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A GLP tissue residue depletion in calves following oral / buccal administration of meloxicam
There is widespread acknowledgement from beef producers, consumers, and industry and government bodies, that pain associated with surgical or non-surgical husbandry practices in cattle must be managed effectively. In Australia, meloxicam is registered as an injectable product for use in cattle and currently has a broad anti-pyretic, analgesic and anti-inflammatory claim. The use of this non-steroidal anti-inflammatory drug (NSAID) therapy by parenteral administration is undesirable from an on-farm occupational health and safety risk minimisation perspective. For calves up to six, perhaps nine months of age, the preferred route of administration for meloxicam is oral trans mucosal (OTM) (or buccal) whereby the dose is applied into the sulcus between the molar teeth and the inside of the cheek. Buccal administration of specifically formulated medications can result in rapid absorption. Comparison of the bioavailability of oral and buccal meloxicam formulations administered to sheep showed that high serum levels of meloxicam were detected within 8 minutes of buccal dosing. These levels approximate reported therapeutic levels in other species.
A residue depletion study was required to establish a meat withholding period (WHP) and export slaughter interval (ESI) to satisfy product registration requirements. The GLP (Good Laboratory Practice) study described in this report determined the meloxicam tissue residue depletion profile in cattle following buccal administration of a meloxicam formulation (10 mg meloxicam/mL) at the maximum proposed dose rate of 0.5 mg meloxicam per kg bodyweight.
The study complied with national and international standards such as the OECDs Series on Principles of Good Laboratory Practice and Compliance Monitoring; APVMA RGL23 and VICH GL48 and GL49. Thirty-one trial cattle were allocated to 7 groups (six groups of 5 and one group of 1).
The group of 1 acted as the untreated control group. Calves were treated with the test formulation according to individual bodyweight and sacrificed at pre-determined time intervals. Following euthanasia, muscle, liver, kidney, peri-renal fat and masseter muscle (treatment side) tissue samples were collected, processed, frozen and sent for analysis. Analysis of meloxicam in bovine tissues was performed using a validated liquid chromatography tandem mass spectrometry (LC/MS/MS) method.
Sample preparation was based on acidic hydrolysis prior to neutralisation. Following addition of an internal standard and extraction into an organic solvent by salt-induced liquid-liquid partitioning the samples were analysed by LC/MS/MS. The analytical methodology had a validated limit of quantitation (LOQ) of 5.0 g/kg in all tissues. A limit of detection (LOD) of 1.01 g/kg, 0.37 g/kg, 0.76 g/kg, and 1.21 g/kg was established for liver, kidney, muscle (including masseter muscle), and peri-renal fat respectively. Meloxicam tissue residues were below the Australian MRLs of 0.1 mg/kg for liver, 0.2 mg/kg for kidney and 0.01 mg/kg for meat on Day 10 post-treatment.
This page was last updated on 25/07/2017
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