Animal Health & Drugs

Safety and Effectiveness
by Food and Drug Administration (FDA)

(Page 2 of 3)

Under the Federal FD&C Act of 1938, manufacturers of human or animal drugs only had to show that their products were safe. In 1962, amendments to the act required them to show that their products were also effective. The 1962 amendments generally did not distinguish between human and animal drugs; in 1968, Congress passed legislation to strengthen provisions of the act that pertained to the regulation of animal drugs. Animal drugs, medicated feeds, and food additives were required to be safe for the animal they were intended to be used in and, in the case of food-producing animals, safe for human consumption and safe for the environment. Effectiveness was required to be shown by substantial evidence from one or more adequate and well-controlled studies.

Contaminants and Residues

Every year, infections occur as a result of people ingesting animal products that have been contaminated with various kinds of germs such as salmonella. Furthermore, animal-derived foods can be contaminated by industrial chemicals such as dioxin, natural toxins produced by molds and fungi, and residues of drugs such as antimicrobials. Antimicrobials include antibiotics and other drugs to combat bacteria, viruses, fungi, and certain parasites.

Public health officials were concerned about antibiotic residues in food-producing animals as early as the 1950s, just a few years after penicillin became widely used, says FDA Historian Suzanne White Junod, Ph.D. The government used "milk check stuffers" to remind farmers to pull their cows off antibiotics for a few days before milking them, she says. "The government paid farmers to produce milk then, and the reminder was stuffed in an envelope with the milk check, knowing it would get their attention. That was their way of educating farmers about the need to prevent drug residues in food and to get their voluntary compliance."

Today, the CVM's efforts to keep the food supply safe from contaminants and harmful residues include conducting educational programs for industry and farmers, sending Warning Letters to veterinarians and industry, giving guidance to industry, requiring drug labeling changes, and establishing stringent requirements for new drug approval. In some cases, such as with the antibiotic chloramphenicol, the CVM has withdrawn approval to protect public health.

Chloramphenicol was a best seller in the United States in the 1950s. The FDA approved the antibiotic to treat people with meningitis, typhoid fever, and other serious infections. But in some people, this "wonder drug" had a horrible side effect: aplastic anemia, a bone marrow disorder that could be fatal.

The CVM had approved chloramphenicol to treat infections in dogs and cats, but it had never approved it to treat food-producing animals because of the fear that harmful residues would remain in food products. During the early 1980s, testing of American meat samples showed potentially dangerous residue levels of chloramphenicol, indicating that veterinarians and farmers were using the drug illegally to treat cattle and pigs.

This practice presented a danger not only to consumers, but also to those administering the drug. Getting the oral solution into the animal was a messy procedure, and farmers could easily get the drug on themselves. In 1981, a feedlot owner in Kansas used chloramphenicol in hundreds of cattle with pneumonia. The drug seeped into a cut in his hand, and he died later that year from aplastic anemia.

The CVM sent warning letters to thousands of veterinarians nationwide, stating its intent to eliminate all use of chloramphenicol in food-producing animals. In 1986, the CVM banned the oral solution of chloramphenicol for pets to prevent it from being diverted to use in food-producing animals.

Today, chloramphenicol is not found in domestically produced food, but the CVM continues to fight the drug in imported food. Low levels of chloramphenicol have been detected in shipments of imported honey, shrimp, and crayfish from Asia. The FDA has increased its sampling of imported food and works with importers, the FDA's Office of Regulatory Affairs, and the FDA's Center for Food Safety and Applied Nutrition to prevent foods contaminated with chloramphenicol from entering the United States.

CVM scientists also are developing new methods to test for the presence of the drug with greater sensitivity, says CVM Director Stephen F. Sundlof, D.V.M., Ph.D. "In fact, we're working with other laboratories in Europe to make sure that our methods are similar."

"Chloramphenicol is just one of many potentially harmful substances that CVM is developing methods to detect for," adds Sundlof. Because the FDA never approved many of the drugs that it has found in some imported food, we don't have methods to check for residues, he says. "Now we have to go back and develop them."

The CVM continues to monitor drugs that may potentially contribute to antibiotic-resistant strains of pathogens in people. In 2003, the CVM announced a regulatory pathway it had developed so that pharmaceutical sponsors could seek approval of antimicrobial drugs while ensuring that their use would not create drug-resistant bacteria harmful to public health.

The CVM is working with other countries to reach consensus on food and drug standards, says Sundlof. Through organizations such as the Codex Alimentarius Commission, an international food standard-setting group based in Rome, the CVM works with its counterparts in foreign nations to harmonize veterinary drug residue requirements among Codex's more than 160 member countries.

"We have made substantial progress without lowering the high standards of product safety and efficacy that consumers and industry expect from FDA," says Sundlof.

About the Author

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FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.