The role of thromboxane A2 in increased whole blood platelet aggregation in oral contraceptive users

Norris, Lucy; Devitt, M.; Bonnar, J.

doi:10.1016/0049-3848(96)00013-8

Cited by 7 publications

(5 citation statements)

References 30 publications

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“…In accordance with others (Rahmann & Billington, 2000), we noted significantly lower ADPPA in garlic consumers. We could also confirm an increased PA induced by collagen in OC users (Miller et al , 1995; Norris et al , 1996). However, the influence of oestrogen‐containing OC on platelet function remains a controversial issue (Saleh et al , 1995).…”

Section: Discussionsupporting

confidence: 52%

Variables influencing Platelet Function Analyzer‐100^TM closure times in healthy individuals

et al. 2005

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Summary We investigated the relationship between platelet function analyzer (PFA‐100TM) closure times (CT) and bleeding time (BT), platelet aggregation (PA) induced by ADP, arachidonic acid, and collagen, blood cell counts, and von Willebrand factor (VWF) in 120 well‐characterised healthy individuals. Pre‐analytical and analytical conditions were standardised comprehensively. In a substantial number of cases the differences between duplicate measurements exceeded 15%. The reference range (5th and 95th percentiles) for CT with the collagen/epinephrine (CEPI) and the collagen/ADP (CADP) cartridge was 93–223 s and 64–117 s respectively. Re‐examination of 11 individuals with CEPI‐CT above the 95th percentile revealed considerable batch‐to‐batch variation of CEPI‐CT. Males had significantly longer CADP than females (P = 0·002). CEPI and CADP‐CT measured pm were significantly longer than corresponding values determined am (P = 0·003 and P < 0·0001 respectively). Blood group O was associated with greater CEPI and CADP‐CT and lower VWF levels compared with non‐O blood groups (P = 0·008, P = 0·0003 and P < 0·0001 respectively). Linear regression analysis revealed association between CEPI‐CT, CADP‐CT and VWF (P < 0·0001), but no relationship was found between CT and BT or between CT and PA. We conclude that VWF plasma levels modulate PFA‐100TM CT to a greater extent than platelet function. Establishment of reliable reference ranges and careful standardisation of pre‐analytical and analytical conditions is a prerequisite for obtaining reliable PFA‐100TM results. Duplicate measurements are necessary.

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Section: Discussionsupporting

confidence: 52%

Variables influencing Platelet Function Analyzer‐100^TM closure times in healthy individuals

et al. 2005

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“…12 Alterations in the balance between proaggregatory and antiaggregatory prostanoids were observed in women taking third-generation progestogens with ethinyl estradiol (ie, 75 mg gestodene or 150 mg desogestrel combined with 30 mg ethinyl estradiol) explained by whole blood platelet aggregation. 45 The increased platelet aggregation in the study was inhibited by the thromboxane synthetase inhibitor, dazmegrel. Therefore, it was suggested that platelet activation among COC users may be mediated by an activation of the platelet cyclooxygenase enzyme.…”

Section: Changes In Coagulation Markers Due To Hc Usementioning

confidence: 98%

“…Consequently, inhibitors of thromboxane synthetase may counteract the aggregatory effects of COCs. 45 Another important physiological inhibitor of blood coagulation that has been attracting attention is TFPI. Previously, it was shown that immune depletion of TFPI, in rabbits, significantly decreases the threshold, triggering coagulation by tissue factor and induction of disseminated intravascular coagulation.…”

Section: Changes In Coagulation Markers Due To Hc Usementioning

confidence: 99%

Risk Factors for Heart Attack, Stroke, and Venous Thrombosis Associated With Hormonal Contraceptive Use

Zakharova

Meyer

Brandy

et al. 2010

Clin Appl Thromb Hemost

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The search for a safe and effective method of contraception has been ongoing for centuries. During the last century, a variety of hormonal contraceptives, including combined hormonal oral contraceptives (COCs), have been introduced into the market. COCs have evolved through modifications of different hormonal components to minimize the risk of thrombotic events including stroke, myocardial infarction, and venous thrombosis. The evolution of COC development led to the reduction in the estrogen dose, in an attempt to lower the risk of vascular diseases. Although the risk of thrombotic events due to COC use has been substantially reduced since their inception, the quest for developing safer methods of birth control continues. It is of great interest to study coagulation effects of newer COCs, as well as progestin only, as rigorously as older COCs.

