25 - Poisoning and STOPP START Flashcards
What is pharmacological toxicity usually due to?
A predictable extension of the desired effect of the drug at the known site
Give some examples of how the following drugs can have pharmacological toxicity at slightly supratherapeutic doses:
- Warfarin
- Loop Diuretic
- AChE Inhibitors
Insulin
Exaggeration of their desired effect
What are some of the pharmacologically toxic effects of the following (not related to the drugs usual desired effects):
- Statin
- B-agonist
- Thalidomide
- B-blocker
What are some effects seen in large overdoses of the following drugs:
- Beta Blocker
- Opioids
- Theophylline
- Carbamazepine
- Phenobarbital
- Myocardial depression
- Respiratory depression, tachycardia, hypotensive
- Convulsions, arrhythmias
- Respiratory depression
- Respiratory depression
Identify five common UK poisons.
- Paracetamol
- Hypnotics (diazepam, zoplicone)
- Salicylates
- Ecstasy
- Opiates
What is biochemical toxicity?
- A drug or active metabolite which causes cellular damage to macromolecules such as structural proteins and enzymes
- Drugs on the market are tested for this but at supratherapeutic doses they often have build up of toxic metabolites
What are the antidotes for an overdose of the following drugs:
- Digoxin
- Cocaine
- Paracetamol
- Benzodiazepene
- Opiate
- Beta Blocker
- Can also give chelating agents that complex with the poison to reduce the amount of free drug (e.g in lead, cyanide and iron salt poisoning)
- Digibound is antibody (so is antivenom)
How does the antidote for paracetamol overdose work?
N-Acetyl Cysteine
- Donates thiol to glutathione to drive phase 2 and prevent build up of toxic metabolites to stop centrilobular necrosis
- In OD the glutathione is saturated so cannot conjugate anymore NAPQI so build up of NAPQI
How can we overcome biological toxicity of drugs that are used at therapeutic levels e.g the DMARD cyclophosphamide?
- Use Mesna 2 hours before orally or in IV with cyclophosphamide
- Has a thiol group for cytoprotection and a polar group so it can get renally excreted and get to the right place to protect bladder epithelium
- Mesna helps stop haemorraghic cystitis
In general what are the management principles for a drug overdose?
Immediately:
- Remove person from contact with poison
- Take vital signs and look for injuries
- Take history from patient, chaperone, written notes or packaging
What are some scenarios you need to consider that might need supportive measures to correct when a person is having a drug overdose?
How can we prevent absorption of a drug and increase it’s elimination in a drug overdose?
- Never gastric lavage due to risk of aspiration
- Give lots of activated charcoal in water if conscious to prevent absorption
What is fomepizole used for?
Stops ethylene glycol and methanol poisoning by altering the metabolism to stop the production of toxic metabolites
What is the antidote for organophosphate poisoning?
ATROPINE: Antimuscarinic
What is polypharmacy?
When a patient is taking 4-6+ medicines concurrently
Which patients should have their medications reviewed regularly?
Helps to improve the clinical outcomes for the patient and our economy as ensures investing in the right place
What are some things that need to be checked in a medication review?
- Is the medication right for the patient?
- Time limited medications (e.g clopidogrel, GORD treatment)
- Medications considered during admission but not on discharge (e.g hypnotics)
- Age-life expectancy and risk benefit
- Is the medication producing a measurable outcome (e.g HbA1c change)
- Cost
- DDIs, ADRs and contraindications
- Concordance
- Over the counter and complimentary medications
- Lifestyle modifications
What is the STOPP START tool?
Screening tool of older people’s prescriptions and screening tool to alert to right treatment
Used in over 65s to stop and start certain drugs to prevent inappropriate prescribing and reduce DDIs and ADRs
