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. 1996 Summer;43(3):85–91.

The relationship between pH and concentrations of antioxidants and vasoconstrictors in local anesthetic solutions.

S O Hondrum 1, J H Ezell 1
PMCID: PMC2148769  PMID: 10323112

Abstract

pH affects the efficacy of local anesthetics by determining the percentage of the lipid-soluble base form of the anesthetic available for diffusion and penetration of the nerve sheath. The purpose of this study was to determine the relationship between pH and the concentrations of antioxidant and vasoconstrictor in dental local anesthetic solutions over real-time and after accelerated aging. Several batches of lidocaine and mepivacaine with vasoconstrictors were tested. Results showed that, immediately upon receipt from the manufacturers, three batches were below the USP pH limit (pH 3.3), and two batches contained less than the minimum limit of vasoconstrictors (90%). Real-time tests on batches that were within normal limits revealed that solutions were stable past 4 yr. Accelerated aging tests revealed a strong correlation between a decrease in pH and loss of antioxidants and vasoconstrictors. In conclusion, a quality batch of local anesthetic should remain efficacious long past the manufacturer's stated shelf life; a batch that is less than optimal, or one that is exposed to environmental stresses, will degrade rapidly, and efficacy may be affected by decreases in pH and loss of vasoconstrictor. pH may be an inexpensive, readily available screening test for efficacy of local anesthetics.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bonhomme L., Postaire E., Touratier S., Benhamou D., Martre-Sauvageon H., Preaux N. Chemical stability of lignocaine (lidocaine) and adrenalin (epinephrine) in pH-adjusted parenteral solutions. J Clin Pharm Ther. 1988 Aug;13(4):257–261. doi: 10.1111/j.1365-2710.1988.tb00190.x. [DOI] [PubMed] [Google Scholar]
  2. Brown R. D. The failure of local anaesthesia in acute inflammation. Some recent concepts. Br Dent J. 1981 Jul 21;151(2):47–51. doi: 10.1038/sj.bdj.4804633. [DOI] [PubMed] [Google Scholar]
  3. DiFazio C. A., Carron H., Grosslight K. R., Moscicki J. C., Bolding W. R., Johns R. A. Comparison of pH-adjusted lidocaine solutions for epidural anesthesia. Anesth Analg. 1986 Jul;65(7):760–764. [PubMed] [Google Scholar]
  4. Fiset L., Getz T., Milgrom P., Weinstein P. Local anesthetic failure: diagnosis and management strategies. Gen Dent. 1989 Sep-Oct;37(5):414–417. [PubMed] [Google Scholar]
  5. Fyhr P., Brodin A. The effect of anaerobic conditions on epinephrine stability. Acta Pharm Suec. 1987;24(3):89–96. [PubMed] [Google Scholar]
  6. Gangarosa L. P., Halik F. J. A clinical evaluation of local anaesthetic solutions containing graded epinephrine concentrations. Arch Oral Biol. 1967 May;12(5):611–621. doi: 10.1016/0003-9969(67)90080-5. [DOI] [PubMed] [Google Scholar]
  7. Hajratwala B. R. Kinetics of sulfite-induced anaerobic degradation of epinephrine. J Pharm Sci. 1975 Jan;64(1):45–48. doi: 10.1002/jps.2600640108. [DOI] [PubMed] [Google Scholar]
  8. Hondrum S. O., Seng G. F., Rebert N. W. Stability of local anesthetics in the dental cartridge. Anesth Pain Control Dent. 1993 Fall;2(4):198–202. [PubMed] [Google Scholar]
  9. Hondrum S. O. The U.S. Army Institute of Dental Research dental materials shelf-life survey: questionnaire results. Mil Med. 1991 Sep;156(9):488–491. [PubMed] [Google Scholar]
  10. Jastak J. T., Yagiela J. A. Vasoconstrictors and local anesthesia: a review and rationale for use. J Am Dent Assoc. 1983 Oct;107(4):623–630. doi: 10.14219/jada.archive.1983.0307. [DOI] [PubMed] [Google Scholar]
  11. Kaufman E., Weinstein P., Milgrom P. Difficulties in achieving local anesthesia. J Am Dent Assoc. 1984 Feb;108(2):205–208. doi: 10.14219/jada.archive.1984.0470. [DOI] [PubMed] [Google Scholar]
  12. Kelly J. R., Dalm G. W. Stability of epinephrine in dental anesthetic solutions: implications for autoclave sterilization and elevated temperature storage. Mil Med. 1985 Feb;150(2):112–114. [PubMed] [Google Scholar]
  13. Kirchhoefer R. D., Allgire J. F., Juenge E. C. Stability of sterile aqueous lidocaine hydrochloride and epinephrine injections submitted by U.S. hospitals. Am J Hosp Pharm. 1986 Jul;43(7):1736–1741. [PubMed] [Google Scholar]
  14. Kirchhoefer R. D., Thornton L. K., Allgire J. F. Stability of sterile aqueous epinephrine injections submitted by U.S. hospitals. Am J Hosp Pharm. 1986 Jul;43(7):1741–1746. [PubMed] [Google Scholar]
  15. Milam S. B., Giovannitti J. A., Jr Local anesthetics in dental practice. Dent Clin North Am. 1984 Jul;28(3):493–508. [PubMed] [Google Scholar]
  16. Milano E. A., Waraszkiewicz S. M., Dirubio R. Aluminum catalysis of epinephrine degradation in lidocaine hydrochloride with epinephrine solutions. J Parenter Sci Technol. 1982 Nov-Dec;36(6):232–236. [PubMed] [Google Scholar]
  17. Passon C., Hatch R. A., Chasteen J. E. Route of entry of vapors into anesthetic cartridges. Gen Dent. 1992 Jul-Aug;40(4):293–297. [PubMed] [Google Scholar]
  18. Roda R. S., Blanton P. L. The anatomy of local anesthesia. Quintessence Int. 1994 Jan;25(1):27–38. [PubMed] [Google Scholar]
  19. Sixsmith D. G., Watkins W. M., Kokwaro G. O. The stability of adrenaline ophthalmic solutions on sterilization and storage. J Clin Hosp Pharm. 1982 Sep;7(3):205–207. doi: 10.1111/j.1365-2710.1982.tb01024.x. [DOI] [PubMed] [Google Scholar]
  20. Thoma K., Struve M. Untersuchung der Stabilität handelsüblicher Adrenalin-Lösungen. 3. Mitteilung zur Stabilität von Adrenalin-Lösungen. Pharm Acta Helv. 1986;61(3):66–68. [PubMed] [Google Scholar]
  21. Thoma K., Struve M. Untersuchungen zur Photo- und Thermostabilität von Adrenalin-Lösungen 1. Mitteilung zur Stabilität von Adrenalin-Lösungen. Pharm Acta Helv. 1986;61(1):2–9. [PubMed] [Google Scholar]
  22. Wong M. K., Jacobsen P. L. Reasons for local anesthesia failures. J Am Dent Assoc. 1992 Jan;123(1):69–73. doi: 10.14219/jada.archive.1992.0004. [DOI] [PubMed] [Google Scholar]
  23. Yagiela J. A. Local anesthetics: a century of progress. Anesth Prog. 1985 Mar-Apr;32(2):47–56. [PMC free article] [PubMed] [Google Scholar]

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