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Carbomix
c
(Beacon)
Powder
,
activated charcoal,
net price 25-g pack =
£8.50,
50-g pack = £11.90
Charcodote
c
(TEVA UK)
Oral suspension
,
activated charcoal 1 g/5 mL, net
price 50-g pack = £11.88
Specific drugs
Alcohol
Acute intoxication with alcohol (ethanol) is common in
adults but also occurs in children.
The features include
ataxia,
dysarthria,
nystagmus,
and drowsiness,
which
may progress to coma,
with hypotension and acidosis.
Aspiration of
vomit is a special
hazard and hypoglyc-
aemia may occur in children and some adults.
Patients
are managed supportively,
with particular attention to
maintaining a clear airway and measures to reduce the
risk of aspiration of gastric contents. The blood glucose
is measured and glucose given if indicated.
The National
Poisons Information Service (Tel:
0844 892 0111) will provide specialist advice on all
aspects of poisoning day and night
Analgesics (non-opioid)
Aspirin
The main features of salicylate poisoning are
hyperventilation,
tinnitus,
deafness,
vasodilatation,
and
sweating. Coma is uncommon but indicates very severe
poisoning.
The associated acid-base disturbances are
complex.
Treatment must be in hospital, where plasma salicylate,
pH,
and electrolytes can be measured;
absorption of
aspirin may be slow and the plasma-salicylate concen-
tration may continue to rise for several hours, requiring
repeated measurement.
Plasma-salicylate
concentra-
tion may not
correlate with clinical
severity in the
young and the elderly,
and clinical
and biochemical
assessment is necessary. Generally, the clinical severity
of
poisoning is less below a plasma-salicylate concen-
tration of
500 mg/litre (3.6 mmol/litre),
unless there is
evidence of metabolic acidosis.
Activated charcoal
can
be given within 1 hour of ingesting more than 125 mg/
kg of aspirin. Fluid losses should be replaced and intra-
venous
sodium bicarbonate may be given (ensuring
plasma-potassium concentration is within the reference
range) to enhance urinary salicylate excretion (optimum
urinary pH 7.5–8.5).
Plasma-potassium concentration should be corrected
before
giving
sodium bicarbonate
as
hypokalaemia
may complicate alkalinisation of the urine.
Haemodialysis is the treatment
of
choice for
severe
salicylate poisoning and should be considered when
the plasma-salicylate concentration exceeds 700 mg/
litre (5.1 mmol/litre) or in the presence of severe metab-
olic acidosis.
NSAIDs
Mefenamic acid has important consequences
in overdosage because it can cause convulsions, which if
prolonged or recurrent require treatment,
see p.
33.
Overdosage with ibuprofen may cause nausea,
vomi-
ting,
epigastric pain,
and tinnitus,
but
more serious
toxicity is very uncommon. Activated charcoal followed
by symptomatic measures are indicated if
more than
400 mg/kg has been ingested within the preceding hour.
Paracetamol
In cases
of
intravenous
paracetamol
poisoning
contact
the National
Poisons Information Service
for advice on risk assessment and management.
Single or
repeated doses totalling as little as 10–15 g
(20–30 tablets)
or 150 mg/kg of
paracetamol
ingested
within 24 hours may cause severe hepatocellular necro-
sis and,
much less frequently,
renal
tubular
necrosis.
Patients at
high-risk
of
liver damage,
including those
taking enzyme-inducing drugs or who are malnourished
(see p.
35),
may develop liver toxicity with as little as
75 mg/kg of paracetamol (equivalent to approx. 5 g (10
tablets)
in a 70-kg patient)
taken within 24 hours.
Nausea and vomiting, the only early features of poison-
ing,
usually settle within 24 hours.
Persistence beyond
this time,
often associated with the onset of
right sub-
costal
pain and tenderness,
usually indicates develop-
ment of hepatic necrosis. Liver damage is maximal 3–4
days after ingestion and may lead to encephalopathy,
haemorrhage,
hypoglycaemia,
cerebral
oedema,
and
death.
Therefore, despite a lack of significant early symptoms,
patients who have taken an overdose of
paracetamol
should be transferred to hospital urgently.
Administration of activated charcoal
should be consid-
ered if
paracetamol
in excess of
150 mg/kg or
12 g,
whichever is the smaller (or
in excess of
75 mg/kg
for those considered to be at
high risk
,
see below),
is
thought to have been ingested within the previous hour.
Acetylcysteine protects the liver if
infused up to,
and
possibly beyond, 24 hours of ingesting paracetamol. It is
most effective if given within 8 hours of ingestion, after
which effectiveness declines. In patients who present 8–
36 hours after a potentially toxic ingestion,
acetylcys-
teine treatment should commence immediately even if
plasma-paracetamol
concentrations are not
yet
avail-
able; if more than 24 hours have elapsed since ingestion
advice should be sought
from the National
Poisons
Information Service.
Giving acetylcysteine by mouth
[unlicensed route] is an alternative if intravenous access
is not possible—contact the National
Poisons Informa-
tion Service for advice. In remote areas, methionine by
mouth is an alternative only if acetylcysteine cannot be
given promptly.
Once the patient reaches hospital
the
need to continue treatment
with the antidote will
be
assessed from the plasma-paracetamol
concentration
(related to the time from ingestion).
Patients at risk of
liver damage and therefore requiring
treatment can be identified from a single measurement
of the plasma-paracetamol concentration, related to the
time from ingestion,
provided this time interval
is not
less than 4 hours;
earlier samples may be misleading.
The concentration is plotted on a paracetamol
treat-
ment
graph,
with a reference line (‘normal
treatment
line’) joining plots of 200 mg/litre (1.32 mmol/litre) at 4
hours and 6.25 mg/litre (0.04 mmol/litre)
at
24 hours
(see p.
35).
Those whose plasma-paracetamol
concen-
tration is above the
normal
treatment
line
are treated
with acetylcysteine by intravenous infusion (or, if acetyl-
cysteine is not
available,
with methionine by mouth,
provided the overdose has been taken within 10–12
hours
and
the patient is not vomiting).
34
Emergency treatment of poisoning
BNF 61
Emergency treatment of poisoning