Prescription items are NON-RETURNABLE and NON REFUNDABLE Primor Indications For Use 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 mirabilis susceptible to sulfadimethoxine/ormetoprim. Description Primor is an antimicrobial drug containing sulfadimethoxine and ormetoprim in a 5 to 1 ratio. The combination of these 2 compounds results in the potentiation of sulfadimethoxine, providing increased efficacy, a broadened spectrum of activity to include some sulfonamide-resistant organisms, and reduction in the rate of resistance development. Sulfadimethoxine is a white, almost tasteless and odorless powder. Chemically, it is N1-(2,6-dimethoxy-4pyrimidinyl)-sulfanila-mide. The structural formula is: Ormetoprim is a white, almost tasteless powder. Chemically, it is 2,4-diamino-5-(4,5- dimethoxy-2methylbenzyl)-pyrimidine. The structural formula is: Toxicity And Safety 1 Toxicity data for Primor indicates that the drug is safe when used at the recommended dosage. Following oral administration of Primor to dogs at 27.5 mg/kg/day (12.5 mg/lb/day) for 8 weeks, no changes were noted in hematology, blood chemistry, urinalysis, gross pathology, and histopathology, except for elevated serum cholesterol, increased thyroid and liver weights, enlarged basophilic cells in the pituitary, and mild follicular thyroid hyperplasia. These changes are known to be associated with prolonged administration of sulfonamides to dogs and have been shown to be reversible. Adverse Reactions Conditions reported following use of sulfonamides or potentiated sulfonamides include polyarthritis, urticaria, facial swelling, fever, hemolytic anemia, polydypsia, polyuria, hepatitis, vomiting, anorexia, diarrhea, and neurologic disorders. In rare instances, neurologic signs including behavioral changes, ataxia, seizures, aggression, and hyperexcitability have been reported. Keratitis sicca, possibly due to prolonged use of sulfonamides, has been reported. Individual animal hypersensitivity may result in local or generalized reactions. Anaphylactoid reactions, although rare, may also occur. Antidote Epinephrine for anaphylactoid reactions. 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. Contraindications Primor should not be used in dogs showing marked liver parenchymal damage, blood dyscrasias, or in those with a history of sulfonamide hypersensitivity. Primor 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. 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. How Supplied Primor is available as scored tablets for the following potencies: 120 mg, 240 mg, 600 mg, and 1200 mg. Storage Store at controlled room temperature 15°-30°C (59°-86°F) Primor Caution Not for human use. For use in dogs only. Warning Keep out of reach of children.
