DCAS Pharmacology for Paramedics 3

Question 1

Salbutamol (albuterol) acts as a bronchodilator by:

Accepted Answer

Selective beta-2 receptor agonism causing bronchial smooth muscle relaxation

Answer

Salbutamol selectively activates beta-2 adrenoceptors in bronchial smooth muscle, activating adenylate cyclase and increasing cAMP, causing relaxation of the bronchial smooth muscle and bronchodilation.

Question 2

Dextrose 10% (rather than 50%) is recommended for treating hypoglycaemia in adults because:

Accepted Answer

Lower concentration reduces the risk of tissue necrosis from extravasation and is safer in IV administration

Answer

Dextrose 50% is highly hyperosmolar and causes severe tissue necrosis if extravasated; 10% dextrose (still effective) is much safer if the IV line is not patent, requiring a larger volume but reducing complication risk.

Question 3

Ondansetron is used in pre-hospital care to treat:

Accepted Answer

Nausea and vomiting — serotonin (5-HT3) receptor antagonist, preferred as it does not cause sedation

Answer

Ondansetron blocks 5-HT3 receptors in the CNS and GI tract, providing effective anti-emetic action without the sedation or extrapyramidal side effects of older anti-emetics like metoclopramide or prochlorperazine.

Question 4

Nitroglycerin (GTN) is contraindicated in chest pain patients taking:

Accepted Answer

Phosphodiesterase-5 inhibitors (sildenafil/Viagra, tadalafil) within the past 24-48 hours

Answer

Both nitrates and PDE-5 inhibitors cause vasodilatation via cGMP pathways; combination produces profound, potentially fatal hypotension — GTN is absolutely contraindicated within 24 hours of sildenafil and 48 hours of tadalafil.

Question 5

Diazepam's mechanism of action in seizure management is:

Accepted Answer

Enhancing GABA-A receptor activity, increasing chloride channel opening and neuronal inhibition

Answer

Benzodiazepines bind to GABA-A receptors and enhance the effect of GABA (the main inhibitory neurotransmitter), increasing the frequency of chloride channel opening, hyperpolarising neurons and reducing seizure activity.

DCAS Practice Test

DCAS Practice Test

DCAS Pharmacology for Paramedics 3