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Co-trimoxazole

Review literature: (Simon and Stille, 1997).

Co-trimoxazole is an antibiotic with a fixed combination of trimethoprim (dihydrofolate reductase inhibitor) and sulfamethoxazole (sulfonamide).

Mechanism of Action of Co-trimoxazole

Co-trimoxazole is bactericidal due to the double inhibition of bacterial folic acid synthesis.

Antibiotic Spectrum of Co-trimoxazole:

Bacteria causing urinary tract infection such as E. coli, Enterococci, Mycoplasma, Klebsiella, Serratia, Enterobacter (KES group), but with increasing resistance rates.

Urologic Indications for Co-trimoxazole:

Treatment or prevention of urinary tract infection.

Pharmacokinetics of Co-trimoxazole

• Elimination half life 10–12 h.
• Renal elimination 60% (trimethoprim) to 90% (sulfamethoxazole)

Side Effects of Co-trimoxazole

Allergy:

Skin rash, rarely severe skin reactions (Stevens-Johnson and Lyell syndrome).

Kidney:

Exacerbation of renal failure (reversible).

Blood:

Bone marrow depression in case of long-term therapy, rarely agranulocytosis.

Drug Interactions with Co-trimoxazole

Co-trimoxazole enhances the effect of phenytoin and sulfonylureas. Increased toxicity of cyclosporine, barbiturates, p-aminosalicylic acid and methotrexate.

Contraindications of Co-trimoxazole

• Folic acid deficiency
• Severe liver disease
• Renal failure
• Pregnancy, newborns
• Glucose-6-phosphate dehydrogenase deficiency
• Acute hepatic porphyria
• Bone marrow insufficiency

Dosage of Co-trimoxazole

The ratio between trimethoprim and sulfamethoxazole is 1:5. The dosage for adults is 480 mg (80 mg trimethoprim and 400 mg sulfamethoxazole) 1-0-1 p.o. to 960 mg p.o. 1-0-1. The dosage for children is 24 mg/kg p.o. co-trimoxazole 1-0-1.

In uncomplicated acute cystitis of women, co-trimoxazole is given for 3 days. In any other urinary tract infection, the recommended treatment duration is at least 7 days.

References

Simon und Stille 1997 SIMON, C. ; STILLE, W.:

Antibiotika-Therapie in Klinik und Praxis.
9. Auflage.
Stuttgart New York : Schattauer, 1997

  Deutsche Version: Cotrimoxazol