From the Guidelines
Losartan and amlodipine are not commonly associated with hyponatremia, and the risk is not explicitly stated in the provided guideline evidence. According to the 2018 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1, the primary concern with antihypertensive medications is their potential to cause hyperkalemia, hypokalemia, or other electrolyte imbalances, but hyponatremia is not specifically mentioned as a common side effect of losartan or amlodipine.
Key Points to Consider
- The guideline provides a comprehensive list of oral antihypertensive drugs, including their usual doses, daily frequencies, and potential comments or warnings 1.
- Losartan, an angiotensin II receptor blocker (ARB), is listed with a usual dose of 50–100 mg/d and a daily frequency of 1 or 2, but there is no mention of hyponatremia as a potential side effect 1.
- Amlodipine, a calcium channel blocker, is listed with a usual dose of 2.5–10 mg/d and a daily frequency of 1, but again, there is no mention of hyponatremia as a potential side effect 1.
- The guideline does emphasize the importance of monitoring for electrolyte imbalances, such as hyponatremia and hypokalemia, when using thiazide or thiazide-type diuretics, but this is not directly related to losartan or amlodipine 1.
Clinical Implications
- Patients taking losartan or amlodipine should be aware of the potential risks and benefits associated with these medications, but hyponatremia is not a commonly reported side effect.
- Regular monitoring of electrolyte levels is still recommended, especially when starting these medications or adjusting dosages, but the primary focus should be on other potential side effects, such as hyperkalemia or hypokalemia.
- Clinicians should be cautious when prescribing losartan or amlodipine, especially in patients with underlying kidney disease, heart failure, or liver disease, as these conditions may increase the risk of electrolyte imbalances 1.
From the Research
Losartan and Hyponatremia
- There is evidence to suggest that losartan can cause hyponatremia, as reported in a case study where a 73-year-old patient developed severe hyponatremia after taking losartan for 3.5 months 2.
- The patient's serum sodium level was found to be 123 meq/L, and the Naranjo adverse drug reaction probability scale suggested that it was "probable" that oral losartan was responsible for the development of severe hyponatremia.
Amlodipine and Hyponatremia
- There is no direct evidence in the provided studies to suggest that amlodipine can cause hyponatremia.
- However, a study comparing the effects of losartan and amlodipine on blood pressure in patients with isolated systolic hypertension did not report any cases of hyponatremia in the amlodipine group 3.
Comparison of Losartan and Amlodipine
- A study comparing the effects of losartan and amlodipine on blood pressure in patients with isolated systolic hypertension found that both drugs were effective in reducing blood pressure, but losartan was better tolerated with fewer adverse events 3.
- Another study found that the combination of amlodipine and losartan caused additive hemodynamic changes compared to monotherapy with either drug, but did not report any cases of hyponatremia 4.
Other Relevant Information
- A case report of significant hyperkalemia and hyponatremia secondary to telmisartan/hydrochlorothiazide treatment suggests that angiotensin II receptor blockers (ARBs) like losartan can cause electrolyte imbalances, including hyponatremia 5.
- A study comparing the effects of losartan and amlodipine on the activation of the sympathetic nervous system, renin-angiotensin-aldosterone system, and brain natriuretic peptide in elderly hypertensive patients found that losartan reduced norepinephrine and aldosterone concentration, but did not report any cases of hyponatremia 6.