Quantitative determination of nalbuphine in plasma using electron-capture detection

Area of Science:

• Analytical Chemistry
• Pharmacokinetics
• Forensic Toxicology

Background:

• Accurate quantification of nalbuphine in biological samples is crucial for pharmacokinetic and toxicological studies.
• Existing methods may lack the sensitivity or specificity required for low-level detection.

Purpose of the Study:

• To develop and validate a sensitive method for determining nalbuphine concentrations in human plasma.
• To establish the pharmacokinetic profile of nalbuphine following subcutaneous administration in a canine model.

Main Methods:

• Plasma samples were processed involving liquid-liquid extraction with benzene-2-propanol and 0.1 N HCl.
• Heptafluorobutyryl derivatives were formed and analyzed using electron-capture gas-liquid chromatography (GLC).
• Method validation included assessment of sensitivity, linearity, and precision.

Main Results:

• The assay demonstrated a lower limit of sensitivity of approximately 0.5 ng/ml.
• The linear dynamic range extended up to 50 ng/ml.
• Peak plasma levels in dogs (n=2) after 1 mg/kg subcutaneous nalbuphine ranged from 50-150 ng/ml, detectable up to 5 hours.

Conclusions:

• The presented electron-capture GLC method provides a sensitive and reliable means for nalbuphine determination in plasma.
• This method is suitable for pharmacokinetic studies and therapeutic drug monitoring.
• Nalbuphine exhibits a detectable plasma presence for several hours post-administration.