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Plasma Lidocaine, Monoethylglycinexylidide, and Glycinexylidide Concentrations After Epidural Administration in Geriatric Patients
  1. Taeko Fukuda, M.D.,
  2. Yoshihiro Kakiuchi, B.S. Pharm.,
  3. Masayuki Miyabe, M.D.,
  4. Naomitsu Okubo, M.D.,
  5. Yuichi Yaguchi, M.D.,
  6. Yukinao Kohda, Ph.D. and
  7. Hidenori Toyooka, M.D.
  1. From the Departments of Anesthesiology (T.F., M.M., N.O., Y.Y., H.T.) and Clinical Pharmacy (Y.K., Y.K.), Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan.
  1. Reprint requests: Taeko Fukuda, M.D., Department of Anesthesiology, Institute of Clinical Medicine, University of Tsukuba, Tsukubacity, Ibaraki, 305-8575, Japan. E-mail: taekof{at}


Background and Objectives The purpose of this study was to evaluate the effect of age on the pharmacokinetics of lidocaine after epidural administration.

Methods Two percent lidocaine with epinephrine (5 μg/mL) was administered in two different age groups: an adult group (age 42 ± 6 years, n = 10) and an elderly group (age 77 ± 4 years, n = 10). Concentrations of lidocaine and its active metabolites, monoethylglycinexylidide (MEGX) and glycinexylidide (GX), were measured in plasma samples obtained after 15, 30, 45, 60, 90, 120, 150, and 180 minutes of administration using high-performance liquid chromatography with ultraviolet detection.

Results No significant differences in plasma concentrations of lidocaine and its metabolites were observed between the two groups during the 3 hours of study. However, the elderly group showed significantly longer mean residence times (MRTs) and lower plasma clearance of lidocaine during the period compared with the adult group (P < .05). Plasma concentration ratios of MEGX/lidocaine were significantly lower in the elderly group after 2 hours of lidocaine administration (P < .05).

Conclusions The increase in plasma lidocaine concentration after epidural anesthesia in elderly patients was not as high as anticipated. However, the elderly patients showed longer MRTs, lower clearance, and lower ratios of MEGX/lidocaine than did the adult (middle-age) patients.

  • Epidural anesthesia
  • Geriatric
  • Lidocaine
  • MEGX
  • GX

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