Classifying RX and OTC Animal Drugs

FDA is responsible for determining the marketing status (prescription, over-the-counter, or VFD[3]) of animal drug products based on whether or not it is possible to prepare "adequate directions for use" under which a layperson can use the drugs safely and effectively. Prescription (Rx) products can be dispensed only by or upon the lawful written order of a licensed veterinarian. Safe use includes safety to the animal, safety of food products derived from the animal, safety to the persons associated with the animal, and safety in terms of the drug's impact on the environment.

Effective use of a drug product assumes that an accurate diagnosis can be made with a reasonable degree of certainty, that the drug can be properly administered, and that the course of the disease can be followed so that the success or lack of success of the product can be observed.

The same drug substances can be marketed in a number of different dosage forms, intended for use by different routes of administration, and in different species of animals. Thus, these drug products may be appropriately labeled Rx in some cases and OTC in others. Rx products must bear the legend:

"Caution: Federal law restricts this drug to use by or on the order of a licensed veterinarian."