Viegas O A, Koh S C, Ratnam S S
Department of Obstetrics and Gynaecology, National University Hospital, Singapore.
Contraception. 1996 Oct;54(4):219-28. doi: 10.1016/s0010-7824(96)00192-8.
Prolonged use of reformulated and the original 2-rod Norplant implants showed similar changes in most hemostatic parameters studied. Raised hemoglobin concentration and hematocrit values with not enhanced platelet activation or significant changes in platelet numbers were seen. Factor VII showed an increase from 18 months compared to the first 12 months of original Norplant implant use, while with reformulated Norplant implant, the level at 36 months was significantly higher than the first 24 months of implant use. Fibrinogen levels were significantly elevated by 36 months of both implant use. No evidence of enhanced activation of coagulation, fibrinolysis/inhibitor were observed during prolonged implant use. Overall, no significant changes in tissue plasminogen activator (t-PA) levels were observed but urokinase-like plasminogen activator (u-PA) levels were significantly reduced, indicating no enhancement of tissue breakdown. Plasminogen activation inhibitor (PAI-1) antigen levels were significantly reduced from 12 to 36 months with original Norplant implant use compared to the pre-insertion levels, while a nonsignificant decreased trend was seen with prolonged reformulated Norplant implant use. The increased levels of fibrinogen and FVII at the end of 36 months of implant use require further observation as these factors are known markers of hypercoagulation and associated with increased arteriosclerotic and cardiovascular risks. This study is on-going to evaluate the effects of levonorgestrel-containing subdermal reformulated Norplant implants on hemostasis after five years of use.
长期使用重新配方的和原来的两根Norplant皮下埋植剂，在所研究的大多数止血参数方面显示出相似的变化。观察到血红蛋白浓度和血细胞比容值升高，而血小板活化未增强，血小板数量也无显著变化。与最初使用Norplant皮下埋植剂的前12个月相比，因子VII从18个月起有所增加，而对于重新配方的Norplant皮下埋植剂，36个月时的水平显著高于植入使用的前24个月。两种皮下埋植剂使用36个月时，纤维蛋白原水平均显著升高。在长期植入使用期间，未观察到凝血、纤维蛋白溶解/抑制剂活化增强的证据。总体而言，未观察到组织纤溶酶原激活物（t-PA）水平有显著变化，但尿激酶型纤溶酶原激活物（u-PA）水平显著降低，表明组织分解未增强。与植入前水平相比，使用原来的Norplant皮下埋植剂从12个月到36个月，纤溶酶原激活抑制剂（PAI-1）抗原水平显著降低，而长期使用重新配方的Norplant皮下埋植剂则呈现出非显著的下降趋势。植入使用36个月结束时纤维蛋白原和因子VII水平升高需要进一步观察，因为这些因子是已知的高凝标志物，与动脉粥样硬化和心血管风险增加有关。这项研究正在进行中，以评估含左炔诺孕酮的重新配方的Norplant皮下埋植剂使用五年后对止血的影响。
