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Iron salts
Iron poisoning in childhood is usually accidental.
The
symptoms are nausea, vomiting, abdominal pain, diarr-
hoea,
haematemesis,
and rectal
bleeding.
Hypotension
and hepatocellular
necrosis
can occur
later.
Coma,
shock,
and metabolic acidosis indicate severe poison-
ing.
Advice should be sought
from the National
Poisons
Information Service if a significant quantity of iron has
been ingested within the previous hour.
Mortality is reduced by intensive and specific therapy
with desferrioxamine, which chelates iron. The serum-
iron concentration is measured as an emergency and
intravenous desferrioxamine given to chelate absorbed
iron in excess of the expected iron binding capacity.
In
severe toxicity intravenous desferrioxamine should be
given
immediately
without waiting for the result of the
serum-iron measurement.
DESFERRIOXAMINE MESILATE
(Deferoxamine Mesilate)
Indications
iron poisoning;
chronic iron overload
(section 9.1.3)
Cautions
section 9.1.3
Renal impairment
section 9.1.3
Pregnancy
section 9.1.3
Breast-feeding
section 9.1.3
Side-effects
section 9.1.3
Dose
. By continuous intravenous infusion,
ADULT
and
CHILD
up to 15 mg/kg/hour,
reduced after 4–6 hours;
max.
80 mg/kg in 24 hours (in severe cases,
higher doses
on advice from the National Poisons Information
Service)
Preparations
Section 9.1.3
Lithium
Most cases of lithium intoxication occur as a complica-
tion of
long-term therapy and are caused by reduced
excretion of
the drug because of
a variety of
factors
including dehydration,
deterioration of
renal
function,
infections, and co-administration of diuretics or NSAIDs
(or
other
drugs that
interact).
Acute deliberate over-
doses may also occur with delayed onset of symptoms
(12 hours or more) owing to slow entry of
lithium into
the tissues and continuing absorption from modified-
release formulations.
The early clinical
features are non-specific and may
include apathy and restlessness which could be con-
fused with mental
changes arising from the patient’s
depressive illness.
Vomiting,
diarrhoea,
ataxia,
weak-
ness,
dysarthria,
muscle twitching,
and tremor
may
follow. Severe poisoning is associated with convulsions,
coma,
renal
failure,
electrolyte imbalance,
dehydration,
and hypotension.
Therapeutic serum-lithium concentrations
are within
the range of 0.4–1 mmol/litre; concentrations in excess
of
2 mmol/litre are
usually associated with serious
toxicity and such cases
may need treatment
with
haemodialysis if neurological symptoms or renal failure
are present.
In acute overdosage much higher serum-
lithium concentrations may be present without features
of
toxicity and all
that
is usually necessary is to take
measures to increase urine output
(e.g.
by increasing
fluid intake but
avoiding diuretics).
Otherwise,
treat-
ment
is supportive with special
regard to electrolyte
balance,
renal
function,
and control
of
convulsions.
Gastric lavage may be considered if it can be performed
within 1 hour of ingesting significant quantities of
lith-
ium.
Whole-bowel
irrigation should be considered for
significant ingestion,
but advice should be sought from
the National Poisons Information Service,
p.
32.
Phenothiazines and related drugs
Phenothiazines cause less depression of consciousness
and respiration than other
sedatives.
Hypotension,
hypothermia,
sinus tachycardia,
and arrhythmias may
complicate poisoning.
Dystonic reactions
can occur
with therapeutic doses (particularly with prochlorper-
azine and trifluoperazine), and convulsions may occur in
severe cases. Arrhythmias may respond to correction of
hypoxia, acidosis, and other biochemical abnormalities,
but
specialist
advice should be sought
if
arrhythmias
result
from a prolonged QT interval;
the use of
some
anti-arrhythmic drugs
can worsen such arrhythmias.
Dystonic reactions are rapidly abolished by injection
of
drugs such as procyclidine (section 4.9.2)
or diaze-
pam (section 4.8.2,
emulsion preferred).
Atypical antipsychotic drugs
Features of
poisoning by atypical
antipsychotic drugs
(section 4.2.1)
include drowsiness,
convulsions,
extra-
pyramidal
symptoms,
hypotension,
and ECG abnorm-
alities (including prolongation of the QT interval). Man-
agement is supportive. Activated charcoal can be given
within 1 hour of
ingesting a significant
quantity of
an
atypical antipsychotic drug.
Stimulants
Amfetamines
Amfetamines cause wakefulness, exces-
sive activity, paranoia, hallucinations,
and hypertension
followed by exhaustion, convulsions, hyperthermia, and
coma.
The early stages can be controlled by diazepam
or
lorazepam;
advice
should
be
sought
from the
National
Poisons
Information Service (p.
32)
on the
management
of
hypertension.
Later,
tepid sponging,
anticonvulsants,
and
artificial
respiration
may
be
needed.
Cocaine
Cocaine stimulates the central
nervous sys-
tem,
causing
agitation,
dilated
pupils,
tachycardia,
hypertension, hallucinations,
hyperthermia, hypertonia,
and hyperreflexia;
cardiac effects include chest
pain,
myocardial infarction,
and arrhythmias.
Initial
treatment
of
cocaine poisoning involves intra-
venous administration of diazepam to control
agitation
and cooling measures for hyperthermia (see Body tem-
perature,
p.
33);
hypertension
and
cardiac
effects
require specific treatment and expert advice should be
sought.
38
Emergency treatment of poisoning
BNF 61
Emergency treatment of poisoning