Comparison of the Plasma Concentrations of Nalbuphine after Epidural and Intravenous Administration / 대한마취과학회지

ABSTRACT

BACKGROUND: Nalbuphine is one of the opioid agonist-antagonists and is used frequently in the anesthetic field. Usage is focused on potent analgesic action and the adjuvant of narcotics because of less complications with preserved analgesia. The most common routes of administration for postoperative pain control are epidural and intravenous, so we compared both pharmacokinetic profiles. METHODS: Twelve patients were randomly divided into two groups. All patients were given a spinal anesthesia with tetracaine hydrochloride. One group (n = 6) received nalbuphine 10 mg via epidural route and another group (n = 6) received the same dose via intravenous route. Venous blood was drawn at 0, 0.25, 0.5, 1, 2, 4, 6 and 8 hours to measure plasma nalbuphine concentrations. Analysis was performed by high performance liquid chromatography with an electrochemical detector. RESULTS: At 0.25 hour, the plasma concentration of nalbuphine was significantly higher in the epidural administration group (49.48 +/- 4.98 ng/ml) than in the intravenous administration group (40.44 +/- 1.64 ng/ml). At 6 and 8 hours, the plasma concentration of nalbuphine was significantly higher in the epidural administration group (5.98 +/- 1.86 ng/ml, 3.85 +/- 0.94 ng/ml) than in the intravenous administration group (3.80 +/- 0.33 ng/ml, 2.43 +/- 0.32 ng/ml). Clearance, elimination half life, volume of distribution and AUC were not significantly different between the two groups. CONCLUSIONS: The plasma concentrations of nalbuphine via epidural route and intravenous route were similar in both groups after 0.25 hour to 6 hours. At 0.25 hour and after 6 hours, the epidural administration group had a higher plasma concentration of nalbuphine than the intravenous administration group.