However, Voltarol Emulgel contains diclofenac diethylammonium, in which a 1.16% concentration is equivalent to a 1% concentration of the sodium salt. In 2016 Voltarol was one of the biggest selling branded over-the-counter medications sold in Great Britain, with sales of £39.3 million.On 14 January 2015, diclofenac oral preparations were reclassified as prescription-only medicines in the UK. The topical preparations are still available without prescription.Diclofenac formulations are available worldwide under many different trade names. Ecological effects
Use of diclofenac for animals is controversial due to toxicity when eaten by scavenging birds that eat dead animals; the medication has been banned for veterinary use in several countries.Use of diclofenac in animals has been reported to have led to a sharp decline in the vulture population in the Indian subcontinent – a 95% decline by 2003 and a 99.9% decline by 2008. The mechanism is presumed to be renal failure; however, toxicity may be due to direct inhibition of uric acid secretion in vultures. Vultures eat the carcasses of livestock that have been administered veterinary diclofenac, and are poisoned by the accumulated chemical, as vultures do not have a particular enzyme to break down diclofenac. At a meeting of the National Wildlife Board in March 2005, the Government of India announced it intended to phase out the veterinary use of diclofenac. Meloxicam is a safer alternative to replace use of diclofenac.
Causes
Common causes include infection, or reaction to medication such as an analgesic, anti-inflammatory, or antibiotics such as methicillin (meticillin). Reaction to medications causes 71% to 92% of cases. Drugs
This disease is also caused by other diseases and toxins that damage the kidney. Both acute and chronic tubulointerstitial nephritis can be caused by a bacterial infection in the kidneys known as pyelonephritis, but the most common cause is by an adverse reaction to a medication. The medications that are known to cause this sort of reaction are β-lactam antibiotics such as penicillin
and cephalexin, and nonsteroidal anti-inflammatory drugs (aspirin less frequently than others), as well as proton-pump inhibitors, rifampicin, sulfa medications, fluoroquinolones, diuretics, allopurinol, mesalamine, and phenytoin. The time between exposure to the drug and the development of acute tubulointerstitial nephritis can be anywhere from 5 days to 5 months (fenoprofen-induced). Diagnosis
The condition can appear without symptoms. When present they may appear widely varied and can occur rapidly or gradually.When caused by an allergic reaction, the symptoms of acute tubulointerstitial nephritis are fever (27% of patients), rash (15% of patients), and enlarged kidneys. Some people experience dysuria, and lower back pain. In chronic tubulointerstitial nephritis the patient can experience symptoms such as nausea, vomiting, fatigue, and weight loss. Other conditions that may develop include a high concentration of potassium in the blood, metabolic acidosis, and kidney failure. Blood tests
About 23% of patients have a high level of eosinophils in the blood. Urinary findings
Urinary findings include:

Eosinophiluria: Original studies with Methicillin-induced AIN showed sensitivity of 67% and specificity of 83%.