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U.S. Department of Health and Human Services


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Estimates of Antibacterial Drug Sales in Human Medicine

Caution Regarding Comparisons of Human and Animal Antibacterial Drug Sales Data

FDA has assembled an estimate of human antibacterial drug sales (PDF - 49KB) based on IMS Health, IMS National Sales Perspectives™ data.

However, before making comparisons between human and animal sales and distribution data, there are a number of differences in the circumstances of use of antibacterial drugs in human and veterinary medicine that must be carefully considered, including:

  • The number of humans in the population compared to the number of animals in each of the many veterinary populations (veterinary data provided to FDA are not broken down by species)
  • Differences in physical characteristics of humans compared to various animal species (e.g., weight)
  • Antibacterial drug use in humans can be for the treatment or prevention of an infection, whereas animal use may include treatment, control, prevention, and growth promotion. The available animal data are not reported to the FDA by indication and so do not allow us to distinguish between or among these different types of uses. For example, the majority of antimicrobial drugs used in animal feed are approved for both therapeutic and production purposes. Therefore, the route of use cannot be used as a simple proxy for indication.
  • Milligram dosages for different antibacterial drugs differ (e.g., the usual adult human dosage for amoxicillin is different from the usual adult dosage for doxycycline). Total weights across different antibacterial drug classes (and even, to a lesser extent, within classes) are therefore difficult to interpret.
  • Duration and dosage of antibacterial drug administration may also vary by indication and, in general, between the various animal species and humans.

It is, therefore, difficult to draw definite conclusions from any direct comparisons between the quantity of antibacterial drugs sold for use in humans and the quantity sold for use in animals. These points should be carefully considered when interpreting the data presented in the report (PDF - 49KB) .

It is also important to note that for human antibacterial drugs, these sales data represent the volume of product being sold to the various outlets from the manufacturer, not the volume of product being sold by the outlets to patients. Therefore, these sales data do not provide a direct estimate of human use. Similarly, the animal data represent a summary of the volume of product sold or distributed (through various outlets) by the manufacturer, and not the volume of product purchased by the end user for administration to animals.