Intra- and interindividual variations in contraceptive steroid levels during 12 treatment cycles: no relation to irregular bleedings

A safety evaluation of current medications for adult women with the polycystic ovarian syndrome not pursuing pregnancy

INTRODUCTION

The polycystic ovary syndrome (PCOS) is a very prevalent disorder in premenopausal women. Cardiovascular risk factors cluster in these patients, raising concern about the safety of the drugs commonly used to ameliorate symptoms of androgen excess in in this population at risk of cardiovascular morbidity.

AREAS COVERED

This review summarizes the clinical efficacy and safety profiles of drugs commonly used for the management of hyperandrogenic symptoms and endometrial protection in adult women with PCOS who do not seek pregnancy.

EXPERT OPINION

Antiandrogenic drugs usually used in adult women with PCOS carry a low risk of severe side effects. In spite of the cardiovascular risk profile of women with PCOS, and that individualized risk assessment is of paramount importance, there is no solid evidence supporting that the use of combined oral contraceptives in these women increases the risk of cardiovascular or thromboembolic events compared with the general population. However, virtually all these drugs are used in an off-label fashion. Large, high-quality studies addressing the long-term safety of pharmacological treatments in women with PCOS are definitely needed.

An open-label, two-period comparative study on pharmacokinetics and safety of a combined ethinylestradiol/gestodene transdermal contraceptive patch

We investigated the pharmacokinetics and safety profiles of a newly developed combined ethinylestradiol (EE)/gestodene (GSD) transdermal contraceptive patch after a single-dose administration and compared with the market available tablet formulation in healthy adult subjects. An open-label, two-period comparative study was conducted in 12 healthy women volunteers. A single dose of the study combined EE/GE transdermal contraceptive patch and oral tablet (Milunet^®) were administered. Blood samples at different time points after dose were collected, and concentrations were analyzed. A reliable, highly sensitive and accurate high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC/MS/MS) assay method was developed in this study to determine the plasma concentrations of EE and GSD. Compared to the tablet, the study patch had a significantly decreased maximum plasma concentration (C_max), extended time to reach the C_max and half-life, as well as increased clearance and apparent volume of distribution. The half-lives of EE and GSD of the patch were 3.3 and 2.2 times, respectively, than the half-life of the tablet. The areas under the plasma concentration–time curve (AUCs) of EE and GSD of the patch were 8.0 and 16.2 times, respectively, than the AUC of the tablet. No severe adverse event was observed during the whole study, and the general safety was acceptable. In conclusion, compared to the oral tablet Milunet, the study contraceptive patch was well tolerated and showed potent drug exposure, significant extended half-life and stable drug concentrations.

Extended and Continuous Use of Hormonal Contraceptives to Reduce Menstruation

During the use of long-cycle regimens of monophasic oral contraceptives, the total number of bleeding and cycle-dependent complaints is considerably lower than during conventional treatment with oral contraceptives. Despite an initially higher rate of irregular bleeding, the majority of women prefer the long-cycle treatment since it may improve quality of life. As this regimen provides an enhanced ovarian suppression, it may prevent pregnancies, especially in noncompliant women or patients who are concomitantly treated with drugs that may impair the efficacy of oral contraceptives. Postponement or suppression of withdrawal bleeding also reduces menses-associated disorders such as menorrhagia and dysmenorrhea, and has beneficial effects in patients with hemorrhagic diathesis, endometriosis, uterine leiomyomas and polycystic ovary syndrome. Long-term studies are necessary to assess the impact of long-term use of extended regimens of oral contraceptives on safety, for example, the risk of cancer and cardiovascular disease, and on fertility after discontinuation of treatment.

Pharmacokinetic overview of ethinyl estradiol dose and bioavailability using two transdermal contraceptive systems and a standard combined oral contraceptive

