Pharmacology for Paramedics Flashcards

Salbutamol (albuterol) acts as a bronchodilator by:

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.

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

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.

Ondansetron is used in pre-hospital care to treat:

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.

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

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.

Diazepam's mechanism of action in seizure management is:

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.

Hydrocortisone IV is used as an adjunct in anaphylaxis because:

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.