Trimethoprim-Sulfamethoxazole/Bactrim/Septra



- Discussion:
    - for UTI, otitis media, acut exacerbation of chronic bronchitis, pneumocystis carini;
    - has an excellent spectrum of activity against beta lactamase-producing staph, and can be effective as an antistaphylococcal agent;
    - septra not effective vs. group A strep;
    - adult dose:
          - 1DS Tab PO bid (DS = 160mg trimethoprim / 800mg sulfamethoxazole) or TMP/SMX 5/20mg/kg/24hr for 1 month IV in 3-4 daily divided doses- or for UTI 7-10 days;
          - IV: 10 ml: 160 mg trimethoprim and 800 mg of sulfamethoxazole;
          - pneumocystis: 20mg/kg/day (trimethoprim component) in 4 DD by IV infusion for 14 days;
    - peds:
          - 1 tab/10 kg/day or 1 cc/kg/day q 12hr 5-10 days;
          - supplied: tab 80 mg TMP/400 mg SMX;  suspension 40 mg TMP/200 mmg SMX/5 ml
    - diffusion from blood into CSF adequate w/ or w/o Inflammation;
    - note: during sulfa therapy, an alkaline urine should help prevent the the formation of sulfoamide crystals.

- Cautions:
    - renal:
          - may cause dramatic increase in Creatinine (from competitive binding);
          - trimethoprim competitively inhibits renal tubular creatinine secretion and may cause an artificial increase in serum creatinine, particularly in patients with a pre-existing renal insufficiency;
                 - however, GFR is unchanged;
          - renal failure in patients with underlying renal insufficiency is probably secondary to intersitial nephritis or tubular necrosis and is generally  reversibile upon drug discontinuation;
          - it is clear that potential for sulfamethoxazole metabolity accumulation and toxicity exists in the renal dz population, although these effects have not been elucidated; 
    - thrombocytopenia
    - megaloblastic anemia from folate deficiency;
    - use w/ caution in impaired renal/hepatic function, G6Pd, may cause hemolysis, and in patients with severe allergy or bronchial asthma;
    - should not be mixed with aminophylline or Na bicarbonate



Absence of Cross-Reactivity between Sulfonamide Antibiotics and Sulfonamide Nonantibiotics

Bactericidal activity of orally available agents against methicillin-resistant Staphylococcus aureus.

Ambulatory treatment of multidrug-resistant Staphylococcus-infected orthopedic implants with high-dose oral co-trimoxazole (trimethoprim-sulfamethoxazole).



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Friday, November 30, 2012 11:07 am