Trimethoprim / Sulfamethoxazole, commonly known by its brand name Bactrim or Septra, is a widely used antibiotic combination that has been a cornerstone in the treatment of various bacterial infections for decades. This medication combines two antibiotics: trimethoprim and sulfamethoxazole, which work synergistically to inhibit the growth of bacteria. Understanding the proper dosage of Trimethoprim / Sulfamethoxazole is crucial for ensuring the safe and effective treatment of infections while minimizing the risk of side effects and antibiotic resistance.
The dosage of Trimethoprim / Sulfamethoxazole can vary significantly depending on the type and severity of the infection being treated, as well as the patient's age, renal function, and overall health status. This guide aims to provide a comprehensive overview of Trimethoprim / Sulfamethoxazole dosage, including standard recommendations, special considerations for different patient populations, and important safety information.
Standard Dosage Recommendations
The standard dosage of Trimethoprim / Sulfamethoxazole for adults and children over 12 years of age varies depending on the condition being treated. For uncomplicated urinary tract infections (UTIs), the typical dosage is one double-strength (DS) tablet, which contains 160 mg of trimethoprim and 800 mg of sulfamethoxazole, every 12 hours for 10 to 14 days. For more severe infections or those caused by specific bacteria, the dosage may be increased or the treatment duration extended.
Dosage for Specific Infections
For certain infections, specific dosage recommendations may apply:
- Pneumocystis jirovecii pneumonia (PCP): The recommended dosage for PCP prophylaxis is one single-strength (SS) tablet (80 mg trimethoprim / 400 mg sulfamethoxazole) daily, while for treatment, the dosage is increased to 15 to 20 mg/kg trimethoprim and 75 to 100 mg/kg sulfamethoxazole per day, divided into four equal doses.
- Traveler's diarrhea: A common dosage for traveler's diarrhea is one DS tablet every 12 hours for 3 to 5 days.
- Shigellosis: For shigellosis, the recommended dosage is one DS tablet every 12 hours for 5 to 7 days.
| Infection Type | Dosage | Duration |
|---|---|---|
| Uncomplicated UTI | 1 DS tablet every 12 hours | 10 to 14 days |
| PCP Prophylaxis | 1 SS tablet daily | Variable |
| Traveler's Diarrhea | 1 DS tablet every 12 hours | 3 to 5 days |
Key Points
- Trimethoprim / Sulfamethoxazole dosage varies based on infection type, severity, and patient factors.
- Standard adult dosage for uncomplicated UTIs is one DS tablet every 12 hours for 10 to 14 days.
- Specific infections like PCP, traveler's diarrhea, and shigellosis have unique dosage recommendations.
- Renal function and patient age are critical factors in determining the appropriate dosage.
- Adherence to prescribed dosages and treatment durations is crucial for effective treatment and preventing antibiotic resistance.
Special Considerations
Certain patient populations require special consideration when it comes to Trimethoprim / Sulfamethoxazole dosing:
Renal Impairment
For patients with renal impairment, dosage adjustments are necessary to prevent accumulation of the medication and potential toxicity. The creatinine clearance (CrCl) is used to guide these adjustments.
Pediatric Dosage
In pediatric patients, the dosage of Trimethoprim / Sulfamethoxazole is based on the child's weight. The usual pediatric dosage is 6 to 12 mg/kg trimethoprim and 30 to 60 mg/kg sulfamethoxazole per day, divided into two doses.
Safety and Adverse Effects
While Trimethoprim / Sulfamethoxazole is generally well-tolerated, it can cause adverse effects. Common side effects include gastrointestinal disturbances, allergic reactions, and photosensitivity. More serious but rare side effects include Stevens-Johnson syndrome, toxic epidermal necrolysis, and hematologic abnormalities.
What is the standard dosage of Trimethoprim / Sulfamethoxazole for uncomplicated urinary tract infections?
+The standard dosage for adults and children over 12 years of age is one double-strength tablet (160 mg trimethoprim / 800 mg sulfamethoxazole) every 12 hours for 10 to 14 days.
How does renal impairment affect Trimethoprim / Sulfamethoxazole dosing?
+For patients with renal impairment, dosage adjustments are necessary based on creatinine clearance to prevent drug accumulation and potential toxicity.
What are some common side effects of Trimethoprim / Sulfamethoxazole?
+Common side effects include gastrointestinal disturbances, allergic reactions, and photosensitivity.