Sulfamethoxasole + Trimethoprim
Antibiotic
View Brand Names (2)Dose and dosage
For susceptible infections:
a) For UTI: 30 mg/kg PO q24h for 7–14 days.
For UTI, soft tissue infections: 15 mg/kg PO q12h for 7–14 days.
b) 30 mg/kg q12h (if treating Nocardia, double dose)
c) For toxoplasmosis: 15 mg/kg PO q12h for 28 days
d) For bacterial UTI: 30 mg/kg q12h PO
a) 30 mg/kg PO twice daily
b) For coccidiosis: 30 mg/kg PO once daily for 14 days.
For susceptible infections:
a) For UTI, pyoderma, soft tissue infections: 30 mg/kg PO q24h (not soft tissue infections) or 15 mg/kg PO q12h for 14 days.
For chronic pyoderma, acanthamebiasis: 30 mg/kg PO q12h for 21– 42 days.
For systemic infections; bacteremia: 30–45 mg/kg PO q12h for 3–5 days.
b) For bacterial UTI: 30 mg/kg q12h PO
c) For protozoal diseases:
For toxoplasmosis: 15 mg/kg, PO q12h for 28 days.
For Neospora: 15 mg/kg, PO q12h for 4 weeks. Used concurrently with clindamycin (10 mg/kg q12h for 4 weeks) or pyrimethamine (1 mg/kg PO once daily for 4 weeks).
For Hepatazoon canis: 15 mg/kg, PO q12h for 2–4 weeks. Used concurrently with clindamycin (10 mg/kg PO q8h for 2–4 weeks) and pyrimethamine (0.25 mg/kg PO once daily for 2–4 weeks)
d) For coccidiosis: 30 mg/kg PO once daily for 10 days (Matz 1995)
e) For pneumocystosis (Pneumocystis carinii): 15 mg/kg PO q8h or 30 mg/kg PO q12h, both for 3 weeks. May be given with cimetidine and levamisole as potential immune stimulants.
f) For Hepatazoon americanum: TMP/sulfa (15 mg/kg PO q12h), pyrimethamine (0.25 mg/kg PO q24h), and clindamycin (10 mg/kg q8h).
g) For Hepatazoon americanum: TMP/sulfa (15 mg/kg PO q12h for 14
days), pyrimethamine (0.25 mg/kg PO q24h for 14 days), and clindamycin
(10 mg/kg q8h for 14 days). Once remission attained decoquinate
For neosporosis: pyrimethamine (1 mg/kg PO daily) with TMP/sulfa (15–30 mg/kg PO twice daily.
a) Sulfadiazine has a very short half-life (approx. 1 hour) in rabbits.
b) Chinchillas, Gerbils, Guinea Pigs, Hamsters, Mice, Rats: 15–30 mg/kg PO q12h; or 30 mg/kg IM q12h
c) Chinchillas: 30 mg/kg PO, SC or IM q12h
For susceptible infections:
a) 44 mg/kg once daily IM or IV using 48% suspension
b) 25 mg/kg, IV or IM q24h
c) Calves: 48 mg/kg IV or IM q24h
For susceptible infections:
a) For respiratory tract infections: 15–30 mg/kg PO q12h. Give 30 minutes prior to feeding hay (grain is OK)
b) Foals: 15 mg/kg IV q12h; 30 mg/kg PO q12h
c) 22 mg/kg IV q24h or 30 mg/kg, PO q24h
d) 30 mg/kg PO once daily or 21.3 mg/kg IV once daily
e) Foals: 15 mg/kg PO or IV twice daily
48 mg/kg, IM q24h
For susceptible infections:
a) Using TMP/SMX oral suspension (240 mg/5 mL): 2 mL/kg PO twice daily. Good for many gram-positive and negative enteric and respiratory infections, particularly in hand-fed babies. May cause emesis in Macaws.
b) For respiratory and enteric infections in psittacines using the 24% injectable suspension: 0.22 mL/kg IM once to twice daily. For coccidiosis in toucans and mynahs using TMP/SMX oral suspension (240 mg/5 mL): 2.2 mL/kg once daily for 5 days. May be added to feed. For respiratory and enteric infections in hand-fed baby psittacines using TMP/SMX oral suspension (240 mg/5 mL): 0.22 mL/30 grams twice daily to three times daily for 5–7 days.
c) Using oral suspension: 50–100 mg/kg (of combined product) PO q12h
d) Ratites: For Toxoplasma gondii: 30–50 mg/kg IM twice daily
Hypersensitivity to sulfas, thiazides, or sulfonylurea agents; severe renal or hepatic impairment; Doberman pinschers
Alone, sulfonamides are bacteriostatic agents and trimethoprim is bactericidal, but when used in combination, the potentiated sulfas are bactericidal. Potentiated sulfas sequentially inhibit enzymes in the folic acid pathway, inhibiting bacterial thymidine synthesis. The sulfonamide blocks the conversion of para-aminobenzoic acid (PABA) to dihydrofolic acid (DFA), and trimethoprim blocks the conversion of DFA to tetrahydrofolic acid by inhibiting dihydrofolate reductase. Infected tissue and cellular debris can inhibit the activity of trimethoprim/sulfa by secreting PABA and thymidine.
AMANTADINE: A human patient developed toxic delirium when receiving amantadine with TMP/sulfa
ANTACIDS: May decrease the bioavailability of sulfonamides if administered concurrently
CYCLOSPORINE: TMP/sulfa may increase the risk of nephrotoxicity
DIGOXIN: TMP/sulfa may increase digoxin levels
DIURETICS, THIAZIDE: May increase risk for thrombocytopenia
HYPOGLYCEMIC AGENTS, ORAL: TMP/sulfa may potentiate effects
METHOTREXATE: TMP/sulfa may displace from plasma proteins and
increase risk for toxic effects; it can also interfere with MTX assays
(competitive protein binding technique)
PHENYTOIN: TMP/sulfa may increase half-life
TRICYCLIC ANTIDEPRESSANTS: TMP/sulfa may decrease efficacy
WARFARIN: TMP/sulfa may prolong INR/PT
keratoconjunctivitis sicca (which may be irreversible), acute neutrophilic hepatitis with icterus, vomiting, anorexia, diarrhea, fever, hemolytic anemia, urticaria, polyarthritis, facial swelling, polydipsia, polyuria and cholestasis.
Manifestations of an acute overdosage can include clinical signs of GI distress (nausea, vomiting, diarrhea), CNS toxicity (depression, headache, and confusion), facial swelling, bone marrow depression and increases in serum aminotransferases. Oral overdoses can be treated by emptying the stomach, (following usual protocols), and initiating symptomatic and supportive therapy.
Acidification of the urine may increase the renal elimination of trimethoprim, but could also cause sulfonamide crystalluria, particularly with sulfadiazine containing products. Complete blood counts (and other laboratory parameters) should be monitored as necessary. Bone marrow suppression associated with chronic overdoses may be treated with folinic acid (leucovorin) if severe. Peritoneal dialysis is not effective in removing TMP or sulfas from the circulation.
Safety of trimethoprim/sulfa has not been clearly established in pregnant animals. Reports of teratogenicity (cleft palate) have been reported. Studies thus far in male animals have not demonstrated any decreases in reproductive performance