Toxicology

Question 1

A patient presents with an overdose metabolic acidosis, dilated pupils, tachycardia with widening of QRS on ECG. They are known to have a background of depression and hypertension. What is the likely drug and treatment?

Answer 1

Tricyclic Antidepressant overdose e.g amitriptyline
Treatment is IV bicarbonate

Question 2

A car mechanic presents after a divorce with confusion, slurred speech and dizziness. ECG shows sinus tachycardia. Bloods show metabolic acidosis with a high anion gap and high osmolar gap. What is the cause and treatment?

Answer 2

Cause - Ethylene Glycol Toxicity (found in anitfreeze)

Treatment - Fomepizole (inhibits alcohol dehydrogenase)

Question 3

What are the features of heparin induced thrombocytopenia?

Answer 3

50% reduction in platelets

thromobosis

Skin allergy

Treatement is to switch to either danaparoid or a direct thrombin inhibitor such as argatroban

Question 4

A patient is being treated for depression presents with rigidity, sweating, confusion, hyperreflexia and monoclonus. He admits to taking st johns wort over the counter. What is the diagnosis and treatment?

Answer 4

Likely serotinin syndrome

Management - IV fluids + benzodiaxepines

severe cases - cyproheptadine and Chlorpromazine

Question 5

A patient with known schizophrenia presents with raised temperature, sweating, rigidity and reduced reflexes. What is the diagnosis and treatment?

Answer 5

Neuroleptic malignant syndrome due to antipsychotics

IV fluids and benzodiazepines

Sever cases treated with Dantrolene

Question 6

What drugs can prescipitate lithium toxicity?

Answer 6

Thiazides e.g. Indapamide
ACE inhibitors / ARBs
Metronidazole
NSAIDs

Question 7

What are the features of lithium toxicity?

Answer 7

coarse tremor
hyperreflexia
acute confusion
polyuria
seizure
coma

Question 8

How is lithium toxicity managed?

Answer 8

IV fluids
haemodialysis in severe toxicity
Sodium bicarbonate increases the alkalinity of urine promoting lithium excretion.

Question 9

What is the King’s College criteria for liver transplantation following a paracetamol overdose?

Answer 9

1. Arterial pH < 7.3 24 hours after ingestion

OR all of the following:
- prothrombin time > 100s
- creatinine >300
- grade 3 or 4 encephalopathy

Question 10

What are the cardiovascular adverse effects of cocaine?

Answer 10

Cardiovascular - coronary artery spasm (MI), tachycardia / bradycardia, HTN, QRS widening, Qt prolongation, aortic dissection

Question 10

What is the mechanism of action of cocaine?

Answer 10

blocks uptake of dopamine, noradrenaline and serotonin

Question 11

What is the treatment for cocaine toxicity?

Answer 11

benzodiazpeines

Chest pain - benzos and GTN

HTN - benzos and sodium nitroprusside

Question 12

What are the neurological features of cocaine toxicity?

Answer 12

seizures
mydriasis
hypertonia
hyperreflexia

Question 13

A farmer presents with diarrhoea, excess salivation and hypotension. On examination he is bradycardia, with small pupils and muscle fasciculations.
What is the diagnosis and treatment?

Answer 13

Organophosphate poisoning.
Treated with atropine

Question 14

Which tuberculosis medication requires visual acuity checks before and during treatment and why?

Answer 14

Ethambutol can cause optic neuritis

Question 15

Which TB drug can cause hepatitis?

Answer 15

Rifampicin, Isoniazid, Pyrazinamide

Question 16

Which TB drug can cause orange secretions?

Answer 16

Rifampicin

Question 17

Which TB drug can cause gout?

Answer 17

Pyrazinamide - can cause hyperuricaemia and gout.

Question 18

Which TB drug can cause agranulocytosis, peripheral neuropathy, hepatitis

Answer 18

Isoniazid

Question 19

What channels does flecainide block to slow down cardiac conduction?

Answer 19

Nav1.5 sodium channels

Question 20

What are the contraindications to flecainide?

Answer 20

• post MI
• structural heart disease e.g. HF
• sinus node dysfuction e.g. second degree AV block
• Atrial flutter.

Question 21

What are the inducers of the P450 system?

Answer 21

CRAP GPS
Carbamazepine
Rifampicin
Alcohol (chronic)
Phenytoin
Griseofulvin
Phenobarbitone
St Johns wort / smoking

Question 22

What are the inhibitors of the P450 system?

Answer 22

SICK FACES.COM
Sodium Valproate
Isoniazid
Cimetidine
Ketoconazole

Fluconazole
alcohol (acute) and grapefruit juice
Chloramphenicol
Erythromycin
Sulfonamides

Ciprofloxacin
Omeprazole
Metronidazole

Question 23

What are the indications for haemodialysis in salicylate overdose?

Answer 23

Indications for haemodialysis in salicylate overdose
serum concentration > 700mg/L
metabolic acidosis resistant to treatment
acute renal failure
pulmonary oedema
seizures
coma

Question 24

What might the abg show for salicylate od

Answer 24

mixed respiratory alkalosis and metabolic acidosis due to respiratory depression and then acute renal failure.