DCAS Pharmacology for Paramedics 2 — Questions and Answers
Question 1: Magnesium sulphate's mechanism of action in eclampsia treatment is:
- Blocking NMDA receptors and reducing neuronal excitability, preventing seizure recurrence (Correct answer)
- Binding to clotting factors
- Causing uterine relaxation only
- Reducing blood pressure through direct vasodilation
Correct answer: Blocking NMDA receptors and reducing neuronal excitability, preventing seizure recurrence
Magnesium sulphate blocks NMDA glutamate receptors, reducing neuronal excitability and preventing seizure propagation; it also causes some vasodilation (contributing to antihypertensive effect) and uterine muscle relaxation.
Question 2: Naloxone (Narcan) has a shorter half-life than most opioids, which means:
- Re-narcotisation can occur after naloxone wears off — repeat doses or infusion may be needed (Correct answer)
- It permanently blocks opioid receptors
- A single dose provides 12 hours of reversal
- It cannot reverse all types of opioids
Correct answer: Re-narcotisation can occur after naloxone wears off — repeat doses or infusion may be needed
Naloxone's duration of action (30-90 minutes) is often shorter than the opioids it reverses (especially long-acting ones); patients can re-sedate as naloxone wears off, requiring observation, repeat dosing, or IV infusion.
Question 3: Rocuronium used for RSI requires reversal with which agent if intubation fails?
- Sugammadex — cyclodextrin molecule that encapsulates and inactivates rocuronium (Correct answer)
- Neostigmine only
- Atropine
- No reversal is possible — use surgical airway immediately
Correct answer: Sugammadex — cyclodextrin molecule that encapsulates and inactivates rocuronium
Sugammadex (16mg/kg) can rapidly reverse even deep rocuronium-induced neuromuscular blockade within minutes, providing a critical safety option in CICO scenarios when using rocuronium for RSI instead of succinylcholine.
Question 4: Fentanyl's advantage over morphine for pre-hospital analgesia includes:
- Faster onset, shorter duration, and suitability for intranasal administration — fewer haemodynamic effects (Correct answer)
- Greater potency requiring larger doses
- Oral bioavailability for conscious patients
- No risk of respiratory depression at any dose
Correct answer: Faster onset, shorter duration, and suitability for intranasal administration — fewer haemodynamic effects
Fentanyl's faster onset (1-3 min IV, 5-10 min IN), shorter duration, intranasal route availability (no IV access needed), and greater haemodynamic stability make it preferred in many pre-hospital pain management protocols.
Question 5: Amiodarone's mechanism of action as an antiarrhythmic is primarily as a:
- Class III antiarrhythmic — potassium channel blocker, prolonging action potential and refractory period (Correct answer)
- Class I sodium channel blocker
- Calcium channel blocker (Class IV)
- Beta-blocker (Class II)
Correct answer: Class III antiarrhythmic — potassium channel blocker, prolonging action potential and refractory period
Amiodarone is classified primarily as a Class III agent (potassium channel blockade) but also has Class I, II, and IV properties, making it a broad-spectrum antiarrhythmic effective for both atrial and ventricular arrhythmias.
Question 6: The maximum dose of lignocaine (lidocaine) for local infiltration anaesthesia (without epinephrine) is:
- 3mg/kg (maximum 200mg) (Correct answer)
- 10mg/kg
- 0.5mg/kg
- Fixed dose 500mg regardless of weight
Correct answer: 3mg/kg (maximum 200mg)
Lignocaine without adrenaline has a maximum dose of 3mg/kg (up to 200mg); with adrenaline (vasoconstriction slowing absorption), the maximum is 7mg/kg — exceeding these limits risks local anaesthetic systemic toxicity (LAST).
DCAS Pharmacology for Paramedics 2
Magnesium sulphate's mechanism of action in eclampsia treatment is: