Abstract
The widespread use of moxidectin (MOX), a parasiticide used in the sheep breeding, has induced the parasite resistance in Brazilian farms. As a consequence, the farmers often increase the dose and frequency of drug utilization, and disregards safety of meat or milk. In order to establish adequate therapeutic treatment it is necessary to know the pharmacokinetics of the drug in the animal's body. Thus, high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) method was developed for the determination of MOX in serum lamb. Serum samples were treated with acetonitrile to precipitate proteins. A clean up by dispersive extraction in solid phase (SPE-d), using primary/secondary amine (PSA) and C18 sorbents, followed by freezing was performed. Method validation presented precision (coefficient of variation) and accuracy (recovery%) between 1.7-6.7 and 80.0-107.3%, respectively. The limit of quantification (LOQ) of the method was 2.0 ng mL-1 and a linear response was obtained over a range of 2.0 to 100 ng mL-1. This method was successfully applied to the determination of MOX in serum from suffolk lamb to evaluate the pharmacokinetic profile.
Highlights
The infections with gastrointestinal nematodes have constituted major obstacle to the expansion of the sheep industry in Brazil
It is important to emphasize that analytical methods based on liquid chromatography coupled to mass spectrometry (HPLC-MS) are sufficiently sensitive and selective to quantify the compounds in very low amounts, not being necessary a derivatization step
In the negative electrospray ionization mode, the mobile phase used favored the MOX deprotonation resulting in a significant increase in signal
Summary
The infections with gastrointestinal nematodes have constituted major obstacle to the expansion of the sheep industry in Brazil. The gastrointestinal parasitism is associated with physiological changes in animals, such as bowel dysfunction and nutritional stress that result in decreased body condition, lower weight gain and death of animals. Among the most important parasites that affect sheep flocks we can highlight the Haemonchus contortus.[1] The parasiticide agents allowed for controlling endo and ecto-parasites in sheep, the macrocyclic lactones, have been widely employed over the world because of its high efficiency and broad-spectrum activity.[2] The moxidectin (MOX) (Figure 1), semisynthetic derivative of nemadectin, is a macrocyclic lactone obtained by the fermentation of Streptomyces cyanogriseus.[3] In the last
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