TRIMETHOPRIM-SULFAMETHOXAZOLE (TMP-SMZ)
(tri-meth'o-prim-sul-fa-meth'ox-a-zole)
Bactrim, Co-Trimoxazole, Septra
Classifications:
antiinfective; urinary tract agent; sulfonamide / Systemic Infections
Adult: PO 160 mg TMP/800 mg SMZ (1 double strength [DS] tablet) q12hIV 8–10 mg/kg/d TMP divided q6–12h infused over 60–90 min
Child: PO >2 mo & <40 kg, 4 mg/kg/d TMP q12h; >40 kg, 160 mg TMP/800 mg SMZ (1 DS tablet) q12hIV >2 mo, 8–10 mg/kg/d TMP divided q6–12h infused over 60–90 min
Pneumocystis carinii Pneumonia
Adult: IV 20 mg/kg/d TMP divided q6h infused over 60–90 min
Prophylaxis for Pneumocystis carinii Pneumonia
Adult: PO 160 mg TMP/800 mg SMZ q24h
Child: PO 150 mg/m2 TMP/750 mg/m2 SMZ b.i.d. 3 consecutive d/wk (max: 320 mg TMP/d)
Renal Impairment
Clcr 10–30 mL/min: reduce dose by 50%; <10 mL/min: reduce dose by 75% / Fixed combination of sulfamethoxazole (SMZ), an intermediate acting antiinfective sulfonamide, and trimethoprim (TMP), a synthetic antiinfective. Both components of the combination are synthetic folate antagonist antiinfectives. Mechanism of action is principally enzyme inhibition, which prevents bacterial synthesis of essential nucleic acids and proteins. / Pneumocystis carinii pneumonitis, Shigellosis enteritis, and severe complicated UTIs due to most strains of the Enterobacteriaceae. Also children with acute otitis media due to susceptible strains of Haemophilus influenzae, and acute episodes of chronic bronchitis in adults. / Skin: Mild to moderate rashes (including fixed drug eruptions), toxic epidermal necrolysis. GI: Nausea, vomiting, diarrhea, anorexia, hepatitis, pseudomembranous enterocolitis, stomatitis, glossitis, abdominal pain. Urogenital: Kidney failure, oliguria, anuria, crystalluria. Hematologic: Agranulocytosis (rare), aplastic anemia (rare), megaloblastic anemia, hypoprothrombinemia, thrombocytopenia (rare). Body as a Whole: Weakness, arthralgia, myalgia, photosensitivity, allergic myocarditis. / Hypersensitivity to TMP, SMZ, sulfonamides, or bisulfites; group A beta-hemolytic streptococcal pharyngitis; megaloblastic anemia due to folate deficiency; creatinine clearance <15 mL/min; pregnancy (category C), lactation. Not recommended for infants <2 mo. /
NURSING IMPLICATIONS
Assessment & Drug Effects· Be aware that IV Septra contains sodium metabisulfite, which produces allergic-type reactions in susceptible patients: Hives, itching, wheezing, anaphylaxis. Susceptibility (low in general population) is seen most frequently in asthmatics or atopic nonasthmatic persons.
· Lab tests: Baseline and followup urinalysis; CBC with differential, platelet count, BUN and creatinine clearance with prolonged therapy.
· Monitor coagulation tests and prothrombin times in patient also receiving warfarin. Change in warfarin dosage may be indicated.
· Monitor I&O volume and pattern. Report significant changes to forestall renal calculi formation. Also report failure of treatment (i.e., continued UTI symptoms).
· Older adult patients are at risk for severe adverse reactions, especially if liver or kidney function is compromised or if certain other drugs are given. Most frequently observed: Thrombocytopenia (with concurrent thiazide diuretics); severe decrease in platelets (with or without purpura); bone marrow suppression; severe skin reactions.
· Be alert for overdose symptoms (no extensive experience has been reported): Nausea, vomiting, anorexia, headache, dizziness, mental depression, confusion, and bone marrow depression.