Introduction

Name

• Trimethoprim/Sulfonamide.

Class of drug

• Potentiated sulfonamide antibiotic.

Uses

Indications

• Many organisms are susceptible includingNocardia Nocardia spp ,Brucella Brucella canis , gram-negative bacilli, some gram-positive organisms (Streptococcispp Streptococcus spp ,Pneumocystis carinii Pneumocystis carinii ,Toxoplasma gondii Toxoplasma gondii and coccidial species Coccidioides immitis ).
• Pseudomonasspp Pseudomonas andLeptospiraspp are usually resistant.
• Trimethoprim/sulfonamide is useful in the management of urinary, respiratory tract and prostatic infections, but are ineffective in the presence of necrotic tissue.
• Trimethoprin alone may be used for urinary, prostatic Acute prostatitis , systemic salmonella and respiratory tract infections.
• Fewer adverse effects are seen with trimethoprin alone.

Administration

Pharmacokinetics

Precautions

Interactions

with other drugs

• The anticoagulant effect of warfarin Warfarin may be enhanced by trimethoprim/sulfonamide.

• May decrease the bioavailability of sulfonamides if administered concurrently.
• Although sulfonamides may displace other plasma protein-bound drugs such as methotrexate, oral hypoglycemics, phenylbutazone Phenylbutazone , phenytoin Phenytoin , probenecid , thiazide diuretics and salicylates Acetyl salicylic acid , the clinical relevance of such interactions is unclear. However, patients should be monitored for enhanced effects of displaced agents.
• Concomitant use of drugs containing procaine Procainamide may inhibit sulfonamide action.

with diagnostic tests

• When using the Jaffe alkaline picrate reaction assay for creatinine determination trimethoprim/sulfonamide may cause an over estimation of approximately 10%.

Adverse Reactions

Further Reading

Publications

Refereed papers

• Wilcke J R (1988)Therapeutic application of sulfadiazine/trimethoprim in dogs and cats - a reviewComp Cont Ed2, 3-8.

Other sources of information

• Based onSmall Animal Formulary.Tennant, Bryn (1999) 3rd edn. Cheltenham: BSAVA.