Effect of two low-dose gestodene containing monophasic oral contraceptives on hemostasis in Bulgarian women

Hemorheological mechanisms for increased thrombosis in subjects using gestodene

There are several possible mechanisms by which combined oral contraceptives (COC) use increase venous thromboembolism (VTE) risk. Melodene® is a monophasic COC containing the third-generation progestin Gestodene (GSD), which is associated with increased risk of VTE. Therefore, the aim of this study was to investigate the possible alterations in viscoelastic parameters of whole blood and plasma clots along with the biophysical characteristics of erythrocytes and specifically fibrin fibers in females using a COC containing GSD. GSD appeared to have a significant impact on the biophysical characteristics of fibrin fiber networks. When GSD is combined with ethinylestradiol the viscoelastic properties of whole blood clots tend to become more prothrombotic. The alterations to and aggregation of erythrocytes accompanied with spontaneous formation of a fibrin "blanket" provides a possible mechanism for the increased occurrence of "red" clots, which can lead to occlusions in the vascular system. Thus, the increased risk of VTE associated with these COCs can be attributed to these erythrocyte-and-fibrin-rich-clots occluding venous vessels. However, our findings also propose that these changes to the biophysical properties of both erythrocytes and fibrin, specifically spontaneous expansion of deformed fibrin networks, can also occlude vessels in the microcirculation, which could have lasting, subclinical complications for female users. We recommend that a thorough risk assessment, with specific focus on coagulation and other factors affecting fibrin formation, be done for each female before prescribing a GSD-containing COC. Females that "qualify" then need to be monitored on a regular basis to lower the risk of thrombotic events. RESEARCH HIGHLIGHTS: Gestodene in combination with ethinyl estradiol significantly impacts the biophysical characteristics of erythrocytes and fibrin fiber networks. These changes, specifically spontaneous expansion of deformed fibrin networks, can occlude vessels in the microcirculation, which could have lasting, subclinical complications for the female user. The changes observed for specifically erythrocytes and fibrin show that the hormone formulation investigated contribute to a thrombogenic profile for female users.

Types of progestogens in combined oral contraception: effectiveness and side-effects

BACKGROUND

The progestogen component of combined oral contraceptives (COC) has undergone changes since it was first recognised that it's chemical structure could influence the spectrum of minor adverse and beneficial effects. The major determinants of effectiveness are compliance and continuation which may be influenced by cycle control and common side effects. The rationale of this review is to provide a systematic comparison of COCs containing the progestogens currently in use worldwide.

OBJECTIVES

To compare currently available low-dose COCs containing ethinyl estradiol and different progestogens in terms of contraceptive effectiveness, cycle control, side effects and continuation rates.

SEARCH STRATEGY

A search of PubMed, LILACS, EMBASE, Popline, CINAHL and the Cochrane Central Register of Controlled Trials databases was conducted in September 2010 to update the 2004 review.

SELECTION CRITERIA

Randomised trials reporting clinical outcomes were considered for inclusion. We excluded studies comparing monophasic with multiphasic pills, crossover trials, trials in which the difference in total content of ethinyl estradiol between preparations exceeded 105 µg per cycle and those comparing continuous dosing regimens.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed methodological quality, applied inclusion criteria and extracted data.

MAIN RESULTS

Thirty trials with a total of 13,923 participants were included, generating 16 comparisons. Overall the quality of trials was low. Only four trials were double-blind. At least twenty-three trials were sponsored by pharmaceutical companies. There was less discontinuation with second-generation compared with first-generation monophasic progestogens (3 trials, 2,709 women, Relative Risk (RR) 0.76, 95% Confidence Interval (CI) 0.67-0.86); this remained significant when only double-blind trials were considered (812 women, RR 0.79, 95% CI 0.66-0.94).Women using monophasic COC's containing third-generation progestogens were less likely to discontinue than the second-generation group (3 trials, 1,815 women, RR 0.77, 95% CI 0.60-0.98) but this was not significant when only double-blind trials were considered (RR 0.79, 95% CI 0.50-1.26]. Women in the third-generation group experienced less intermenstrual bleeding than the second-generation group (one double-blind trial, 456 women, RR 0.71, 95% CI 0.55-0.91).Compared to desogestrel (DSG), women in the drospirenone (DRSP) group were more likely to complain of breast tenderness (5 trials, 4,258 women, RR 1.39, 95% CI 1.04-1.86) and nausea (6 trials, 4,701 women, RR 1.46, 95% CI 0.96-2.21].Pregnancy rates overall were comparable but the trials had insufficient power to find potentially important differences.

AUTHORS' CONCLUSIONS

Women using COCs containing second-generation progestogens may be less likely to discontinue than those using COCs containing first-generation progestogens. Based on one small double-blind trial, third-generation progestogens may be preferable to second-generation preparations with regard to bleeding patterns but further evidence is needed. Without blinding as to treatment group, comparisons between the various "generations" of progestogens used in COCs cannot be made. Until this widespread methodological flaw is overcome in better trials conducted according to CONSORT guidelines and internationally accepted definitions, no further conclusions can be drawn.