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OPRA Pharmacokinetics and Pharmacodynamics QUESTION #3841
Question 1
For what pharmacokinetic reason is epinephrine (adrenaline) incorporated into some injectable local anaesthetic preparations?
  • Decrease the local action of the anaesthetic
  • Reduce local blood flow✔️
  • Increase the amount of local anaesthetic to administer
  • Block nerve fibres by depolarising the membrane
Correct Answer Explanation
Epinephrine causes local vasoconstriction, thereby reducing blood flow to the injection site. This slows systemic absorption of the local anaesthetic, prolonging its duration of action and reducing toxicity.