Stability of cabergoline in fox baits in laboratory and field conditions
Stuart McLean A , Susan Brandon A and Roger Kirkwood B CA School of Pharmacy, University of Tasmania, Private Bag 26, Hobart, Tas. 7001, Australia.
B Research Department, Phillip Island Nature Parks, PO Box 97, Cowes, Vic. 3922, Australia.
C Corresponding author. Email: rkirkwood@penguins.org.au
Wildlife Research 34(3) 239-246 https://doi.org/10.1071/WR06094
Submitted: 28 July 2006 Accepted: 16 March 2007 Published: 6 June 2007
Abstract
Cabergoline is a potent inhibitor of prolactin release and a potential fertility control agent for foxes. To understand how cabergoline could behave in baits deployed for fox control, we conducted laboratory and field trials to investigate the stability of cabergoline when (1) in solution, (2) injected into a bait (deep-fried liver and Foxoff®) and (3) exposed to a range of environmental conditions, including burial. Cabergoline, dissolved in a 1% acetic acid solution, and its carboxylic acid hydrolysis product can be assayed using high-performance liquid chromatography. When stored at 4°C and at room temperature, cabergoline in solution was stable for up to 36 days. When stored under cool (≤15°C), dry conditions, cabergoline (800 µg) in commercial Foxoff® and deep-fried ox-liver baits was stable for 28 and 7 days, respectively; stability was reduced by increases in temperature (tested up to 40°C) and humidity. Recovery of cabergoline from buried baits exposed to a range of field conditions decreased rapidly in the first week, but after 56 days remained detectable at levels of 6–22% of the injected amounts. This study has important implications for baiting campaigns that use cabergoline for fox control.
Acknowledgements
We thank the research and ranger staff at Phillip Island Nature Parks, in particular Stuart Murphy, for assistance with the baits. We are grateful to Clive Marks (Nocturnal Wildlife Research Pty Ltd, Vic.), and Frank Busana and Frank Gigliotti (Department of Primary Industry, Vic.) for helpful discussions. The mass spectroscopic analyses were performed by Noel Davies, Central Science Laboratory, University of Tasmania. Heather Galloway, School of Pharmacy, University of Tasmania, assisted with the bait analyses. Three anonymous referees assisted by reviewing an earlier draft. The project was supported by funding from the Phillip Island Nature Parks and the Vertebrate Pest Research Unit, Department of Primary Industries, Victoria.
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