Описание
Trimethoprim blocks renal tubular secretion of potassium, acting like a potassium-sparing diuretic; combined with losartan's reduction of aldosterone-mediated potassium excretion, the risk of hyperkalaemia is substantially increased.
Механизм
Trimethoprim inhibits the epithelial sodium channel (ENaC) in the distal nephron, reducing potassium secretion; losartan blocks angiotensin II AT1 receptors, lowering aldosterone-driven potassium excretion; additive potassium retention is the result.
Клиническое значение
Population-based studies associate trimethoprim use with elevated sudden death risk in patients on renin-angiotensin-aldosterone inhibitors, attributed to hyperkalaemia-induced arrhythmia.
Тактика ведения
Monitor serum potassium within 1 week of starting trimethoprim in patients on ARBs; reduce potassium supplementation; use an alternative antibiotic in high-risk patients.
Медицинский отказ от ответственности
This content is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making medication decisions.