May 14, 2007 -- A May 11 announcement by the Food and Drug Administration has allayed fears that the recall of pergolide mesylate will result in the loss of the medication as a treatment for Cushing's disease in horses.
The manufacture of pergolide for human use was halted by the FDA in March after studies showed that 22 percent of Parkinson's patients taking the drug developed cardiac abnormalities. Because pergolide was never approved for veterinary applications, it is considered an "off label" medication for horses, meaning it is prescribed to treat conditions for which it was not tested.
Pergolide for Cushing's horses has usually been obtained through compounding pharmacies, which can legally produce formulations of FDA-approved products. However the drug's recall put the legality of this practice into question: When production of pergolide pills stopped, compounders had to rely on bulk ingredients to create the drug, a violation of FDA guidelines.
Worried that pergolide in any form may ultimately become unavailable for the treatment of Cushing's, Eleanor Kellon, VMD, gathered 4,800 signatures on an online petition urging the FDA to help find a solution to the supply problem. "There is precedent for publishing an exception to the prohibition against bulk compounding," says Kellon, co-owner of the Equine Cushing's and Insulin Resistance internet groups. "Adding pergolide to that list would solve the problem."
The FDA did not go that far but did agree to a compromise: It would exercise "enforcement discretion as appropriate over the pharmacy compounding of pergolide," so long as certain criteria are met--for example the drug can be made only with a valid prescription for an individual animal, and bulk ingredients must be clearly marked "for veterinary use only."
"What it boils down to is that they are allowing it for now," says Kellon, "but if an actual drug company decides to start up manufacturing the pill form again or if a drug company wants to go down an official pathway to get it approved for equine use, the bulk compounding will again be considered illegal as soon as that source is up and running."
Pergolide has been given to horses with pituitary pars intermedia dysfunction (PPID, or Cushing's disease) for more than a decade. The drug helps regulate hormonal imbalances that can lead to obesity, insulin resistance and laminitis. Kellon estimates that more than 10 to 20 million 1 mg doses of pergolide are needed to treat the country's Cushing's horses every month.
Look for more about Cushing's disease in the August 2007 issue OF EQUUS magazine. For more on the pergolide situation, visit The Jurga Report.