Determination of nefopam in equine plasma by gas chromatography-mass spectrometry with chemical ionization.

This study demonstrates the development of a method using gas chromatography-mass spectrometry for determining nefopam, a non-narcotic pain reliever that is sometimes abused in horse doping, in equine plasma.

Background of the Research

• The research focused on nefopam, a non-narcotic analgesic used in humans for treating pain related to musculoskeletal disorders. This drug has also been misused for doping purposes in horses.
• The researchers aimed to establish a relationship between the plasma concentration of nefopam and its potential impact on horse performance.
• For this purpose, the development of an effective method to measure nefopam in equine plasma was necessary.

Earlier Methods of Nefopam Determination and Their Limitations

• Prior to this research, the determination of nefopam in human plasma was carried out using gas chromatography with flame-ionization and nitrogen-selective detection.
• However, due to the low concentration of nefopam anticipated in equine plasma, these previously established methods were insufficient.

Development of the New Technique

• Recognizing this limitation, the researchers developed a method using gas chromatography-mass spectrometry (GC-MS). This technique is more sensitive and precise, making it suitable for detecting lower concentrations.
• The novel method incorporated the use of deuterium-labelled nefopam as an internal standard. In mass spectrometry, an internal standard is a known compound added to the sample in a known amount. It provides a consistent reference to compare sample components and can help account for variations in analysis.
• This development signifies an important contribution towards the accurate detection and measurement of nefopam in equine plasma, which could help in controlling its misuse in horse doping.