Toxicology

Question 1

What is the mechanism of action of organophosphate insecticide poisoning and what is the typical presentation of symptoms?

Answer 1

Inhibits acetylcholinesterase enzyme - accumulation of acetylcholine - cholinergic crisis = SLUDGE 
S - salivation 
L - lacrimation 
U - urinary incontinence 
D - defecation (diarrhoea)
G - gastric upset 
E - emesis 

Typically present very sweaty + vomiting + sinus bradycardia + hypotension + small pupils

Question 2

What is 1st line treatment for organophosphate poisoning after initial resuscitation?

Answer 2

Atropine (an acetylcholine antagonist!)

Question 3

What is the principle poison in antifreeze and what can be used as an antidote?

Answer 3

antifreeze = Ethylene glycol

antidote for ethylene glycol / methanol = ethanol or fomepizole
+//- may need haemodialysis

Question 4

What is the 1st line agent for reversing beta blocker overdose?

Answer 4

1st line = Glucagon

alternative = atropine

Question 5

In what window is activated charcoal useful in poisoning scenarios?

Answer 5

Within 1 hr of ingestion to reduce absorption of most tablets.

(can give repeated doses after 1hr to aid ELIMINATION of quinine, theophylline, phenobarbitol, carbamazepine and dapsone)

HOWEVER SHOULD NOT USE ACTIVATED CHARCOAL WITH ANYTHING THAT IS CORROSIVE (ALCOHOL, METAL SALTS, CYANIDE, PETROL)

Question 6

Tx for iron overdose

Answer 6

desferrioxamine

Question 7

Tx for opioid overdose

Answer 7

naloxone

Question 8

Tx for warfarin overdose

Answer 8

phytomenadione / vitamin K

Question 9

Which drugs are associated with causing jaundice?

Answer 9

Nitrofurantoin 
Erythromycin 
Isoniazid
Aspirin 
Indomethacin 
Methyldopa

Question 10

Which anti-arrythmic causes night glare and metallic taste disturbance?

Answer 10

Amiodarone

Question 11

Which drugs commonly cause gynaecomastia?

Answer 11

Spironolactone 
Finasteride 
Cimetidine (H2 antagonist) 
Gosarelin 
Calcium channel blockers

Question 12

Which drugs commonly cause tardive dyskinesia (repetitive involuntary movements face, neck and limbs)

Answer 12

Metoclopramide

Anti-psychotics

Question 13

which class of drug is commonly associated with rhabdomyolysis?

Answer 13

statins

Question 14

Which drug is associated with acquired hearing loss?

Answer 14

gentamicin

Question 15

Common drug causes of erectile dysfunction?

Answer 15

Alcohol
Anti-hypertensives
Anti-depressents
Nicotine

Question 16

Ingestion of paraquat -> toxidrome and Mx?

Answer 16

Painful ulcers in oesophagus + mouth + renal failure + pulmonary fibrosis

mx -> activated charcoal and magnesium sulphate laxative

Question 17

Mx of beta blocker overdose?

Answer 17

1st - > IV atropine to try and correct the bradycardia

Cardiogenic shock not responsive to atropine -> IV glucagon

Question 18

Anticholinergic toxidrome -> drugs that cause it, the presentation and the antidote?

Answer 18

Anticholinergic agents = tricyclic antidepressents (amitriptyline)
Atropine
Hyoscine
Sedating antihistamines

Presentation = ^ HR/BP/RR/Temp, DILATED pupils, flushed, halllucinating, urinary retention

Tx:
Tricyclic antidepressents = SODIUM BICARBONATE
Others = PHYSOSTIGMINE

Question 19

Neuroleptic malignant syndrome -> drugs that cause it, the presentation and the antidote?

Answer 19

Causes =
Antipsychotics (typical have ^ risk = Haloperidol, Chlorpromazine, Levomepromazine, Prochlorperazine)
Antiemetics -> Domperidone, Metoclopramide

Presentation = ^ HR/BP/RR/Temp, DILATED pupils, muscle rigidity + rhabdomyolysis, liver + renal failure, hyperkalaemia, metabolic acidosis

Tx = DANTROLENE (reduces muscle rigidity)

Question 20

Sympatho-mimetic toxidrome?

Answer 20

= cocaine, amphetamine, nicotine, caffeine

Presentation = ^ HR/BP/RR/very high temp dilated pupils, paranoia

Tx -> no specific antidote -> cooling + benzodiazepines
Give immediate aspirin if cocaine associated chest pain

Question 21

Serotinergic toxidrome?

Answer 21

SSRIs 
MAOinhibitors 
Tramadol 
Amphetamine 
MDMA / Ecstasy 

= high RR/BP/HR/Temp + dilated pupils + tremor/^ reflexes/rigidity

Tx = CYPROHEPTADINE

Question 22

Withdrawal from sedatives presentation?

Answer 22

= withdrawal from alcohol / benzodiazepines

^ HR/RR/BP/Temp + agitated/hallucinations

Tx = reducing dose of benzodiazepines

Question 23

Opioid toxidrome?

Answer 23

REDUCED HR/BP/RR/Temp + CONSTRICTED pupils + HYPOreflexia + PULMONARY OEDEMA

= opioids = heroin, morphine, methadone

Tx = Naloxone IV (initially 400 micrograms then titrate up to response (max 4mg)

Question 24

Sedative toxicity ?

Answer 24

EXCESS of alcohol, benzodiazepines, phenobarbitone

Presentation = constricted pupils, reduced HR/BP/RR/Temp

Tx -> Flumazenil

Question 25

Cholinergic toxicity?

Answer 25

Cholinergics -> organophosphate poisoning!!

= SLUDGE!!! (excess of parasympathetic activity) 
S - salivation 
L - lacrimation 
U - urination 
D - diarrhoea 
G - GI upset 
E - emesis (vomiting) 

CONSTRICTED pupils

Mx = ATROPINE