Effects of combined oral contraceptives containing levonorgestrel or chlormadinone on the endothelium

Although the use of combined oral contraceptives (COCs) is associated with an increased risk of arterial and venous thromboembolic events, less is known about the impact of COCs on endothelial function. The present study evaluated the effects on the endothelium of healthy women of combinations of 30 mcg ethinylestradiol (EE)/2 mg chlormadinone acetate (CMA) and 30 mcg EE/150 mcg levonorgestrel (LNG).

Sixty-four healthy women were evaluated, 21 using a nonhormonal contraceptive method (control) and 43 using COCs, randomized to EE 30 mcg /CMA 2 mg or to EE 30 mcg/LNG 150 mcg. Anthropometric parameters, systolic arterial pressure (SAP), diastolic arterial pressure (DAP), ultrasound markers of endothelial function, flow-mediated dilation (FMD) of the brachial artery, intima-media thickness (IMT) and common carotid artery stiffness were measured at randomization and 6 months later.

Relative to baseline, EE/CMA users showed a significant reduction in mean DAP at 6 months (p=.02), and EE/LNG users showed a significant increase in mean IMT (p=.02) and a significant reduction in mean FMD (p=.01) at 6 months. DAP at 6 months was significantly lower in COC users than in controls (p=.01). Intergroup evaluations showed that, at 6 months, mean SAP (p=.02) was significantly lower in EE/LNG users than in controls (p=.02) and that mean DAP was significantly lower in EE/CMA (p<.01) and EE/LNG (p=.01) users than in controls. EE/LNG users experienced a mean FMD reduction almost threefold greater than that of EE/CMA users. Compared to controls, EE/LNG users experienced a 7.5-fold greater reduction in mean FMD.

COC containing LNG is associated with more pronounced changes in the FMD and IMT of healthy women than a COC containing CMA and nonhormonal contraception. Further studies are needed to determine whether these differences may lead to higher risk of arterial thromboembolic events.