An injectable drug to control fever in horses has been approved by the US Food and Drug Administration (FDA).
Zimeta (injectable dipyrone) is produced by Kindred Biosciences Inc, a California-based biopharmaceutical company.
The company notes that there are more than eight million horses in the United States, and more than one million are seen by a vet each year for fever.
Fever, more formally known as pyrexia, is associated with several underlying diseases and can trigger major problems, including dehydration, laminitis, muscle wasting, weight loss, and in some cases death.
Among performance horses, it can also lead to loss of training and competition days.
Kindred Biosciences says Zimeta is the first and only FDA-approved medication for the control of fever in horses.
“The equine community has been eagerly anticipating an FDA-approved safe and effective product to control fever in horses,” said Denise Bevers, the company’s president and chief operating officer.
She describes equine pyrexia as an attractive market for KindredBio, with high unmet medical need and a commitment to treat.
It said the product took five years to develop, at a cost of $US5 million.
Zimeta is classified as a nonsteroidal anti-inflammatory drug (NSAID). It is said to target fever centrally in the brain, where it originates.
In a clinical study, Zimeta showed rapid and effective fever reduction in horses with naturally occurring fever.
The most common cause of fever in horses is respiratory disease, both viral and bacterial, but fever also can occur with other infections or inflammation of any body system.
Zimeta is given intravenously at 30 mg/kg once or twice daily, at 12-hour intervals, for up to three days. The overall number of doses and duration of treatment is dependent on the fever reduction observed.
The FDA, in approval documentation, said Zimeta has not been evaluated for use in horses intended for human consumption or food-producing animals, including lactating dairy animals.
In 1977, the FDA formally withdrew the approval of all dipyrone-containing drugs intended for use in humans after becoming aware of reports of agranulocytosis — an acute condition involving a severe and dangerous leukopenia (lowered white blood cell count).
Dipyrone is now prohibited for use in humans in several countries.
However, the data generated to support the approval of Zimeta did not indicate that agranulocytosis occurred in horses treated with the drug, it said.
Following the removal of the human drug product from the US market, sales of an unapproved equine dipyrone product continued. However, in 1996, the FDA removed the unapproved equine dipyrone product from the market due to concerns about its use in food-producing animals.
Subsequently, the FDA noted increased distribution of compounded dipyrone sold for use in horses.
The FDA said it strongly encouraged use of an FDA-approved dipyrone animal drug product, when dipyrone is indicated, for use in horses for the control of fever.
FDA-approved drugs have been shown to be safe and effective for their intended use and have been consistently manufactured to preserve the drugs’ identity, strength, quality and purity.
As with all approved animal drugs, the FDA will monitor and evaluate submitted adverse event reports for Zimeta.
It said the effectiveness of Zimeta was shown in an adequate and well-controlled clinical field study in 138 horses, followed by an extended-use field-safety phase in 87 horses.
One hundred thirty-seven horses (103 administered Zimeta and 34 administered an inactive control) were included in the statistical analysis for effectiveness.
Horses over one year of age with naturally occurring fevers (rectal temperature of 102.0°F or higher) were administered Zimeta intravenously at 30 mg/kg. A horse was considered a treatment success if, six hours are receiving a single dose, its rectal temperature fell by 2.0°F or more, or the temperature decreased to normal. Based on this definition, the success rate was 74.8% (77/103) in Zimeta-treated horses and 20.6% (7/34) in control-treated horses.
The agency urged caution around compounded forms of injectable dipyrone.
Compounded animal drug preparations are not FDA-approved drugs, nor are they FDA-approved generic drug products. Compounded formulations of dipyrone have not been evaluated by the FDA for safety or effectiveness and may vary in quality, potency, and bioavailability, it said.
There are also no requirements for the mandatory reporting of adverse drug experience reports for compounded preparations.