DCAS Pharmacology for Paramedics 3 — Questions and Answers
Question 1: Salbutamol (albuterol) acts as a bronchodilator by:
- Selective beta-2 receptor agonism causing bronchial smooth muscle relaxation (Correct answer)
- Alpha receptor stimulation causing vasoconstriction
- Leukotriene receptor antagonism
- Mast cell stabilisation
Correct answer: Selective beta-2 receptor agonism causing bronchial smooth muscle relaxation
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:
- Lower concentration reduces the risk of tissue necrosis from extravasation and is safer in IV administration (Correct answer)
- 50% dextrose raises blood glucose faster
- 10% dextrose has higher caloric content
- 50% dextrose is not available in the UAE
Correct answer: Lower concentration reduces the risk of tissue necrosis from extravasation and is safer in IV administration
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:
- Nausea and vomiting — serotonin (5-HT3) receptor antagonist, preferred as it does not cause sedation (Correct answer)
- Anaphylaxis
- Seizures
- Hypotension
Correct answer: Nausea and vomiting — serotonin (5-HT3) receptor antagonist, preferred as it does not cause sedation
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:
- Phosphodiesterase-5 inhibitors (sildenafil/Viagra, tadalafil) within the past 24-48 hours (Correct answer)
- Beta-blockers
- Aspirin
- Statins
Correct answer: Phosphodiesterase-5 inhibitors (sildenafil/Viagra, tadalafil) within the past 24-48 hours
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:
- Enhancing GABA-A receptor activity, increasing chloride channel opening and neuronal inhibition (Correct answer)
- Blocking sodium channels in neurons
- Blocking NMDA glutamate receptors
- Stimulating glycine receptors only in the spinal cord
Correct answer: Enhancing GABA-A receptor activity, increasing chloride channel opening and neuronal inhibition
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.
Question 6: Hydrocortisone IV is used as an adjunct in anaphylaxis because:
- It reduces late-phase allergic responses and biphasic reactions — but does not replace epinephrine as first-line (Correct answer)
- It reverses anaphylaxis faster than epinephrine
- It acts within seconds of IV administration
- It is the primary treatment for laryngeal oedema in anaphylaxis
Correct answer: It reduces late-phase allergic responses and biphasic reactions — but does not replace epinephrine as first-line
Corticosteroids reduce late inflammatory responses and may reduce biphasic anaphylaxis risk, but take hours to work — they are adjuncts to, not replacements for, epinephrine which works within minutes.
DCAS Pharmacology for Paramedics 3
Salbutamol (albuterol) acts as a bronchodilator by: