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Uniprim Powder, by Macleod Pharmaceuticals, is Trimethoprim 67 mg/gram and sulfadiazine 333 mg/gram. Palatable top-dressed broad-spectrum antibiotic for use in horses that is active against a wide spectrum of bacterial pathogens, both gram-negative and gram-positive, including Escherichia, Streptococcus, Proteus, Salmonella, Pasteurella, Shigella and Haemophilus. Indicated where potent systemic antibacterial action is required against abscesses, wound infections, urogenital infections, strangles and respiratory tract infections.

Item# Item Name Our Price Qty Add
602-010287 UniPrim 1 Dose 37.5gm Powder
602-031272 UniPrim 1200gm Powder
602-036016 UniPrim 2000gm
602-001038 UniPrim 200gm Powder
602-037328 UniPrim 200gm Powder, Apple Flavored
602-018859 UniPrim 30-Dose Bulk Back, 1125gm
602-030115 UniPrim 400gm Powder
602-037329 UniPrim 400gm Powder, Apple Flavored
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For Use in Horses

DESCRIPTION: UNIPRIM POWDER contains 67 mg trimethoprim and 333 mg sulfadiazine per gram.

UNIPRIM POWDER is a combination of trimethoprim and sulfadiazine in the ratio of 1 part to 5 parts by weight, which provides effective antibacterial activity against a wide range of bacterial infections in animals.

Trimethoprim is 2, 4 diamino-5-(3, 4, 5- trimethoxybenzyl) pyrimidine.


Microbiology: Trimethoprim blocks bacterial production of tetrahydrofolic acid from dihydrofolic acid by binding to and reversibly inhibiting the enzyme dihydrofolate reductase.

Sulfadiazine, in common with other sulfonamides, inhibits bacterial synthesis of dihydrofolic acid by competing with para-aminobenzoic acid.

Trimethoprim/sulfadiazine thus imposes a sequential double blockade of bacterial metabolism. This deprives bacteria of nucleic acids and proteins essential for survival and multiplication, and produces a high level of antibacterial activity which is usually bactericidal.

Although both sulfadiazine and trimethoprim are antifolate, neither affects the folate metabolism of animals. The reasons are: animals do not synthesize folic acid and cannot, therefore, be directly affected by sulfadiazine; and although animals must reduce their dietary folic acid to tetrahydrofolic acid, trimethoprim does not affect this reduction because its affinity for dihydrofolate reductase of mammals is significantly less than for the corresponding bacterial enzyme.

Trimethoprim/sulfadiazine is active against a wide spectrum of bacterial pathogens, both gram-negative and gram-positive. The following in vitro data are available, but their clinical significance is unknown. In general, species of the following genera are sensitive to trimethoprim/sulfadiazine:

Very Sensitive

Escherichia, Streptococcus, Proteus, Salmonella, Pasteurella, Shigella, Haemophilus.


Staphylococcus, Neisseria, Klebsiella, Fusiformis, Corynebacterium, Clostridium, Bordetella.

Moderately Sensitive

Moraxella, Nocardia, Brucella.

Not Sensitive

Mycobacterium, Leptospira, Pseudomonas, Erysipelothrix.

As a result of the sequential double blockade of the metabolism of susceptible organisms by trimethoprim and sulfadiazine, the minimum inhibitory concentration (MIC) of trimethoprim/sulfadiazine is markedly less than that of either of the components used separately. Many strains of bacteria that are not susceptible to one of the components are susceptible to trimethoprim/sulfadiazine. A synergistic effect between trimethoprim and sulfadiazine in combination has been shown experimentally both in vitro and in vivo (in dogs).

Trimethoprim/sulfadiazine is bactericidal against susceptible strains and is often effective against sulfonamide-resistant organisms. In vitro sulfadiazine is usually only bacteriostatic.

The precise in vitro MIC of the combination varies with the ratio of the drugs present, but action of trimethoprim/sulfadiazine occurs over a wide range of ratios with an increase in the concentration of one of its components compensating for a decrease in the other. It is unusual, however, to determine MIC’s using a constant ratio of one part trimethoprim in twenty parts of the combination.

The following table shows, MIC’s, using the above ratio, of bacteria which were susceptible to both trimethoprim (TMP) and sulfadiazine (SDZ). The organisms are those most commonly involved in conditions for which trimethoprim/sulfadiazine is indicated:



TMP Alone

SDZ Alone




Escherichia coli





Proteus species





Staphylococcus aureus





Pasteurella species





Salmonella species





β Streptococcus





The following table demonstrates the marked effect of the trimethoprim and sulfadiazine combination against sulfadiazine-resistant strains of normally susceptible organisms:



TMP Alone

SDZ Alone




Escherichia coli





Proteus species





Susceptibility Testing: In testing susceptibility to trimethoprim/sulfadiazine, it is essential that the medium used does not contain significant amounts of interfering substances which can bypass the metabolic blocking action, e.g., thymidine or thymine.

The standard SxT disc is appropriate for testing by the disc diffusion method.

Pharmacology: Following oral administration, trimethoprim/sulfadiazine is rapidly absorbed and widely distributed throughout the body tissues. Concentrations of trimethoprim are usually higher in tissues than in blood. The levels of trimethoprim are high in lung, kidney, and liver, as would be expected from its physical properties.

Serum trimethoprim concentrations in horses following oral administration indicate rapid absorption of the drug; peak concentrations occur in 1.5 hours. The mean serum elimination half-life is 2 to 2.5 hours. Sulfadiazine absorption is slower, requiring 2.5 to 6 hours to reach peak concentrations. The mean serum elimination half-life for sulfadiazine is about 4 to 5.5 hours.

Usually, the concentration of an antibacterial in the blood and the in vitro MIC of the infecting organism indicate an appropriate period between doses of a drug. This does not hold entirely for trimethoprim/sulfadiazine because trimethoprim, in contrast to sulfadiazine, localizes in tissues and therefore, its concentration and ratio to sulfadiazine are higher there than in blood.

The following table shows the average concentration of trimethoprim and sulfadiazine, as measured in either serum or plasma, in twenty-four adult horses observed after a single dose of UNIPRIM Powder:


Trimethoprim (5 mg/kg)

Sulfadiazine (25 mg/kg)

1 hr

3 hr

6 hr

10 hr

24 hr

1 hr

3 hr

6 hr

10 hr

24 hr











Excretion of trimethoprim/sulfadiazine is chiefly by the kidneys, by both glomerular filtration and tubular secretion. Urine concentrations of both trimethoprim and sulfadiazine are severalfold higher than blood concentrations. Neither trimethoprim nor sulfadiazine interferes with the excretion pattern of the other.

INDICATIONS AND USAGE: Trimethoprim/sulfadiazine is indicated in horses where potent systemic antibacterial action against sensitive organisms is required. Trimethoprim/sulfadiazine is indicated where control of bacterial infections is required during treatment of:

Acute Strangles, Respiratory Tract Infections, Acute Urogenital Infections, Wound Infections and Abscesses

Trimethoprim/sulfadiazine is well tolerated by foals.

CONTRAINDICATIONS: Trimethoprim/sulfadiazine should not be used in horses showing marked liver parenchymal damage, blood dyscrasias, or in those with a history of sulfonamide sensitivity.

WARNING: Do not use in horses intended for human consumption.

ADVERSE REACTIONS: No adverse reactions of consequence have been noted following administration of trimethoprim/sulfadiazine. During clinical trials, one case of anorexia and one case of loose feces following treatment with the drug were reported.

Individual animal hypersensitivity may result in local or generalized reactions, sometimes fatal. Anaphylactoid reactions, although rare, may also occur. Antidote: Epinephrine.

PRECAUTION: Water should be readily available to horses receiving sulfonamide therapy.

TOXICITY AND SIDE EFFECTS: Toxicity is low. The acute toxicity of trimethoprim/sulfadiazine is more than 5 g/kg orally in rats and mice. No significant changes were recorded in rats given doses of 600 mg/kg per day for 90 days.

Horses treated intravenously with trimethoprim/sulfadiazine 48% injection have tolerated up to five times the recommended daily dose for 21 consecutive days without clinical effects or histopathological changes.

Lengthening of clotting time was seen in some of the horses on high or prolonged dosing in one of two trials. The effect, which may have been related to a resolving infection, was not seen in a second similar trial.

Slight to moderate reductions in hematopoietic activity following high, prolonged dosage in several species have been recorded. This is usually reversible by folinic acid (leucovorin) administration or by stopping the drug. During long-term treatment of horses, periodic platelet counts and white and red blood cell counts are advisable.

TERATOLOGY: The effect of trimethoprim/sulfadiazine on pregnancy has not been determined. Studies to date show that there is no detrimental effect on stallion spermatogenesis with or following the recommended dose of trimethoprim/sulfadiazine.

DOSAGE AND ADMINISTRATION: The recommended dose is 3.75 g trimethoprim/sulfadiazine per 110 lbs (50 kg) body weight per day. Administer trimethoprim/sulfadiazine Powder orally once a day in a small amount of palatable feed.

The usual course of treatment is a single, daily dose for five to seven days.

Continue acute infection therapy for two or three days after clinical signs have subsided.

If no improvement of acute infections is seen in three to five days, re-evaluate diagnosis.

Trimethoprim/sulfadiazine may be used alone or in conjunction with intravenous dosing. Following treatment with trimethoprim/sulfadiazine 48% injection, therapy can be maintained using oral powder.

A complete blood count should be done periodically in patients receiving trimethoprim/sulfadiazine for prolonged periods. If significant reduction in the count of any formed blood element is noted, treatment with trimethoprim/sulfadiazine should be discontinued.

HOW SUPPLIED: UNIPRIM POWDER is available in 37.5 g packets, 1125 g packets, 200g jars, 400g jars, 1200 g jars, 2000 g pails and 12 kg boxes.

CAUTION: Federal (U.S.A.) law restricts this drug to use by or on the order of a licensed veterinarian.

ANADA # 200-033, approved by FDA

Macleod Pharmaceuticals, Inc., Fort Collins, CO 80525 U.S.A.

UP093759 Rev. 9/07

NAC No.: 14160003

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