S14.1 Poisons & clinical influences on prescribing

Question 1

Name some common poisons

Answer 1

Paracetamol, hypnotics, ecstasy

Question 2

What are the clinical features of poisoning?

Answer 2

Alcohol on breath, needle marks, blisters

Question 3

Describe the effects of poisons on pupils and ventilation

Answer 3

Pupils: may be dilated from anticholinergics, or constricted from opiates
Ventilation: hypoventilation from opiates, hyperventilation from salicylates

Question 4

Outline the 3 management steps of overdose

Answer 4

Immediate actions: remove poison and monitor vital signs.
Prevention of absorption: give activated charcoal.
Enhance elimination: continue activated charcoal, give sodium bicarbonate to increase pH

Question 5

Outline the main 6 antidotes for poisoning/ overdose

Answer 5

Naloxone for opiate overdose
Flumazenil for benzodiazepine overdose
Atropine for bradycardia
N-acetylcysteine for paracetamol overdose
Glucagon for β/calcium channel blockers
Digibind for digoxin toxicity

Question 6

What is the dose-response curve?

Answer 6

With an increasing dose you get a greater response until you reach max response.
Some people need higher/lower doses for max response.
Some are non-responders.
Higher doses more likely to have ADRs

Question 7

What are medication errors

Answer 7

A preventable event which may cause patient harm when using medication. Can be from prescribing or polypharmacy errors

Question 8

Describe pharmacokinetics in older people

Answer 8

Impaired first-pass metabolism (increased bioav), reduced renal and hepatic clearance.

Question 9

Describe pharmacodynamics in older people

Answer 9

Reduction in receptor sites, Reduced homeostatic reserve (increased sensitivity to drugs).