Amlodipine: Can act as an antioxidant in patients with transfusion‐dependent β‐thalassemia? A double‐blind, controlled, crossover trial

Background and Aim This study aimed to assess the antioxidant effects of amlodipine in transfusion‐dependent β‐thalassemia (TDT) patients. Methods This crossover trial consisted of two sequences (AP and PA). In the AP sequence, nine cases received amlodipine 5 mg daily (phase I) and then were switched to placebo (phase II). In PA sequence, 10 patients took the placebo (phase I) and were shifted to amlodipine (phase II). The washout period was 2 weeks. The length of each phase was 6 months. Serum malondialdehyde (MDA, μmol/L), carbonyl (protein CO, μM/L), glutathione (GSH, nM/L), and total antioxidant capacity (TAC, μmol FeSO4/L) were measured in the beginning and at the end of phases I and II. The clinical significance was viewed as a minimum change difference of 5% for each outcome between amlodipine and placebo. Results Seventeen cases completed the study. According to the baseline MDA values, the adjusted Hedges's g for MDA was −0.59, 95% confidence interval [CI] −1.26 to 0.08. After controlling the baseline protein CO values, Hedges's g computed for protein CO was −0.11, 95% CI −0.76 to 0.55. The estimated values of the adjusted Hedges's g for GSH and TAC were also 0.26, 95% CI −0.40 to 0.91, and 0.42, 95% CI −0.24 to 1.09, respectively. The change difference for MDA was 8.3% (protein CO 2.2%, GSH 3.1%, and TAC 12.9%). Conclusion Clinically, amlodipine therapy is an efficacious adjuvant treatment with conventional iron chelators for improving the levels of MDA and TAC in patients with TDT. This one‐year crossover trial (two 6 month phases and a 2 week washout) assessed the antioxidant effect of amlodipine in β‐thalassemia patients compared with the placebo. Seventeen cases completed the study. The study's outcomes were the serum levels of MDA, protein CO, GSH, and TAC. The change differences were calculated for the outcomes between amlodipine and placebo based on the baseline values. At the end of the study, the improvement in MDA, protein CO, GSH, and TAC levels were 8.3%, 2.2%, 3.1%, and 12.9%, respectively. Moreover, the computed values of the number needed to treat (NNT) for MDA, protein CO, GSH, and TAC were 4, 17, 7, and 5, respectively.