Opiates
Naloxone will reverse the effect of opiate overdose, typically in the presence of CNS and respiratory
depression.
- It competitively binds opioid receptors, causing a blockade
- Usually given IV for fastest action (<1 min)
- Opioid overdose typically seen in heroin users who have been incarcerated / ‘gone cold turkey’ who subsequently return to heroin abuse. Upon returning to opioid use they often take the same dose they were taking before cessation, which, in the absence of tolerance, can be fatal.
- CAUTION – the half-life of naloxone is shorter than that of opiates, thus the naloxone can wear off, and the patient can go back into a state of opiate overdose.
Benzodiazepines
symptoms: agitation, euphoria, blurred vision, slurred speech, ataxia, slate-grey cyanosis
Flumazenil – can reverse the effect of benzodiazepines, however, is not always recommended. It is mainly used to reduce the sedative / drowsiness effects of benzodiazepines
- In long-term benzo abusers, it can induce withdrawal (including seizures), thus use is not recommended
- It competitively binds benzodiazepines
- Its half-life is shorter than benzodiazepines, so multiple doses may need to be administered
Overdose Signs + Symptoms
- Nausea / vomiting
- Hepatic necrosis causes:
- Renal failure
- Oliguria
- Metabolic Acidosis
- Often asymptomatic, until 24-72 hours after when acute liver failure occurs
Investigations
- Paracetamol (+ salicylate) level - Only accurate if >4 hours after ingestion
- LFT’s
- Glucose
- U+E’s
- Prothrombin time is a very good measure of acute renal failure
- ABG – checking for metabolic acidosis
Management if <8 hours after ingestion
Activated Charcoal
- Not suitable in all instances. Only if:
- >12g or 150mg/Kg paracetamol
- <2hrs (most effective if <1hr) after overdose
Acetylcysteine
- Promotes conjugation of circulating paracetamol. Should only be administered if you have a plasma paracetamol level. Then, look at the treatment graph. Patients above the treatment line (or above the high risk line if they are high risk) should receive acetylcysteine.
- Greatest effect if given <12 hours after ingestion
- Once administration has begun, it usually continues for 24 hours regardless of plasma level of paracetamol
Management if >8 hours after ingestion
Give acetylcystiene if >12g or >150mg/Kg has been ingested, regardless of current plasma level (don’t wait for blood result)
- Proven to decrease mortality in late presentations even if liver failure is present
- Administer with 5% dextrose
- 5% of patients will have allergic rash
Management if >24 hours after ingestion
- Controversial, seek expert advice
- Often Toxobase is used
Aspirin (salicylic acid)
Note that Pepto-Bismol(R) <
