A quick and simple method for the determination of ivermectin in dog plasma by LC–MS/MS

Ivermectin is an endectocide belonging to the macrocyclic lactone class, commonly used in dogs as a heartworm preventative and for the treatment of several external and internal parasite infections. Among the analytical methods for ivermectin determination in plasma available in literature, many require a laborious clean-up step on SPE cartridge, and use fluorescence detection instead of the more reliable mass spectrometry. In the context of a project aimed at its pharmacokinetic evaluation in this species, a liquid chromatography-tandem mass spectrometry method for the determination of ivermectin in dog plasma was developed and validated, using blank plasma provided by a local canine blood transfusion service. Samples underwent a quick liquid-liquid extraction before analysis in the LC–MS/MS system, operating in selected reaction monitoring (SRM) mode. The method provided satisfactory linearity (R2 >0.99), accuracy (bias <3%) and precision (CV <10%) over the 0.5–20.0 ng/mL range. • This is to our knowledge the first validated LC–MS/MS method for ivermectin determination in dog plasma.• Sample preparation is simple, rapid and inexpensive, without compromising sensitivity.• The modest amount of plasma required makes the proposed technique suitable for pharmacokinetic studies also in small dogs.