Editor’s Note: FDA Response to Reporting on Controversial Animal Drug

In response to the January 25, 2012 article by the Food & Environment Reporting Network, “Dispute Over Drug in Feed Limiting US Meat Exports,” the Food and Drug Administration said it reviewed its data on “adverse drug experience” related to the use of ractopamine in pigs.

Previously, the FDA had published on its web site that 218,116 animals had suffered from reported adverse drug events, between the time the drug was approved and March 2011. This number, accessed by reporter Helena Bottemiller, was subsequently removed from the FDA web site when the FDA changed its reporting method for adverse effects. (A discussion of the data, and where it can be accessed, is explained in this previous article, Ractopamine in Pigs: Looking at the Numbers, by Helena Bottemiller.)

Upon its subsequent review, the FDA said, “The number of 218,116 which appears on this website is not precise because it includes reports of ineffectiveness, meat abnormalities and fertility abnormalities.  Ineffectiveness and meat abnormalities are reported as adverse events, but are not considered signs of morbidity.  Fertility abnormalities should not be included in the figure, because the drug is not approved for swine intended for breeding.”

The FDA said that the upon review of the data, the number of animals that suffered reported adverse effects related to morbidity was 160,917. In a second data set that includes more recent data, the number was 170,400. The difference between these two numbers was due to additional ADE reports being entered from a backlog.

The FDA’s analysis of the underlying data was made available to the Food & Environment Reporting Network on March 14, 2012.

The FDA further stated that “the quality of many of the ADE reports is lacking.  For example, several of the ADE reports did not include actual numbers of animals treated or reacted.  This is not unusual for ADE reports submitted for animals managed as a herd.  In these cases, the reporting firm generally estimates the number of animals that may have been involved  … In addition, the 218,116 figure from the prior Cumulative ADE Summaries web page does not take into account any potential confounding factors, such as dosage, concomitant drug use, the medical and physical condition of the animals at the time of treatment, environmental and management factors, and/or extra-label uses.”

It further stated: “It is also inappropriate to make use of ADE data to compare the safety of different drugs.  For example, if a drug is widely used to treat certain conditions, there may be more ADEs for that drug than another product that is not used as often. This does not mean that the first drug was more unsafe than the second. The number of reports simply represents the numbers of ADEs received for a particular drug, by species, and route of administration.”

Bottemiller’s article, however, did not attempt to calculate the relative risk of using ractopamine, only stating that pigs had more absolute numbers of ADEs from ractopamine than from any other drug. Elanco declined to release usage data on ractopamine.

Finally, the FDA added: “FDA’s Center for Veterinary Medicine continues to believe that ractopamine is safe and effective when used in accordance with the approved labeling.”