Rosiglitazone causes endothelial dysfunction in humans

We explored the impact of rosiglitazone on endothelial function in normal volunteers and its interaction with glyceryl trinitrate (GTN)-induced abnormalities in endothelial function. We hypothesized that rosiglitazone would have a neutral effect on endothelial function in normal volunteers and would favorably modify endothelial dysfunction induced by GTN.

In this double-blind, randomized, placebo-controlled study, 44 participants were randomized to placebo, rosiglitazone (4 mg twice daily), transdermal GTN (0.6 mg/h), or both GTN and rosiglitazone. After 7 days of treatment, participants underwent measures of forearm blood flow during brachial artery infusion of acetylcholine (Ach). Serum glucose concentrations and insulin sensitivity were assessed.

Unexpectedly, rosiglitazone-treated participants experienced blunted responses to endothelium-dependent responses to Ach (P < .05 vs placebo). Sustained GTN administration caused similar abnormalities in endothelial function (P < .05 vs placebo) and rosiglitazone + GTN (P < .05 vs placebo; P = ns vs rosiglitazone). Interestingly, co-infusion of the antioxidant vitamin C improved endothelial responses in those randomized to rosiglitazone and GTN alone (P = not significant [ns] compared with placebo), but it did not improve endothelial function in those treated with rosiglitazone + GTN. Neither rosiglitazone nor GTN treatment modified the measures of glucose metabolism.

Unexpectedly, therapy with rosiglitazone caused abnormalities in endothelial function in normal volunteers. These findings have important implications with respect to drug development and surveillance.