Objective: To determine the relative bioavailability of ethinyl estradiol (EE) and gestodene (GSD) after application of a novel transdermal contraceptive patch vs. a standard combined oral contraceptive (COC) pill (study 1), and to evaluate the pharmacokinetics (PK) of EE after application of the EE/GSD patch compared with an EE/norelgestromin (NGMN) patch (study 2). Materials: Participants were healthy, non-obese women aged 18 – 45 years (study 1) or 18 – 35 years (study 2). Compositions of study treatments were as follows: 0.55 mg EE/2.1 mg GSD (EE/GSD patch); 0.02 mg EE/0.075 mg GSD (standard COC); 0.6 mg EE/6 mg NGMN (EE/NGMN patch). Methods: In study 1, which consisted of 3 treatment periods (each followed by 7 patch- or pill-free days), treatments were administered in one of two randomized orders: either P–M–E (EE/GSD patch (P) every 7 days for 28 days → COC (M) once-daily for 21 days → two 7-day patch-wearing periods followed by one 10-day patch-wearing phase (E)), or the same treatments administered in sequence M–P–E. For study 2, participants received either the EE/GSD patch or EE/NGMN patch for seven treatment cycles (one patch per week for 3 weeks followed by a 7-day patch-free interval). Results: In study 1, average daily exposure to EE was similar for treatments P and M; the mean daily area under the concentration-time curve (AUC) ratio of treatment P vs. treatment M for EE was 1.06 (90% confidence interval (CI): 0.964 – 1.16), indicating average daily delivery similar to oral administration of 0.019 – 0.023 mg EE. For unbound GSD, average daily exposure was lower for treatment P vs. treatment M. The mean AUC ratio of treatment P vs. treatment M for unbound GSD was 0.820 (90% CI: 0.760 – 0.885), indicating average daily delivery from the patch of 0.057 – 0.066 mg GSD. Prolonged patch wearing did not result in a distinct decline in GSD and EE serum concentrations. In study 2, AUC at steady state (AUC_0–168,ss), average steady-state serum concentration, and maximum steady-state serum concentration for EE was 2.0 – 2.7-fold higher for the EE/NGMN patch vs. the EE/GSD patch. The EE/GSD patch was well tolerated in both studies. Conclusions: Based on the 90% CI of the AUC ratio of oral treatment vs. patch application for unbound GSD and EE, the daily doses of GSD and EE released from the EE/GSD patch over the 7-day application period provided the same systemic exposure as those recorded after daily oral administration of a COC containing 0.02 mg EE and 0.06 mg GSD. The EE/GSD patch showed reduced EE exposure compared with the EE/NGMN patch. Together with its good tolerability, these properties support the EE/GSD patch as an effective and well-tolerated alternative to available transdermal and oral contraceptives.

Pharmacokinetics and adhesion of a transdermal patch containing ethinyl estradiol and gestodene under conditions of heat, humidity, and exercise: A single-center, open-label, randomized, crossover study

In this open-label, randomized study, 36 women (18-45 years) applied an ethinyl estradiol/gestodene contraceptive patch once-weekly for 3 weeks followed by a 1-week, patch-free interval, in 3 treatment periods. The primary objective was to evaluate the pharmacokinetics of ethinyl estradiol and gestodene under conditions of heat, humidity, and exercise. The secondary objective was to evaluate patch adhesion under the same conditions. Weeks 1 and 2 of each period comprised "standardized normal activity" (SNA); in week 3, SNA continued or women used a sauna, whirlpool, swimming pool, or performed an exercise combination. Thirty-one women completed the study; 23 yielded evaluable pharmacokinetic data. Analyses were exploratory and conducted using an analysis of variance. Area under the concentration-time curve from 0 to 168 hours (AUC0-168 ) for gestodene and ethinyl estradiol during sauna, swimming, and whirlpool was equivalent to previous SNA recordings. For exercise combination, the gestodene AUC0-168 was 12% lower compared with SNA, albeit not considered clinically relevant. Two women lost a total of 3 patches during sporting activities; other detachments during this week were not correlated with sporting activity. Overall, hormone delivery using the ethinyl estradiol/gestodene patch under conditions of heat, humidity, and exercise corresponded to delivery under normal conditions.

Bleeding pattern and cycle control of a low-dose transdermal contraceptive patch compared with a combined oral contraceptive: a randomized study

OBJECTIVE(S)

The aim of this study was to investigate the bleeding pattern and cycle control of a contraceptive patch containing 0.55 mg ethinyl estradiol (EE) and 2.1 mg gestodene (GSD) compared with a combined oral contraceptive (COC) containing 0.02 mg EE and 0.1 mg levonorgestrel (LNG).

STUDY DESIGN

In this phase III, randomized, controlled, double-blind, double-dummy, multicenter trial, healthy women aged 18-45 years (smokers aged 18-35 years) received either the EE/GSD patch and a placebo tablet (n=171), or a placebo patch and the COC (n=175) for seven 28-day cycles. Bleeding control was assessed in two 90-day reference periods.

