PON1 and heart failure: Olmesartan is therapeutically effective for the treatment of patients with heart failure by decreasing cytokines and oxidative stress through its anti-inflammatory effects.5 Regarding calcium channel blockers, in vitro studies proved that calcium channel blockers, including amlodipine, exhibit inhibitory effects on PON-1 at low concentrations.6 However, studies conducted in vivo in people with type 2 diabetes evaluating effects of antihypertensive agents on PON-1 are lacking.