TRIMETHOPRIM SULFA
(For veterinary information only)
IMPORTANT NOTE: Tell your veterinarian if your pet has currently, or has ever had, liver disease, kidney disease, or blood disorders, before starting treatment with trimethoprim sulfa.
As with all medications, it is extremely important that this medication be used ONLY for the pet for which it is prescribed.
BRAND NAME: SEPTRA DS®
HOW THIS MEDICATION IS USED
Septra DS® is a combination of trimethoprim and sulfamethazole. Trimethoprim sulfa is a broad spectrum antibiotic used in the treatment of susceptible gram positive and gram negative bacterial infections and coccidial infections. Trimethoprim sulfa is not generally effective against Pseudomonas auruginosa. Trimethoprim sulfa can enter not only abscessed tissue but can penetrate the prostate gland, the blood brain barrier, and eye and treat infections in these locations. Another advantage of trimethoprim sulfa is that it has minimal effect on the normal flora of the gastrointestinal tract, which means less potential for antibiotic induced diarrhea.
SIDE EFFECTS
Although side effects of trimethoprim sulfa are rare, they do have potential for seriousness so it is important to become familiar with what to look for. The following syndromes represent idiosynchratic reactions which mean their occurrence has nothing to do with the amount of drug given but instead represent an unpredictable individual’s sensitivity to any dose of trimethoprim sulfa:
Joint inflammation: A broad inflammatory syndrome which includes arthritis, fever, muscle soreness, and even kidney inflammation, and inflammation in the eye. This syndrome has been formally studied and has been found to occur almost exclusively after a previous uneventful exposure to trimethoprim sulfa and occurs 8-20 days after therapy has started. The Doberman pinscher seems to be over-represented and complete recovery can be expected within one week of discontinuing the medication.
Skin rashes: They may begin around the start of treatment and vanish with cessation of administration of the drug.
Inability to produce adequate tears: Sulfa drugs of any kind are capable of disrupting tear function. Classically, this occurs after long term therapy (ie weeks to months) of use but occasionally certain individuals suffer from dry eyes after only one dose of sulfa. In most cases, tear function resumes normally after the drug is discontinued.
Hepatitis: Liver failure can result when a sensitive individual receives this medication. Nausea, jaundice, and all the other complications that occur with liver failure of any origin may result. Discontinuing the medication should lead to recovery.
Blood dyscrasias: Blood dyscrasias are abnormal blood cells or proportions of different blood cells. Blood dyscrasias might lead to immune dysfunction, bleeding tendency, or other problems depending on which blood cells are affected. With trimethoprim sulfa, loss of red blood cells, platelets, and white blood cells have been reported.
Sulfa bladder stones: Bladder stones made of the sulfa antibiotic can form. This has been reported in patients taking prescribed doses of sulfas for routine (as opposed to extended) periods of time.
INTERACTIONS WITH OTHER DRUGS
Trimethoprim sulfa will interfere with thyroid function testing. It is not known precisely how long trimethoprim sulfa should be discontinued in order to get a valid thyroid reading.
The following drugs may be enhanced by trimethoprim sulfa use: phenylbutazone (an NSAID), thiazide diuretics, aspirin, anticoagulants (blood thinners), phenytoin and methotrexate (a cancer medication).
Trimethoprim sulfa should not be used with cyclosporine (used for allergies, perianal fistulas, and immune suppression). This combination increases toxicity of the cyclosporine and reduces its beneficial effects.
CONCERNS AND CAUTIONS
If treatment lasts over 14 days, monitoring of the blood and tear production is advised.
Trimethoprim sulfa is not to be used in patients hypersensitive (allergic) to it. Large dog breeds may be more likely to be allergic to it than smaller dog breeds.
Trimethoprim sulfa is not to be used in pets with liver disease, kidney disease, or blood disorders, or those that are pregnant or nursing. Birth defects have been reported after this medication was given to pregnant rats.
Trimethoprim sulfa may cause hypothyroidism with long term (6 weeks) use in dogs.
Shake the suspension well before each use. It does not need to be refrigerated.
Water should be available at all times and the animal should be encouraged to drink. Your pet must not become dehydrated during treatment or sulfa crystals may form in the urine.
Keep all medicines out of the reach of children.
If you have any questions, please feel free to call us at 672-7800.