© 2003-17 Susan K. Mikota DVM and Donald C. Plumb, Pharm.D. Published by
Elephant Care International
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Chemistry – Flunixin meglumine, a nonsteroidal anti-inflammatory agent that is a highly substituted derivative of nicotinic acid, is unique structurally when compared to other NSAIDs. The chemical name for flunixin is 3-pyridine-carboxylic acid.
Storage/Stability/Compatibility – All flunixin products should be stored between 2-30°C (36-86°F). It has been recommended that flunixin meglumine injection not be mixed with other drugs because of unknown compatibilities.
Pharmacology – Flunixin is a very potent inhibitor of cyclooxygenase and like other NSAIDs, it exhibits analgesic, anti-inflammatory and antipyrexic activity. Flunixin does not appreciably alter GI motility in horses and may improve hemodynamics in animals with septic shock.
Pharmacokinetics – In the horse, flunixin is rapidly absorbed following oral administration with an average bioavailability of 80% and peak serum levels in 30 minutes. The onset of action is generally within 2 hours; peak response occurs between 12-16 hours and the duration of action lasts up to 36 hours. It is unknown how extensively flunixin is bound to plasma proteins or where it distributes in the body. It is unclear if the drug is extensively metabolized and exactly how the drug is removed from the body. Serum half-lives have been determined in horses ≈ 1.6 hours, dogs ≈ 3.7 hours; cattle ≈ 8.1 hours. Flunixin is detectable in equine urine for at least 48 hrs. after a dose.
Uses/Indications – In the United States, flunixin meglumine is approved for use in horses and cattle. However, it is approved for use in dogs in other countries. The approved indications for its use in the horse are for the alleviation of inflammation and pain associated with musculoskeletal disorders and alleviation of visceral pain associated with colic in the horse. In cattle it is approved for the control of pyrexia associated with bovine respiratory disease and endotoxemia, and for the control of inflammation in endotoxemia.
Flunixin has been touted for many other indications in various species, including: 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. It should be noted that the evidence supporting some of these indications is equivocal and flunixin may not be appropriate for every case.
Contraindications/Precautions – The only contraindication the manufacturer lists for flunixin’s use in horses is for patients with a history of hypersensitivity reactions to it. It is suggested, however, that flunixin be used cautiously in animals with preexisting GI ulcers, renal, hepatic or hematologic diseases. When using to treat colic, flunixin may mask the behavioral and cardiopulmonary signs associated with endotoxemia or intestinal devitalization and must be used with caution.
In cattle, the drug is contraindicated in animals who have shown prior hypersensitivity reactions to it and is not recommended to be used in breeding bulls (lack of reproductive safety data).
Although reports of teratogenicity, effects on breeding performance, or gestation length have not been noted, flunixin should be used cautiously in pregnant animals.
Flunixin is usually considered to be contraindicated in cats, but some clinicians may use it short term (see doses).
Adverse Effects/Warnings – In horses following IM injection, reports of localized swelling, induration, stiffness, and sweating have been reported. Do not inject intra-arterially as it may cause CNS stimulation (hysteria), ataxia, hyperventilation, and muscle weakness. Symptoms are transient and generally do not require any treatment. Flunixin appears to be a relatively safe agent for use in the horse, but the potential does exist for GI intolerance, hypoproteinemia, and hematologic abnormalities to occur. Flunixin is not to be used in horses intended for food.
In horses and cattle, rare anaphylactic-like reactions have been reported, primarily after rapid IV administration.
In dogs, GI distress is the most likely adverse reaction. Symptoms may include, vomiting, diarrhea, and ulceration with very high doses or chronic use. There have been anecdotal reports of flunixin causing renal shutdown in dogs when used at higher dosages pre-operatively.
Overdosage – No clinical case reports of flunixin overdoses were discovered. It is suggested that acute overdosage be handled by using established protocols of emptying the gut (if oral ingestion and practical or possible) and treating the patient supportively.
Drug Interactions – Drug/drug interactions have not been appreciably studied for flunixin, but if it follows other NSAIDs it should be used cautiously with highly protein bound drugs such as phenytoin, valproic acid, oral anticoagulants, other anti-inflammatory agents, salicylates, sulfonamides, and the sulfonylurea antidiabetic agents. Additionally, use flunixin cautiously with warfarin, methotrexate, and aspirin or other ulcerigenic agents. Flunixin could theoretically reduce the saluretic and diuretic effects of furosemide. Use with caution in patients with severe cardiac failure.
a) Injectable: 1.1 mg/kg IV or IM once daily for up to 5 days. For colic cases, use IV route and may redose when necessary.
Oral Paste: 1.1 mg/kg PO (see markings on syringe—calibrated in 250 lb. weight increments) once daily. One syringe will treat a 1000 lb. horse for 3 days. Do not exceed 5 days of consecutive therapy.
Oral Granules: 1.1 mg/kg PO once daily. One packet will treat 500lbs of body weight. May apply on feed. Do not exceed 5 consecutive days of therapy. (Package Inserts – Schering Animal Health for Banamine®)
b) 1.1 mg/kg IM or IV q12h to treat moderate to severe pain. (Clark and Becht 1987)
c) 1.1 mg/kg IM or IV; duration of effect averages 4-36 hrs depending upon cause and severity of abdominal pain. (Muir 1987)
a) Anecdotal doses of 1 mg/kg every 24 hours (route of administration not specified) have been reported. This is based on a survey of 20 zoo veterinarians in the U.S. (Mortenson, 1998, 1998, 2001).
a) Mortenson,J., 2001. Determining dosages for antibiotic and anti-inflammatory agents. In: Csuti,B., Sargent,E.L., and Bechert,U.S. (Editors), The Elephant’s Foot. Iowa State University Press, Ames pp. 141-144
a) Mortenson,J. 1998. Determining dosages for anti-inflammatory agents in elephants. Proceedings AAZV and AAWV Joint Conference. Pages: 477-479
a) Mortenson,J. and Sierra S. 1998. Determining dosages for antibiotic and anti-inflammatory agents in elephants. Proceedings of the First North American Conference on Elephant Foot Care and Pathology. Pages: 50-55
Monitoring Parameters –
1) Analgesic/anti-inflammatory/antipyrexic effects
2) GI effects in dogs
3) CBC’s, occult blood in feces with chronic use in horses
Client Information – If injecting IM, do not inject into neck muscles.
Dosage Forms/Preparations/FDA Approval Status/Withholding Times –
Veterinary-Approved Products: Flunixin is approved only for use in horses not intended for food; for beef cattle and non-lactating dairy cattle. Slaughter withdrawal time in cattle = 4 days.
Flunixin Meglumine for Injection 50 mg/ml; in 50 and 100 ml vials; Banamine® (Schering); (Rx)
Flunixin Meglumine Oral Paste 1500 mg/syringe; 30 gram syringe containing 1500 mg flunixin in boxes of 6; Banamine® (Schering); (Rx)
Flunixin Meglumine Oral Granules 250 mg: 10 gram sachets, each sachet contains 250 mg flunixin in boxes of 50. 500 mg: 20 g sachets, each sachet contains 500 mg flunixin in boxes of 25; Banamine® (Schering); (Rx)
Flunixin may also be known as Finadyne®.
Human-Approved Products: None