DILUTING LIDOCAINE AND MEPIVACAINE IN BALANCED SALT SOLUTION REDUCES THE PAIN OF INTRADERMAL INJECTION

Background and Objectives. Intradermal injection of local anesthetics prior to percutaneous needle insertion is often painful. This study ev aluated the effect of diluting lidocaine and mepivacaine with balanced salt solution on perception of pain on intradermal injection. Methods . Twenty healthy volunteers were each intradermally injected with six solutions in random order. These solutions were: normal saline (NS), 0 .9% benzyl alcohol in NS, 0.2% lidocaine in NS, 0.2% lidocaine in bala nced salt solution, 0.2% mepivacaine in NS, and 0.2% mepivacaine in ba lanced salt solution. Discomfort of each injection was reported on a 0 -2 pain scale. The degree of anesthesia at each site was evaluated by pinprick every minute for 20 minutes. Results. Benzyl alcohol and lido caine and mepivacaine in balanced salt solution caused the least injec tion pain. However, mepivacaine in NS and NS alone caused the most pai n. The anesthetic effect of benzyl alcohol was judged adequate for onl y 4 minutes whereas both lidocaine and mepivacaine in either NS or bal anced salt solution gave adequate anesthesia for at least 15 minutes. Conclusions. The dilution of lidocaine and mepivacaine with balanced s alt solution produces a solution that is both painless on injection an d of moderate duration.