Which pair of vasoconstrictors can be administered with local anesthetic to prolong the block and reduce bleeding?

• A. Lidocaine and Epinephrine
• B. Epinephrine and Cocaine
• C. Epinephrine and Norepinephrine
• D. Phenylephrine and Ephedrine

Answer: (B)

Prolonging a local anesthetic block while minimizing bleeding hinges on strong local vasoconstriction at the injection site. Epinephrine is the classic vasoconstrictor used with local anesthetics because it acts on alpha receptors to squeeze blood vessels, slowing the anesthetic’s absorption and reducing bleeding, which also lengthens the block’s duration.

Cocaine is unique in that it serves as a local anesthetic and also causes significant vasoconstriction by increasing norepinephrine in the synapse. Using epinephrine together with cocaine can produce additive vasoconstriction, further decreasing bleeding and prolonging the effect of the anesthetic.

The other pairings either don’t provide two vasoconstrictors, or involve combinations that aren’t standard or safe in practice, making them less suitable for achieving the goal.