Comparison of plasma levels of renin, vasopressin and atrial natriuretic peptide in hypertensive amlodipine induced pedal oedema, non-oedema and cilnidipine treated patients

Introduction: Amlodipine is a third generation dihydropyridine group of calcium channel blocker and having an excellent antihypertensive profile. Pedal Oedema (PE) is the major drawback of amlodipine therapy and the incidence of Amlodipine Induced Pedal Oedema (AIPE) has been found significantly high. Several neurohumoral factors influence the incidence of oedema. AIM: We aimed to compare the plasma levels of renin, vasopressin and atrial natriuretic peptide in hypertensive AIPE, non-oedema and cilnidipine treated patients. Materials and Methods: The present prospective, interventional study was conducted on 104 mild to moderate hypertensive patients (52 patients in each group), after due consideration of eligibility criteria. Plasma Renin (PR), Vasopressin (VAS), and the Atrial Natriuretic Peptide (ANP) was estimated by ELISA test and compared between the AIPE, Amlodipine Treated Non-Oedema (ATNE) in Phase I, and AIPE and Cilnidipine Treated (CT) Groups in Phase II. Results: The clinical and demographic parameters were matched. PR was significantly high in AIPE group than the ATNE, and it was significantly reduced after one month follow up with the substitution of cilnidipine. The median (IQR) value of PR was 4.87 (3.58, 6.63), 3.50 (1.44, 5.47) and 2.66 (1.02, 5.66) ng/ml in AIPE, ATNE, CT group respectively. VAS was significantly high in AIPE group than ATNE, and it significantly reduced after one month follow up with CT group. The median (IQR) value of vasopressin was 6.78 (2.55, 9.16), 2.58 (1.61, 5.73) and 2.50 (1.23, 5.00) ng/ml in AIPE, ATNE and CT groups respectively. There was no significant difference seen in plasma ANP levels between the groups. The p-value was <0.05 which is statistically significant. Conclusion: The AIPE may not be volume overload or fluid retention; it may be due to persistent raise in adrenergic activity followed chronic amlodipine therapy. Cilnidipine relatively suppresses the sympathetic activity, and completely resolves the AIPE by significantly reducing PR and VAS levels. ANP did not show a difference between groups. Cilnidipine is the suitable alternative antihypertensive drug for AIPE patients.