RESULTS

Mean number of bleeding/spotting days was comparable across treatment groups in both reference periods (p>.05). Mean number of bleeding/spotting episodes was also comparable in reference period 1; however, there were fewer bleeding/spotting episodes for COC in reference period 2 (3.4 versus 3.1; p=.01). Mean length of bleeding/spotting episodes was comparable across treatment groups for both reference periods (p>.05). Withdrawal bleeding occurred consistently in both groups over the entire treatment period, but its absence was more common in the COC group in cycles 4 and 6 of reference period 2 (p<.01). Intracyclic bleeding was comparable between groups.

CONCLUSION(S)

Bleeding pattern and cycle control with the EE/GSD patch was comparable to an EE/LNG-containing COC.

IMPLICATIONS STATEMENT

The findings suggest that bleeding patterns with the EE/GSD patch are similar to an EE/LNG-containing COC, except for absence of withdrawal bleeding, which was less common in patch users. The EE/GSD patch may constitute an additional contraceptive option for women.

A comparison of bleeding patterns and cycle control using two transdermal contraceptive systems: a multicenter, open-label, randomized study

OBJECTIVE(S)

To investigate the bleeding pattern and cycle control parameters of a contraceptive patch containing 0.55 mg ethinyl estradiol (EE) and 2.1 mg gestodene (GSD) compared with a patch containing 0.6 mg EE and 6 mg norelgestromin (NGMN).

STUDY DESIGN

In this phase III, open-label, randomized, parallel-group trial, healthy women aged 18-35 years (smokers aged 18-30 years) received either the EE/GSD patch (n=200) or the EE/NGMN patch (n=198). Treatment consisted of one patch per week for 3 weeks followed by a 7-day, patch-free interval for seven cycles. Bleeding control was assessed in two 90-day reference periods.

RESULTS

In reference period 1, mean number of bleeding/spotting days was comparable across treatment groups (p>0.05). However, in reference period 2, there were fewer bleeding/spotting days in the EE/GSD patch group (15.7 versus 18.4; p<0.0001). Mean number of bleeding/spotting episodes was comparable across groups for both reference periods, but bleeding/spotting episodes were shorter for the EE/GSD patch than the EE/NGMN patch during reference period 1 (5.13 days versus 5.53 days, respectively; p<0.05) and reference period 2 (5.07 versus 5.66; p=0.0001). Both treatment groups showed a similar frequency of withdrawal bleeding episodes; however, across all seven cycles, the length of these episodes was consistently shorter with the EE/GSD patch (p<0.01). There were no notable treatment differences in intracyclic bleeding.

CONCLUSION(S)

Bleeding pattern and cycle control achieved with the EE/GSD patch was similar to that of the EE/NGMN patch.

IMPLICATIONS STATEMENT

The paper presents data on the bleeding pattern and cycle control parameters of an investigational transdermal contraceptive patch containing EE and GSD compared with an approved contraceptive patch containing EE and NGMN. This descriptive study found that bleeding patterns associated with the EE/GSD patch were similar to those of an EE/NGMN patch providing higher EE exposure.

Effect of a low-dose contraceptive patch on efficacy, bleeding pattern, and safety: a 1-year, multicenter, open-label, uncontrolled study

This Phase III, uncontrolled, open-label, multicenter study was conducted to investigate the contraceptive efficacy, bleeding pattern, and cycle control of a novel once-a-week contraceptive patch, delivering low-dose ethinyl estradiol (EE) and gestodene (GSD) at the same systemic exposure seen after oral administration of a combined oral contraceptive containing 0.02 mg EE/0.06 mg GSD. Participants were women aged 18 to 35 years, all of whom received the EE/GSD patch for 13 cycles each of 21 treatment days (one patch per week for 3 weeks) followed by a 7-day, patch-free interval. The primary efficacy variable was the occurrence of unintended pregnancies during the study period as assessed by life table analysis and the Pearl Index. Secondary efficacy variables were days with bleeding during four 90-day reference periods and during 1 treatment year, bleeding pattern, and cycle control. The Kaplan-Meier probability of contraceptive protection after 364 treatment days was 98.8% and the adjusted Pearl Index was 0.81. The percentage of participants with intracyclic bleeding/spotting decreased over time, from 11.4% to 6.8% in cycles 1 and 12, respectively. Almost all participants (range: 90.8%-97.6%) experienced withdrawal bleeding across the study period. Compliance was very high (mean: 97.9%; median: 100%). The most frequent adverse events were headache (9.5%) and application site reaction (8.5%); no clinically significant safety concerns were observed. Results suggest the EE/GSD patch is highly effective in preventing pregnancy. Menstrual bleeding pattern was favorable and within the ranges expected of a healthy female population. The patch was well tolerated and treatment compliance was high.

