Primor Tabs 240mg Sulfadimethoxine / Ormetoprim 500 Tab By Zoetis

Ormetoprim is a white, almost tasteless powder. Chemically, it is 2,4-diamino-5-(4,5-dimethoxy-2-methylbenzyl)-pyrimidine. The structural formula is:

Blood Levels:¹ Therapeutically effective blood levels of both sulfadimethoxine and ormetoprim are obtained and maintained in dogs when using the recommended Primor dosing regimen of 25 mg/lb on day one and of 12.5 mg/lb on following days. Blood levels of sulfadimethoxine and ormetoprim were studied in 2 male and 2 female dogs. The initial drug dose was administered at zero hours. Blood samples were taken at 11 intervals, 6 of which are reported in Table 1. A second dose of Primor was administered immediately following the 24-hour blood samples and blood values were determined 2 hours later (26 hours from the initial dose).

Table 1. Blood levels (mcg/mL) obtained with administration of a 25 mg/lb dose of Primor followed with a 12.5 mg/lb dose at 24 hours

*Sample collected before administration of the second dose.

INDICATIONS AND USAGE: Primor is for the treatment of skin and soft tissue infections (wounds and abscesses) in dogs caused by strains of Staphylococcus aureus and Escherichia coli and urinary tract infections caused by Escherichia coli, Staphylococcus spp., and Proteus mirabilissusceptible to sulfadimethoxine/ormetoprim.

CONTRAINDICATIONS: Primor should not be used in dogs showing marked liver parenchymal damage, blood dyscrasias, or in those with a history of sulfonamide hypersensitivity.

WARNING: Not for human use. For use in dogs only. Keep out of reach of children.

PRECAUTIONS: Decreased water consumption and aciduria enhance the probability of the formation of sulfonamide crystals in the urine. Monitoring urine samples for crystal formation is recommended from animals with acid urine receiving the drug. As with any sulfonamide therapy, make certain dogs maintain adequate water intake. If dogs show no improvement within 2 or 3 days, reevaluate the diagnosis. Safety in breeding dogs has not been established.

DOSAGE AND ADMINISTRATION: Administer an initial oral dose of 25 mg/lb (55 mg/kg) of body weight on the first day of treatment. Administer subsequent daily doses at the rate of 12.5 mg/lb (27.5 mg/kg) of body weight. Continue treatment for at least 2 days after remission of clinical signs. Do not extend treatment for more than 21 consecutive days. Suggested dosage schedules follow:

For optimal therapeutic effect: (1) the drug must be given early in the course of the disease; (2) therapeutically effective levels must be maintained in the body throughout the treatment period; (3) treatment should continue for at least 2 days after remission of clinical signs; and (4) the causative bacterial agents must be sensitive to the drug.

STORAGE: Store at controlled room temperature 15°-30°C (59°-86°F)

HOW SUPPLIED: Primor is available as scored tablets for the following potencies: 120 mg, 240 mg, 600 mg, and 1200 mg.

PRIMOR 120: 100 mg sulfadimethoxine/20 mg ormetoprim

PRIMOR 240: 200 mg sulfadimethoxine/40 mg ormetoprim

PRIMOR 600: 500 mg sulfadimethoxine/100 mg ormetoprim

PRIMOR 1200: 1000 mg sulfadimethoxine/200 mg ormetoprim

REFERENCES:

1. Data on file, Pfizer Animal Health.

2. Bevill RF: Sulfonamides. Booth NM, MacDonald LE (eds), Veterinary Pharmacology and Therapeutics, 5th ed, The Iowa State University Press, Ames, Iowa, chapter 48, 1982.

3. Bridges JW, Kirby MR, Walker SR, et al: Species differences in the metabolism of sulfadimethoxine. Biochem J 109:851, 1968.

4. Baggot JD: Some aspects of drug persistence in domestic animals. Res Vet Sci 11(2):130, 1970.

*BBL^® and Sensi-Disc^® are registered trademarks owned by Becton, Dickinson and Company, Paramus, New Jersey.

NADA #100-929, Approved by FDA