From the Guidelines
Digoxin and Bactrim can interact with each other, and this interaction requires monitoring, as trimethoprim may increase serum digoxin levels in some elderly people. When considering the management of patients on digoxin and Bactrim, it's crucial to be aware of potential interactions that could affect morbidity, mortality, and quality of life. The key interaction to consider is the potential for trimethoprim, a component of Bactrim, to increase serum digoxin levels, as noted in the British Thoracic Society guidelines for the management of non-tuberculous mycobacterial pulmonary disease (NTM-PD) 1.
This interaction is significant because elevated digoxin levels can lead to digoxin toxicity, characterized by symptoms such as nausea, vomiting, visual disturbances, confusion, and cardiac arrhythmias. Given the potential for increased serum digoxin levels, particularly in elderly patients, monitoring of digoxin levels is advisable within 1-2 weeks after starting Bactrim. In some cases, a reduction in digoxin dosage may be necessary to prevent toxicity while on Bactrim therapy.
The decision to use both medications should be made with caution, especially in patients with risk factors for digoxin toxicity, such as elderly individuals and those with renal impairment. Healthcare providers should carefully weigh the benefits of concurrent therapy against the potential risks and implement appropriate monitoring strategies to mitigate adverse effects, as suggested by the guidelines 1.
Key considerations for managing patients on both digoxin and Bactrim include:
- Monitoring for signs of digoxin toxicity
- Regular checking of digoxin levels
- Potential adjustment of digoxin dosage
- Close observation in elderly patients and those with kidney problems
- Consultation with a pharmacist to discuss all potential drug interactions, as the information provided is not inclusive of all drug interactions 1.
From the FDA Drug Label
Digoxin Monitor serum digoxin levels Increased digoxin blood levels can occur with concomitant sulfamethoxazole and trimethoprim therapy, especially in elderly patients
- Yes, sulfamethoxazole and trimethoprim can interfere with digoxin, potentially increasing digoxin blood levels, especially in elderly patients.
- It is recommended to monitor serum digoxin levels when co-administering sulfamethoxazole and trimethoprim with digoxin 2, 2.
From the Research
Interaction between Digoxin and Bactrim
- There are no direct studies that investigate the interaction between digoxin and Bactrim in the provided evidence.
- However, it is known that digoxin has a narrow therapeutic index and its toxicity can be exacerbated by other medications or conditions that affect renal function 3, 4, 5, 6, 7.
- Bactrim, an antibiotic, can affect renal function, particularly in patients with pre-existing renal impairment.
- The studies provided focus on the effects of digoxin on renal function and its toxicity, but do not specifically address interactions with Bactrim.
- It is essential to consider the potential risks of drug interactions and monitor patients closely when administering digoxin with other medications, including Bactrim, especially in those with renal impairment 4, 5, 6.