Abstract
A high performance liquid chromatographic method has been developed for the simultaneous determination of (±) fenfluramine (Fen) and phentermine (Phen) in addition to three other sympathomimetic amines—ephedrine (E), norephedrine (NE) and 2‐phenylethylamine (2‐PEA), using cyclohexylamine (CX) as an internal standard in plasma. The compounds were derivatized with 4‐(4,5‐diphenyl‐1__H__‐imidazole‐2‐yl)benzoyl chloride (DIB‐Cl) to give the DIB‐derivatives. The derivatives were then separated using an isocratic HPLC system with UV detection. The limits of detection for Fen, Phen, E, NE and 2‐PEA in plasma ranged from 0.32 to 22.9 pmol on column at a signal‐to‐noise ratio of 3. The recoveries following alkaline extraction from plasma samples of known concentrations were found to be more than 94% for the studied compounds. This method might be useful for the screening of the studied sympathomimetic amines in human plasma samples in forensic as well as toxicological studies. Furthermore, the developed method was modified for the simultaneous determination of Fen and Phen in human and rat plasma using fluoxetine as an internal standard. The methods are reproducible and precise. Finally, the two drugs were administered intraperitonealy to rats in combination, and their plasma levels over the investigated time course were successfully determined. Copyright © 2001 John Wiley & Sons, Ltd.
Abbreviations used:
CX
cyclohexylamine
DIB‐Cl
4‐(4,5‐diphenyl‐1__H__‐imidazole‐2‐yl)benzoyl chloride
E
ephedrine
Fen
fenfluramine
FLX
fluoxetine
NE
norephedrine
NorFen
norfen fluramine
2‐PEA
2‐phenylethylamine
Phen
phentermine.