Vulture-toxic drugs linger

Commercial diclofenac formulations available in India. Photo credit: Jacob Graham Savoie

In a recent study, a team of researchers has found that the vulture-toxic drug diclofenac, now banned for veterinary use, is still available in pharmacies in India. Most of the available alternatives to diclofenac were also toxic to these birds, highlighting the immediate need to ban them.

The six-year-long study, conducted between 2012 and 2018, involved researchers from India, Nepal, Bangladesh, the UK and Australia. Local volunteers covertly set out to buy high doses of diclofenac for veterinary uses, without a prescription, from pharmacies in India, Nepal, and Bangladesh. The drug has been banned in India and Nepal since 2006, and in Bangladesh since 2010.

“We were aware that despite the ban, diclofenac was available to vets and livestock owners in India,” says John Mallord, the corresponding author of the study. He is a conservation scientist at the RSPB Centre for Conservation Science, UK. In the current study, published in the journal Bird Conservation International, Mallord and other researchers partnered with conservationists from the Bombay Natural History Society (BNHS).

“Monitoring the non-steroidal anti-inflammatory drugs available in pharmacies for veterinary use has been one of the cornerstones of our work since the ban on veterinary diclofenac in 2006,” says Mallord, talking about the study.

Critically endangered

As scavengers, vultures are nature’s ‘clean-up crew’, that devour carcasses of dead animals, thus preventing the spread of infectious diseases. India was once home to about 40 million vultures belonging to nine species. In the last four decades, the numbers have nose-dived to just a few thousand. Four species—white-rumped vultures (Gyps bengalensis), Indian vultures (Gyps indicus), slender-billed vultures (Gyps tenuirostris), and the red-headed vultures (Sarcogyps calvus)—are today critically endangered.

In 2006, scientists investigating the massive decline in vulture numbers in Soth Asia made a startling discovery. They identified that diclofenac, a commonly-used non-steroidal anti-inflammatory drug (NSAID), was the culprit. The drug is often used to ease the pain of dying cattle. It is safe for human and livestock consumption but fatal to vultures that eat cattle carcasses containing traces of diclofenac. “Consumption of even small quantities of diclofenac causes elevated uric acid levels within the blood of vultures. It then leads to the deposition of uric acid crystals on and within the internal organs, resulting in kidney failure and death,” explains Mallord.

The discovery was soon followed by a ban on the use of diclofenac for veterinary purposes, and the decline in three species of endangered Gyps vultures slowed down. However, people circumvented the ban and bought multiple vials of the drug meant for humans, for their cattle. In 2015, the sale of multi-dose vials of diclofenac was also banned to prevent its misuse. But, have these bans helped in keeping this vulture-toxic drug at bay? Are India’s vultures safer than before? Not really.

Lurking dangers of NSAIDs

Not only diclofenac, but most of the widely-used veterinary NSAIDs, like ketoprofen, aceclofenac, nimesulide, and carprofen, are known to be toxic to vultures. “Flunixin, another NSAID which is now available in India, is associated with dead Eurasian Griffons in Spain,” says Mallord. So far, meloxicam is the only NSAID that has been proven safe for vultures. Conservationists are rooting for the use of this drug as an alternative to other NSAIDs.

The current study found that, despite the ban, there has been little success in actually taking diclofenac off the shelves of pharmacies. Throughout the survey, conducted in Uttar Pradesh, Gujarat, Assam, Madhya Pradesh, Jharkhand, and Uttarakhand, the trends in the availability of NSAIDs varied. In 2012, diclofenac was the most sold NSAID in India. Although its sales dropped over time, thanks to awareness campaigns against its use, they are still sold. In contrast, diclofenac has virtually disappeared from Nepal and Bangladesh; import of the drug from India remains the primary concern now.

In India, the researchers observed that after a year into the ban of multi-dose vials of diclofenac, they could still be bought in all the states studied. In 2017, about half the NSAIDs sold by pharmacies in Gujarat was diclofenac. After the ban in 2015, most of these vials were still being illegally manufactured by pharmaceutical companies. Meloxicam, proven to be safe for vultures, constituted only about 36% of NSAID sales in India in 2017. Nimesulide, also toxic to vultures, was comparable in its availability. In Haryana, around a dedicated ‘vulture safe zone’ where all vulture-toxic NSAIDs are banned within a radius of 100 kilometres, meloxicam was sold only about 40% of the time.

The threat of NSAIDs to vultures may not be limited to South Asia. “NSAIDs are, indeed, a global issue,” acknowledges Mallord. Vulture populations are already declining in countries in Africa and the European Union, for many reasons and the wide availability of toxic NSAIDs could potentially add to the problem. “So far, deaths of vultures through diclofenac poisoning have only been confirmed in South Asia. However, we know that this drug is used by veterinarians elsewhere in the world where vultures occur,” he says.

With India’s vulture population on the edge of extinction, the availability of toxic NSAIDs, as found in the study, is a ticking time bomb. “It threatens to undo two decades of hard-fought and expensive conservation achievements,” rues Mallord. “The Indian government must act now to prevent the extinction of vultures,” he urges.

Science and awareness

Over the last two decades, rigorous scientific evidence has been an elixir for India’s vultures. Studies have not only helped recognise diclofenac as the cause of the massive decline in vulture numbers but also identified meloxicam as a vulture-safe drug alternative. Continued monitoring of vulture populations has shown partial signs of recovery. “However, the science is only the first step,” says Mallord, who is also a member of the Technical Advisory Committee at SAVE. It is an international consortium working towards the recovery of vultures in South Asia. “What is needed is effective advocacy,” he points out.

The study calls for the government to bring in legislation that bans all vulture-toxic NSAIDs, and implement them strictly. It also suggests having ongoing awareness programs for local stakeholders, including livestock owners, vets, and pharmacists, to reduce the use of harmful drugs.

Could these steps help Indian vultures soar high and reclaim the skies? It is a tight ropewalk and we need to act now. “At the height of the vulture crisis in the 1990s and early 2000s, populations were declining by nearly 50% per year. With numbers now down to the tens of thousands compared to the tens of millions, it would not take very long for vulture species to become extinct,” warns Mallord. Perhaps, we could learn a lesson or two from Nepal, where the government’s action in promoting meloxicam has been instrumental in regaining the lost vultures.

“But, yes, there are huge challenges,” concedes Mallord. “Changing government policy is a slow process and convincing local people to change their behaviour in a huge country like India, to benefit vultures, is difficult.”

(The writer is with Research Matters, Bengaluru)