Quinapril, an ACE inhibitor, reduces markers of oxidative stress in the metabolic syndrome.

OBJECTIVE Patients with the metabolic syndrome often have abnormal levels of proinflammatory and pro-oxidative mechanisms within their vasculature. We sought to determine whether the ACE inhibitor quinapril regulates markers of oxidative stress in the metabolic syndrome. RESEARCH DESIGN AND METHODS Forty patients with the metabolic syndrome were randomized in a double-blind manner to either the ACE inhibitor quinapril (20 mg/day) or matching placebo for 4 weeks. Serum markers of vascular oxidative stress were measured. RESULTS After 4 weeks of therapy, serum 8-isoprostane was reduced by 12% in the quinapril group when compared with placebo (quinapril, 46.7 +/- 1.0; placebo, 52.7 +/- 0.9 pg/ml; P = 0.001). Erythrocyte superoxide dismutase activity increased 35% in the quinapril group when compared with placebo (quinapril, 826.3 +/- 17.1; placebo, 612.3 +/- 6.9 units/g Hb; P < 0.001). In addition, lag time to oxidation of LDL, a marker of oxidative stress, was increased by 48% in the quinapril group when compared with placebo (quinapril 89.2 +/- 9.2 vs. placebo 60.1 +/- 12.3 min; P < 0.001). Therapy with quinapril was well tolerated. CONCLUSIONS The addition of the ACE inhibitor quinapril reduces markers of vascular oxidative stress and may attenuate the progression of the pathophysiology seen in the metabolic syndrome.