Differential effects of amlodipine and ramipril on fluid compartments, sodium balance, and edema in hypertensive patients

Abstract

Background: Calcium channel blockers (CCBs) and angiotensin-converting enzyme (ACE) inhibitors differ in how they affect body fluid balance and kidney function. This study compares the effects of Amlodipine and Ramipril on body fluid compartments in hypertensive patients. Methods: Sixty-four patients with stage 1 hypertension were treated for 8 weeks with either Amlodipine 10 mg (n = 32) or Ramipril 5 mg (n = 32). Body water compartments were assessed using bioimpedance analysis. Blood pressure, kidney function, electrolytes, and spot urine sodium levels were also evaluated. Results: In the Amlodipine group, 23 of 32 patients (72%) showed an increase in total body water, mainly due to interstitial (extracellular) fluid accumulation. Six female patients developed ankle edema. In the Ramipril group, 27 of 32 patients (84%) also had increased total body water, but fluid shifts were more often intracellular or mixed, and no patients developed edema. Ramipril reduced kidney filtration (GFR) and increased potassium levels, while Amlodipine had the opposite effect. No clear link was found between urinary sodium changes and fluid volume shifts in either group. Conclusion: Amlodipine commonly causes extracellular fluid buildup and visible edema, while Ramipril leads to subtle fluid changes and renal effects. Bioimpedance monitoring may help guide individualized treatment.