Pharmacology for Paramedics Flashcards

The mechanism of action of ondansetron differs from metoclopramide in that ondansetron:

Answer: Selectively blocks 5-HT3 receptors without dopamine D2 antagonism — no extrapyramidal side effects

Ondansetron's selectivity for 5-HT3 receptors avoids the dopamine D2 blockade of metoclopramide, eliminating the risk of extrapyramidal side effects (dystonia, akathisia, tardive dyskinesia) — important for conscious patients.

Thiamine 100mg IV is given before or with dextrose in malnourished patients because:

Answer: Glucose administration without thiamine can precipitate Wernicke's encephalopathy in thiamine-deficient patients

In thiamine-deficient patients (chronic alcoholics, malnourished), glucose administration depletes the remaining thiamine reserves, precipitating Wernicke's encephalopathy (confusion, ataxia, eye movement disorders) and Korsakoff's syndrome.

The correct site for IM epinephrine injection in anaphylaxis is:

Answer: Anterolateral mid-thigh — fastest absorption into muscle and systemic circulation

The anterolateral thigh has higher muscle vascularity and achieves faster peak blood levels than deltoid IM or subcutaneous injection; the vastus lateralis provides the most reliable and rapid drug delivery in anaphylaxis.

Hypertonic saline (3% or 7.5%) in pre-hospital head injury management aims to:

Answer: Reduce cerebral oedema through osmotic gradient — drawing water from brain cells into the vasculature

Hypertonic saline creates an osmotic gradient across the blood-brain barrier, drawing water from swollen brain tissue into the intravascular space, reducing ICP while simultaneously providing intravascular volume.

Enoxaparin (low molecular weight heparin) differs from unfractionated heparin in that it:

Answer: Has more predictable pharmacokinetics allowing subcutaneous dosing without laboratory monitoring

LMWH has more predictable dose-response (consistent bioavailability), allowing weight-based SC dosing without aPTT monitoring, making it more practical and safer than UFH in outpatient and pre-hospital settings.

Labetalol IV is used in hypertensive emergencies in pregnancy because it:

Answer: Provides combined alpha and beta blockade — safe for foetus with good efficacy in controlling BP

Labetalol's combined alpha and beta blockade reduces BP while preserving uteroplacental blood flow better than pure vasodilators; it is a recommended agent for severe hypertension in pre-eclampsia/eclampsia.