Poisoning and Antidotes Flashcards

1
Q

How many admissions yearly for self-poisoning in England and Wales

A

160k

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2
Q

How many adults conscious on arrival to hospital after self-poisoning

A

80%

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3
Q

Who is more likely to take an overdose

A

Females

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4
Q

Who is more likely to be successful in suicide

A

Males using measures that don’t involve medication

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5
Q

Define poisoning

A

Exposure to a drug, chemical, pollutant in enough quanitity to produce an adverse effect
Can be acute or chronic

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6
Q

How many cases of poisoning are accidental

A

almost 50%

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7
Q

Percentages of poisoning at home, workplace and related to oral adminsitration

A

90%
5%
90%

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8
Q

How many cases of poisoning are deliberate

A

25%

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9
Q

How many cases of poisoning are due to therapeutic error

A

20%

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10
Q

Examples of accidental poisoning

A

Children e.g. household chemicals and parents medications
Duplication of therapy
Confusion over doses
Prescribing or dispensing errors
Counterfeit drugs that may contain harmful ingredients of contaminants

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11
Q

Examples of deliberate poisoning

A

Deliberate poisoning is when you poison others to cause harm
Overtaking medicines for beenfits e.g. thyroxine for weight loss
Drug misuse, self-harm and suicide

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12
Q

What is the case in most scenarios when there is deliberate poisoning: adminsitration, how many drugs, most commonly implicated 2nd agent

A

Self administration of a prescribed or OTC medicine or illicit drug
Most patients have taken 1+ drug, alcohol is the most commonly implicated 2nd agent

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13
Q

What is occupational poisoning

A

Chemicals found in place of work e.g. Xrays, lead, mercury, asbestos, pesticides, solvents, corrosive agents, fertilisers, snake bites

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14
Q

What is environmental poisoning

A

e.g. air, water, soil pollution
CO poisoning from dodgy boilet in rented properties is common

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15
Q

Stats for CO poisoning

A

50 deaths/year
4k medical visits for CO exposure

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16
Q

Poisoning in pregnancy

A

Unborn child can be very vulnerable to the effects of drugs and chemials
Lots of teratogenic medicines e.g. isotretinoin, valproate, alcohol etc
Also environmental poisoning

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17
Q

Majory of poisons reported are due to…

A

Poisons

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18
Q

Top 3 common drugs taken in overdose and stats

A

Paracetamol (~170k/year reported on ToxBase)
Ibuprofen (~55k/year)
Codeine (~40k/year)

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19
Q

Nicotine poisoning

A

Highly toxic by ingestion, inhalation and skin contact
As little as 40mg nicotine can be fatal in adults
Small amounts can be life threatening
Vapes can be appealing to children - sweet smell, colours etc
Increased no. of people being admitted to hospital from vaping

20
Q

Signs of nicotine toxicity

A

Nicotine is a stimulant
Sympathomimetic drug - released dopamine
Large amounts = increased HR, contractility, BP and massive release of dopamine

21
Q

SE of nicotine

A

Dizziness, headache, sleep disturbances, irritability
Tachycardia, increased or decreased HR, increased BP, CAD
Nausea, dry mouth, dyspepsia, diarrhoea, heartburn

22
Q

What is the EU tobacco product directive 2014

A

A lot more regulation around vapes to reduce incidence of hospital admissions
Must be >18 to buy
No advertising on TV, radio, newspapers/magazine
Only can advertise at point of sale or local advertising
Consumer product = max 20mg/ml nicotine allowed to be sold
>20mg/ml needs to have medicinal license
Max quantitiy 10ml (refill contianer) or 2ml (cigarette, cartridge)
Must be child resistant

23
Q

What age does most poisoning occur in children

A

<5
Poisonous substances found in accessible cupboards, medicines can look similar to sweets

24
Q

Top 3 substances ingested by childen </5

A

Paracetamol
Ibuprofen
Multivitamins

25
Q

Most common household poisons

A

Fabric cleaning liquid tablets, diffusers, bleach, air fresheners, disinfectants

26
Q

Batteries

A

Post major risk to children and toddlers
Can cause serious damage in just a short time

27
Q

Pharmacist role in preventing self-poisoning - paracetamol

A

Reduction of paracetamol pack sizes, 1998
32 OTC, 16 GSL
Led to large reduction in number of poisoning and reduction in number of people needing liver transplant
Maximum 100 paracetamol can be sold at any one time in a pharmacy
Supermarkets can sell up to 32 capsules/tablets
Use professional judgement to decide appropriate quantity to supply and what limits to impose

28
Q

Pharmacist role in preventing self poisoning - general

A

Child resistant drug containers and safe storage of medicines
Medication reviews
Patients understanding the dose of medicine the maximum daily dose
Disposal of expired and unused medicines
Monitoring of sale/sipply of medicines subject to abuse
Ensure quality of imported products

29
Q

Pharmacist role in treatment of poisoning

A

Recognise poisoning has occured
Establish a patient’s drug history
ID any agents involved
Give advice on antidote use - posions unit/TOXBASE
Ensure availability of appropriate antidotes
Provide patient info

30
Q

Things to ask e.g. if a child is taken into A&E by a parent who finds them playing with a handful of small white tablets

