Large increase in plasmatic 11-dehydro-TxB2 levels due to oral contraceptives.

Coagulation factors, 11-dehydro-TxB2 (metabolite of TxA2) and 6-keto-PGF1 alpha (metabolite of PGI2) levels in 87 women who were treated for 9 months with oral contraceptives (OC) containing low doses of oestrogens and progestogens (Triquilar, Trinovum or Cilest) were investigated. In plasma, increases in F I, II, VII, VIII-c and 11-dehydro-TxB2 levels, but no modification of 6-keto-PGF1 alpha were observed. In urine, FPA concentration rose, but no change occurred in 11-dehydro-TxB2 and 6-keto-PGF1 alpha levels. No marked difference between the 3 OC preparations were noted. These data, and particularly the large increase of 11-dehydro-TxB2 (p < 0.01) suggest that a hypercoagulable state persists in low dosage OC users.