From the Guidelines
The prophylactic dose of Bactrim (trimethoprim-sulfamethoxazole) while on steroids is typically 480 mg/day (single-strength) or 960 mg three times a week, with reduced doses (eg, half-strength, daily) also being effective and associated with fewer adverse events.
Key Considerations
- The decision to start prophylaxis should be based on the risk-benefit ratio, taking into account the dose and duration of glucocorticoid treatment, as well as the presence of other immunosuppressants and risk factors for Pneumocystis jirovecii pneumonia (PCP) 1.
- Patients on daily doses of glucocorticoids >15–30 mg of prednisolone or equivalent for >2–4 weeks may benefit from prophylaxis 1.
- Alternative prophylactic medications include atovaquone, dapsone, or nebulised pentamidine, which may be used in patients with sulfa allergies or intolerance 1.
Prophylaxis Regimen
- The most commonly used prophylaxis scheme is trimethoprim/sulfamethoxazole (TMP-SMX) 480 mg/day (single-strength) or 960 mg three times a week 1.
- Reduced doses (eg, half-strength, daily) may also be effective and associated with fewer adverse events 1.
Monitoring and Precautions
- Patients on TMP-SMX prophylaxis should be monitored for adverse events, such as nausea, headache, and rash, which affect about 20% of patients 1.
- Kidney function should be monitored during treatment, and adequate hydration is important to prevent crystalluria 1.
From the FDA Drug Label
The recommended dosage for prophylaxis in adults is 4 teaspoonfuls (20 mL) of sulfamethoxazole and trimethoprim oral suspension daily. The prophylactic dose of Bactrim (trimethoprim/sulfamethoxazole) for adults, including those on steroids, is 4 teaspoonfuls (20 mL) daily 2.
- This dose is for prophylaxis and may not be applicable for treatment of active infections.
- The dose for children is different and is based on body surface area.
- Patients with impaired renal function may require a reduced dosage.
From the Research
Prophylactic Dose of Bactrim while on Steroids
- The standard agent for primary Pneumocystis jirovecii pneumonia (PCP) prophylaxis is trimethoprim/sulfamethoxazole (TMP-SMX) 3.
- However, there is no specific mention of the prophylactic dose of Bactrim (TMP-SMX) while on steroids in the provided studies.
- A study on patients undergoing hemodialysis found that low-dose TMP-SMX was an appropriate regimen to maintain a balance between PCP prophylaxis and prevention of adverse events due to TMP-SMX administration 4.
- Another study found that TMP-SMX is the most effective agent for PCP prophylaxis and the only agent to confer a mortality benefit, but it is also the most toxic agent with a greater risk of discontinuation due to adverse events 5.
- The dosage of TMP-SMX should be adjusted when the creatinine clearance decreases to less than 30 ml/min 6.
Considerations for PCP Prophylaxis
- PCP prophylaxis is recommended for patients receiving prolonged systemic steroids and other immunosuppressive agents 7.
- The choice of PCP prophylaxis regimen should be based on the individual patient's risk factors and medical history.
- TMP-SMX is considered the first-line agent for PCP prophylaxis, but alternative regimens such as aerosolized pentamidine and atovaquone may be considered in patients who are intolerant to TMP-SMX 3, 5.