A

Ask what the tablets could be - what medication is in the house
If she has the tablets, look for at characteristics: marking, size, shape, score down the middle etc
Has the child actually taken any
Do you know how many they have taken
Child’s symptoms
Can the child communicate
Identify tablets
Treat the symptoms
Tictac is a database that can help medications - may give you one or a list of medicines it vcould be, then work out it could be from there by asking Qs

31
Q

Management of posioning

A

Some may be managed in primary care
Hospital admission criteria - potentially life threatening or delayed action poisons, self-harm/deliberate poisoning
Most management is symptomatic, continuous assessment and monitoring
Psychiatric/social assessment - accidental or intentional poisoning/self harm
Patient often rescuscitated first before identification of agents ingested

32
Q

Define toxidrome

A

Group of symptoms used to identify agents

33
Q

Classic toxidrome for opioid overdose and anticholinergics

A

Opioid overdose: unconscious, hypertension, respitatory depression, pinpoint pupils
Anticholinergic: dilated pupils, dry mucous membrane, urinary retention, tachycardia

34
Q

3 types of specific treatment for poisoning

A

Gut decontamination to stop medication being absorbed
Enhanced elimination
Antidotes

35
Q

Gut decontamination - activated charcoal

A

Absorbs ingested substances preventing their absorption into systemic circulation
Must be fully conscious or have a protected airway
Will only work up to the point that medicines are absorbed
Most drugs absorbed 20 mins - 1 hour from ingestion so if OD was 3 hours ago, there is no point giving charcoal
Activated charcoal is ideal up to 1 hour, max 2 hours

36
Q

Gut decontamination - whole bowel irrigaiton e.g. polyetheylene glycol

A

Cleanses the entire bowel through enteral administration of large amounts of an osmotically balanced solution like polyethelyene glycol
Used for high doses of iron, lithium

37
Q

Enhanced elimination with urinary alkalisation

A

e.g. NAHCO3
Increases eliminaiton of weak acids like aspirin
Administration titrated against urinary pH
Try keep urinary pH between 7.5-8.6 to prevent aspirin being ionised and reabsorbed in renal tubules
Blood gases and K levels must be measured

38
Q

Enhanced elimination with haemodialysis/hemoperfusion

A

Remove blood and put it back in
Only used for a limited subset of drugs/chemicals e.g. severe aspirin, lithium, ethylene glycol, methanol

39
Q

Antidotes and their mechanisms

A

Substances that can counteract a form of poisoning by a variety of mechanisms:
- forming an inert complex with the poison
- accelerating detoxification of poision
- reducing rate of conversion of the poison to a more toxic compound
- competing with the poison for essential receptor sites
- blocking essential receptors through which the toxic effects are mediated
- bypassing the effect of the poison

40
Q

What is used for digoxin toxicity

A

Digi-fab

41
Q

What is digi-fab

A

Used for digoxin toxicity
Forms an inert complex with digoxin and it is no longer toxic and will be excreted to the body
Binds in a 1:1 ratio - need to work out how much a patient has taken, and from that work out how much Digi-fab to give
Digoxin is a potent inhibitor of Na/K-ATPase to toxicity will result in strong inhibition of it = increased intracellular sodium = increased intracellular calcium = increased conttacility and tachycardia

42
Q

N-acetylcysteine (NAC) for paracetamol

A

Normal therapeutic dose: ~95% metabolised via glucuronide mechanism and forms a conjugate which is excreted in urine, only ~5% forms the toxic NAPQI metabolite
When too much paracetamol is taken, the other pathway become satruated meaning a lot more of the paracetamol is metabolised ot the toxic ANPQI, causing hepatoxicity
NAC replenishes gutathione to accelerate detoxiifcaiton of paracetamol
- does this by metabolising to glutathione
- the glutahtione will bind to NAPQI to form to non-toxic metbaolites as well to force more through the other pathway

43
Q

Ethylene glycol (anti-freeze) poisoning and antidote

A
  • Metabolites of ethylene glycol are toxic
    e.g. oxalic acid clogs renal microcirculation and acute tubular necrosis
    e.g. formic acid causes damage to retina leading to blindness
    e.g. glycolic acid causes metabolic acidosis
  • antidote: ethanol or fomepizole - reduces rate of conversion of ethylene glycol ot toxic metabolites
  • either will give 40% alcohol or give femepizole (competitive antaognist, more expensive)
44
Q

Naloxone for opioids like morphine, heroin, oxycodone

A

Direct inhibitor of opioid receptors
Has high affinity for opioid receptors in brain
Displaced opioid from the receptors and it will be metabolised and excreted from bodt
Has short half life so may need repeated doses or infusion depending on how much morphine was given to patient

45
Q

Phytomenadione (Vitamin K) for warfarin

A

By passes effect of warfarin inhibiting VKOR
Warfarin commonly implicated in poisoning
When you give warfarin, it blocoks VKOR, stopping conversion of vit K to reduced vit K which is involved in clotting factors
Too much warfarin = not enough clotting factors = increased risk of bleeding and bruises
Give vitamin K to help regenerate the required clotting factors
Does not inhibit warfarin