Toxicology

Question 1

Explain the GABA receptor mechanism behind alcohol withdrawal

Answer 1

Chronic alcoholics GABA receptors lose sensitive due to overstimulation. Therefore, in withdrawal. In response glutamate (excitatory is produced in excess. In withdrawal, there is a removal of that inhibitor, and an imbalance leading to over-excitation

Question 2

Symptoms of alcohol withdrawal

Answer 2

6-12h: tremor, sweating, headache, craving, anxiety.
12-24h- hallucination
24-48h: seizure
24-72h: delirium tremens

Question 3

Treatment of alcohol withdrawal

Answer 3

Give thiamine. If CIWA >10, give a benzodiapine. In alcohol withdrawal without delirium tremens or seizures, give chlordiazepoxide. If delirium tremens or seizures, give short acting like lorazepam. Preferably symptom based approach.

Question 4

Treatment of delirium tremens.

Answer 4

High dose diazepam or lorazepam + antipsychotics if not controlled after >130 mg chlordiazepoxide in 1h give antipsychotics (haloperidol or olanzapine)

Question 5

Classic triad wernickes encephalopathy

Answer 5

Ataxia, oculomotor dysfunction, acute encephalopathy

Question 6

Korsakoff syndrome causes

Answer 6

Chronic alcoholism, malabsorption, glucose infusion

Question 7

Triad of korsakoff syndrome

Answer 7

Confabulation, irreversible anterograde and retrograde amnesia

Question 8

Signs of opioid overdose

Answer 8

Needle track marks, pinpoint pupils, bradypnoea

Question 9

Opioid overdose treatment

Answer 9

Naloxone

Question 10

Effect of TCA by different blocking mechanisms

Answer 10

Anticholinergic: mydriasis, confusion, dry mucous membranes, hot and flushed
Serotonin reuptake inhibitor: seizures
Alpha-adrenergic blockade (present in arteries): hypotension due to vasodilation
Na channel blockade: widened QRS and dominant R wave in AVr

Question 11

Management of TCA toxicity

Answer 11

If <2h, activated charcoal

If hypotension, arrhythmia or acidosis, IV sodium bicarbonate

Question 12

Symptoms and management of benzodiazepine overdose

Answer 12

Main features are extreme sedation, unremarkable vital signs and anterograde amnesia. In severe cases in can progress to coma and respiratory depression.

Management - supportive mainly and can give flumazenil in non-benzo dependent ppl but not to benzo dependent due to risk of seizure

Question 13

Explain physiology of aspirin overdose

Answer 13

Initially, aspirin stimulates the brain stem causing tachypnoea - respiratory alkalosis.

Then, uncoupling of oxidative phosphorylation causes buildup of acid products leading to a metabolic acidosis.

Question 14

Symptoms of salicylate poisoning and management

Answer 14

Tachypnoea, confusion, coma,convulsions, N&V

Management includes activated charcoal if patient presents within 1h, , supportive measures, management of fluids and hypokalaemia.

Question 15

Blood results in paracetamol overdose (LFTs, PT, INR, lactate)

Answer 15

LFTs: deranged
Lactate: high with acidosis
PT: prolonged
INR: high

Question 16

Management of paracetamol overdose

Answer 16

<8h
Activated charcoal if within 1h
Take paracetamol conc at 4h. If warranted treat with acetylcystein until INR <1.4

> 8h
Take paracetamol conc STAT and start acetylcystein if indicated.

Question 17

When to give acetylcystein immediately

Answer 17

When >150mg/kg and cannot get a paracetamol concentration within 8h of overdose. Or anytime after 24 with hepatic issues
Given as 150mg/kg over 1h, then 50mg over 4h, then 100mg over 16h.

Question 18

Diagnostic ABG finding of CO poisoning and management

Answer 18

Carboxyhaemoglobin>20%. 100% oxygen via mask, hyperbaric oxygen if available.

Question 19

Cocaine overdose symptoms

Answer 19

Hyper adrenergic state: agitation, anxiety, dilated pupil, diaphoresis, hyperreflexia, hyperthermia, hallucination…

Question 20

When can you safely discharge a patient with paracetamol overdose

Answer 20

And at the end of the 24 hour treatment ALT is less than two times the upper limit of normal and a ALT is not more than double the admission measurement and I and our is 1.3 or less

Question 21

A pattern of substance use that is causing damage or harm to the user

Answer 21

Harmful use. Can be physical, psychological or social.

Question 22

A cluster of symptoms that occur after repeated substance use where taking the substance takes over aspects of life. Leads to tolerance, compulsion, withdrawal.

Answer 22

Dependency

Question 23

Classical Pavlovian conditioning

Answer 23

Cravings become associated with cues

Question 24

Operant conditioning

Answer 24

Drug makes you feel good so you want to do it again.

Question 25

Social learning theory of dependence

Answer 25

Social learning

Question 26

Neurobiological model of dependence

Answer 26

Increased activation of the dopaminergic neurotransmitter pathway

Question 27

175 ml of wine is how many units?

Answer 27

2

Question 28

1 pint is how many units

Answer 28

2/3 units

Question 29

Equation for finding units

Answer 29

Volume (ml) x alcohol strength /1000

Question 30

Recommended level of alcohol consumption per day

Answer 30

All genders: 14 units per day.

Men: 3-4 per day
Women: 2-3 per day

Question 31

Symptoms of lithium toxicity and management

Answer 31

Begins with tremor, slurred speech, confusion, hypereflexia. Progresses to ataxia, seizures (convulsions). Manage with supportive measure of haemodyalisis + sodium bicarbonate if very bad.