The effects of reformulated 2-rod Norplant ® implant on hemostasis after three years

Abstract

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 no 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 Norpant implant use, while with reformulated Norpant 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 activator 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.