Toxicology/Pharmacology

Question 1

Tricyclic overdose
Signs/Symptoms?
ECG signs?
Management?

Answer 1

Anticholinergic (dry mouth, dilated pupils, agitation, sinus tachycardia, blurred vision)
Severe: arrythmia, seizure, metaolic acidosis, coma

ECG: bradycardia, QRS widening (>100ms associated with seizure, >160ms associated with vent arrythmia), QT prolongation

Mx:

• IV bicarbonate for hypotension/arrythmia
• Anti-arrythmia drugs

Question 2

What receptor types do following drugs act on?

1. Endogenous hormones (e.g. insulin)
2. Exogenous lipid solubble (e.g. levothyroxine, pred)
3. Opioids, adrenoceptors
4. Local anaesthetics

Answer 2

1. Tyrosine kinase receptors
2. Nuclear receptors
3. G-protein coupled
4. Ligand gated ion channels

Question 3

Salicylate overdose
Associated acid-base disorder?
Management?
Dialysis indications?

Answer 3

mixed respiratory alkalosis & metabolic acidosis.
Early stimulation of resp centre –> respiratory alkalosis direct acid effects of salicylates (+ AKI) –> acidosis

general (ABC, charcoal)
urinary alkalinization with IV sodium bicarbonate
haemodialysis

Serum level >700
Resistant met acidosis
Acute renal failure
Pulmonary oedema
Seizure/coma

Question 4

Carbon monoxide poisoning
Pathology?
Features?
Investigations?
Management?

Answer 4

CO has higher affinity for O2 vs Hb –> L shift of O2 dissociation curve –> tissue hypoxia

Headache, N&V, confusion, vertigo
severe toxicity: ‘pink’ skin and mucosae, hyperpyrexia, arrhythmias, extrapyramidal features, coma, death

Ix: ABGs
Carboxyhaemoglobin level:
< 3% non-smokers
< 10% smokers
10 - 30% symptomatic: headache, vomiting
> 30% severe toxicity

Mx
100% O2 through non-rebreathe. Aim for sats 100%. Cont for at least 6h/until symptoms resolve