Toxicology

Question 1

How is paracetamol overdose treated

Answer 1

Staggered - start NAC
1 hour / 4 hour / 16 hour bags
150mg/kg 50mg/kg / 100mg/kg

Toxicity = >150mg/kg usually with >12g ingestion

NAC greatest benefit if started <15 hours of ingestion

single ingestion
<4hr - activated charcoal + level after 4 hrs
>4 hr do level
refer to treatment graph and treat with NAC if indicated

Psych review post

assess suicidal intent and need for 1:1
CAMHS history?
SADPERSONS

If not tolerating NAC - use IV methionine
Aim is anti-oxidant of toxic metabolite

Question 2

What medication is used if NAC is not tolerated in PCT Overdose

Answer 2

IV methionine

Question 3

How is digoxin toxicity managed?

Answer 3

cardiac monitor
anti-emetics
atropine

Digibind if toxic
magnesium
lignocaine
Phenytoin if digibind not available

Question 4

How is torasdes des pointes managed?

Answer 4

Magnesium

Cardioversion

Question 5

How does tricyclic overdose present and how is it managed?

Answer 5

profound anti-musc / anti ACh

Sedation and coma
Seizures
Hypotension
Tachycardia
Broad complex dysrhythmias
Anticholinergic syndrome

Sodium bicarbonate 100mmol boluses if QT>100ms
Fluids
hyperventilate to correct acidosis

QRS > 100 ms is predictive of seizures
QRS > 160 ms is predictive of ventricular arrhythmias (e.g. VT)

If arrhythmias occur,

• give more sodium bicarbonate.
• Lidocaine (1.5mg/kg) IV is a third-line agent (after bicarbonate and hyperventilation)

Avoid Ia (procainamide) and Ic (flecainide) antiarrhythmics, beta-blockers and amiodarone as they may worsen hypotension and conduction abnormalities.

Admit the patient to the intensive care unit for ongoing management.

Question 6

What drug can stain tears red - important for soft contact lenses

Answer 6

isoniazid

Question 7

What TB treatment can cause peripheral neuropathy - how is this managed?

Answer 7

isoniazid

Pyridoxine given simultaneously

Question 8

What medication causes yellow vision in high doses?

Answer 8

Digoxin

digibind / mag / phenytoin

Question 9

What medication can cause blue vision?

Answer 9

Sildenfail

inhibits PDE-5 normally but also cross over to PDE 6 which has a role in the visual pathway

Question 10

What medications can cause loss of colour vision?

Answer 10

ethambutol
hydroxychloroquine

both can cause optic neuritis

Question 11

How is BB OD managed?

Answer 11

Glucagon

Question 12

What is antifreeze and how is OD managed?

Answer 12

Ethylene glycol
Managed with FOMEPIZOLE

Fomepizole inhibits alcohol dehydrogenase
This prevents breakdown of ethylene glycol to OXALIC ACID - TOXIC METABOLITE

Therefore treatment is to aim to reduce metabolite production

Question 13

What are the symptoms of lead poisoning and how is it treated?

Answer 13

Treated by chelation using

• DMSA oral
• EDTA 2nd ine IV for severe

peripheral motor neuropathy + myalgia
lethargy
confusion
dementia

Question 14

How is Copper overload treated

Answer 14

Copper chelation

• Penicillamine D
• Trientine
• Zinc - for asymptomatic disease without liver injury but no cirrhosis or neurological involvement

Question 15

What are the added effects of steroids in pregnancy

Answer 15

weight gain

• DM + macrosomia
• therefore increased risk complications / still birth / miscarriage

Question 16

How is CMV active infection treated?

Answer 16

e.g. CMV retinitis or colitis in HIV infection or secondary to azathioprine or anti-tnf immunosuppression.

IV ganciclovir
oral Valganciclovir (ganciclovir prodrug with same efficacy)

Question 17

What effect does HRT have have on DVT risk?

Answer 17

Increases risk by 2-4 times

no increased risk of CAD

Progesterone only formulations are not associated with increased risk esp if given via depo

Question 18

What common antibiotic class can cause photoxic reactions

Answer 18

quinolones

nitrofurantoin / ciprofloxacin

Question 19

Amisulfide reactions?

Answer 19

Anti-psychotic which can lead to neurloeptic malignant syndrome

athetosis
raised CK
eczema
pyrexia
dystonia
dyskinesis

Question 20

How does cisplatin effect renal function?

Answer 20

Deposits in cells with basolateral ammonia / bicarb transporters
Causes defects

Therefore causes RTA type 2
failed absorption of bicarbonate
= alkalosis
= hypokalaemia due to blood acidaemia