Background
- Sulfonamide antibiotic
Brand Names
- Septra
- Bactrim (US)
- TMP-SMX
Dosing
- Traditionally based on the trimethroprim component
| Form | TMP | SMX | Conversion |
|---|---|---|---|
| Intravenous | 16 mg/ml | 80 mg/ml | 10 mL |
| Oral suspension | 8 mg/ml | 40 mg/ml | 20 mL |
| Oral SS tab | 80 mg | 400 mg | 2 tabs |
| Oral DS tab | 160 mg | 800 mg | 1 tab |
- Resistant Gram-negative infections
- Cystitis: 160 mg (1 SS tab) IV/PO q12h
- Other infections: 8 to 12 mg/kg/day IV/PO divided q8-12h (max 960 mg total daily dose)
- Nocardia: 10 mg/kg TDD
- Pneumocystis jirovecii: 15-20 mg/kg TDD
- CNS infections: 15-20 mg/kg TDD
Oral Dosing
- Ranges from 1 SS tab BID (160 mg TMP TDD) to 3 DS tabs TID (1440 mg TMP TDD)
Intravenous Dosing
- 10 to 20 mg/kg TMP total daily dose, split TID to QID
TMP 10 mg/kg per day
| Weight (kg) | Total dose TMP (mg/day) | Dose (IV) | Dose (PO) |
|---|---|---|---|
| 40-49 | 480 | 10 mL q8h | 1 DS tab q8h |
| 50-64 | 640 | 10 mL q6h | 1 DS tab q6h, or 2 DS tabs q12h |
| 65-74 | 720 | 15 mL q8h | 3 SS tabs q8h |
| 75-99 | 960 | 15 mL q6h | 2 DS tabs q8h, or 3 SS tabs q6h |
| 100-129 | 1280 | 20 mL q6h | 2 DS tabs q6h |
TMP 15 mg/kg per day
| Weight (kg) | Total dose TMP (mg/day) | Dose (IV) | Dose (PO) |
|---|---|---|---|
| 40-44 | 640 | 10 mL q6h | 1 DS tab q6h, or 2 DS tabs q12h |
| 45-49 | 720 | 15 mL q8h | 3 SS tabs q8h |
| 50-69 | 960 | 15 mL q6h | 2 DS tabs q8h, or 3 SS tabs q6h |
| 70-79 | 1200 | 25 mL q8h | 5 SS tabs q8h |
| 80-89 | 1280 | 20 mL q6h | 2 DS tabs q6h |
| 90-99 | 1440 | 30 mL q8h | 3 DS tabs q8h |
| 100-109 | 1600 | 25 mL q6h | 2/2/3/3 DS tabs q6h, or 5 SS tabs q6h |
| 110-119 | 1680 | 35 mL q8h | 7 SS tabs q8h |
| 120-129 | 1920 | 30 mL q6h | 3 DS tabs q6h |
TMP 20 mg/kg per day
| Weight (kg) | Total dose TMP (mg/day) | Dose (IV) | Dose (PO) |
|---|---|---|---|
| 40-54 | 960 | 15 mL q6h | 2 DS tabs q8h, or 3 SS tabs q6h |
| 55-69 | 1280 | 20 mL q6h | 2 DS tabs q6h |
| 70-79 | 1440 | 30 mL q8h | 3 DS tabs q8h |
| 80-89 | 1600 | 25 mL q6h | 2/2/3/3 DS tabs q6h, or 5 SS tabs q6h |
| 90-104 | 1920 | 30 mL q6h | 3 DS tabs q6h |
| 105-119 | 2240 | 35 mL q6h | 3/3/4/4 DS tabs q6h, or 7 SS tabs q6h |
| 120-134 | 2560 | 40 mL q6h | 4 DS tabs q6h |
Renal Dosing
| CrCl (mL/min) | Bacterial infection (TMP) | PJP (TMP) |
|---|---|---|
| > 30 | 8-12 mg/kg/day in 2-4 divided doses | 15-20 mg/kg/day in 2-4 divided doses |
| 10 to 29 | 75% of usual dose | 12-15 mg/kg/day in 2-4 divided doses |
| < 10, including PD | Generally not recommended; use 50% of usual dose | Generally not recommended; use 7.5-10 mg/kg/day in 2-4 divided doses |
| Hemodialysis | 50% of usual dose, scheduled post-dialysis | 50% of usual dose, scheduled post-dialysis |
| CRRT | 7.5 mg/kg/day in 2-4 divided doses | 15 mg/kg/day in 2-4 divided doses |
Adverse Drug Reactions
- Systemic allergic reactions
- Cutaneous reactions
- High rate of SJS/TEN
- Other non-specific rash
- Erythema multiforme
- Urticaria
- Photodermatitis
- GI upset, including nausea at higher doses
- Drug-drug interactions
- Increases warfarin levels
- Anemia, neutropenia and thrombocytopenia
- It is a mild folate antagonist
- Hepatotoxicity
- Hyperkalemia
- Hyponatremia
- Hypoglycemia
- Acute kidney injury, though it also increases tubular creatinine reabsorption
- Renal tubular acidosis
Further Reading
- Considerations when prescribing trimethoprim-sulfamethoxazole. CMAJ. 2011;183(16):1851-1858. doi: 10.1503/cmaj.111152
- Review of adverse events
