by suppressing the vomiting reflex
(in which the stomach muscles con-
tract to expel the stomach contents),
which is triggered by nerve activity in
the balance centre of the inner ear.
Motility stimulants
work by increasing
movement through the gastrointestinal
tract. The most powerful antiemetics
are used to control nausea and vomit-
ing associated with radiotherapy or
anticancer drugs
and include
serotonin
antagonists,
such as
ondansetron,
and
nabilone.
These drugs act on
neurotrans-
mitters
in the brain.
SIDE EFFECTS
Only certain antiemetics are used to
treat vomiting in early pregnancy because
some can damage the developing fetus.
Many antiemetics can cause drowsiness.
WARNING
Antiemetics should not be taken regu-
larly except on medical advice since they
may mask a serious underlying disorder.
antifreeze poisoning
Most antifreeze in the UK contains eth-
ylene glycol, which is poisonous. Most
cases of antifreeze poisoning, which is
extremely rare, occur as a result of acci-
dental swallowing.
SYMPTOMS
Drinking antifreeze initially produces
effects similar to
alcohol intoxication,
but
vomiting, stupor, seizures, and coma
may follow; acute
kidney failure
may
occur within 24 to 3 6 hours.
TREATMENT
Any person believed to have drunk
antifreeze requires immediate medical
attention. Until such help arrives, small
amounts of alcohol (preferably a spirit
such as brandy or whisky) should be
given,
if
possible,
because
alcohol
reduces the rate at which antifreeze is
metabolized by the body.
Hospital
treatment
may
include
removing the antifreeze from the stom-
ach using a stomach pump (see
lavage,
gastric)
and giving
diuretic drugs,
alcohol,
and bicarbonate, intravenously, to correct
excess
acidity
in
the
body
fluids.
Haemodialysis
(see
dialysis)
may be
required to remove ethylene glycol from
the blood and to treat kidney failure.
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