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Low-Dose Amiloride Reduces Arterial Stiffness and Blood Pressure in Adults With Metabolic Syndrome
In a 24-week randomized controlled trial, low-dose amiloride (5 mg daily) significantly reduced arterial stiffness as measured by carotid-femoral pulse wave velocity (cfPWV) and lowered systolic blood pressure by a mean of 5.6 mmHg at 24 weeks in adults with overweight or obesity and features of metabolic syndrome. These findings translate a previously preclinical mechanism — epithelial sodium channel (ENAC) activation driving vascular stiffening — into a clinically observed effect in a human population, with no severe adverse events reported.
What Was Studied
This trial investigated whether pharmacological inhibition of the epithelial sodium channel (ENAC) using amiloride could reduce arterial stiffness and blood pressure in adults with obesity and insulin resistance. The primary outcomes were carotid-femoral pulse wave velocity (cfPWV), a validated measure of large-artery stiffness, and blood pressure, assessed at baseline, 12 weeks, and 24 weeks, with secondary attention to broader vascular function including brachial artery flow-mediated dilation.
How It Was Studied
This was a phase II, 24-week, randomized, double-blind, placebo-controlled trial conducted at a single center. A total of 137 adults aged 30 to 70 years with overweight or obesity and at least one feature of metabolic syndrome were enrolled. Participants were allocated in a 2:1 ratio to receive either amiloride 5 mg daily or placebo, meaning approximately 91 participants received the active drug and approximately 46 received placebo. Vascular assessments were performed at three time points: baseline, 12 weeks, and 24 weeks.
What Was Observed
- Arterial stiffness was significantly reduced with amiloride. cfPWV decreased at both 12 and 24 weeks in the amiloride group, while no meaningful change was observed in the placebo group. The abstract does not provide the absolute magnitude of cfPWV reduction in numerical terms, which limits precise quantification of this vascular benefit.
- Systolic blood pressure fell by a clinically relevant margin. The amiloride group experienced a mean reduction of 5.6 mmHg in systolic blood pressure at 24 weeks, a difference regarded as meaningful in the context of cardiovascular risk reduction in metabolic syndrome populations.
- Older participants derived greater benefit. Older age within the study cohort was associated with larger reductions in both cfPWV and systolic blood pressure, suggesting a possible age-dependent enhancement of the treatment response to ENAC inhibition.
- Amiloride produced favorable metabolic and electrolyte changes without serious safety signals. Serum potassium increased and fasting glucose decreased in the amiloride group. Brachial artery flow-mediated dilation — a measure of endothelial function — was not significantly affected. No severe adverse events were reported across the trial duration.
Why This Matters
Obesity and insulin resistance are recognized in this study as conditions that promote both arterial stiffening and hypertension, compounding cardiovascular risk. Prior to this trial, evidence supporting ENAC’s role in vascular stiffening came predominantly from preclinical models; this study now demonstrates that ENAC inhibition with amiloride produces measurable reductions in both arterial stiffness and blood pressure in affected human adults. The data position ENAC as a tractable pharmacological target for addressing vascular dysfunction specifically in individuals with metabolic syndrome features.
How to Read This Result
This well-designed phase II RCT provides meaningful positive evidence for amiloride’s vascular effects in this population, though the absence of quantified cfPWV effect sizes in the abstract and the single-center design warrant careful interpretation before these findings are broadly generalized.
Limitations
The abstract does not explicitly report study limitations.