How does celecoxib's selective COX-2 inhibition affect prostacyclin formation and platelet thromboxane?

At clinical doses (200–400 mg daily), celecoxib's selective COX-2 inhibition reduces systemic, and possibly endothelial, prostacyclin formation without affecting platelet thromboxane, although a dose-dependent effect on thromboxane B2 formation has been observed at high doses.