Flumixine Vet

Horses: foal diarrheas, shock, colitis, respiratory disease, post-race treatment, and pre- and post ophthalmic and general surgery; 

Dogs: disk problems, arthritis, heat stroke, diarrhea, shock, ophthalmic inflammatory conditions, pre- and post ophthalmic and general surgery, and treatment of parvovirus infection; 

Cattle: acute respiratory disease, acute coliform mastitis with endotoxic shock, pain (downer cow), and calf diarrheas; 

Swine: agalactia/hypogalactia, lameness, and piglet diarrhea.

Do not use in calves to be processed for veal. Do not use in bulls intended for breeding because reproductive effects in this class of cattle have not been studied

Flunixin is a potent NSAID widely used in large animals. Like other NSAIDs, it produces analgesic and anti-inflammatory effects by inhibiting the synthesis of prostaglandins. The enzyme inhibited by NSAID is the COX enzyme. The COX enzyme exists in two isoforms: COX-1 and COX-2. COX-1 is primarily responsible for synthesis of prostaglandins important for maintaining a healthy GI tract, renal function, platelet function, and other normal functions. COX-2 is induced and responsible for synthesizing prostaglandins that are important mediators of pain, inflammation, and fever. However, it is understood that there is some crossover of COX-1 and COX-2 effects in some situations, and COX-2 activity is important for some biological effects. Flunixin is not selective for either COX-1 or COX-2.

Pharmacokinetics: In horses, the half-life is 2 hours, oral absorption of paste is 77%, and absorption of granules is 85%. However, access to hay delays peak concentrations and oral absorption from granules and paste mixed with feed may be more erratic. In adult cattle, the half-life is 3–4 hours IV but 6 hours in calves. The half-life is longer when administered IM or SQ compared to IV administration. Oral absorption in cattle is 60%. There are age-related differences in pharmacokinetics in cattle, with young calves showing a slower clearance and longer half-life than older calves. In healthy weaned calves, the half-life was 6–7 hours, but in veal calves, the half-life was 13 hours, with a volume of distribution of 0.6 L/kg. The transdermal formulation of flunixin exhibits different pharmacokinetics in cattle than the injectable form. The half-lives of the transdermal form are 9.3 and 13.2 hours in 2-and 8-month- old calves, respectively, with absorption of 40% and 63%, respectively. After transdermal application of 3.3 mg/kg to Holstein calves, the bioavailability is 48% with a half-life of 6.4 hours.

Drug/drug interactions have not been appreciably studied for flunixin and the label does not mention any drug interactions. However, the following drug interactions have either been reported or are theoretical in humans or animals receiving other NSAIDs and may be of significance in veterinary patients receiving flunixin:
ASPIRIN: When aspirin is used concurrently with NSAIDs, plasma levels of the NSAID could decrease and an increased likelihood of GI adverse effects (blood loss) could occur
CYCLOSPORINE: NSAIDs may increase cyclosporine blood levels and increase the risk for nephrotoxicity
DIGOXIN: NSAIDs may increase serum levels of digoxin; use with caution in patients with severe cardiac failure
ENROFLOXACIN: Has been shown in dogs to increase the AUC and elimination half-life of flunixin and flunixin increases the AUC and elimination half-life of enrofloxacin; it is unknown if other NSAIDs interact with enrofloxacin in dogs. Enrofloxacin and flunixin did not interact in rabbits.
FUROSEMIDE & OTHER DIURETICS: NSAIDs may reduce the saluretic and diuretic effects of furosemide
METHOTREXATE: Serious toxicity has occurred when NSAIDs have been used concomitantly with methotrexate; use together with caution
NEPHROTOXIC AGENTS (e.g., amphotericin B, aminoglycosides, cisplatin, etc.): Potential for increased risk of nephrotoxicity if used with NSAIDs
PROBENECID: May cause a significant increase in serum levels and halflife of some NSAIDs
WARFARIN: Use with NSAIDs may increase the risk for bleeding

Most severe adverse effects are related to the GI system. Flunixin causes gastritis and GI ulceration with high doses or prolonged use. Reduced renal perfusion has also been documented. In horses, flunixin administration may affect recovery after ischemic injury to the intestine. In horses, if given IM, it can result in myositis and abscess at the injection site. It can also cause irritation and injection-site lesions if injected SQ or IM in cattle. If used in dogs, treatment should not go beyond 4 consecutive days.

Gastric ulceration is a distinct possibility in horses that have received overdoses of flunixin. Consider using anti-ulcer medications in overdosed horses.

In a system evaluating the safety of drugs in canine and feline pregnancy (Papich 1989), this drug is categorized as in class: C.

Avoid use in pregnant animals near term.

Meat: Up to 4 days.

Milk: 1.5 days