Drug Overdose Flashcards
What are 2 symptoms of paracetamol overdose?
N+V
Asymptomatic
Give 2 groups at increased risk of paracetamol overdose
Those on enzyme inducers e.g. Rifampicin, Phenytoin, Carbamazepine, St Johns Wort
Malnourished/ not eaten for a few days
What is the management of paracetamol overdose?
Activated charcoal if <1h
N acetylcysteine infusion delivered over 1h
Liver transplantation
What are the 4 indications for N-acetylcysteine in paracetamol OD?
plasma conc. on/ above a single tx line joining points of 100 mg/L at 4h
Staggered OD or doubt over time of ingestion, regardless of plasma concentration
Pt presenting 8-24h after ingestion of an acute OD of >150 mg/kg, even if plasma conc not yet available
patients who present >24h if they are clearly jaundiced or have hepatic tenderness/ ALT is above upper limit of normal
What adverse effects may be seen when infusing N-Acetylcysteine for paracetamol OD?
How should this be managed?
Anaphylactoid reaction (non IgE mediated mast cell release)
Stop the infusion, then restart at a slower rate.
What are 5 symptoms of salicylate overdose with mild toxicity?
N+V
Epigastric pain
Tinnitus + deafness
Dizziness
Lethargy
What are 3 symptoms of salicylate overdose with moderate toxicity?
Sweating
Fever
Dyspnoea: Hyperventilation (centrally stimulates respiration)
What are 3 symptoms of salicylate overdose with severe toxicity?
Confusion
Convulsions
Coma
What acid base picture is found in salicylate overdose?
mixed respiratory alkalosis + metabolic acidosis
Give 4 signs of salicylate overdose on examination
Warm peripheries + bounding pulse
Tachypnoea + hyperventilation
Cardiac arrhythmia
Acute pulmonary oedema
What bedside investigations should be performed in salicylate overdose?
Basic obs: tachycardia + taachypnoea
ECG: monitor for arrhythmia
CBG: exclude hypoglycaemia/ ketoacidosis
ABG: Acid base balance
What bloods should be taken in salicylate overdose?
Salicylate conc. >,2h after ingestion + repeat every 2h
Paracetamol conc.: identify mixed OD
FBC
U+Es: Electrolyte disturbances
LFTs: Hepatic dysfunction
Coagulation: INR + PT may be increased in hepatic dysfunction
What peak salicylate levels define mild, moderate and severe salicylate toxicity?
Mild: <300 mg/L
Moderate: 300 to 700 mg/L
Severe: >700 mg/L
Describe initial management of salicylate overdose
A-E
Activated charcoal if <1h
IV NaCl
K+ replacement
IV sodium bicarbonate (urinary alkalisation, enhances excretion in urine)
Give 2 indications for haemodialysis in salicylate overdose
Serum conc > 700mg/L
Tx resistant Metabolic acidosis
Give 4 complications of salicylate overdose
Acute respiratory distress syndrome
Seizures
Drug-induced hepatitis
Cardiac arrest (prolongation of QT)
What are 3 symptoms/ signs of opioid overdose?
Bradypnoea (resp. depression)
Pinpoint pupils (miosis)
Drowsiness/ Coma (altered mental status)
Give 4 measurable signs of opioid overdose?
Bradycardia
Hypotension
Hypothermia
Constipation (reduced BS)
What is used for management of opioid overdose?
IV/ IM Naloxone
(Rapid onset, relatively short duration of action, may need to repeat/ infusion)
What are 8 symptoms of benzodiazepine overdose?
Reduced level of consciousness (inc. coma)
Resp. depression: can result in hypoxia +
inadequate tissue perfusion.
Ataxia + dysarthria
Nystagmus
Hypotension
Bradycardia
Rhabdomyolysis
Hypothermia
What can coma lead to in Benzodiazepine overdose?
Loss of airway tone + reflexes leading to hypoxia
Describe management of Benzodiazepine overdose
A-E assessment
Maintain airway
Supportive e.g. fluids
Activated charcoal if <1h since ingestion if awake
+/- Flumazenil
When is flumazenil use indicated in a benzodiazepine overdose?
- CNS depression so severe requires ventilation
- Confidence only benzos have been taken (e.g. no possibility of a mixed OD)
- Patient is not known to be benzo dependent
Why must 3 conditions be met for flumazenil to be used in benzodiazepine overdose?
Use outside these conditions risks precipitating seizures
(e.g. if a patient has also taken TCAs)
v difficult to treat due to the GABA antagonism caused by Flumazenil.
Give 4 symptoms of TCA overdose
Dry mouth
Hot, dry skin
Confusion + hallucinations
Palpitations
What are symptoms of TCA overdose mediated by?
anticholinergic toxicity + the result of sodium channel blockade
Give 4 severe effects of TCA overdose
arrhythmia
cardiovascular collapse
convulsions
coma.
Describe management of TCA overdose
Activated charcoal if <1h since ingestion.
Sodium bicarbonate: in arrhythmia + acidosis to prevent progression to ventricular arrhythmias
What are the key investigations in TCA overdose? What will be seen?
ECG: QRS widening or QTc prolongation
ABG: acidosis.
Which antiarrhythmetics should be avoided in TCA overdose?
Class 1a (e.g. Quinidine) + 1c (e.g. Flecainide) as they prolong depolarisation.
Class III (e.g. amiodarone) as they prolong the QT interval.
What are 4 symptoms of lithium overdose?
N+V
Abdo pain
Diarrhoea
Coarse Tremor
Describe management of lithium overdose
Mild-mod: volume resus with normal saline
Haemodialysis: if severe toxicity
Sodium bicarbonate: increases alkalinity of urine thus promotes lithium excretion. Sometimes used but limited evidence to support
Describe management of Warfarin overdose
Vitamin K1
What drug is used for heparin overdose?
Protamine sulphate
What drugs are used in beta blocker overdose?
If Bradycardic: atropine
In resistant cases glucagon may be used
