Moxidectin and Closantel Residue Concentrations in Milk and Cheese from Dairy Goats

IEZZI, S.; LIFSCHITZ, A.; SALLOVITZ, J.; FARIAS, C.; NEJAMKIN, P.; MANAZZA, J.; LLOBERAS, M.; LANUSSE, C.; IMPERIALE, F.

Noordwijkerhout

Congreso; 12th International Congress of the European Association for Veterinary Pharmacology and Toxicology (EAVPT).; 2012

Introduction: Moxidectin (MXD) (a macrocyclic lactone) and closantel (CLS) (a salicylanilide compound) are highly lipophilic antiparasitic drugs which strongly bind to plasma proteins. Both compounds are now extralabely used as a therapeutic alternative in small ruminants, when nematode resistance to other approved drugs is present. The plasma and milk disposition of MXD and CLS in goats have been characterized. However, information on residue concentrations in milk and derived-products is needed to protect consumer´s safety before the use of these anthelmintic drugs in food-producing animals. The current work aimed to evaluate the concentration profiles of both MXD and CLS in plasma and milk from lactating dairy goats, and to characterize the pattern of drug residues in cheese made with milk from MXD and CLS-treated goats. Material and Methods: Twelve (12) female Saanen dairy goats (35-56 kg) were divided in two groups (n=6). Animals were orally treated with either MXD (0.4 mg/kg) (Cydectin®, Fort Dodge) or CLS (10 mg/kg) (Galgosantel ®, Biogénesis Bagó). Blood and milk samples were collected between 0 and 36 days post-treatment to characterize the plasma and milk disposition kinetics. The whole milk production of each experimental group was collected at 1, 4, 7 and 10 days post-treatment to produce a soft cheese following a standard protocol. MXD and CLS concentrations in plasma, milk and cheese were determined by HPLC. Results: Both MXD and CLS parent compounds were detected in plasma and milk between 8 h and 36 days post-treatment in lactating dairy goats. Milk residue concentrations increased progressively to reach peaks of 100 ng/ml (MXD) and 1.5 µg/ml (CLS) attained at 0.9 and 1 day post-treatment, respectively. After day 2 post-administration, MXD residues in milk were below the maximum residue limit (MRL) established for sheep´s milk (40 µg/kg; EMEA, 2004). MXD milk residues were between 2- and 4-fold higher than those measured in plasma. However, this pattern differed for CLS where milk residue concentrations were lower than those measured in the bloodstream and above the proposed MRL for sheep´s milk (45 µg/kg; EMEA, 2012) throughout the sampling period. MXD residues ranging between 40 and 560 ng/g and CLS between 1.9 and 3.7 µg/g were measured in cheese. Cheese residue concentrations for both compounds were markedly higher than those measured in the milk from treated animals used for cheese elaboration at days 1, 4, 7 and 10. Conclusions: The pharmacokinetic results reported here confirm that MXD and CLS are both excreted by milk in lactating dairy goats. It is important to highlight that those drug residue concentrations recovered in soft cheese are between 3- (CLS) and 6-fold (MXD) higher than those obtained in the milk utilized for cheese making. Thus, the data on the large residue concentrations recovered in soft cheese should be seriously considered before issuing any recommendation on the manufacturing of milk from dairy goats under antiparasitic treatment with either MXD or CLS. References - EMEA. 2004. Moxidectin. EMEA/MRL/906/ 04-Final. - EMEA. 2012. Closantel. EMEA/CVMP/813350/ 2011.