MSD Tetracyycline Hydrochloride powder water soluble (2.5g/25kg)

IV. EFFECTIVENESS

NADA 065-123 was originally approved as safe for use as labeled on April 27, 1955. The drug was the subject of National Academy of Sciences/National Research Council (NAS/NRC) reports which were published in the FEDERAL REGISTER of July 8, 1970 (35 FR 10966). The Academy evaluated this drug as probably effective for oral treatment of animal diseases when such diseases are caused by pathogenic microorganisms sensitive to tetracycline hydrochloride, diseases such as:

1. Enteric and respiratory diseases in poultry
2. Gastrointestinal and respiratory diseases in swine;
3. Infected wounds, gastrointestinal and respiratory diseases in calves, sheep, and goats;
4. Digestive system and respiratory diseases, pyelonephritis, peritonitis, infected wounds, abscesses, ulcers, and secondary bacterial invaders in dogs and cats;
5. Coccidiosis in dogs; and
6. Hexamitiasis in turkeys.

The Academy concluded that:

1. Most of the dosage directions provide for a less than effective dose, and the recommended minimum oral dose for large animals is 10 milligrams per pound of body weight daily in divided doses and for small animals 25 milligrams per pound of body weight in divided doses;
2. Claims for the treatment of viral diseases must be limited to microorganisms belonging to the psittacosis-lymphogranuloma group;
3. Each disease claim should be properly qualified as "appropriate for use in (name of disease) caused by pathogens sensitive to (name of drug), "and if the disease cannot be so qualified the claim must be dropped;
4. Claims made "for prevention of" or "to prevent" should be replaced with "as an aid in the control of" or "to aid in the control of";
5. As applicable, the manufacturer's label should warn that treated animals must actually consume enough medicated water or medicated feed to provide a therapeutic dose under the conditions that prevail as a precaution, the label should state the desired oral dose per unit of animal weight per day for each species as a guide to effective use of the preparation in drinking water or feed.

The Food and Drug Administration concurs with the Academy's findings, interpreting the phrase "...cannot be so qualified..." in paragraph (3) to mean "...is not supported by adequate data..." (See Fed. Reg. vol. 35, NO. 131-Wed., July 8, 1970). FDA proceeded to review all available data relating to the effectiveness of products subject to NADA 065-123 to determine which label claims were supported by the requisite proof of effectiveness. That review resulted in a letter to the sponsor dated July 1, 1992, in which the agency stated that it had concluded that such data supported effectiveness only for the control and treatment of certain bacterial diseases susceptible to tetracycline hydrochloride in chickens and turkeys.

Thereafter, the sponsor complied with the evaluation of NAS/NRC and FDA's conclusions in the following manner:

1. The 25 mg per pound body weight and 400 mg/gal are appropriate for turkeys and 200-800 mg/gal is appropriate for chickens.
2. Claims for viral diseases have been deleted from the labeling completely.
3. Each disease claim on the label has been properly qualified with the appropriate genus and species of bacteria susceptible to tetracycline hydrochloride. Disease claims which were not so qualified have been deleted.
4. Claims made for prevention have been revised to read "Control of..." where appropriate.
5. The manufacturer's label carries the warning statement that treated animals must have the medicated water adjusted to compensate for variation in age and the weight of the animal, the nature and severity of disease signs, and environmental temperature and humidity, each of which affects water consumption.