Therapeutics and Toxicology

Question 1

Which medication to avoid in cocaine induced chest pain?

Answer 1

Bisoprolol.

Beta-blockers should be avoided in cocaine-induced chest pain. The rationale is that beta-antagonism may result in unopposed alpha-mediated coronary vasospasm.

Question 2

Management for Amiodarone induced thyroxicosis Type 1?

Answer 2

AIT Type 1:
- Excess iodine-induced thyroid hormone synthesis.

• Goitre: Present
• Management: Carbimazole or potassium perchlorate

Amiodarone should be stopped if possible in patients who develop AIT

Question 3

Management for Amiodarone induced thyroxicosis Type 2?

Answer 3

AIT Type 2:
- Amiodarone-related destructive thyroiditis.

• Goitre: Absent
• Management: Corticosteroids

Amiodarone should be stopped if possible in patients who develop AIT

Question 4

Management for severe serotonin syndrome?

Answer 4

More severe cases of Serotonin Syndrome are managed using serotonin antagonists such as Cyproheptadine and Chlorpromazine.

Question 5

Mx for cocaine toxicity?

Answer 5

Signs of cocaine toxicity with dilated pupils, hypertension, tachycardia, anxiety.

Benzodiazepines are generally first-line for most cocaine-related problems

Question 6

Tx for Amiodarone induced hypothyroidism?

Answer 6

Treating the deficit with levothyroxine, Amiodarone can be continued.

Question 7

ECG changes seen in TCA overdose (amitryptiline)?

Answer 7

ECG changes include:
- sinus tachycardia
- widening of QRS
- prolongation of QT interval

Widening of QRS > 100ms is associated with an increased risk of seizures whilst QRS > 160ms is associated with ventricular arrhythmias.

Question 8

Mx for TCA overdose?

Answer 8

IV sodium bicarbonate.

Question 9

Treatment for salicylate overdose?

Answer 9

Treatment:
1. General (ABC, charcoal)
2. Urinary alkalinization with intravenous sodium bicarbonate - enhances elimination of aspirin in the urine
3. Haemodialysis

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

Question 10

Linezolid should not be given with which class of medications?

Answer 10

In combination with serotonin agonists there is a risk of serotonin syndrome. Therefore, when using linezolid it must be considered to discontinue SSRIs.

Question 11

How to screen for Paraquat overdose?

Answer 11

Urine dithionate testing.

Question 12

Complication from IVIg treatment?

Answer 12

Aseptic Meningitis.

Aseptic meninigits occurs in 1% of patients with intravenous immunoglobulin. The key is to rule out any infective causes and to stop the immunoglobulin treatment until this is been done.

Question 13

Features of lithium toxicity?

Answer 13

• Coarse tremor (a fine tremor is seen in therapeutic levels)
• Hyperreflexia
• Acute confusion
• Polyuria
• Seizure
• Coma

Question 14

Mx for Cyanide poisoning?

Answer 14

Supportive measures: 100% oxygen

Definitive: Hydroxocobalamin (intravenously), also combination of amyl nitrite (inhaled), sodium nitrite (intravenously), and sodium thiosulfate (intravenously)

Question 15

Adverse effect of Trastuzumab?

Answer 15

Trastuzumab (Herceptin) is a monoclonal antibody directed against the HER2/neu receptor.

Adverse effects:
- Flu-like symptoms and diarrhoea are common
- Cardiotoxicity

Question 16

Tx for Methanol poisoning?

Answer 16

Methanol poisoning causes both the effects associated with alcohol (intoxication, nausea etc) and also specific visual problems, including blindness. These effects are thought to be secondary to the accumulation of formic acid.

• Fomepizole (competitive inhibitor of alcohol dehydrogenase) or ethanol
• Haemodialysis
• Cofactor therapy with Folinic acid to reduce ophthalmological complications

Question 17

Treatment for LA toxicity?

Answer 17

Local anesthetic toxicity can be treated with IV 20% lipid emulsion.

Question 18

Which medication can cause a slate grey appearance?

Answer 18

Amiodarone can cause a bluish-grey discolouration of the skin due to the deposition of lipofuscin pigments. This effect is particularly noticeable on sun-exposed areas such as the face and hands. The condition is usually reversible upon discontinuation of the drug, although it may take several months for the skin colour to return to normal.

Question 19

Tramadol administered with SSRIs can cause what?

Answer 19

Serotonin syndrome.

This is because tramadol acts as a central serotonin reuptake inhibitor and so further increases serotonin levels.

Question 20

Biochemical abnormality seen in ethylene glycol toxicity?

Answer 20

Ethylene glycol is a type of alcohol used as a coolant or antifreeze

Metabolic acidosis with high anion gap and high osmolar gap.

Question 21

Symptoms of organophosphate poisoning? (insecticide poisoning)

Answer 21

Muscarinic side effects.

Salivation
Lacrimation
Urination
Defecation/diarrhoea
Cardiovascular: hypotension, Bradycardia
also: small pupils, muscle fasciculation

Mx: ATROPINE.

Question 22

Which condition is gentamicin contraindicated in?

Answer 22

Myasthenia gravis.

Question 23

How to determien dosing of gentamicin based on peak and troughs?

Answer 23

1. Both peak (1 hour after administration) and trough levels (just before the next dose) are measured.
2. If the trough (pre-dose) level is high the interval between the doses should be increased.
3. If the peak (post-dose) level is high the dose should be decreased.

Question 24

Mx for malignant hyperthermia?

Answer 24

1. Condition often seen following administration of anaesthetic agents
   characterised by hyperpyrexia and muscle rigidity.
2. Cause by excessive release of Ca2+ from the sarcoplasmic reticulum of skeletal muscle.

Mx: IV Dantrolene

Question 25

Which overdoses can be haemodialysed?

Answer 25

BLAST

Barbiturates
Lithium
Alcohols e.g. ethylene glycol
Salicylates
Theophyllines