What is the interaction between Trimethoprim/Sulfamethoxazole (Bactrim) and Pioglitazone (Actos)?

From the Guidelines

Bactrim (Trimethoprim/Sulfamethoxazole) and Actos (Pioglitazone) can be taken together as they don't have significant direct drug interactions mentioned in the provided evidence. When considering the interaction between these two medications, it's essential to look at the broader context of the patient's health, particularly if they have diabetes and are taking Pioglitazone for blood sugar control. The provided evidence [ 1 ] discusses various drug interactions related to hyperglycemia treatment but does not specifically mention an interaction between Trimethoprim/Sulfamethoxazole and Pioglitazone. However, it's crucial to monitor patients for any potential side effects when taking these medications together, such as skin rash, nausea, or kidney issues from Bactrim, and weight gain, fluid retention, or rarely, bladder cancer from Actos. Patients with diabetes should also be aware that certain medications, including some antibiotics, might occasionally affect blood glucose readings, making more frequent blood sugar monitoring advisable when starting a new antibiotic like Bactrim [ 1 ]. Both medications should be taken as prescribed, with Bactrim typically taken twice daily and Actos once daily, regardless of meals. It's always important to inform healthcare providers about all medications being taken to ensure safe combined use and to adjust treatment plans as necessary to prioritize morbidity, mortality, and quality of life outcomes.

From the FDA Drug Label

Like other sulfonamide-containing drugs, sulfamethoxazole and trimethoprim potentiates the effect of oral hypoglycemic that are metabolized by CYP2C8 (e.g., pioglitazone, repaglinide, and rosiglitazone) or CYP2C9 (e.g., glipizide and glyburide) or eliminated renally via OCT2 (e.g., metformin). Additional monitoring of blood glucose may be warranted.

The interaction between Trimethoprim/Sulfamethoxazole (Bactrim) and Pioglitazone (Actos) is that Trimethoprim/Sulfamethoxazole may potentiate the effect of Pioglitazone, which is an oral hypoglycemic metabolized by CYP2C8.

• Key points:
  • Potential increased effect of Pioglitazone
  • Additional monitoring of blood glucose is recommended when coadministering these drugs 2 2

From the Research

Interaction between Trimethoprim/Sulfamethoxazole and Pioglitazone

There are no research papers to assist in answering this question regarding the interaction between Trimethoprim/Sulfamethoxazole (Bactrim) and Pioglitazone (Actos). However, the provided studies discuss the effects of Trimethoprim/Sulfamethoxazole on potassium levels and its potential to cause hyperkalemia 3, 4, 5, 6.

Effects of Trimethoprim/Sulfamethoxazole on Potassium Levels

• Trimethoprim/Sulfamethoxazole can cause hyperkalemia, a potentially lethal adverse reaction 3, 4.
• Trimethoprim acts like the potassium-sparing diuretic amiloride and reduces renal potassium excretion 3, 4, 6.
• The risk of hyperkalemia is increased with higher dosages of Trimethoprim and underlying renal impairment 5, 6.

Interaction with Other Medications

• Trimethoprim/Sulfamethoxazole can interact with other medications, such as repaglinide, to cause symptomatic hypoglycemia 7.
• Trimethoprim can inhibit the CYP2C8 enzyme, increasing the plasma concentration of certain medications, such as repaglinide 7.

Clinical Implications

• Clinicians should be aware of the potential for hyperkalemia and hypoglycemia when prescribing Trimethoprim/Sulfamethoxazole, especially in patients with renal impairment or those taking other medications that can interact with Trimethoprim/Sulfamethoxazole 7, 5, 6.