Nalbuphine pharmacokinetics

Pharmacokinetics Onset of action occurs within 2 to 3 minutes after IV administration, and in less than 15 minutes following subcutaneous or IM injection. Nalbuphine is metabolized in the liver plasma half-life is 5 hours. The duration of analgesic activity ranges from 3 to 6 hours. Approximately 7% is excreted unchanged in the urine. 

Pharmacokinetic properties Due to intensive first-pass metabolism, nalbuphine has a low oral bioavailability of less than 10%. After intramuscular administration peak plasma concentrations are reached after 30 min, half-life time is about 5 h. The compound is metabolized by glucuronidation and to a minor extent by N-dealkylation, and less than 10% is excreted unmetabolized (Lo et al., 1987). 

Even small doses of fentanyl can cause respiratory depression. Delayed respiratory depression can be a particular problem in the elderly, in whom the half-life is approximately three times longer than in younger patients (6). Respiratory depression has been reversed with nalbuphine doxapram could only antagonize this effect for 2-5 minutes (7). However, the need for prolonged treatment of respiratory depression with naloxone, because of pharmacokinetic variability and/or transdermal drug reservoir, has been emphasized by several authors (SEDA-16, 80) (SEDA-17, 80). 

E. Nicolle, S. Veitl, C. Guimier and G. Bessard, Modified method of nalbuphine determination in plasma validation and application to pharmacokinetics of the rectal route, J. Chromatogr. B, 1997, 690, 89-97. 

F. de Cazanove, J.M. Kinowski, M. Audran, A. Rochette and F. Bressolle, Determination of nalbuphine in human plasma by high-performance liquid chromatography with electrochemical detection. Application to a pharmacokinetic study. J. Chromatogr. B, 1997, 690, 203-210. 

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