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Why is epinephrine sometimes added to a local anesthetic?
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anesthetic
How anesthesia works.
Epinephrine is sometimes added to a local anesthetic solution to induce local vasoconstriction, which is the narrowing of blood vessels.1
Because the dispersal of a local anesthetic from the injection site depends in part on the blood flow through that region, this vasoconstrictive effect helps to slow the drug's absorption into the bloodstream. Consequently, the addition of epinephrine serves to prolong the duration of the anesthetic's action.1