A new experimental study led by the Indian Veterinary Research Institute confirms the acute toxicity to vultures of veterinary painkiller, nimesulide. The authors point out that, with equally affordable and safe alternatives available, there is no justification for continued licensing of this drug which poses a major threat to vulture populations.
The scientifically controlled safety testing experiment was carried out in Haryana, India. Two Himalayan Griffon Vultures Gyps himalayensis, which are less threatened than the most endangered species, were given nimesulide at a dose comparable to those found in the carcass of a treated cow or buffalo. To avoid too many birds being killed by exposure to a potentially harmful drug, only two birds were given a dose of a drug during of the experiment. Two more control birds were treated with saline solution. After treatment, both treated birds had increased concentrations of uric acid in the blood, and despite appearing healthy on the first day, they both died within two days of dosing. This rapid effect is typical of poisoning and kidney failure caused by other toxic NSAIDs, such as diclofenac and ketoprofen. The study confirms results from previous experimental trials work in South Africa on closely related vultures, which found the same result. This rigorously managed and published safety testing evidence of toxicity is required by the drug regulation authorities in India before a ban will be considered. There was already strong evidence that nimesulide was toxic because two independent research groups had previously found dead wild vultures in India with visceral gout, a sign of major kidney failure, and levels of nimesulide in their bodies.
To avoid too many birds being exposed to a potentially harmful drug, only two birds are given a dose of a drug in the initial phase of the experiment, and if at least one of these birds die then the experiment is stopped and the drug declared toxic. In this case, sadly both birds died.
Dr Pawde of IVRI commented: “Our studies have proved that the painkiller nimesulide is toxic to vultures when they eat flesh containing nimesulide. It is high time to ban such toxic drugs so that these important species can be saved from extinction”.
Vibhu Prakash, vulture expert, formerly with BNHS said: “The whole point of such difficult work is to get the urgently needed removal of such toxic drugs that silently threaten vulture populations across the country – we have already been requesting such a step in the form of a national nimesulide ban for veterinary use but this further strengthens the need and urgency”.
Dr Karikalan, first author, IVRI added: “When there are at least two known safe alternatives available – meloxicam and tolfenamic acid, and these are no more expensive, it seems entirely reasonable that responsible manufacturers and veterinarians will accept the need to use those drugs for the cattle, and not the highly toxic nimesulide”.
Co-author Professor Rhys Green of Cambridge University, UK said: “The recently gazetted bans announced in India for aceclofenac and ketoprofen were important good news, but it is puzzling and of concern that veterinary use of nimesulide was not banned at the same time. The authorities had been informed of the previously published studies of toxicity to wild vultures in India and the experiments in South Africa and were given advance information about the IVRI’s study too. I hope that this study now being published in a peer-reviewed scientific journal will help to speed up regulatory action.”.
Jemima Parry-Jones, SAVE Chair, said: “India showed important leadership in 2006 with the diclofenac ban, which probably saved several vulture species from extinction and was quickly taken up by other countries. If nimesulide can now be similarly removed from the Indian environment through urgently needed legislation, this will further demonstrate India’s commitment to Saving Asia’s Vultures from Extinction!”
The work was funded by Ministry of Environment & Climate Change, Government of India, with crucial support from Haryana Forest Department, BNHS, RSPB and SAVE.