Meclofenamate for Veterinary Use
by Barbara Forney, VMD
Nonsteroidal anti-inflammatory drug (NSAID)
May Be Prescribed by Vets for:
Chronic and acute inflammatory diseases of the musculoskeletal system.
Meclofenamate is commercially available as a capsule
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Meclofenamate is chemically the same compound as meclofenamic acid, which was marketed under the trade name of Arquel®. It is an anthranilic acid derivative with similar pharmacologic activity as aspirin. Like other NSAIDs, meclofenamate is a potent inhibitor of the enzyme cyclooxygenase. It is well-absorbed orally with detectable levels being reached within 30 minutes and peak levels at one to four hours post administration. Interestingly, full clinical response is thought to take 36 - 96 hours. Meclofenamate is highly protein-bound; it is metabolized by the liver and excreted in the urine and feces. Although meclofenamate has a transient effect on platelet aggregation, it does not affect bleeding times. Meclofenamate was at one time used as an NSAID in dogs, but now there are other canine-specific NSAIDs that are considered safer.
Meclofenamate is used to treat acute and chronic inflammation of the musculoskeletal system, including soft-tissue injury, bone and joint pathology, and laminitis. It is thought to be particularly useful in chronic problems of the hoof, including navicular syndrome and laminitis.
Because meclofenamate has a slow onset of full clinical action, other NSAIDs are used more commonly to treat colic or to reduce fevers.
Recent research has investigated the use of meclofenamate in embryo transfer programs to improve conception rates when the synchronization of the recipient mares is not within the ideal window. Normally, embryo transfer in the horse is most successful when the recipient mare ovulates one to two days after the donor mare. In a study done at the University of Cambridge, 81% of the recipient mares treated with meclofenamate became pregnant even when they had ovulated as early as two to three days prior to the donor mare.
Meclofenamate is permitted under the therapeutic substance rules of the USEF. Further information regarding NSAID use at USEF competitions may be found on its Web site, www.USEF.org.
Meclofenamate Side Effects
The most-common side effects are those seen with all NSAIDs: decreased packed-cell volume due to bleeding, ulceration of the mouth and GI tract, colic, and diarrhea.
- NSAIDs should be used with particular caution in horses with liver disease, decreased renal function, or pre-existing GI problems.
- Horses with heavy infestations of Gastrophelus may be more likely to develop colic.
- Hypoproteinemic animals may require a lower dose in order to prevent signs of toxicity.
- Meclofenamate crosses the placenta and has been shown to delay parturition in other species. It also has been shown to be teratogenic in rodents although this research has not been borne out in the horse. It should be used only in pregnant mares when the benefits of therapy outweigh the potential risks.
Meclofenamate should be used with additional caution with other drugs that may cause GI ulceration, including corticosteroids or other NSAIDs. In particular, combination with aspirin may increase blood loss due to GI side-effects.
- Early signs of chronic NSAID toxicity include anorexia, colic, diarrhea, and ulcers.
- In the event of an acute overdose, GI emptying through nasogastric lavage and supportive monitoring and care may be helpful. In humans, seizures and renal failure have occurred following massive overdose. Electrolyte and fluid balance should be monitored and managed. IV diazepam may be used for seizures.
About the Author
Dr. Barbara Forney is a veterinary practitioner in Chester County, Pennsylvania. She has a master's degree in animal science from the University of Delaware and graduated from the University of Pennsylvania School of Veterinary Medicine in 1982.
She began to develop her interest in client education and medical writing in 1997. Recent publications include portions of The Pill Book Guide to Medication for Your Dog and Cat, and most recently Understanding Equine Medications published by the Bloodhorse.
Dr. Forney is an FEI veterinarian and an active member of the AAEP, AVMA, and AMWA.
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