Toxicology. Flashcards
How quickly does diamorphine start to take effect/last?
1 minute onset and 2 hour duration.
What do we need to remember about the timings of naloxone vs diamorph?
naloxone lasts an hour and heroin 2 hours, so need to make sure we keep them in as they can die after an hour of being fine in overdose.
What can toxidromes help us with?
can help us identify the poison if we know the stereotyped syndromes.
What is the syndrome associated with TCA OD?
anticholinergic: flushing arrhythmias (long QRS) dry dilated pupils tachycardia hypotension acidotic
What is the problem with acidosis and the heart?
acid is negatively inotropic.
What should we give for acidosis in TCA overdose?
sodium bicarbonate and airway support.
What are the indications for sodium bicarbonate in TCA OD?
hypo tension unresponsive to fluid resus
long QRS
What are the different types of alcohol?
ethanol
methanol
ethylene glycol
What happens in alcohol toxicity?
different alcohol are fine but are metabolised into harmful metabolites in the liver by alcohol dehydrogenase.
How do we treat methanol or ethylene glycol poisoning?
give them alcohol as this has preferential binding with alcohol dehydrogenase meaning the others aren’t broken down into their toxic metabolites.
What are the symptoms of serotonin syndrome?
has sympathetic effects so: hypertension tachycardia hyperthermia agitation (can result in rhabdo)
What is the treatment of serotonin syndrome?
supportive and
dantrolene for malignant hyperthermia (although might work well for other drug hyperthermia better e.g. sux/volatiles).
What is organophosphate syndrome?
(weedkillers) cholinergic: hypotension, bradycardia small pupils, lacrimation and salivation
How do we treat organophosphate poisoning?
atropine (or praladoxine).
What are the different sympathomimetic drugs?
cocaine, speed etc.
What does cocaine do to the body?
sympathetic: hypertension, tachycardia, increased RR, big pupils
cardiotoxic.
Might have funny neuro thinks like parasthesia from vasoconstriction.
Why is cocaine cardiotoxic?
sympathetic effect so causes vasoconstriction that may result in coronary vasospasm and MI. Aslo have increased O2 demand from tachy.
Why should we never use a beta blocker in cocaine?
Beta and alpha receptors are being triggered, if we block beta, its all alpha and this can result in a hypotensive crisis.
How do we treat cocaine toxicity?
benzodiazepines e.g. diazepam and GTN for chest.
What can we use to treat ADME in drug OD?
A: activated charcoal causes adsorption, stopping drug absorption
D: intralipid (fat mops up from blood)
M: antidotes
E: fluids, dialysis or haemofiltration and urinary alkinylisation
How quickly must we give activated charcoal and why?
Within 1 hour as drugs will still be in the stomach.
or when can see still vomiting pills, or in drugs that cause gastropareses can give later.
What is intralipid traditionally used as an antidote for?
lidocaine toxicity
How quickly do people with paracetamol OD die?
in 5-7 days of fulminant hepatic failure.
Never die straight away, see nothing for 24-48 hours, then vomit/abdo pain, then yellow, then dead.
What part of paracetamol is toxic?
the inactive metabolites.
The active ones give the anlagesic effects.
What happens to paracetamol inactive metabolites normally?
they are conjugated for excretion with glutathione in the liver.
What happens to inactive paracetamol metabolites in OD?
they overwhelm the amount of glutathione and so are toxic.
How do we treat paracetamol OD?
charcoal if within an hour.
Do paracetamol levels at 4 hours
if within 12-24 hours can give parvolex if blood levels are high enough on nomogram.
What is the real name for parvolex?
Acetylcysteine
What are the side effects of parvolex?
How can we counteract this?
10% get an uritcarial hypersenstivity type reaction.
So can prescribe prophylactic antihistamies with it.
When do paracetamol levels in the blood peak?
4 hours after ingestion.
Reverses the effects of benzodiazepine overdose?
Flumazenil
What does Lignocaine do?
blocks the activity of sodium channels
What does morphine work on?
Morphine is mu receptor agonist.
Does morphine have active metabolites?
yes, One of its metabolites is active and indeed more potent than morphine.
What is paraquat?
An organophosphate in weedkiller.
What is the antidote for beta blocker over dose?
glucagon 5-10ml (for pre-filled).
What is the normal dose of glucagon for hypo?
1mg IM.
What are the side effects of giving glucagon for B blocker overdose?
they vomit, so need to watch airway.
If someone has OD’d on co-codamol, what should we give as an antidote?
naloxone
parvolex
What kind of picture should we expect to see with Co-codamol OD?
opioid type features.
When prescribing aspirin what do we need to be aware of?
Check weight in skinny people (need to be over 50kg for full dose).
What is a classic symptom of aspirin overdose?
ringing in ears.
What blood tests do we see in aspirin overdose?
mixed metabolic and respiratory acidosis.
How do we treat aspirin overdose?
Take bloods at 4 hours for levels (combined test with paracetamol).
if over nomogram levels then alkylyse urine (sodium bicarb) and fluids.
Where do we find drug level nomograms?
toxbase.
In real life, who is the only people we should give flumazenil to for benzo OD? (not the exam answer)
ones that we have OD’d by mistake.
Flumazenil, lowers seizure threshold, so if you don’t know a patients background. Reversing the benzo’s may cause seizure. If this happens because you have blocked benzo’s, you have a lack of options of how to treat them.
