Local anesthetic additives to increase stability and prevent organism growth

Abstract Local anesthetics are manufactured with "inactive" ingredients to maintain sterility and prolong the "shelf-life" of the final product. Specific additives such as methylparaben are added to provide antibacterial activity, bisulfites and ethylenediaminetetraacetate (EDTA) are added for their antioxidant properties, hydrochloric acid and sodium bicarbonate are added to adjust the pH of the final solution, and solutions of sodium chloride and dextrose serve as vehicles. Clinicians must recognize that even local anesthetics labeled as "preservative-free" contain "inactive" ingredients. Therefore, attention must be paid to what is actually present in the local anesthetic product to be administered if toxicity associated with these substances is to be minimized.