Drug overdose Flashcards
What causes hepatic problems in paracetamol overdose?
The toxic metabolite N-acetyl p-benzoquinone imine (NAPQI) results from depletion of glutathione stores, causing fulminant hepatic necrosis after several days
How can paracetamol overdose present?
No symptoms
Nausea and vomiting
Loin pain
Haematuria and proteinuria
Jaundice
Abdominal pain
Coma
Severe metabolic acidosis
How do you manage paracetamol overdose if ingestion < 1 hour ago + dose > 150 mg/kg?
Activated charcoal
How do you manage paracetamol overdose if ingestion < 4 hours ago?
Wait until 4h to take level + treat with NAC based on level
How do you manage paracetamol overdose if ingestion within 4-8 hours + dose > 150mg/kg?
Start NAC immediately if there is going to be a delay of > 8 hours obtaining paracetamol level
How do you manage paracetamol overdose if ingestion within 8-24 hours + dose > 150mg/kg?
Start NAC immediately
How do you manage paracetamol overdose if ingestion > 24h?
Start NAC immediately if:
1) Jaundice
2) RUQ tenderness
3) Elevated ALT
4) INR > 1.3
5) Paracetamol concentration is detectable
How do you manage paracetamol overdose if staggered?
Start NAC immediately
How do you decide whether to treat paracetamol overdose with NAC?
Based on a normogram - if paracetamol levels are above the treatment line then start NAC
When should NAC be started regardless of normogram?
1) Patient presents after 16h
2) Uncertainty about timing
3) Staggered overdose
What is a side effect of NAC?
NAC is associated with anaphylactoid reactions -these are not true anaphylactic reactions and can usually be managed by stopping the infusion temporarily and then restarting at a lower rate
When else would you administer NAC immediately?
If there is increased risk of toxicity:
1) Patient on long-term enzyme inducers
2) Regular alcohol excess
3) Pre-existing liver disease
4) Glutathione-deplete states: eating disorders, malnutrition and HIV
What is the UK treatment normogram threshold for paracetamol overdose at 4 hours?
100 mg/L in all groups
What are symptoms of SSRI overdose?
1) Prolonged QT (risk of TdP)
2) CNS depression
3) Seizures
What are the two key additional symptoms that should prompt concern about serotonin syndrome?
1) Hyperreflexia
2) Pyrexia
How is SSRI overdose managed?
1) Cooling
2) Fluids
3) Benzodiazepines
4) Intensive therapy support
Are SNRIs e.g. venlafaxine more or less toxic than SSRIs?
More toxic bc also inhibits noradrenaline reuptake
What are the symptoms of TCA overdose?
1) Metabolic acidosis
2) CNS depression
3) QRS widening (due to sodium channel blockade)
4) Arrhythmias
How do you manage TCA overdose?
1) IV sodium bicarbonate (if QRS widened)
2) Supportive ± ITU
What are the symptoms of opiate overdose e.g. heroin?
1) Itching
2) Miosis
3) Hypoventilation leading to respiratory arrest
How do you manage opioid overdose?
IV/IM naloxone - usually titrated to the point of adequate respiratory function
What are the key considerations with naloxone?
1) Be aware that reversal can be immediate, precipitating agitated behaviour due to withdrawal effects
2) The half-life of naloxone is shorter than most opiates (~20min) so repeat dosing ± an infusion may be required
What are the signs of cocaine use?
Potent sympathomimetic
1) Euphoria
2) Hypervigilance
3) Tachycardia
4) Hypertension
What are the signs of cocaine toxicity?
1) Severe agitation
2) Myocardial infarction
3) Arrhythmias
4) Seizures
5) Intracranial bleeding
