What antioxidant is commonly used as a preservative in local anesthetics containing a vasoconstrictor?

The antioxidant commonly used as a preservative in local anesthetics that contain a vasoconstrictor is sodium bisulfite. This compound is particularly important because vasoconstrictors, such as epinephrine, can oxidize and lose their effectiveness over time. Sodium bisulfite works by preventing this oxidation, thereby prolonging the shelf life of the anesthetic solution and ensuring that the vasoconstrictor remains effective when the anesthetic is administered.

Additionally, sodium bisulfite helps maintain stability in the presence of oxygen and light, which can further degrade the anesthetic. It is widely used in anesthetic formulations to ensure that patients receive the intended therapeutic effects during procedures. Other preservatives or antioxidants do not serve the same critical function in local anesthesia formulations specifically containing vasoconstrictors.