Cocaine toxicity
Cocaine is a classic sympathomimetic, used by the Incas as an appetite suppressant and noted for its analgesic properties we now use it medically as a local anaesthetic (Sodium channel blockade of the nerves). Recreational cocaine is used as a party drug which can be potentially lethal in overdose. Find out how to investigate and manage the complications.
- Ingestion of >1g is potentially lethal (average line is 20-30mg)
- Life threats include hyperthermia, hypertension, dysrhythmias, ischaemia, seizures, dissections, intracerebral haemorrhage, and cerebral oedema.
- Mainstay of treatment is with benzodiazepines (agitation, hypertension, tachycardia and hyperthermia)
- Treat dysrhythmias with sodium bicarbonate or if refractory lignocaine
- Beta blockers are contraindicated
- Thrombolysis is relatively contraindicated
TOX TUTE – Cocaine
The show notes are presented as a ‘show and reveal‘ mini quiz.
Question 1
Resus: How would you treat Ventricular tachycardia, what dose and what drug and dose would you use if your initial treatment failed?
Reveal the Answer
- VT is initially treated with 50-100 mmol of sodium bicarbonate. Defibrillation is also used along normal protocols but may not be successful (hence the addition of sodium bicarbonate – [DDET + Sodium Channel Blockade and the ECG]https://vimeo.com/127679225[/DDET])
- Failing the above treatment 1.5mg/kg IV of lignocaine followed by an infusion of 2mg/minute. Those astute pharmacologists will be aware that lignocaine is also a sodium channel blocker. The theory that it acts as a competitive inhibitor to cocaine (and other sodium channel blocking drugs) at a receptor level, it also interacts less with the sodium channel receptors leaving them free to work as a sodium channel.
Question 2
Resus: As mentioned we would avoid giving beta-blockers in an acute coronary syndrome
Beta blockers and the adrenoceptors
…But what would you give?
Reveal the Answer
- Aspirin (and other anti platelets depending on your hospital protocols)
- Nitroglycerine
- Calcium channel antagonists
- Coronary angiography +/- stenting
Question 3
Resus: What symptoms or pathology would be a contraindication to using thrombolytics in an acute coronary syndrome?
Reveal the Answer
- Severe hypertension
- Seizures
- Intracranial haemorrhage
- Aortic dissection
Question 4
Resus: What drugs could you use for a supra ventricular tachycardia?
Reveal the Answer
- Benzodiazepines
- Verapamil 5mg IV
- Adenosine 6-12mg IV
- Cardioversion if unstable
Question 5
Resus: What drugs could you use if your patient is refractory to benzodiazepines for hypertension? What drug should you not use?
Reveal the Answer
- Phentolamine 1mg IV repeated every 5 mins. This drug maybe more familiar to those in the operating theatre during phaeochromocytoma as it is used to control blood pressure. It is a reversible nonselective alpha-adrenergic antagonist. Its primary action is vasodilatation due to alpha 1 blockade.
- A vasodilator infusion such as sodium nitroprusside or glyceryl trinitrate.
- AVOID Beta blockers.
Question 6
Resus: You’ve used titrated doses of benzodiazepines and controlled your patient’s blood pressure, tachycardia and agitation but their temperature is still sitting at 40 degrees celsius. What do you do now?
Reveal the Answer
- Hyperthermia needs aggressive management to prevent multi-organ failure.
- This patient will require external cooling via ice packs and cool fluids. This will of course be uncomfortable and elicit shivering in the conscious patient. Therefore they need paralysis, intubation and ventilation.
Question 7
Risk assessment: What complications do you need to exclude when a patient has taken cocaine? (and hence tailor your investigations appropriately).
Reveal the Answer
- CNS: Agitation, Aggression, Psychosis, Myoclonic movements, Seizures, intra-cerebral bleeds and Cerebral oedema.
- CVS: Tachycardia, Dysrhythmias, Acute coronary syndrome, Acute pulmonary oedema, Aortic or Carotid dissection and Ischaemic Colitis
- Other: Hyperthermia, Pneumothorax, Rhabdomyolysis and Pneumomediastinum
Question 8
Risk assessment: What is the safe anaesthetic dose of cocaine compared to the usual dose in a line of cocaine and the potentially lethal dose of cocaine?
Reveal the Answer
- Anaesthetic dose = 1-3mg/kg
- Line of cocaine = 20-30mg
- Potentially lethal = 1g
- Cocaine should be on your list of ‘1-2 pills can kill’ for children.
Question 9
Investigations: Your patient develops chest pain with ST elevation in the lateral leads and also has a severe headache. Unfortunately you have a long transfer to get this patient to a coronary angiogram. The cardiologist is recommending you anticoagulant this patient. What investigation could you do to help weigh up the risk?
Reveal the Answer
CT brain. This should always be strongly considered even when the patient is going to angiogram as it is likely he will get anti coagulated if necessary.
Question 10
Disposition: A child presents to ED who may have been playing with some cocaine. The necessary child protection issues are being processed when they ask you “at what time will the child be medically cleared?” What would your response be?
Reveal the Answer
This child will need to be observed 4 hours post potential ingestion. If they do not develop any symptoms during this time they may be cleared.
Additional Resources
- Richards J. Controversies with giving beta-blockers is it just dogma? LITFL
- Afonso L. Mohammad T. Thatai D. Crack whips the heart: a review of the cardiovascular toxicity of cocaine. American Journal of Cardiology 2007; 100(6):1040-1043.
- Hatsukami DK, Fischman MW. Crack cocaine and cocaine hydrochloride. Are the differences myth or reality? Journal of the American Medical Association 1996; 276:1580-1588.
- Lange RA, Hillis LD. Cardiovascular Complications of Cocaine Use. New England Journal of Medicine. 2001; 345(5):351-358.
- Shih RD, Hollander JE, Burstein JL et al. Clinical safety of lidocaine in patients with cocaine-associated myocardial infarction. Annals of Emergency Medicine 1995;26:702-706.
Video
Sodium Channel Blockade and the ECG
Adrenoceptors and the sympathomimetic syndrome
Toxicology Library
DRUGS and TOXICANTS
Dr Neil Long BMBS FACEM FRCEM FRCPC. Emergency Physician at Kelowna hospital, British Columbia. Loves the misery of alpine climbing and working in austere environments (namely tertiary trauma centres). Supporter of FOAMed, lifelong education and trying to find that elusive peak performance.