Crystallization of Ropivacaine and Bupivacaine When Mixed With Different Adjuvants: A Semiquantitative Light Microscopy Analysis

( Reg Anesth Pain Med . 2022:rapm-2022-103610) The use of adjuvants to local anesthetics may prolong their duration or speed the onset of action. Amino-amide local anesthetics have the potential to precipitate when mixed with commonly used adjuvants, which can result in crystal deposition in the perineural or vascular regions. This study aimed to assess the occurrence of crystallization with commonly employed local anesthetic-adjuvant combinations, determine if there is a correlation with the solution’s pH, and assess if there is a change over time in crystallization grade.