Agriculture Business Week

The use of drugs in animals may seem a simple matter but improper use of drugs in animals can have significant influence on human health. Animals, like people, are treated with drugs when they are sick. In addition, food animals are dosed with preventive levels of antibiotic drugs even before they actually get sick, and when there is a great threat of getting sick. Because of the general tendency to look at animals as more dispensable than human beings, we tend to self-medicate animals more than we do human patients. One potential problem in veterinary medicine is extra-label drug use.

WHAT IS EXTRA-LABEL DRUG USE?
Many drugs are used in both pet and food animals in ways other than what they are indicated for. Extra-label drug use is defined simply as the use of an approved drug in a manner that is not in accordance with the approved label directions. The use of antibiotic drug preparation for humans in treating animal infections is an example of extra-label drug use, because nothing is specified in the label of such drug preparation about their use in animals. Another example of extra-label drug use is when a drug whose label direction says “for use only in cattle” but is used in pigs or other animal species.

Perhaps the most frequently violated label direction for animal drug use is the warning that says “Use only under the supervision of a licensed veterinarian.” In the Philippines, many veterinary drugs can be obtained without a veterinarian’s prescription and can be used by non-veterinarians. Many of these drugs are potentially dangerous to the animals that receive them as well as to the persons who administer these drugs.

Is extra-label drug use illegal? Before we can say that an action is legal or illegal, there should be an existing law (or rules and regulations) on which we can base our judgment whether or not such action is legal. The truth is there is no local law that directly addresses extra-label drug use in veterinary medicine in the Philippines. However, two administrative orders jointly approved by the Department of Agriculture (DA) and the Department of Health (DOH) are indirectly concerned with extra-label drug use in animals. The first one is DA Administrative Order No. 11 (also DOH A.O. 105) which stipulates the requirements for labeling materials of veterinary drugs and products; the other is DA Administrative Order No. 111B(also DOH A.O. 105) which laid out the rules and regulations on dispensing veterinary drugs and products.

DOES EXTRA-LABEL DRUG USE APPLY TO ALL DRUGS?
There are two general types of drugs according to how they can be dispensed: (1) Over-the-counter drugs and (2) Prescription drugs. Over-the-counter drugs are those that can be purchased and used without the owner and patients establishing relationship with a veterinarian. Drugs under this classification are those that can be used without endangering the health or life of the patients provided the drugs are used at the usual recommended doses and purposes. Most cough medicines for human use are over-the-counter drugs, but those containing addicting ingredients such as opiate can only be purchased with a doctor’s prescription. Antibiotics for treatment of internal infections should be classified as prescription drugs, and yet some antibiotics for animals are marketed as over-the-counter drugs.

Prescription drugs (usually indicated with the symbol Rx) are those that can be purchased and used only on the order of a veterinarian within the context of a valid veterinarian-client-patient-relationship (VCPR). It is with the prescription drugs and drug use in food animals that the rules of extra-label drug use most significantly apply.

VCPR is a written agreement between the owner of the animals and the veterinarian on matters pertaining to diagnosis and treatment of the animals with prescribed drugs. With a valid VCPR, the veterinarian assumes the responsibility of making medical judgments regarding the health of the animal patients. He has sufficient knowledge to initiate diagnosis of medical condition of the animals. And, the veterinarian is available for follow-up in case of adverse reactions or failure of treatment. A valid VCPR should, according to law, accompany a drug order, which is a prescription for purchase of drugs to be used for a number of farm animals. Prescriptions for pet animals such as dogs and cats, however, take the form similar to those issued by physicians for human patients, and do not require a VCPR, although a virtual VCPR exists when the owner brought the pet to the veterinarian for medical treatment. The VCPR and drug prescription imply that the responsibility of extra-label drug use rests heavily on the veterinarian; neither on the drug manufacturer nor the animal owner or producer.

WHAT ARE THE CONDITIONS FOR EXTRA-LABEL, DRUG USE?
Currently there are no veterinary drugs available for use in every medical situation. For instance, most medicines used for treatment of dogs and cats are actually also drugs used for humans, and local veterinarians use human drug preparations for medical conditions of pet animals. This practice is clearly extra-label use and yet they seem to be allowed. In fact, this practice is permissible on the basis of the following conditions: (1) There’s no animal drug approved for the intended use; (2) The approved drug for intended use is not in the required dosage form; and (3) The approved drug has been found ineffective when used as labeled.

Following what is being practiced in the United States, approved human drugs can be used in pets even if approved animal drugs are available. However, in food animals, use of approved human drugs should not be permitted, if approved animal drug can be used. It is also imperative that all extra-label drug use should be recorded for reference in case of adverse reactions.

Compounding of drugs is another problem that can have implications on extra-label drug use. Compounding refers to the manipulation of drugs to obtain products that differ from the starting materials in an approved dosage form. A good example of compounding is a “home-made” mixture of several drug ingredients to make a dermatological cream. Compounding is not necessarily improper as long as the resulting product is in accordance with an officially recognized drug formulary and approved by a government regulatory agency. Compounded drugs, however, should not be used if an approved drug can be used at its approved dose and dosage form.

WHAT SHALL WE Do?
Recently, I was invited by the Philippine Veterinary Drug Association (PVDA) to speak before its members about extra-label drug use in animal agriculture. For a long time I, as a veterinary pharmacologist, have been waiting for such an opportunity to reach out to them and discuss matters regarding proper use of drugs in animals, particularly food animals. Although we have existing laws (or administrative orders) on proper prescribing, reality shows that we don’t follow them to the letter. Ever since the administrative order was issued requiring VCPR and proper drug order (prescription) for farm animals, I have yet to see a strict implementation of that order. At the end of my talk before the PVDA, I suggested, as a take home message, that the government, the academe, the animal business sectors, the drug manufacturers and distributors, and the different veterinary specialty groups all work together in promoting scientific, rational and safe use of drugs in animals.