Poisoning & Overdose Flashcards
What is the lethal dose of nicotine for adults?
40mg
What is the MoA of nicotine? (5)
- A sympathomimetic drug
- Releases catecholamines (dopamine)
- Increases HR and cardiac contractility
- Constricts cutaneous and coronary blood vessels
- Transiently increases BP
- Increases breathing rate
What is the pharmacist’s role in preventing self-poisoning? (5)
- Limit stockpiling of meds
- Safe storage of medicines and caustic substances
- Child-resistant containers
- Monitoring of susceptible patient’s Rx
- Patients understanding dose and maximum daily doses e.g. paracetamol 4g daily
What are the general steps in treatment of poisoning? (5)
- Establish DHx
- ID agents involved
- Advise on antidote use - TOXBASE
- Ensure availability of antidotes
- Provide patient with information
What is the general treatment to poisoning?
- Symptomatic and supportive care
- Check for infection and/or trauma an metabolic derangements
- Continuous assessment and monitoring
- Case specific management
- Patients resuscitated before identification of agents ingested
What treatments are used in poisoning treatment?
- Gut decontaminators
- Enhanced elimination
- Antidotes
What is used in gut decontamination?
- Activated charcoal: Absorbs ingested substance preventing absorption into circulation (most effective given within 2 hours)
- Whole bowel irrigation e.g. polyethylene glycol
What is used to enhance elimination?
- Urinary alkylation e.g. NaHCO3: Increases elimination of weak bases e.g. Aspirin. Blood gases and potassium MUST be monitored
- Haemodialysis/Haemoperfusion
By what mechanisms can antidotes exert their effects?
- Forming inert complex with substance
- Accelerating detoxification of substance
- Reducing rate of conversion to a more toxic compound
- Competing with substance for essential receptor sites
- Blocking essential receptors
- Bypassing effect of the poison
What is the antidote to digoxin toxicity and its MoA?
- Digi-fab
- Forms inert complex with Digoxin
What are the signs and symptoms of Digoxin toxicity? (6)
- Heart arrhythmias
- N&V
- Fatigue and weakness
- Weight loss
- Confusion
- Visual disturbances
What is the antidote for Paracetamol poisoning and its MoA?
- N-acetylcysteine
- Accelerates detoxification of paracetamol
- Is a precursor to Glutathione, so increases Glutathione available for conjugation to NAPQI into non-toxic metabolites
What are the signs and symptoms of Paracetamol toxicity?
Short-term: Fatigue, abdominal pain, nausea, sweating
Long-term (few days): Yellowish skin, blood clotting problems, confusion
What are the antidotes to Ethylene glycol (antifreeze) poisoning? and their MoA?
- Ethanol
- Fomepizole
- Reduces rate of conversion of ethylene glycol to toxic metabolites e.g. glycolaldehyde
What are the symptoms of ethylene glycol toxicity?
- N&V
- Convulsions
- Stupor (decreased alertness)
- Coma
What is the antidote to opioid toxicity? And its MoA?
- Naloxone
- Has a greater affinity to opioid receptors than opioids such as heroin or oxycodone so blocks the receptors and replaces opioids already on receptors
What are the signs of opioid toxicity?
- Altered mental state
- Pinpoint pupils
- Respiratory depression
What is the antidote for Warfarin toxicity? And its MoA?
- Phytomenadione
- Competes with warfarin for essential receptor sites
- Catalyses the hepatic synthesis of blood clotting factors including prothrombin
What are the symptoms of Warfarin poisoning?
- Excessive bruising and bleeding e.g. nose bleeds
- Red spots on skin
- Blood in urine
- Black or bloody stools
What is the antidote for beta-blocker overdose? And its MoA?
- Glucagon
- Bypass the blocked Beta-receptor to exert inotropic and chronotropic cardiac effects
What are the signs and symptoms of beta-blocker overdose?
- Irregular heartbeat
- Low BP
- Heart failure (SoB + swelling of legs)
