ANIMAL DRUG APPROVALS AND MARKETED PRODUCTS

By Dr. Neal Bataller

This article compares the current number of New Animal Drug Applications (NADAs) that are being marketed with the historical data on the number of NADAs being approved. Data concerning NADA approvals were compiled from the FDA/CVM Submission Tracking and Reporting System (STARS) database. STARS is the Center's corporate database where information is recorded for all stages of new animal drug approvals. Information and data for the number of new animal drugs marketed were compiled from the FDA/CVM Drug Listing Database. The Drug Listing Database contains information on many aspects of new animal drugs that are currently being marketed in U.S., including both approved and unapproved animal drugs.

Table 1 presents the number of NADAs approved for each of the last seven decades (number of NADAs approved). Also, the number of these approved NADAs that were withdrawn (number of NADAs withdrawn) and the number of NADAs that are currently being marketed (number of NADAs currently marketed) is presented by the decade of approval. The table also expresses these numbers as percentages of the total number of NADAs approved.

Table 1. The Number of NADAs Originally Approved, Withdrawn, Currently Approved, and Currently Marketed.

¹ The number of NADAs withdrawn divided by the number of NADAs originally approved, expressed as a percentage.

² The number of NADAs currently approved divided by the number of NADAs originally approved, expressed as a percentage.

³ The number of NADAs currently marketed divided by the number of NADAs originally approved, expressed as a percentage.

⁴ The number of NADAs currently marketed divided by the number of NADAs currently approved, expressed as a percentage.

The approval rate has fluctuated when comparing the number of approvals across decades. The fewest approvals occurred during the 1990s. Many factors may account for differences in approval activity. Some decades may be associated with industry investments in certain products, such as medicated feeds. Other decades may reflect various regulatory activities, such as enactment of the animal drug amendments of 1968 and NAS-NRC Drug Efficacy Studies of the 1970s.

Similarly, NADA withdrawals may reflect either disinterest in certain types of drugs by the veterinary community or disfavor because of safety or environmental concerns, or because of the availability of newer and better drugs. The majority of NADAs approved during the 1930-1960 decades have been voluntarily withdrawn by the drug sponsor, while to date no approvals from the 1990s have been withdrawn. FDA-identified safety or efficacy issues may sometimes result in an NADA being withdrawn, but this number is small. A number of NADAs in the STARS database are not associated with an approval date. These NADAs represent old approvals and all, except for one, have been withdrawn. Not surprisingly, the more recently a drug has been approved, the more likely it is to be marketed.

Of notable interest is the percentage (by decade) of currently approved new animal drugs that are being currently marketed (percentage of number of currently approved currently marketed). Categorized by the decade of approval, only 30 to 47% of the currently approved NADAs are being marketed. Conversely, this means that 53 to 70% of the currently approved NADAs are not being marketed. Several factors influence whether a drug remains actively on the market. The drug sponsor or manufacturer bases their decision to distribute any one product on economic and market considerations. At present only 38% (535) of current NADAs (those available for marketing [1415]) are marketed. Even for the 1990's, approximately only half of approved NADAs are being marketed. Ultimately, for the vast majority of NADAs, it is the drug industry, and not the FDA, who determines whether an approved NADA is marketed. In order to reduce the administrative burden on the FDA and industry for maintaining NADAs, the FDA/CVM encourages the animal drug industry to voluntarily withdraw NADAs that have been inactive for several years.

Presented in Table 2 is additional information concerning approved NADAs that are currently being marketed. Currently, the marketed products are distributed equally between food and non-food animal intended uses. Certain products are approved for use in both food and non-food animal species. Thus, the sum of the number of food and non-food animals does not equal the number of marketed NADAs.

Table 2. Species of intended use (food vs. non-food) of approved marketed animal drugs

¹The number of NADAs with food animal species indications divided by the number of NADAs currently marketed, expressed as a percentage.

²The number of NADAs with non-food animal species indications divided by the number of NADAs currently marketed, expressed as a percentage.

Presented in Table 3 is the number of NADAs currently marketed classified by their intended therapeutic uses by decade of approval. Certain approved drugs may have more than one type of indicated use, so that the sum of each therapeutic category within a decade does not total the number of currently marketed drugs. Industry product development interest has remained relatively constant over the decades with regard to several therapeutic categories. Systemic antimicrobials have usually been the most active category, followed by antiparasiticides. Analgesic, growth promotant, central nervous system, hormone and dermatologic drug categories have also remained active, although to a lesser extent.

Current and future company mergers, economic constraints and drug utilization profiles could create an animal pharmaceutical marketplace that is substantially different. Considering these factors and the current regulatory issues involving animal health and agriculture, the profile of the marketed animal drug inventory may change over time.

Table 3. Label indications of approved marketed animal drugs^1,2.

¹# -- The number of labeled indications for each therapeutic category.
²%Mktd is the number of labeled indications divided by the number of NADAs currently marketed.