Platelet-vessel wall interactions with third-generation oral contraceptives: No evidence of detrimental effects

Because of the association of oral contraceptives (OC) and cigarette smoking with an increased thrombotic risk, we evaluated thromboxane (TX) and prostacyclin urinary (u) metabolites, as in vivo indices of platelet-vessel wall interactions, in women assigned to third generation OC. Twenty-tight women (15 smokers) underwent a 6-month trial of 30 mu g ethinylestradiol plus 0.150 mg desogestrel. Cotinine plasma levels were elevated only in persons classified as smokers and serum TXB2 determination confirmed the absence of cyclooxygenase inhibition throughout the study. u-TXB2 and 11-dehydro-TXB2 were higher in smokers than in non-smokers. OC decreased u-11-dehydro-TXB2 both in smokers (from (pg/mu mol creatinine) 35.1 +/- 6.9 to 15.8 +/- 2.8; P <0.025) and non-smokers (from 31.7 +/- 9.8 to 20.6 +/- 4.8, P = N.S.). u-6-keto-prostaglandin(PG)F-1 alpha excretion, also higher in smokers compared to non-smokers, was also reduced after OC in smokers (from (pg/mu mol creatinine) 24.3 +/- 5.2 to 14.8 +/- 2.3; P <0.05). Smokers also had a trend to higher u-2.3-dinor-6-keto-PGF(1 alpha), marginally reduced by OC. Thus, the OC regimen used here improves - if anything - platelet vessel wall interactions as assessed by prostanoid production in vivo. The prothrombotic tendency associated with the use of OC in smokers does not appear to be mediated by changes in platelet-vessel wall interactions.