p  H-adjusted Lidocaine Does Not “Sting”

Less Painful Alternatives for Local Anesthesia

“…Our results confirm previous studies which have shown that “neutralization” of lidocaine with epinephrine significantly reduces the infiltration pain of the commercially available preparations without diminishing the anesthetic action of the solution. The pain of infiltration has been attributed to an acidic pH 2 . Our findings do not lend support to this theory because the pH values of bacteriostatic saline solution with epinephrine and lido‐caine with epinephrine diluted with bacteriostatic saline solution were 5.3 and 4.2, respectively.…”

“…Although the mechanism is not known, it has been suggested that the pain may be related to the acidity of the solution 1 . Several investigators have shown that by increasing the pH of lidocaine, with or without epinephrine, the pain of infiltration can be reduced significantly 1–5 . However, no study has demonstrated unequivocally that the pain of infiltration is directly related to the pH.…”

“…METHODS. The study was performed in three phases: 1) double-blind comparison study, 2 and 3) open clinical trials. RESULTS.…”

Buffered Local Anesthetics and Epinephrine Degradation

“…Unfortunately, the acidic pH of local anesthetic agents produces a great deal of patient discomfort during its infiltration. It has become a common practice with surgeons performing soft tissue operations to buffer the lidocaine and epinephrine with small amounts of sodium bicarbonate 4–7 . It is not clear to what degree buffering affects lidocaine and epinephrine degradation.…”