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“…The mechanisms underlying increased VTE risk are unclear, but are thought to be related to the effects of combined oral contraceptives on coagulation and fibrinolysis (7). Combined oral contraceptives may also alter platelet function, although findings to date are variable and have been based primarily on observational or open-label studies (8)(9)(10). In Europe, the haemostatic effects of all new combined oral contraceptives must be compared with those of a 21-day pill regimen with an established risk profile (11).…”

Section: Introductionmentioning

confidence: 99%

Haemostatic effects of a new combined oral contraceptive, nomegestrol acetate/17β-estradiol, compared with those of levonorgestrel/ethinyl estradiol

Gaussem¹,

Alhenc‐Gelas²,

Thomas³

et al. 2011

Thromb Haemost

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Use of oral contraceptives (OC) that combine a progestogen with synthetic ethinyl estradiol (EE) is associated with increased risk of venous thromboembolism. NOMAC/E2 is a new monophasic OC that combines nomegestrol acetate (NOMAC), a highly selective progestogen, with 17β-estradiol (E2). The study objective was to compare the effects on markers of haemostasis of NOMAC/E2 (2.5 mg/1.5 mg) versus the second-generation OC, levonorgestrel (LNG)/EE (100 μg/20 μg). Healthy women (age 18-38 years) received once-daily treatment for three consecutive 28-day cycles in a double-blind, randomised study: either NOMAC/E2 for 24 days with a four-day placebo interval (n=45) or LNG/EE for 21 days with a seven-day placebo interval (n=45) per cycle. Mean changes from baseline to end-of-treatment in coagulation markers, including prothrombin fragment 1+2 (primary endpoint), fibrinolysis markers and platelet functions were assessed. Mean prothrombin fragment 1+2 levels (primary endpoint) did not increase with NOMAC/E2 compared with LNG/EE ( -0.02 vs. +0.08 nM, p<0.01). Other significant differences between NOMAC/E2 and LNG/EE were mean changes in antithrombin (+0.3% vs. -4.4%, p<0.001), activated protein C resistance - normalised ratio (+0.20 vs. +0.46, p<0.01), D-dimer ( -53 vs. +43 ng/ml, p<0.001), plasminogen (+6% vs. +30%, p<0.0001) and plasminogen activator inhibitor-1 ( -3.1 vs. -8.0 ng/ml, p<0.001). There was no effect of either treatment on platelet aggregation. The NOMAC/E2 pill regimen has fewer adverse effects on blood biological coagulation and fibrinolysis markers than LNG/EE. This suggests that NOMAC/E2 could have a more favourable venous thromboembolism risk profile than LNG/EE; further epidemiological data are required to confirm this.

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The role of thromboxane A2 in increased whole blood platelet aggregation in oral contraceptive users

Cited by 7 publications

References 30 publications

Variables influencing Platelet Function Analyzer‐100^TM closure times in healthy individuals

Variables influencing Platelet Function Analyzer‐100^TM closure times in healthy individuals

Risk Factors for Heart Attack, Stroke, and Venous Thrombosis Associated With Hormonal Contraceptive Use

Haemostatic effects of a new combined oral contraceptive, nomegestrol acetate/17β-estradiol, compared with those of levonorgestrel/ethinyl estradiol

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The role of thromboxane A2 in increased whole blood platelet aggregation in oral contraceptive users

Cited by 7 publications

References 30 publications

Variables influencing Platelet Function Analyzer‐100TM closure times in healthy individuals

Variables influencing Platelet Function Analyzer‐100TM closure times in healthy individuals

Risk Factors for Heart Attack, Stroke, and Venous Thrombosis Associated With Hormonal Contraceptive Use

Haemostatic effects of a new combined oral contraceptive, nomegestrol acetate/17β-estradiol, compared with those of levonorgestrel/ethinyl estradiol

Contact Info

Product

Resources

About

Variables influencing Platelet Function Analyzer‐100^TM closure times in healthy individuals

Variables influencing Platelet Function Analyzer‐100^TM closure times in healthy individuals