Investigation of the hemostatic effect of a transdermal patch containing 0.55 mg ethinyl estradiol and 2.1 mg gestodene compared with a monophasic oral contraceptive containing 0.03 mg ethinyl estradiol and 0.15 mg levonorgestrel: an open-label, randomized, crossover study

Background

Transdermal delivery of contraceptives offers several advantages over combined oral contraceptives (COCs), including effective absorption and the provision of relatively constant serum concentrations. Ethinyl estradiol (EE) and the progestin gestodene are well-absorbed through the skin and, therefore, well-suited for use in a transdermal contraceptive patch.

Objective

The objective of this study was to investigate the impact of a once-weekly transparent, transdermal patch delivering low doses of EE and gestodene equivalent to a COC containing 0.02 mg EE and 0.06 mg gestodene on hemostasis parameters compared with a monophasic COC containing 0.03 mg EE and 0.15 mg levonorgestrel.

Methods

In this single-center, open-label, randomized, crossover study, 30 women (aged 18–35 years) received three cycles of each treatment, separated by a two-cycle washout period. The primary outcome measure was the absolute change from baseline in prothrombin fragments 1 + 2 and d-dimer.

Results

For both treatments, prothrombin fragments 1 + 2 remained stable during the first treatment period, and increased only slightly in the second period (mean absolute change 0.025 and 0.028 nmol/L in the novel Bayer patch and COC groups, respectively). Increases in d-dimer were observed in both periods (mean absolute change 107.0 ± 147.2 ng/L for the novel Bayer patch and 113.7 ± 159.0 ng/L for the COC). There were no statistically significant treatment differences in prothrombin 1 + 2 or d-dimer (p = 0.667 and p = 0.884, respectively) and no statistically significant treatment sequence or period effects.

Conclusion

A COC containing 0.03 mg EE and 0.15 mg levonorgestrel and the novel Bayer patch have comparable influence on hemostatic endpoints. Both treatments were well-tolerated by subjects.

Effects of an ethinyl estradiol/gestodene transdermal contraceptive patch on the endometrium: a single-center, uncontrolled study

AIM

This study aims to investigate the effect of a transdermal contraceptive patch containing ethinyl estradiol and gestodene on endometrial proliferation over 1 year.

MATERIALS & METHODS

In this open-label, uncontrolled, Phase IIb study, women (aged 18-35 years) used the patch for 13 cycles of 28 days. The primary variable was histologic endometrial effects at cycle 13. Secondary objectives included contraceptive efficacy and safety.

RESULTS

Overall, 89 women were treated. At all visits, endometrial biopsies were devoid of any abnormalities. One woman became pregnant. The patch was well tolerated, with no safety concerns.

CONCLUSION

The ethinyl estradiol and gestodene patch had an endometrial effect consistent with suppression of endometrial proliferation in most patients. No endometrial abnormalities or other concerns were reported; compliance was good.

Prescribing preferences and personal experience of female gynaecologists in Germany and Austria regarding use of extended-cycle oral contraceptives

OBJECTIVES

To investigate prescribing preferences and personal experience of female gynaecologists with extended-cycle use of combined oral contraceptives (COCs) in Germany and Austria.

METHODS

A questionnaire on prescribing patterns and personal experience with extended COC regimens was delivered to female gynaecologists practising in Germany and Austria.

RESULTS

Of 2,500 delivered questionnaires, 1,113 were returned. After exclusion of 22 invalid questionnaires, the remaining 1,091 (43.6% of delivered questionnaires) remained eligible for analysis and were considered as the full analysis set (100%). Nearly all gynaecologists (97%) reported prescription of extended-cycle regimens to their patients, independent of their personal experience as users. The main medical reasons for prescription were cycle-related headache (93.8%), dysmenorrhoea (88.2%), cycle-related complaints (74.5%), and hypermenorrhoea (70.9%). In total, 863 gynaecologists had personally used COCs, 321 (37.2%) in extended-cycle regimen. The most commonly employed combinations were 30 μg ethinylestradiol (EE) + 2 mg dienogest (n = 114; 37.5%) and 30 μg EE + 3 mg drospirenone (n = 69; 22.7%).

