Abstract:
The non-steroidal anti-inflammatory drug (NSAID) diclofenac is highly toxic to Gyps vultures
and its recent widespread use in South Asia caused catastrophic declines in at least three
scavenging raptors. The manufacture of veterinary formulations of diclofenac has since been
banned across the region with mixed success. However, at least 12 other NSAIDs are available
for veterinary use in South Asia. Aceclofenac is one of these compounds and it is known to
metabolise into diclofenac in some mammal species. The metabolic pathway of aceclofenac in
cattle, the primary food of vultures in South Asia, is unknown. In this study, we give six cattle
the recommended dose of aceclofenac (2 mg/kg), collect blood along a time series and undertake
a pharmacokinetic analysis of aceclofenac and diclofenac-metabolites in their plasma using
liquid chromatography with mass spectrometry. We found that nearly all of the aceclofenac
administered to the cattle was very rapidly metabolised into diclofenac. Therefore, treating
livestock with pure diclofenac or aceclofenac poses the same risk to vultures. This fact, coupled
with the risk that aceclofenac may replace diclofenac in the veterinary market, fortifies the need
for an immediate ban on all aceclofenac formulations that can be used to treat livestock. Without
such a ban, the recovery of vultures across South Asia will not be successful.
