Effect of indapamide on the baroreceptor reflex in essential hypertension.

The effect of chronic treatment with indapamide on blood pressure (BP), baroreceptor sensitivity (BRS) and vascular reactivity (VR) were investigated in 10 patients with essential hypertension. After 3 months of therapy with indapamide 2.5 mg/d the mean arterial pressure (MAP) had decreased from 135 +/- 6 to 112 +/- 2 mmHg (p less than 0.001); the heart rate (HR) had not changed, VR had decreased from 6.1 +/- 1.2 to 4.8 +/- 1.8 (pg . min . kg)-1 (p less than 0.05), and BRS had increased from 8.3 +/- 3.7 to 12.2 +/- 5.3 ms/mmHg (p less than 0.005), with a leftshift of the relationship between BP and heart period. An inverse correlation was found between the pre-treatment systolic blood pressure and the change in baroreceptor sensitivity after indapamide (r = 0.59; p less than 0.05). In conclusion, chronic treatment with indapamide enhances BRS and resets the reflex. The resetting may account for the lack of tachycardia at rest observed after treatment with indapamide. The mechanism by which indapamide interferes with the baroreceptor reflex requires further investigations.