CONCLUSIONS

Although considered off-label use, extended-cycle use of COCs is widely prescribed and personally used by German and Austrian female gynaecologists. The lack of personal experience with extended-cycle use does not impair the prescribing habit of gynaecologists with regard to extended-cycle regimens.

Continuous oral contraceptives: are bleeding patterns dependent on the hormones given?

OBJECTIVE

To estimate whether progestin type or estrogen dose influences bleeding patterns, adverse effects, or satisfaction with combined oral contraceptives dosed continuously.

METHODS

This was a randomized, double blind, 4-arm active treatment study. Subjects received either 100 microg levonorgestrel/20 microg ethinyl estradiol (E2) (20LNG group), 100 microg levonorgestrel/30 microg ethinyl E2 (30LNG group), 1,000 microg norethindrone acetate/20 microg ethinyl E2 (20NETA group), or 1,000 microg norethindrone acetate/30 microg ethinyl E2 (30NETA group) for 180 days. Subjects logged bleeding events and adverse effects on a daily menstrual calendar. An exit survey measured satisfaction with bleeding patterns.

RESULTS

One hundred thirty-nine women were enrolled. Patients in the 20NETA and 30NETA arms had significantly more days of amenorrhea than the 30LNG arm in the second 90 days (P < .008). The 30LNG group reported more spotting days than the 20NETA group over the entire study period (P < .008) and the 30NETA group for the second 90 days (P < .008). Only a small number of bleeding days were reported with no differences between groups. No differences in adverse effects between groups were found. Women in the 30LNG arm reported lower levels of satisfaction with their bleeding patterns than the other groups (30LNG compared with 20NETA, P = .01; 30LNG compared with 30NETA, P = .001).

CONCLUSION

The addition of 10 microg of ethinyl E2 to a 20 microg ethinyl E2 pill containing levonorgestrel or norethindrone acetate did not improve bleeding patterns. During continuous dosing, the use of oral contraceptives containing 1,000 microg norethindrone acetate resulted in more days of amenorrhea and fewer days of spotting than preparations containing 100 microg levonorgestrel.

LEVEL OF EVIDENCE

I.

Contraception for Women with Chronic Medical Conditions

Chronic medical conditions can complicate maternal and fetal health during pregnancy, making unintended or mistimed pregnancy problematic. The use of highly effective reversible contraceptives is important for women with health issues, yet sometimes those same illnesses make the contraceptives themselves less effective or less safe. We review the evidence surrounding contraceptive use by women with six common medical conditions: systemic lupus erythematosus, diabetes mellitus, anticonvulsant use for epilepsy or mood disorder, HIV infection, migraine headache, and obesity. In some instances it is not possible to make a risk-free contraceptive choice, yet pregnancy may be even riskier. Good clinical judgment and patient counseling must be exercised.

Follicular growth during contraceptive pill or vaginal ring treatment depends on the day of ovulation in the pretreatment cycle

BACKGROUND

The aim of this study was to investigate whether the day of ovulation and the duration of a pretreatment cycle were related to the degree of follicular growth during subsequent contraceptive treatment.

METHODS

This randomized, open-label study was performed in 40 healthy female volunteers, who were randomized by a computer-generated list after stratification for the ovulation day in a pretreatment cycle. They received two cycles of NuvaRing (21 subjects) or a combined oral contraceptive (COC) containing 30 microg ethinylestradiol and 150 microg levonorgestrel (19 subjects). Follicular diameter and serum hormone concentrations (FSH, LH, 17beta-estradiol, progesterone) were measured every third day. Data from treatment day 20 onwards were used for analysis.

RESULTS

In the NuvaRing users, subjects with short cycles and early ovulations in the pretreatment cycle developed larger follicles during treatment than subjects with longer cycles and late ovulations. In the COC users, subjects with early ovulations in the pretreatment cycle developed larger follicles during treatment.

CONCLUSIONS

The degree of follicular growth during treatment with a combined hormonal contraceptive is influenced by the duration of the pretreatment cycle and particularly by the duration of the follicular phase.

