- 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