Low-dose oral contraceptives and acquired resistance to activated protein C: a randomised cross-over study

BACKGROUND

We have reported previously that, compared with use of second-generation oral contraceptives, the use of third-generation oral contraceptives is associated with increased resistance to the anticoagulant action of activated protein C (APC). Owing to the cross-sectional design of that study, these observations may have been subject to unknown bias or uncontrolled effects of the menstrual cycle. We aimed to overcome these sources of bias by doing a cycle-controlled randomised cross-over trial.

METHODS

The response to APC in plasma was assessed in 33 women who received two consecutive cycles of a second-generation oral contraceptive (150 microg levonorgestrel and 30 microg ethinyloestradiol) or a third-generation oral contraceptive (150 microg desogestrel and 30 microg ethinyloestradiol), and who switched preparations after two pill-free cycles. Normalised APC sensitivity ratios were calculated by measurement of the effect of APC on thrombin generation in the plasma of these women and in pooled plasma from 90 controls.

FINDINGS

Of the 33 women, five were excluded because not all required plasma samples were available. In the remaining 28 women, the normalised APC sensitivity ratio increased during treatment with both preparations. Compared with levonorgestrel, desogestrel-containing oral-contraceptive treatment caused a highly significant (p<0.0001) additional increase in normalised APC sensitivity ratio (0.51 [95% CI 0.37-0.66]). Normalised APC sensitivity ratios during oral-contraceptive treatment correlated with the values before oral-contraceptive use.

INTERPRETATION

Oral-contraceptive treatment diminishes the efficacy with which APC down-regulates in-vitro thrombin formation. This phenomenon, designated as acquired APC resistance, is more pronounced in women using desogestrel-containing oral contraceptives than in women using levonorgestrel-containing preparations. Whether acquired APC resistance induced by oral contraceptives explains the increased risk of venous thromboembolism in oral-contraceptive users remains to be established.

The influence of thrombotic risk factors when oral contraceptives are prescribed. A control-only study

OBJECTIVES

The aim of this study was to assess preferential prescribing of OC according to different thrombotic risk factors.

MATERIAL AND METHODS

The control group in an ongoing Danish case-control study on stroke and OCs collected in 1994 and 1995 underwent a control-only analysis concerning the occurrence of thrombotic risk factors among users of different types of OC. Specific attention was given to differences between OCs with second and third generation progestagens. The association between specific risk factors and the pill types was assessed crude and after multivariate analysis with confounder control for age and other risk factors, in order to identify risk factors, which after these corrections still had a significant confounding influence on the prescribing of OC.

RESULTS

Users of OCs with third generation progestagens had a significantly higher proportion of familial thrombotic disposition (23.1%) than users of OCs with second generation progestagens (7.1%) (p = 0.01). After correction for age and other risk factors this difference was still highly significant (p = 0.002). Among users of third generation pills the proportion of short time users (< 1 year) (22.4%) was significantly higher than the per cent among users of OCs with second generation progestagens (5.5%) (p < 0.001). This difference was still significant after correction for age and other risk factors (p < 0.001). Smoking, years of schooling, migraine, and body mass index did not differ significantly between the two pill groups.

CONCLUSION

In Denmark, women with familial thrombotic disposition are four times more likely being prescribed OCs with third versus second generation progestagens compared with women without such a disposition. At the same time users of OCs with third generation progestagens include significantly more short time users than users of OCs with second generation progestagens. For thrombotic diseases where familial disposition or duration of use of OCs play a role for the pill-associated risk, these differences may significantly influence the thrombotic risk measures in case-control studies and non-randomized cohort studies unless confounder control is conducted for this selection.

Desogestrel, norgestimate, and gestodene: the newer progestins

OBJECTIVE

To review and compare the newer progestins desogestrel, norgestimate, and gestodene with regard to chemistry, pharmacokinetics, efficacy, and tolerability.

DATA SOURCES

Primary literature on desogestrel, norgestimate, and gestodene was identified from a comprehensive MEDLINE English-literature search from 1984 through 1994, with additional studies selected by review of the references. Indexing terms included progestins, desogestrel, gestodene, norgestimate, levonorgestrel, and norgestrel.

STUDY SELECTION

Only human clinical and pharmacokinetic trials performed in Europe, Canada, and the US were included.

DATA EXTRACTION

All available data from human studies were reviewed; both comparative and noncomparative studies were included because of the paucity of direct comparative information available.

