EQUIOXX is an oral paste produced by Merial containing firocoxib, a coxib class-2 non-steroidal anti-inflammatory drug (NSAID). Coxib class is a term for what has been called cyclooxygenase-inhibitors. This class of NSAID's is thought to be safer than earlier NSAID's including coxib class-1 inhibitors because of lower risk of GI irritation. EQUIOXX has been approved for use in horses by the FDA and is now sold in the USA. This article discusses the dosage, efficacy, safety, cost, and use of firocoxib and compares it with phenylbutazone use in the horse.

Firocoxib (FX), a second-generation coxib, is a highly selective COX-2 inhibitor in horses. It has one of the highest selectivity for the COX-2 receptor. Most of the side effects of NSAIDs comes from blocking the COX-1 receptor so firocoxib should be safer to use. FX has good absorption when taken orally and a long half-life in the horse. Initial dosing regimens took the long half-life into account but did not reflect that it takes several days to reach maximal effective serum concentrations. As a result results when used at label doses are disappointing the first few days. See dosing below for more on this and possible solutions.

Efficacy

Adverse Events

Three safety studies were done at recommended and a range of elevated dosages and compared with a control group that received sham (pasted with no active ingredient) treatment. There were roughly 30 horses in each of these studies and they were done for 30, 42, and 90 days. The highest dose administered was 12.5 times the recommended dosage for 90 days. Clinical and hematological values were monitored during the studies and necropsy performed on some of the participants following the treatment regimen. There were no treatment related deaths during any of these studies. From these studies the important conclusions are:

• Using the label directions EQUIOXX is a very safe NSAID.
• When given at label dosages for up to 30 days no adverse reactions were noted.
• When used beyond 30 days at label dosages horses do exhibit ulceration in the oral and gi system though these changes are mild at recommended dosages for up to 42 days. There are no published studies at recommended levels beyond this point.
• When used above recommended treatment levels ulcers of the mouth, gi tract should be expected. If used for longer than 30 days above recommended treatment levels lesions of the kidneys should be expected but differ considerably from individual to individual. There are some individuals who show increased sensitivity to the drug.

Horses should undergo a thorough history and physical examination before initiation of NSAID therapy. Appropriate laboratory tests should be conducted to establish hematological and serum biochemical baseline data before and periodically during administration of any NSAID. Clients should be advised to observe for signs of potential drug toxicity and be given a Client Information Sheet with each prescription. See Information for Owner or Person Treating Horse section of this package insert. Treatment with EQUIOXX should be terminated if signs such as inappetance, colic, abnormal feces, or lethargy are observed.

As a class, cyclooxygenase inhibitory NSAIDs may be associated with renal and gastrointestinal toxicity. Sensitivity to drug-associated adverse events varies with the individual patient. Patients at greatest risk for adverse events are those that are dehydrated, on diuretic therapy, or those with existing renal, cardiovascular, and/or hepatic dysfunction. Concurrent administration of potentially nephrotoxic drugs should be carefully approached or avoided. NSAIDs may inhibit the prostaglandins that maintain normal homeostatic function. Such anti-prostaglandin effects may result in clinically significant disease in patients with underlying or pre-existing disease that has not been previously diagnosed. Since many NSAIDs possess the potential to produce gastrointestinal ulcerations, concomitant use with other anti-inflammatory drugs, such as NSAIDs or corticosteroids, should be avoided or closely monitored. The concomitant use of protein bound drugs with EQUIOXX Oral Paste has not been studied in horses. The influence of concomitant drugs that may inhibit the metabolism of EQUIOXX Oral Paste has not been evaluated. Drug compatibility should be monitored in patients requiring adjunctive therapy.

The safe use of EQUIOXX Oral Paste in horses less than one year in age, horses used for breeding, or in pregnant or lactating mares has not been evaluated.

Consider appropriate washout times when switching from one NSAID to another NSAID or corticosteroid.

Adverse reactions may include erosions and ulcers of the gums, tongue, lips and face, weight loss, colic, diarrhea, or icterus. Serious adverse reactions associated with this drug class can occur without warning and, in rare situations, result in death. Clients should be advised to discontinue NSAID therapy and contact their veterinarian immediately if any of these signs of intolerance are observed. The majority of patients with drug-related adverse reactions recover when the signs are recognized, drug administration is stopped, and veterinary care is initiated.

Currently we do not have a pricing on this drug.

The recommended dosage of EQUIOXX (firocoxib) for oral administration in horses is 0.045 mg/lb (0.1 mg/kg) of body weight once daily for up to14 days. Each marking on the syringe will treat 250 pounds of body weight, and each notch corresponds to approximately a 50 Ib weight increment. To deliver the correct dose, round the horse's body weight up to the nearest 50 pound increment (if the body weight is an exact 50 pound increment, do not round up). Unlock the knurled ring on the syringe plunger by rotating it 1/4 turn. Slide the knurled ring along the plunger shaft so that the side nearest the barrel is at the appropriate 50 lb weight notch. Rotate the plunger ring 1/4 turn to lock it in place and ensure it is locked.

A Slow Start at Label Doses

EQUIOXX may be given with or without food.

EQUIOXX is available in packs of 20, 72 and 216 individually-boxed syringes. Each syringe contains 6.93 grams of EQUIOXX paste, sufficient to treat a 1250 lb. horse.

For technical assistance or to report suspected adverse reactions, call 1-877-217-3543.

NADA 141-253, Approved by FDA

© 2006 Merial Limited. All Rights Reserved.

U.S. Pat. No.: 5981576, 6020343

EQUIOXX is a registered trademark of Merial Limited, Duluth, Georgia, USA.

Merial Limited, a company limited by shares registered in England and Wales (registered number 3332751) with a registered office at PO Box 327, Sandringham House, Sandringham Avenue, Harlow Business Park, Harlow, Essex CM19 5QA, England, and domesticated in Delaware, USA as Merial LLC.

Marketed by Merial Limited, 3239 Satellite Blvd., Duluth, GA 30096-4640, USA. 1050-2012-01 Rev. 02-06

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