Which of the following local anaesthetic agent is a vasoconstrictor
**Core Concept**
Local anaesthetics can be combined with vasoconstrictors to prolong their action, reduce systemic toxicity, and minimize bleeding at the injection site. Vasoconstrictors work by stimulating alpha-adrenergic receptors, causing blood vessels to constrict and reduce blood flow.
**Why the Correct Answer is Right**
Epinephrine (adrenaline) is a non-selective alpha and beta-adrenergic receptor agonist that causes vasoconstriction. When added to local anaesthetics, it reduces the absorption of the anaesthetic, prolongs its action, and decreases the risk of systemic toxicity. Epinephrine binds to alpha-1 receptors on vascular smooth muscle cells, leading to vasoconstriction and a decrease in blood flow to the affected area.
**Why Each Wrong Option is Incorrect**
**Option A:** Lidocaine is a local anaesthetic agent but does not have vasoconstrictor properties on its own.
**Option B:** Bupivacaine is another local anaesthetic agent, but it does not have inherent vasoconstrictor effects.
**Option C:** Mepivacaine is a local anaesthetic agent with a similar structure to lidocaine and does not have vasoconstrictor properties.
**Clinical Pearl / High-Yield Fact**
When using local anaesthetics with vasoconstrictors, it's essential to be aware of the potential for sympathetic stimulation, which can lead to hypertension, tachycardia, and other cardiovascular complications.
**Correct Answer: C. Mepivacaine**