• Activated charcoal contains several tiny holes that are similar in size to many drug molecules
• Van der Waals forces exerted by these holes cause the drug molecules to stick to the charcoal and therefore prevent them from being absorbed
• Charcoal is most effective immediately after ingestion and the effectiveness decreases with time
• The overdose may lead to delayed gastric emptying, which means that patients who have ingested a large number of tablets may have them in their stomach for a long time, and may benefit from charcoal up to several hours after ingestion
• Repeat doses of charcoal may be useful for treatment of overdose with certain drugs such a phenytoin or carbamazepine
• Charcoal is not useful for treatment of overdose with:
  • Iron
  • Potassium
  • Lithium
  • Alcohols
  • Hydrocarbons

*    For some drugs, whole bowel irrigation may be necessary to flush these drugs out of the patient’s system

• Yes, charcoal should really only be used in a patient that can protect their own airway
• This can be difficult to determine if the patient presents very acutely after an overdose
• Even if the charcoal is effective, the patient may still lose consciousness within half an hour and ultimately require intubation and in this case, it may be beneficial to intubate first

• Respiratory depression
  • If caused by opioid overdose, can be treated with titrated doses of naloxone to prevent hypercapnoeawithout precipitating withdrawal
  • Patients who have taken shorter acting opioids, such as heroin, may only require a single dose
  • Patients with long acting opioids such as MS Contin may require a naloxone infusion
• Paracetamol overdose
  • We have a low threshold for using N-acetyl cysteine, which should be commenced early to minimise liver failure
  • If there is a delay in obtaining a paracetamol level, this level should be approximated and an appropriate infusion of N-acetyl cysteine commenced within 8 hours of overdose

• Your hospital toxicologist
• The Poisons Information Centre on 13 11 26
• You will initially speak to an experienced pharmacist, but your call will be escalated to a toxicologist as deemed appropriate (you may also request to speak to a toxicologist at any stage)
• When to call for help early:
  • If the patient who presents with polypharmacy overdose (e.g. entire Webster pack)
  • If there is a risk of complications
  • If the patient has a cardiac arrest, ring immediately!

• It depends how unwell the patient is and whether or not the hospital can offer them the support required
• Patients that require cardiac monitoring or respiratory support will require a bed in HDU or ICU
• Other patients may require dialysis
• Once patients have been stabilised, they will require psychosocial assessment to determine whether or not the patient requires admission to hospital and what can be done to prevent future overdose and suicide attempt

• If you don’t understand what is going on, don’t guess!
• Ask for help early
• Call the Poisons Information Centre on 13 11 26