In some bird species, diclofenac causes accumulation of uric acid crystals in organs, especially kidneys, triggering acute renal necrosis and visceral gout. Vultures, among other carrion-eating birds, are known to scavenge deceased livestock. In South Asia in the 2000s, vulture populations were decimated by feeding on dead livestock that had been treated with diclofenac. Society and culture
History
In the United States, 1% diclofenac gel was approved by the FDA in 2007. It was approved as a prescription drug and was indicated for the relief of the pain of osteoarthritis of joints responsive to topical treatment; in particular, it was prescribed for the joints in the hands, knees and feet. It has not been shown to work for strains, sprains, bruises or sports injuries. It was intended for the temporary relief of joint pain due to the most common type of arthritis, osteoarthritis. In February 2020, the gel became an over-the-counter drug and the FDA granted the approval of the nonprescription product to GlaxoSmithKline plc. Formulations and trade names
The name "diclofenac" derives from its chemical name: 2-(2,6-dichloranilino) phenylacetic acid. Diclofenac was first synthesized by Alfred Sallmann and Rudolf Pfister and introduced as Voltaren by Ciba-Geigy (now Novartis) in 1973, then in 2015 it was bought by GlaxoSmithKline.Voltaren and Voltarol contain the sodium salt of diclofenac. In the United Kingdom, Voltarol can be supplied with either the sodium salt or the potassium salt, while Cataflam, sold in some other countries, is the potassium salt only.
These additional actions may explain its high potency – it is the most potent NSAID on a broad basis.Marked differences exist among NSAIDs in their selective inhibition of the two subtypes of cyclooxygenase, COX-1 and COX-2. Much pharmaceutical drug design has attempted to focus on selective COX-2 inhibition as a way to minimize the gastrointestinal side effects of NSAIDs such as aspirin. In practice, use of some COX-2 inhibitors with their adverse effects has led to massive numbers of patient family lawsuits alleging wrongful death by heart attack, yet other significantly COX-selective NSAIDs, such as diclofenac, have been well tolerated by most of the population.Besides the COX-inhibition, a number of other molecular targets of diclofenac possibly contributing to its pain-relieving actions have recently been identified. These include:

Blockage of voltage-dependent sodium channels (after activation of the channel, diclofenac inhibits its reactivation also known as phase inhibition)
Blockage of acid-sensing ion channels (ASICs)
Positive allosteric modulation of KCNQ- and BK-potassium channels (diclofenac opens these channels, leading to hyperpolarization of the cell membrane)The action of one single dose is much longer (6 to 8 h) than the very short 1.2–2 h half-life of the drug would indicate. This could be partly because it persists for over 11 hours in synovial fluids. As a veterinary drug
Diclofenac is widely approved as a veterinary drug. It is used in the treatment of companion animals and livestock. In sheep, pigs, cattle and goats, it is used in the management of several bacterial diseases, including diarrhoea, enteritis, dysentery, foot rot and septicaemia.