Title: Trimethoprim Sulfa – Rat Guide
Headings: 
Trimethoprim Sulfa
(trimethoprim sulfadiazine, trimethoprim sulfamethoxazole
synonymous with: Cotrimoxazole, SMX-TMP, TMP-SMX, TMP-SDZ, SDZ-TMP, Co-trimazine)
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Content: tablets, or injectable may be used to make a suspension. Pharmacology
Trimethoprim / sulfa is a combination antimicrobial drug, which by two consecutive steps blocks protein synthesis in susceptible bacteria. When used alone the sulfonamides are bacteriostatic, and the trimethoprim is bactericidal, but when used in combination form the potentiated sulfas are bactericidal. This combination drug has broad-spectrum activity. It is effective against Gram-positive bacteria such as streptococci and some strains of staphylococcus. Gram-negative organisms such as CAR bacillus and those of the Enterobacteriaceae are also susceptible to this drug. The combination of trimethoprim / sulfa also appears to inhibit some protozoa (e.g., Pneumocystis carinii). However, the drug does not appear to be very effective against either mycoplasma, or Pseudomonas aeruginosa. Trimethoprim / sulfa is able to penetrate into exudate and abscessed tissue, as well as, penetrate the blood-brain-eye-placenta barrier. It is well absorbed orally with minimal effect on flora of the GI tract.