Determination of long‐acting release octreotide, an octapeptide analogue of somatostation, in human plasma by liquid chromatography/tandem mass spectrometry

A sensitive and selective method for the determination of long‐acting released octreotide in human plasma has been developed based on liquid chromatography/tandem mass spectrometry (LC/MS/MS). Octreotide and the internal standard, triptorelin, were precipitated from the matrix, washed with dichloromethane and subsequently separated by reversed‐phase high‐performance liquid chromatography (HPLC) employing a 1% formic acid/methanol gradient system. Detection was by electrospray ionization mass spectrometry in the positive ion mode using multiple‐reaction monitoring. The assay was linear in the concentration range 0.0500–50.0 ng/mL with intra‐ and inter‐day precision (as relative standard deviation) of <2.95% and <8.37%, respectively. The limit of detection was 0.0200 ng/mL. The method was applied to a pharmacokinetic study of long‐acting released octreotide in healthy volunteers given an intramuscular injection containing 20 mg octreotide. Copyright © 2007 John Wiley & Sons, Ltd.