Overdose

Question 1

What toxins will not bind to activated charcoal?

Answer 1

Hydrocarbons
Alcohol
Metals
Corrosives
Malathion

Question 2

How is paracetamol metabolised?

Answer 2

Glucuronidation of paracetamol to non-toxic metabolite & excreted
4% metabolised by P450 to toxic NAPQI
Conjugated w/Glutathione to non-toxic mercapturate & excreted in urine
OD = P450 pathway dominant ↓ Glutathione
NAPQI binds to cellular components = hepatocyte death

Question 3

What are the Sx of paracetamol OD?

Answer 3

Asymptomatic
Signs of self-harm
Late = RUQ pain, N&V, jaundice, confusion

Question 4

How is Paracetamol OD investigated?

Answer 4

Paracetamol level: 4hours post-ingestion
Check against paracetamol chart
Bloods: AST & ALT, U&E, INR & prothrombin time
ABG + lactate

Question 5

How is a paracetamol OD treated?

Answer 5

SINGLE OD:
<1hour: Activated Charcoal
<8hours: IV Acetylcysteine + Ondansetron
8-24hours: Evaluate for liver transplant

STAGGERED:
IV Acetylcysteine given IMMEDIATELY

Question 6

What is the regimen for giving Acetylcysteine?

Answer 6

150mg/kg over 1 hour
50mg/kg over 4hours
100mg/kg over 16hours

Question 7

What criteria shows hepatotoxicity is unlikely?

Answer 7

>4hours since last ingestion AND
ALL of following apply
Asymptomatic
Serum paracetamol <10
INR <1.3
ALT normal

Question 8

What are the Sx of Salicylate OD?

Answer 8

N&V
Tinnitus
Lethargy 
Dizziness
Dehydration
Sweating
Restlessness
Warm extremities
Bounding pulse
Coagulopathy
Inc RR- Hyperventilation
CNS: confusion, disorientation, coma & convulsions

Question 9

How is a salicylate OD investigated?

Answer 9

-Salicylate levels:
Sx = 2hrs post-ingestion
aSx = 4hrs post-ingestion
Repeat in 2hours then every 3hours until levels↓
-Bloods: U&E, FBC, INR, Glucose, K+ (CHECK EVERY 3HOURS)
-Urinary pH
-ABG: Mixed respiratory alkalosis & metabolic acidosis w/N or ↑pH
Kids: Metabolic acidosis

Question 10

How is a salicylate OD managed?

Answer 10

<1hour: Activated Charcoal
Gastric lavage: >500mg/kg in <1hour
Aggressive rehydration
Urinary alkalisation: Check hourly
-Sodium bicarb

Haemodialysis

Question 11

How is a salicylate OD monitored?

Answer 11

K+ Levels every 3hours

Urinary pH checked hourly

Question 12

What are the Sx of a TCA OD?

Answer 12

CV & CNS toxicity
Tachy
Hypotension
Mydriasis: Dilated pupils
Warm, dry, flushed skin
Change in mental status
Urinary retention
↓bowel sounds
Ophthalmic signs

Question 13

How is a TCA OD investigated?

Answer 13

ECG: Prolonged QRS
ABG: Metabolic acidosis
Sodium bicarb

Question 14

How is a TCA OD treated?

Answer 14

<2hours since ingestion: Activated Charcoal + Monitor
Sodium Bicarb
Arrhythmia: MgSO4

Question 15

How do the different levels of salicylate toxicity relate to severity?

Answer 15

>125mg/kg = Toxicity mild
>250mg/kg = Toxicity moderate
>500mg/kg = Toxicity severe/fatal

Question 16

How is the severity of a salicylate OD clinically graded?

Answer 16

Mild: N&V, tinnitus
Moderate: Hyperventilation & confusion
Serious: Hallucinations, seizure, coma, cerebral/pulmonary oedema

Question 17

What are the Sx of an opioid OD?

Answer 17

N&V
Sedation/Drowsiness
Hypotension & Tachycardia
Pinpoint pupils (miosis)
Respiratory depression

Question 18

How is an opioid OD investigated?

Answer 18

Test dose of Naloxone
Bloods: FBC, CK, metabolic screen
ABG
ECG

Question 19

How is an opioid OD treated?

Answer 19

-Oxygen & airway Mx
1) IV Naloxone: 0.4-2mg IF coma/resp depression
OR
1) IM Naloxone: If no veins

Question 20

What drug is recommended by NICE for opioid addicts who quit?

Answer 20

Naltrexone: Competitive opiate antagonist that blocks effect of heroin.