Long-Cycle Treatment with Oral Contraceptives

The conventional regimen of oral contraceptive (OC) use mimics the natural cycles by causing regular withdrawal bleeding, which can be avoided by omission of the hormone-free interval of 7 days. Consequently, long-cycle regimens with continuous administration of OCs for 3 or 6 months followed by a hormone-free interval of 7 days may reduce the frequency of menstruations and cycle-dependent complaints. Surveys have revealed that, despite a higher rate of irregular bleeding, the majority of women prefer the long-cycle regimen to the conventional OC regimen with regular bleeds every 4 weeks because it may improve quality of life. As this regimen increases the contraceptive efficacy to a large degree, continuous treatment with OCs may prevent unintended pregnancies in women who miss a pill or are concomitantly treated with drugs that are able to impair the efficacy of OCs. Postponement of withdrawal bleeding may also reduce or prevent menses-associated disorders such as hypermenorrhoea and dysmenorrhoea, and have beneficial effects in patients with haemorrhagic diathesis, endometriosis, uterine leiomyoma and polycystic ovary syndrome. Continuous use of OCs prevents the cyclic fluctuations of serum levels of ethinylestradiol and progestogen and, hence, the cyclic variations of metabolic serum parameters. Although the long-cycle regimen is initially associated with an elevated rate of irregular bleeding, the total number of bleeding days that require sanitary product protection is lower than during conventional OC treatment. Many physicians tend to prescribe extended OC cycles for postponement of menstruation or reduction of frequency of regular bleeding. This review summarises and examines the available data on OC long-cycle regimens. The data suggest that the rate of treatment-related side effects with OCs according to the long-cycle regimen is similar to that of conventional OC regimens. However, clinical trials are necessary to assess the impact of long-term OC long cycles on safety, particularly the risk of cancer and cardiovascular disease, and fertility after discontinuation of treatment.

Comparative absorption and variability in absorption of estradiol from a transdermal gel and a novel matrix-type transdermal patch

OBJECTIVES

To compare the absorption of estradiol from a transdermal gel and a novel matrix-type patch and to study the variability in absorption.

METHODS

Twenty-four healthy postmenopausal women were treated in an open, randomized, cross-over study for 18 days with 1.0 mg estradiol daily as a transdermal gel and a transdermal patch releasing estradiol 50 microg/24 h without a wash-out between the periods. Venous blood samples for estradiol pharmacokinetics were taken on the 15th and 18th study days of the gel period and during the 15th-18th study days during the patch period.

RESULTS

There was no significant difference in peak estradiol level or area under the estradiol time-concentration curve between the gel and the patch. However, trough estradiol concentration was significantly lower and fluctuation higher with the patch. Estradiol time-concentration curves on the 15th and 18th study days with the gel were almost superimposable. A significant difference was observed in peak estradiol levels, whereas area under the curve or trough estradiol level did not differ between the 15th and 18th study days with the gel. Inter- and intra-individual coefficients of variability were around 30% for peak estradiol level and area under the curve, except for the intra-individual coefficient of variability for area under the curve (21%) for the gel. The total coefficient of variability for area under the curve was 35% for the gel and 39% for the patch.

CONCLUSIONS

A daily 1.0 mg estradiol dose as a transdermal gel seems to correspond with a matrix-type patch releasing 50 microg estradiol daily in the extent of estradiol absorption. High variability was associated with both treatments, and both the variabilities within and between the subjects were high with the gel. Wider than generally applied confidence limits should be applied for bioequivalence testing of transdermal estradiol formulations.

Evaluation of the genetic component of variability in CYP3A4 activity: a repeated drug administration method

The CYP3A4 enzyme contributes to the disposition of more than 60 therapeutically important drugs and displays marked person-to-person variability of the catalytic function. However, the extent of genetic contribution to variability in CYP3A4 activity remains elusive. Recently, we showed that a comparison of between- (SDb2) and within-person (SDW2) variances provides an estimate of the genetic component of variability in drug disposition. The aim of the present analysis was to assess the genetic control of CYP3A4 activity in vivo. A computerized literature search was conducted covering 1966 to September 1999 to identify studies reporting repeated administration of CYP3A4 substrates. The genetic contribution (rGC) to disposition of each CYP3A4 substrate was obtained by the formula (SDb2-SDW2)/SDb2. The rGC values approaching 1.0, point to overwhelming genetic control, whereas those close to zero suggest that environmental factors dominate. A total of 16 studies with 10 different CYP3A4 substrates were identified (n = 161 subjects). The rGC for hepatic CYP3A4 activity as measured by midazolam plasma clearance or the erythromycin breath test was 0.96 (0.92-0.98) (95% Cl) and 0.89 (0.65-0.98), respectively (P < 0.05). The point estimates of rGC for composite (hepatic + intestinal) CYP3A4 activity measured after oral administration of cyclosporine, ethinylestradiol, ethylmorphine, nifedipine and nitrendipine, ranged from 0.66-0.98 (median: 0.83) (P < 0.05). Cyclosporine data suggested a higher genetic control of CYP3A4 at night than during the day. These data indicate that further molecular genetic investigations are warranted to identify genetic variants at CYP3A4 or elsewhere in the genome which contribute to regulation of CYP3A4 activity.

