Biosynthesis of TXA2 and prostacyclin. Biosynthesis of TXA₂ (A) and prostacyclin in vivo (B), as assessed by the measurement of 11-dehydro-TXB₂¹³  and 2,3-dinor-6-keto-PGF_1α,¹⁴  respectively, in subjects carrying TLR4 polymorphisms and in subjects carrying TLR4 wild type. (C) Correlation between the urinary excretion of 11-dehydro-TXB₂ and IMT. (D) Prostacyclin/TXA₂ biosynthesis ratio and its correlation with IMT (E). (F) Effects of rofecoxib (25 mg daily) or etoricoxib (90 mg daily) for 5 consecutive days on TXA₂ biosynthesis in vivo; overnight urine collections were obtained to evaluate the urinary excretion of 11-dehydro-TXB₂¹³  before drug administration and after the last dose of the drugs.