Pharmacology for Paramedics Flashcards

Magnesium sulphate's mechanism of action in eclampsia treatment is:

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.

Naloxone (Narcan) has a shorter half-life than most opioids, which means:

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.

Rocuronium used for RSI requires reversal with which agent if intubation fails?

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.

Fentanyl's advantage over morphine for pre-hospital analgesia includes:

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.

Amiodarone's mechanism of action as an antiarrhythmic is primarily as a:

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.

The maximum dose of lignocaine (lidocaine) for local infiltration anaesthesia (without epinephrine) is:

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).