DATA SYNTHESIS

The newer progestins were designed to minimize the adverse effects (e.g., acne, hirsuitism, nausea, carbohydrate and lipid metabolism changes) observed with older oral contraceptives (OCs) while maintaining efficacy and good menstrual cycle control. Desogestrel, norgestimate, and gestodene have minimal amounts of androgenicity and antiestrogenic potential. All of these agents are pharmacokinetically similar to older agents: they are highly bioavailable when administered orally, hepatically metabolized, and obtain steady-state concentrations after 8-10 days of continuous administration. The newer agents have similar Pearl Indexes and slightly better cycle control. Furthermore, the new progestins appear to cause fewer adverse effects, such as acne and hirsuitism, and similar rates of weight gain, blood pressure changes, and lipid and carbohydrate metabolism changes.

CONCLUSIONS

Desogestrel, norgestimate, and gestodene appear to offer clinical advantages because of their decreased androgenicity. Women whose cycles are currently well controlled with other OCs should not be switched to a newer progestin. However, any of the combination OC products that contain these progestins may be prescribed for women intolerant of older agents or to first-time users of OCs. The newer progestins appear to be efficacious and offer similar cycle control, improved safety and tolerability profiles, and comparable price with the older agents.

[Clinical effectiveness of Marvelon]

Clinical results of a new contraceptive pills--Marvelon (Organon) were studied. 32 women, ages 30 +/- 5 years, participated in the study during at least 6 cycles. Marvelon was good tolerated and subjective side-effects were very low. The cycles were regular, duration of withdrawal bleeding was 3-5 days and the amount of the blood lost were unchanged or milder. Marvelon didn't affect body weight and blood pressure. Favourable lipid profile--increased a mean level of HDL-Cholesterol and decreased a mean level of LDL-Cholesterol were noticed. Pearl Index was 0,0.

Multicenter trial of two monophasic oral contraceptives containing 30 mcg ethinylestradiol and either desogestrel or gestodene in Thai women

The efficacy and acceptability of two third generation oral contraceptives in Thai women were evaluated in a prospective, open, group-comparative, randomized, multicenter trial of women asking for contraception. In six Family Planning Centers and Outpatient Gynaecological Clinics in urban areas in Thailand, 783 healthy women who were at risk for pregnancy and did not have contraindications to oral contraceptive use were randomly allocated to one of the two study groups. An oral contraceptive containing 30 mcg ethinylestradiol and 150 mcg desogestrel was given to 394 women and an oral contraceptive with the same amount of ethinylestradiol and 75 mcg gestodene to 389 women during 6 cycles. Criteria of cycle control, side effects and the presence and severity of acne vulgaris were assessed and blood pressure and body weight measured at pretreatment and after cycles 1, 3 and 6. Furthermore, the efficacy was evaluated after the last cycle. No pregnancies occurred with either of the contraceptives. The incidences of irregular bleeding and minor side effects in both groups were very low and decreased after an initial increase in the first cycle. Acne improved in both groups. Blood pressure and body weight remained unchanged. The two oral contraceptives were found to be effective and acceptable in Thai women. Compared to Caucasian women, the incidences of irregular bleeding and side effects were apparently lower in these Asian women. Furthermore, the effects of both oral contraceptives were comparable.

Effects of a low-estrogen, desogestrel-containing oral contraceptive on lipid and carbohydrate metabolism

Fasting serum lipids, lipoproteins and apolipoproteins, and fasting plasma glucose, insulin and C-peptide were measured in 107 non-users and 83 users of an oral contraceptive containing the progestin desogestrel, combined with 20 micrograms ethinyl estradiol. Plasma glucose, insulin and C-peptide concentrations during an oral glucose tolerance test (OGTT) were measured in a subgroup of 69 non-users and 39 users. Compared with non-users, users had higher concentrations of total, high density lipoprotein (HDL), HDL subfraction 3 and very low density lipoprotein (VLDL) cholesterol, total triglycerides, VLDL triglycerides, apolipoproteins AI and AII and fasting plasma insulin. There were no differences in HDL subfraction 2, low density lipoprotein cholesterol and apolipoprotein B. OGTT glucose was 60% higher in the users and OGTT insulin response 19% higher. The OGTT C-peptide response did not differ. The effects of 20 micrograms ethinyl estradiol combined with 150 micrograms desogestrel on lipid, lipoprotein, glucose and insulin metabolism are similar to those described previously with a 30 micrograms ethinyl estradiol combination containing the same dose of desogestrel. The relatively favourable metabolic profile associated with the higher estrogen dose desogestrel combination is maintained at the lower dose.