Poisoning Flashcards
What is the definition of poisoning and the different types out there
The exposure to a drug or chemical or pollutant in enough quantity to produce an adverse effect
Acute: immediate attention and care from large exposure to chemical
Chronic: Slow build up overtime, long time exposure to heavy metals or prolonged use of medicine
Describe accidental poisoning
Makes up majority of poisoning
Children- house hold chemicals or parent’s medication
Duplication of therapy- lemsip- do not take paracetamol with it
Confusion over doses
Counterfeit drugs- can contain harmful ingredients or contaminates
- Parallel imports, internet, manufactured somewhere unsafe
Describe deliberate poisoning
To cause others harm
Overtaking medicines for benefits- thyroxine for weight loss
- Works by causing hyperthyroidism which speeds up metabolism
Risk of tachycardia, angina and osteoporosis
Describe suicide
Self administration of a prescribed or OTC medicine or an illicit drug
Most patients taken more than one drugs and alcohol is the commonly implicit second agent
Describe occupational poisoning
Chemicals found in place of work
For example:
X rays, lead, mercury, asbestos, pesticides, noxious fumes, solvents, corrosive agents, fertilisers, bites by snakes
COSSH risk assessment necessary
Describe environmental poisoning
Air
Water
Soil
Pollution
Describe nicotine poisoning
Highly toxic by ingestion, inhalation and skin contact
Little as 40mg nicotine is fatal in adult
Varying strengths from 6mg per mL to 36mg per mL so small amount can be threatening
What are the signs of nicotine toxicity
Stimulant
Increases heart rate tachycardia
What are some side effects of nicotine
Headache Dizziness Increased or decreased heart rate Increased blood pressure Tachycardia More arrhythmias GI- nausea, dry mouth, diarrhoea, cancer Joint pain Circulation- increased clotting tendency, atherosclerosis
What are the most common household poisons
Surfactants + detergents Bleaches Ethylene glycol Batteries Silica gel White spirit Cyanoacrylate
What are the most common drugs taken in overdose
Paracetamol Ibuprofen Salicylates- aspirins Citalopram Diazepam Zopiclone Compound analgesics Fluoxetine Tramadol Amitriptyline
What is the pharmacist’s role in prevention of self poisoning
Limting stock pile of medicines Reviewing home medicine's cupboard Safe storage of medicines and caustic substances Child resistant drug containers Foil wrapped drugs Dispose of expired and unused medicines
Prescriptions monitored carefully
Patients understanding of medicine doses and maximum daily dose
Reduction of paracetamol pack sizes
Co-proxamol withdrawn from market
Removal of counterfeit or contaminated products
Ensure quality of imported products
What is the pharmacist’s role in treating poisons
Recognising poison has occurred
Establishing a drug history
ID any agents involved
Advice on antidote use- poisons unit or TOXBASE (online database with medicine information)
Ensure medicines are available for appropriate antidotes
Provision of patient information
How do you manage poisons
Psychiatric and social assessment
Careful recording of information
Admission criteria:
Potentially life threatening or delayed action poisons
Self harm or deliberate poisoning
Seek advice from Toxbase if unsure
Monitor patient- liver function, renal function, blood levels, pulse
Describe the general treatment of poisoning
Symptomatic and supportive care
Check for infection and/or trauma and metabolic derangements
Continuous assessment and monitoring
Case specific management
Patients often resuscitated first before identification of agents ingested
Cluster of symptoms and signs- toxidrome
- Patient may have pin point pupils, reduced BP- opioids
Tricyclic anti-depressants- anti-muscarnic effects
Describe the gut decontamination treatment
- Only used where it presents early, fully conscious, significant risk of harm- tube down someone throat, warm water and pumping stomach content back through tube
- Induced vomiting with ipecacuanha or performing gastric lavage (nasty drink)- no evidence of impact on outcome- taken within 30 minutes of exposure
- Activated Charcoal- absorbs ingested substances to prevent absorption into systemic circulation- used within an hour or 2 hours of ingesting medicine
- Whole bowel irrigation- polyethylene glycol- high iron doses, lithium, SR prep, body packers- flushing out via toilet
Describe the enhanced elimination treatment
- Urinary alkalisation- NaHCO3
Increases elimination of weak acids e.g. aspirin
Administration titrated against urinary pH
Blood gases and K must be monitored - Haemodialysis and haemoperfusion (blood pumped via colon with absorption properties)
- Limited subset of drugs and chemicals like severe aspirin, lithium, ethylene glycol, methanol
Describe the antidote treatment
Forming inert complex with poison
Accelerating detoxification of poison
Reduction in rate of conversion of poison to more toxic compound
Competing with poison for more essential receptor sites
Blocking essential receptors which means toxic effects are mediated
Bypassing poison effect
Explain how digi-fab works
Forms an inert complex with digoxin
The digoxin (xenobiotic) binds onto the antibody antidote to form an inert compound
Explain how N-acetylcysteine works
Used in paracetamol overdose- accelerates detoxification of paracetamol
The glucuronide sulfate stores are depleted so paracetamol doesn’t get converted into non toxic metabolite and gets converted to NAPQI (toxic)
The N-acetylcysteine works by replenishing stores of Glucuorinide which detoxifies paracetamol
Explain the poisoning of ethylene glycol
Anti-freeze poisoning
Calcium oxalate crystals form that precipitate in blood stream to clog renal microcirculation causing acute tubular necrosis
Oxalic acid- responsible for nephrotoxicity
Formic Acid- toxic to retina and causes blindness
Glycolic acid- responsible for metabolic acidosis
Explain how ethanol or fomepizole is used against ethylene glycol
Competes against rate of conversion of ethylene glycol to toxic metabolites- 40% used to compete with it
Describe how naloxone works
Stronger affinity to opioid receptors like heroin or oxycodone- so it knocks it off receptors for short time (30 to 90 mins) to allow person to breathe again and reverse dose
Describe the use of phytomenadione
Competes with warfarin for essential receptor sites
Name: Vitamin K
It is a vitamin K antagonist for warfarin as warfarin is structurally similar to vitamin K
