The effect of non-steroidal anti-inflammatory drugs (NSAIDs) on vultures has been the subject of several studies and lines of research following the ecological disaster caused by the NSAID Diclofenac on South Asia´s vulture populations. Despite the wide range of compounds belonging to this family of drugs available in the worldwide market, up to now only 5 NSAIDs – Ketoprofen, Meloxicam, Carprofen, Flunixin and Phenylbutazone – have been tested for toxicity on vultures of the Gyps genus, under controlled conditions. The results of these studies have been published on international journals and are now available for the general public (see for instance “The Safety and Pharmacokinetics of Carprofen, Flunixin and Phenylbutazone in the Cape Vulture (Gyps coprotheres) following Oral Exposure” by Fourie et al., 2015). Out of these 5 NSAIDs, only Meloxicam has proven safe for vultures when used in cattle, not just because of its lower toxicity but thanks to two main characteristics: 1) It can be metabolised in a shorter period of time and thus doesn’t accumulate in the vulture’s liver, and 2) it has a shorter half-life (T1/2, the time it takes for a substance to lose one-half of its pharmacological activity), 0.5 hours against the 12 hours in Diclofenac, meaning the activity of Meloxicam is practically innocuous to vultures one hour after it’s been inoculated whereas Diclofenac is still active 24 h after treatment.
Both Diclofenac and Ketoprofen have already proven fatal for vultures in the wild, whereas the effect of other NSAIDs was merely seen during toxicity trials. One of these drugs, Carprofen, was recently put to the test in an experiment in South Africa, to be eventually used as another “vulture-friendly” NSAID, based on some promising results in earlier tests. However, the safety trial did not go as anticipated, and the researchers found exactly the opposite of what they expected: Not only wasn’t Carprofen safe, in fact it turned out to be lethal for vultures. Although the toxicity levels are not as high as in Diclofenac, the symptoms of the ingestion of Carprofen are not as noticeable as they are on its infamous “cousin”, and instead of showing any signs of lethargy or neck drooping, birds simply dropped dead 3 days after the ingestion.
This situation puts once again pharmaceutical companies and their marketing in the spotlight. The lack of adequate field tests on the potential risk of their products before they are licensed is posing a serious threat on wildlife populations. This refers not only to the NSAIDs, but also to several other compounds that affect the environment and even us, from the “feminization” of fish due to the presence of hormones in the water system, to the appearance of antibiotic-resistant pathogenic bacteria resulting from the high incidence of antibiotics in the environment. If we are not aware of these risks, some day we may have to pay too high a price, and once the damage is done we will look back and regret we didn’t act when it was still possible. The impact that the use of Carprofen may already have on wild vultures has not been assessed so far, although it is available worldwide under several different brand names (see https://www.drugs.com/international/carprofen.html for more information). Is it worth it to take the risk of letting what happened in Asia happen once again for fear of being too cautious?
The recent findings may theoretically be used to ban the marketing of Carprofen in some countries, but this is optimist at the very least, considering current events. Ignoring the facts from Asia, several countries in Europe have in the last few years given approval for the sale of veterinary Diclofenac, and thus putting European vultures at risk – this includes Spain, where over 90% of all European vultures).