In this section : Poisoning
Paracetamol
SSRI Poisoning
Aspirin
Digoxin Poisoning
Tricyclic Antidepressants
Opiates
Benzodiazepines
Gut Decontamination
Deliberate Self Harm
Opiates
Last updated 3rd December 2020
Last updated on 14th May 2014 by Calum Murray
Toxicity
- Adults who have ingested, injected or smoked a toxic dose or more or those who are symptomatic should be referred for assessment.
- The same applies for daily users, if more than their usual dose
- Toxic doses are those in excess of the following:
- Diamorphine (Heroin) 0.2mg/kg
- Morphine 0.4mg/kg
- Methadone 0.4mg/kg
- Tramadol 4mg/kg
- See Toxbase Click Here (Requires Login) for toxic doses of other opiates
- For certain opiates (such as morphine, diamorphine, codeine and pethidine), the risk of toxicity is significantly increased if kidney function is impaired due to reduced elimination of the parent opioid or active metabolite.
Clinical Features
- Milder opiate toxicity may produce nausea, vomiting, nightmares, anxiety, agitation, euphoria, dysphoria, depression, paranoia and hallucinations.
- Severe opiate toxicity produces depression of the respiratory and central nervous systems and pin-point pupils. If untreated the depression of the level of consciousness can lead to deep coma, convulsions and respiratory arrest.
- While pin-point pupils are often present, their absence does not exclude opiate toxicity.
- Opioids, in particular codeine, can cause histamine release, most commonly causing urticaria and pruritis.
- Non-cardiac pulmonary oedema and rhabdomyolysis may occur after intravenous injection of opioid analgesics.
- Some opioids may cause cardiotoxicity e.g. methadone causing prolonged QT and dextropropoxyphene QRS prolongation.
- Intravenous use of street heroin may result in local bacterial infections at the site of injection e.g. abscesses and at distant sites such as endocarditis
- Should consider possibility of HCV and HIV infection in all IV drug users and offer to test routinely
General Mangement
- Always use the ABCDE approach
- Consider activated charcoal 50 g in adults who have taken a potentially toxic amount within 1 hour, provided the airway can be protected.
- For patients who have ingested opiates but have no features of opiate toxicity at any time: monitor BP, pulse, respiratory rate, oxygen saturation and conscious level at least hourly for at least 6 hours after exposure or 12 hours if a sustained release preparation has been taken
- Agitated adults can be sedated with an initial dose of oral or IV diazepam 0.1 – 0.3 mg/kg body weight.
- In the event of cardiac arrest in hospital or witnessed out of hospital cardiac arrest with bystander CPR, resuscitation should be continued for at least 1 hour and only stopped after discussion with a senior clinician
Naloxone
- If the patient develops respiratory depression, airway obstruction or vomiting with impaired consciousness, give naloxone urgently and consider referral for intensive care.
- Give an initial dose of 400 micrograms (0.4 mg) IV. If there is no response after 60 seconds, give a further 800 micrograms (0.8 mg). If there is still no response after another 60 seconds, give another 800 micrograms (0.8 mg). If still no response (after a total of 2 mg), give a further 2 mg dose.
- IM naloxone can be used in patients with very poor IV access.
- Due to short half-life of naloxone some patients may require an infusion. Rx two-thirds of the bolus dose initially required to wakethe patient, per hour.
- Aim for reversal of respiratory depression, not full reversal of consciousness