To the Editor:-Four percent lidocaine is used to topically anesthetize the mucosal lining of the airway. In the process of spraying 4% lidocaine into the mouth and pharynx of approximately 100 very lightly sedated (1 mg intravenous versed; 50 micro gram intravenous fentanyl) adult volunteers for a research project, approximately 50% of the volunteers spontaneously, and with varying degrees of distress, complained of a bitter taste. In the next 75 volunteers (some of whom were repeat volunteers), the addition of one packet of an artificial sweetener (e.g., Sweet n' Low) to 20 ml of the 4% lidocaine resulted in a neutral to sweet taste that completely eliminated spontaneous complaints of bitterness and resulted in much better acceptance by the volunteers.
The addition of Sweet n' Low to 4% lidocaine will not cause any chemical reactions. Saccharin is an ingredient of viscous lidocaine (but not of liquid 4% lidocaine) and does not react with lidocaine (Dr. Phillip Anderson, Pharmacy Department, UCSD Medical Center, personnel communication). In addition, lidocaine does not react with potassium salts (hydrogen tartrate) or calcium salts (saccharin and silicate), [1] which are the only other ingredients in Sweet n' Low. Along this line, I have not observed any suggestion of any precipitation in the mixture of Sweet n' Low and 4% lidocaine.
In summary, the simple safe sweet solution of adding Sweet n' Low to a sometimes troublesome 4% lidocaine bitter problem may be of benefit to other practitioners and awake patients.
Jonathan L. Benumof, M.D.
Professor of Anesthesia; Department of Anesthesia; University of California, San Diego; UCSD Medical Center; 402 Dickinson Street (8812); San Diego, California 92103–8812
(Accepted for publication July 28, 1997.)
