Fate of ivermectin residues in ewes' milk and derived products

Abstract

The fate of ivermectin (IVM) residues was studied throughout the processing of daily bulk milk from 30 ewes (taken up to 33 d following subcutaneous administration of 0 . 2 mg IVM/kg b.w.) in the following milk products: yoghurt made from raw and pasteurized milk; cheese after pressing ; 30-and 60-day ripened cheese; and whey, secondary whey and whey proteins obtained after cheese-making (albumin cheese). The concentration of the H 2 B 1a component of IVM was analysed in these dairy products using an HPLC method with fluorescence detection. The mean recovery of the method was, depending on the matrix, between 87 and 100%. Limits of detection in the order of only 0 . 1 mg H 2 B 1a /kg of product were achieved. Maximum concentrations of IVM were detected mostly at 2 d after drug administration to the ewes. The highest concentration of IVM was found on day 2 in 60-day ripened cheese (96 mg H 2 B 1a /kg cheese). Secondary whey was the matrix with the lowest concentration of IVM (< 0 . 6 mg H 2 B 1a / kg). Residue levels fell below the limits of detection between day 5 (for secondary whey) and day 25 (for all cheese samples). In the matrices investigated, linear correlations between daily concentrations of IVM, milk fat and solid content were evident. During yoghurt production, fermentation and thermal stability of IVM was observed. During cheese production, approximately 35 % of the IVM, present in the raw (bulk) milk samples, was lost. From the results it was concluded that the processing of ewes' milk did not eliminate the drug residues under investigation. The consequences of IVM in the human diet were discussed. Milk from treated animals should be excluded from production of fat products like cheese for longer after treatment with IVM than for lower fat products.

Breed differences in the pharmacokinetics of ivermectin administered subcutaneously to Holstein and Belgian Blue calves

“…Residues of ivermectin in biological fluids are stable for up to one year after freezing (Cerkvenik et al, 2004) and the analysis of ivermectin in the fluids and tissues was performed within 3 months of collection. Ivermectin was analyzed in plasma and tissue by high-performance liquid chromatography (HPLC) with automated solid phase extraction and fluorescence detection according to a previously described method (Lifschitz et al, 2000).…”

Review of methodology for the determination of macrocyclic lactone residues in biological matrices

“…Anastassio et al found that residue levels of ivermectin (sc 200 g/kg bw), reached a maximum concentration of 29 g/kg in buffalo milk at 2.5 days post-treatment and residues were detectable at 20 days post-treatment at a level of 0.6 g/kg [69]. Cerkvenik-Flajs et al investigated the fate of ivermectin residues in ewes' milk and dairy products (raw bulk milk, yoghurt from raw and pasteurised milk, cheese and whey) from ewes undergoing a residue depletion trial [70]. Highest levels of ivermectin residues were determined at 2 days withdrawal in raw milk (22 g/kg), yoghurt (23 g/kg), cheese (96 g/kg) and at 1 day withdrawal in albumin cheese (31 g/kg).…”

“…However, gradient elution has been used by a number of researchers [54,70,119,126,131,138,143,169]. Gradient elution may be used to separate the residues or to remove late eluting interferences from the column that may interfere with subsequent determination [131,132,138,143,169].…”

Ivermectin residues in milk of lactating donkey (Equus asinus): current regulation and challenges for the future

“…Toutain et al (1988) indicated that IVM residues were still excreted in cow's milk at 29 days post subcutaneous application. Furthermore, IVM was detected in milk products made from milk of treated sheep (Cerkvenik et al 2004a;Cerkvenik et al 2004b). IVM is substantially excreted into the milk because of its lipophilicity; for this reason its use during the lactation period must be prohibited.…”

“…IVM is substantially excreted into the milk because of its lipophilicity; for this reason its use during the lactation period must be prohibited. Treatment with IVM is banned at least 21-33 days before lambing (Cerkvenik et al 2004b), but for some, even accidental reasons (Davis 1991), its use with lactating animals cannot always be avoided. The instructions for its use clearly state that the withdrawal time was not determined for milk.…”