A-Textbook-of-Clinical-Pharmacology-and-Therapeutics-5th-edition

450 DRUG OVERDOSE AND POISONING
Case history
A 21-year-old student is brought into your Accident and
Emergency Department having been at a party with his girlfriend.
She reports that he drank two non-alcoholic drinks,
but had also taken ‘some tablets’ that he had been given by
a stranger at the party. Within about one hour he started
to act oddly, becoming uncoordinated, belligerent and
incoherent. When you examine him, he is semi-conscious,
responding to verbal commands intermittently. During the
period when you are interviewing/examining him, he suddenly
sustains a non-remitting grand-mal seizure.
Question 1
What are the agents he is most likely to have taken
Question 2
How would you treat him
Answer 1
The most likely agents that could have caused an altered
mental status and then led to seizures are:
• sympathomimetics (e.g. amphetamines, cocaine,
MDMA);
• hallucinogens: LSD, phencyclidine (PCP) – (latter
unusual in the UK).
• tricyclic antidepressants;
• selective serotonin reuptake inhibitors.
Much less likely causes are:
• antihistamines (especially first-generation
antihistamines in high dose; these are available over
the counter);
• theophylline;
• ethanol and ethylene glycol can also do this, but are
unlikely in this case, because of the patient’s
girlfriend’s account of events.
Answer 2
This patient should be treated as follows:
1. Ensure a clear airway with adequate oxygenation –
avoid aspiration.
2. Ensure that other vital functions are adequate.
3. Prevent him from injuring himself (e.g. by falls (off a
trolley) or flailing limbs).
4. Give therapy to stop the epileptic fit:
diazepam, 10 mg i.v. and repeat if necessary;
if the patient is refractory to this, consider thiopental
anaesthesia and ventilation.
5. Monitor the patient closely, including ECG, and
observe for respiratory depression and further seizures.
Attempt to define more clearly which agent he
ingested to allow further appropriate toxicological
management.
The history from his girlfriend, also a heroin addict, is that
he was released from prison one week earlier and they
moved into an old Victorian flat. They had tried to stay off
heroin for one week (he had obtained a limited supply
while in prison), but both had experienced headaches, nausea,
vomiting, stomach cramps, tremor and diarrhoea.
The patient had told his girlfriend that he had to have
some heroin. She left the flat for six hours to pick up her
unemployment benefit, and returned home to find him
prostrate on the floor with a syringe and needle beside
him. She called an ambulance and attempted to resuscitate
him with CPR and an amphetamine.
Question
Name two possible causes of death.
Answer
Carbon monoxide poisoning and heroin overdose.
Comment
Some of this patient’s symptoms are not typical of heroin
withdrawal, but are characteristics of carbon monoxide
poisoning. His flatmate should be examined neurologically,
a sample taken for carboxyhaemoglobin and the flat
inspected. Oxygen is the antidote to carbon monoxide poisoning,
and naloxone is the antidote to heroin poisoning.
FURTHER READING
Afshari R, Good AM, Maxwell SRJ. Co-proxamol overdose is associated
with a 10-fold excess mortality compared with other paracetamol
combination analgesics. British Journal of Clinical
Pharmacology 2005; 60: 444–7.
Bateman DN, Gorman DR, Bain M. Legislation restricting paracetamol
sales and patterns of self-harm and death from paracetamolcontaining
preparations in Scotland. British Journal of Clinical
Pharmacology 2006; 62: 573–81.
Friberg LE, Isbister GK, Duffull SB. Pharmacokinetic-pharmacodynamic
modelling of QT interval prolongation following citalopram
overdoses British Journal of Clinical Pharmacology 2006; 61:
177–90.
Hawton K, Simkin S, Gunnell D. A multicentre study of coproxamol
poisoning suicides based on coroners’ records in England. British
Journal of Clinical Pharmacology 2005; 59: 207–12.
Jones AL, Dargan PI. Churchill’s pocket book of toxicology. London:
Churchill Livingstone, 2001.
Jones AL, Volans G. Management of self-poisoning. British Medical
Journal 1999; 319: 1414–7.
Pakravan N, Mitchell AJ, Goddard J. Effect of acute paracetamol overdose
on changes in serum electrolytes. British Journal of Clinical
Pharmacology 2005; 59: 650.
Stass H, Kubitza D, Moller JG. Influence of activated charcoal on the
pharmacokinetics of moxifloxacin following intravenous and oral
administration of a 400 mg single dose to healthy males. British
Journal of Clinical Pharmacology 2005; 59: 536–41.
Case history
A 20-year-old known heroin addict who is HIV-, hepatitis C-
and hepatitis B-positive is brought to the Accident and
Emergency Department. It is winter and there is a major flu
epidemic in the area. He is certified dead on arrival.
Many old venepuncture sites and one recent one are visible
on his arms. He does not appear cyanosed.