Meloxicam

Meloxicam is a nonsteroidal anti-inflammatory drug (NSAID) with analgesic and fever reducer effects. It is a derivative of oxicam, closely related to piroxicam, and falls in the enolic acid group of NSAIDs. It was developed by Boehringer-Ingelheim.

Mechanism of action
Meloxicam inhibits cyclooxygenase (COX), the enzyme responsible for converting arachidonic acid into prostaglandin H2—the first step in the synthesis of prostaglandins, which are mediators of inflammation. Meloxicam has been shown, especially at its low therapeutic dose, selectively to inhibit COX-2 over COX-1.

Meloxicam concentrations in synovial fluid range from 40% to 50% of those in plasma. The free fraction in synovial fluid is 2.5 times higher than in plasma, due to the lower albumin content in synovial fluid as compared to plasma. The significance of this penetration is unknown, but it may account for the fact that it performs exceptionally well in treatment of arthritis in animal models.

Adverse effects
Meloxicam use can result in gastrointestinal toxicity and bleeding, tinnitus, blinding headaches, rash, and very dark or black stool (a sign of intestinal bleeding). It has fewer gastrointestinal side effects than diclofenac, piroxicam, naproxen, and perhaps all other NSAIDs which are not COX-2 selective. Although meloxicam does inhibit thromboxane A, it does not appear to do so at levels that would interfere with platelet function.

Veterinary use
Meloxicam is also used in the veterinary field, most commonly in dogs, but also sees off-label use in other animals such as cattle, cats and exotics. The U.S. Food and Drug Administration sent a Notice of Violation to the manufacturer for its promotional materials which included promotion of the drug for off-label use. In the U.S. the drug is indicated for management of pain and inflammation associated with osteoarthritis in dogs only. In Europe, where the product has been available since the early 1990s, it is also prescribed and licensed for other anti-inflammatory benefits including relief from both acute and chronic pain in dogs. Side effects in animals are similar to those found in humans; the principal side effect is gastrointestinal irritation (vomiting, diarrhea and ulceration). Rarer but important side effects include liver and kidney toxicity.

Since 2003, the oral (liquid) formulations of meloxicam have been licensed in the U.S for use in dogs only, with the January 2005 product insert specifically warning in bold-face type: "Do not use in cats." An injectable formulation for use in dogs was approved by the FDA November 2003, with a formulation for cats, for surgical use only, approved in October, 2004.

In the U.S., per the manufacturer's clinical instructions as of July 2010, injectable meloxicam is indicated in operative use with felines as a single, one-time dose only, with specific and repeated warnings not to administer a second dose. In June 2007, a new oral version of meloxicam was licensed in Europe for the long-term relief of pain in cats. As of June 2008, meloxicam is registered for long term use in cats in Australia, New Zealand, and throughout Europe.

Consumer confidence
As issues arise with any drug used off-label, the off-label use of meloxicam in cats has led to many reports of irreversible renal damage and death. A peer-reviewed journal article cites feline overdose of NSAIDs, including meloxicam, as being a cause of severe kidney damage in cats.

Brands
In Europe, meloxicam is marketed under the brand names Movalis, Melox, and Recoxa. In the UK, U.S., Middle East, Argentina, Paraguay, Uruguay and Australia it is marketed under the brand name Mobic, in Germany as Mobec, and in Canada as Mobicox. In Latin America, the drug is marketed as Tenaron, Ilacox, Mavicam, Melocam, or Artriflam. A veterinary formulation of the drug is marketed as Metacam, Meloxidyl, Meloxoral, Meloxidolor or Petcam. In the Philippines, it is generally marketed under the brand name Moxen. In Greece, it is manufactured under licence from aVianex S.A under the name Loxitan.