Effects of progestogens on haemostasis

Epidemiological data suggested an involvement of the progestogen component in the pathomechanism of venous and arterial diseases during intake of oral contraceptives. The influence of progestogens on haemostasis parameters depend on type and dose of the progestogen, the presence of an estrogen, the route of application, and the duration of use. Treatment of women with progestogen-only preparations caused only minor effects on coagulation and fibrinolysis. Similarly, during hormone replacement therapy with natural estrogens, the additional application of progestogens induced no unfavourable changes on haemostasis. In contrast, the use of ovulation inhibitors resulted in an acceleration of coagulation and fibrinolysis. This is primarily induced by the marked action of ethinylestradiol on hepatic and vascular function. Progestogens with androgenic properties may counteract the estrogen-induced changes in the hepatic synthesis of platelet aggregation and readiness for coagulation. Estrogen and progesterone receptors are localized in endothelial and smooth muscle cells of the vessel wall, but there are differences in the response of veins and arteries to sex steroids. Estrogens and progestogens may influence collagen and elastin synthesis, and the release of vasoactive compounds and of factors controlling fibrinolysis from endothelium. In veins, progestogens may increase distensibility and capacitance resulting in a decreased blood flow. In predisposed women, this may lead to venous stasis and thrombosis. In arteries, progestogens may act as vasoconstrictors, and may enhance vasospasms at sites of injured endothelium which finally may lead to ischemic diseases.

The combined oral contraceptive pill: what advice should we give when tablets are missed?

Despite more than 30 years' experience with the pill, being by far the most thoroughly studied drug ever, we must conclude that there still is a remarkable paucity of data that would allow us to assess unambiguously its margins of efficacy. The physiological studies on which we must rely encompass limited numbers of subjects and are unlikely to include sufficient representatives of the vulnerable minority of women that really matter. Even though we realise that this vulnerable minority is there, we still cannot do better than to hypothesise about their characteristics, let alone identify them in advance. This lack of knowledge has contributed to the existence of diverging views on how to advise the general population of pill takers about missed tablets. Against this background, we felt there was a need to make an inventory of the existing data and, subsequently, to incorporate them in advice that in our opinion is most appropriate in the current state of knowledge. We have come to the conclusion, in contrast to what is often held, that it is not the number of tablets missed, but rather the timing relative to the pill-free interval that determines the impact of noncompliance. We further conclude that shortening of the pill-free interval to five or six days could substantially improve the efficacy of the pill: at the low doses currently used in oral contraceptives the total steroid burden would not be substantially increased, while still allowing withdrawal bleeding to occur.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of a biphasic desogestrel-containing oral contraceptive on carbohydrate metabolism and various hormonal parameters

During 6 cycles of treatment of 19 women, the effect of a low-dose biphasic oral contraceptive containing 40 micrograms ethinylestradiol + 25 micrograms desogestrel (7 tablets) and 30 micrograms ethinylestradiol + 125 micrograms desogestrel (15 tablets) on various hormonal parameters and glucose metabolism was compared with the values of the pre- and post-treatment cycle. There was a profound reduction in gonadotropin secretion and ovarian steroid synthesis. The serum levels of testosterone were reduced by 35%, free testosterone by 55%, and DHEA-S by 30%. Cortisol increased by 100%, SHBG by 250%, and TBG by 60%, while FT3 and FT4 were only marginally influenced. Fasting levels of glucose and insulin did not change significantly, but the glucose load revealed a slight impairment of glucose tolerance. Three weeks after termination of pill intake, the various parameters returned to pretreatment levels, except for SHBG and TBG which were still elevated by 20 to 30%. The results demonstrate a marked preponderance of the effect of the estrogen component, a reliable inhibition of ovulation and very good cycle control during treatment with the biphasic formulation.