toxicology Flashcards
what are the common toxidromes?
anticholinergic, cholinergic, opiate, sympathomimetic and sedative - hypnotic.
what are features of anticholinergic toxicity?
tachycardia, pyrexia, dry mouth, mydriasis
(enlarged pupils) and flushing. hallucinations, seizures and
conscious level reduced.
causes of anticholinergic toxidrome?
Antihistamines,
antipsychotics,
tricyclic antidepressants,
atropine (deadly nightshade, belladonna)
features of cholinergic toxidrome?
increased salivation, lacrimation, urination, diarrhoea and vomiting;
the most common cause of mortality for patients with the cholinergic toxidrome is
bradycardia and bronchorrhoea
causes of cholinergic toxidrome?
Organophosphate
pesticides, sarin gas,
physostigmine
features of opioid toxidrome?
depression of conscious level, reduced RR, bradycardia and hypotension. Typically the pupils are grossly constricted, often described as pinpoint.
causes of opioid toxidrome?
Heroin, morphine,
codeine,
dihydrocodiene,
tramadol, methadone
features of sympathomimetic toxidrome?
excited state with dilated pupils, tachycardia, hypertension,
hyperpyrexia. They may progress to have seizures or reduced conscious level and can develop brady or tachyarrythmias.
causes of sympathomimetic toxidrome?
Ecstasy, cocaine,
amphetamines,
cathinones
features of sedative - hypnotic toxidrome?
BP - down
HR - down
RR - down
temp - down
pulls - generally smaller
causes of sedative-hypnotic toxidrome?
Benzodiazepines,
zopiclone
how do you remember anticholingeric toxidrome?
Hot as a hare
o Dry as a bone
o Red as a beet
o Mad as a hatter
o Blind as a bat
cholingeric pneumonic for main features?
DUMBELLS – Diarrhoea, Urination, Miosis (small pupils), Bradycardia, Emesis,
Lacrimation, Lethargy and Salivation
how do you decontaminate skin?
copious irrigation, lavage and dilution with large volumes of water
PPE and ideally a closed drainage system
when is activated charcoal given?
dose?
within 1 hour of ingestion
the usual adult dose is 50g or 1g/kg for children.
how does activated charcoal work?
The activated charcoal adsorbs toxin that is present in the stomach,
preventing systemic absorption. It may be of benefit to take charcoal after 1 hour if
the substance taken is a sustained release medicine.
when is charcoal contraindicated?
if the time lapsed since ingestion is greater than 1 hour, if
the patient’s airway is not protected - either by intact protective reflexes or a cuffed
endotracheal tube, if the ingested substance is not bound by charcoal, or if an oral
antidote has been given.
what substances not adsorbed by activated charcoal?
antidote for paracetamol?
N-acetyl cysteine, methionine
antidote for tricyclics?
Sodium bicarbonate
antidote for BB?
glucagon
antidote for Ethylene glycol and methanol
Ethanol, fomepizole
antidote for cyanide?
Dicobalt edentate, hydroxycobalamin,
nitrates
antidote for iron salts?
Desferrioxamine
antidote for opiods?
naloxone
antidote for organsphospahtes?
Atropine, pralidoxime mesylate
what can you do to increase elimination of toxins?
Urinary alkalinisation
o Haemodialysis
o Haemofiltration
what do you treat with urinary alkalinisation?
what can you treat with haemodialysis
what do you treat with haemofiltration?
what is the toxic metabolite in paracetamol?
N-acetyl-p-benzoquinoneimine (NAPQI)
what predisposes to paracetamol toxicity?
> 75 mg/kg
Glutathione deficiency
Enhanced cytochrome p450 system. commonly caused by i.Prescription drugs i.e. carbamazepine, phenytoin,
phenobarbitone, primidone, rifampicin.
ii. Herbal remedies i.e. St Johns Wort.
iii. Alcohol.