From the Guidelines
For complicated urinary tract infections (UTIs), Sulfatrim (trimethoprim-sulfamethoxazole) is typically dosed at 160mg/800mg (one double-strength tablet) taken orally every 12 hours for 7 days, as short-duration therapy has been shown to be as effective as long-duration therapy in achieving clinical success 1.
Key Considerations
- The treatment duration may be extended to 14 days for severe infections or based on clinical response.
- Patients with renal impairment require dose adjustment: for creatinine clearance 15-30 mL/min, reduce the dose by 50%; for clearance below 15 mL/min, Sulfatrim is not recommended.
- Ensure adequate hydration during treatment to prevent crystalluria.
- Sulfatrim works by inhibiting bacterial folate synthesis at two different points, making it effective against many common UTI pathogens.
- Due to increasing resistance rates, culture and sensitivity testing is important before initiating therapy for complicated UTIs.
- Common side effects include rash, gastrointestinal disturbances, and photosensitivity.
- Patients should complete the full course of antibiotics even if symptoms improve before completion to ensure bacterial eradication and prevent recurrence.
Evidence-Based Recommendation
The most recent and highest quality study, published in 2023, confirms that short-duration therapy (5-7 days) results in similar clinical success as long-duration therapy (10-14 days) for complicated UTIs, including those with bacteremia 1. This study supports the use of a 7-day treatment course with Sulfatrim for complicated UTIs, making it a suitable option for patients with susceptible uropathogens. However, if the susceptibility is not known, an initial intravenous dose of a long-acting parenteral antimicrobial may be recommended 1.
From the FDA Drug Label
Adults: The usual adult dosage in the treatment of urinary tract infections is 1 sulfamethoxazole and trimethoprim double strength tablet or 2 sulfamethoxazole and trimethoprim tablets every 12 hours for 10 to 14 days The recommended dosing for Sulfatrim in the treatment of complicated UTI is:
- 1 double strength tablet (or 2 single strength tablets) every 12 hours for 10 to 14 days 2
- For patients with impaired renal function, a reduced dosage should be employed:
- Creatinine clearance 15-30 mL/min: ½ the usual regimen
- Creatinine clearance below 15 mL/min: use not recommended 2
From the Research
Sulfatrim Dosing for Complicated UTI
- The provided studies do not directly address the dosing of Sulfatrim for complicated UTIs.
- However, some studies discuss the use of trimethoprim-sulfamethoxazole (TMP-SMZ) for urinary tract infections:
- A study from 1982 3 found that a single dose of two double-strength TMP-SMZ tablets (320 mg of TMP and 1,600 mg of SMZ) was effective in treating uncomplicated lower urinary tract infections in women.
- Another study from 1981 4 compared patient compliance and efficacy of trimethoprim and co-trimoxazole in treating acute lower urinary tract infections, with co-trimoxazole being prescribed as two tablets (160 mg trimethoprim, 800 mg sulphamethoxazole) twice a day for seven days.
- A more recent study from 2024 5 compared the effectiveness of fluoroquinolones, trimethoprim-sulfamethoxazole, and high-bioavailability β-lactams for oral step-down therapy in gram-negative bloodstream infections, including those from a urinary tract source, but did not provide specific dosing information for complicated UTIs.
- The study from 1977 6 discusses the use of sulfonamides, trimethoprim-sulfamethoxazole, nitrofurantoin, and nalidixic acid for treating urinary tract infections, but does not provide specific dosing recommendations for complicated UTIs.
- The study from 2017 7 discusses the pharmacokinetic characteristics of oral antimicrobial agents for treating uncomplicated UTIs, but does not provide specific dosing information for complicated UTIs.