Effect of benazepril addition to amlodipine on ankle oedema and subcutaneous tissue pressure in hypertensive patients

The aim of this study was to evaluate the effect of benazepril addition to amlodipine anti hypertensive treatment on ankle-foot volume (AFV) and pretibial subcutaneous tissue pressure (PSTP), two objective measures of ankle oedema. A total of 32 mild to moderate essential hypertensives (DBP>90 and <110 mmHg), aged 30-70 years were studied. After a 4-week placebo period, they were randomized to amlodipine 5 mg o.d. or benazepril 10 mg o.d. or amlodipine 5 mg plus benazepril 10 mg o.d. for 4 weeks, according to a crossover design. At the end of the placebo period and of each active treatment period, blood pressure,AFV and PSTP were evaluated. AFV was measured using the principle of water displacement. PSTP was assessed using a system, the subcutaneous pretibial interstitial environment with a water manometer. Both amlodipine and benazepril monotherapy significantly reduced SBP (-18.2 +/- 4 and -17.8 +/- 4mmHg, respectively, P<0.01 vs baseline) and DBP (-12.1+/-3 and -11.7+/-3 mmHg, respectively, P<0.01); the reduction was increased by the combination (-24.2 +/- 5 mmHg for SBP, P<0.001 and -16.8+/-4mmHg for DBP, P<0.001). Amlodipine monotherapy significantly increased both AFV (+17.1%, P<0.001 vs baseline) and PSTP (+56.6%, P<0.001 vs baseline). As compared to amlodipine alone, the combination produced a less pronounced increase in AFV (+5.5%, P<0.05 vs baseline and P<0.01 vs amlodipine) and PSTP (+20.5%, P<0.05 vs baseline and P<0.01 vs amlodipine). Ankle oedema was clinically evident in 11 patients with amlodipine monotherapy and in three patients with the combination. These results suggest that ACE-inhibitors partially counteract the microcirculatory changes responsible for Ca-antagonists-induced oedema formation.