Stability of Buffered Lidocaine and Epinephrine Used for Local Anesthesia

Abstract

Buffered lidocaine has been recently recommended for local anesthesia, as there is less pain on injection of the buffered solution. Reduced pain on injection of lidocaine and epinephrine buffered to a neutral pH was confirmed in 20 subjects (P less than .01). Concentrations of buffered lidocaine and epinephrine were performed in order to evaluate their stability. Buffered lidocaine dropped to 66.1% of initial concentrations after 4 weeks when stored at 25 degrees C. Buffered epinephrine fell to 1.34% of its initial concentration under similar conditions. Buffered lidocaine and epinephrine maintained 94.54% and 82.04%, respectively, of their initial concentrations after 4 weeks when refrigerated at 0-4 degrees C. Both lidocaine and epinephrine maintained greater than 90% concentration 2 weeks after buffering when stored at 0-4 degrees C. This permits batch buffering of lidocaine with epinephrine and storage for periods up to 2 weeks when properly refrigerated.

Short term stability of pH-adjusted lidocaine-adrenaline epidural solution used for emergency caesarean section

“…5,6 The relative contribution of each, however, appears to be far less important than that of pH itself in the first 20 h after mixing. From our anecdotal enquiries and our own experience, we considered it unlikely that anaesthetists would store pre-prepared epidural mixtures in the refrigerator, for fear of causing discomfort on injection of cold solutions, let alone the possibility of slower onset of block.…”

“…4,5,[7][8][9] Most investigators, however, did not specify their conditions of storage (protected from light or not, containers, temperature, etc), though Murakami et al 6 also showed significantly decreased degradation of adrenaline in alkalinised lidocaine when kept in the dark. Our results and theirs emphasise the importance of both light and pH in the process of degradation.…”

Pediatric Pain and Anxiety in the Emergency Department: An Evidence-Based Approach to Creating an Anti-Pain Environment

“…Buffered lidocaine 1 or 2 % with 1:100,000 epinephrine can be stable for 7 days when packaged in polypropylene syringes and stored in the refrigerator with protection from light [75][76][77]. Buffered lidocaine with epinephrine has a shorter stability date than without epinephrine potentially due to incompatibility of epinephrine and sodium bicarbonate.…”

Stability of Buffered Lidocaine in Glass Vials

“…Two studies examined the chemical stability of buffered lidocaine with and without epinephrine. 4,7 As a result of the work by Stewart and others, 7 the author's hospital assigned an arbitrary expiry period of 7 days to solutions of buffered lidocaine 1%; however, this was extrapolated from data generated for 2% lidocaine solutions. More recently, Pascuet and others 8 clarified the stability of 1% and 2% buffered lidocaine with and without epinephrine packaged in plastic syringes.…”

“…This change to the free base increases the rate of penetration of lidocaine into the nerve cell, which in turn significantly decreases the burning sensation at the time of infiltration and speeds up the onset of anesthesia. [2][3][4][5][6] Although buffered lidocaine has been used in the clinical setting for several years, its long-term physical and chemical stability remains unclear. Two studies examined the chemical stability of buffered lidocaine with and without epinephrine.…”