If a patient is absolutely allergic to LA, the specific drug used in place of it is:

If the patient is allergic: To ester local anesthetics, try an amide local anesthetic. To amide local anesthetics, try an ester local anesthetic. To methylparaben or is allergic to both amide and ester local anesthetics, try a MPF product. To antioxidants or sulfite compounds, review the product ingredients. Some  drugs  like pheniramine,  promethazine,  diphenhydramine have  strong  while others  have  weak  membrane stabilizing  property. MPF= Methyl paraben Free  Reference : KDT pharmacology 8th ed page no 180