Reactive oxygen intermediates and reactive nitrogen intermediates in copper intrauterine device users

The mechanism of action of copper in copper intrauterine devices (Cu IUD) as an antimicrobial agent is not well understood. Copper and iron are supposed to be responsible for release of reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI), which are very active in the presence of infection. The copper in a copper IUD could be responsible for limiting pelvic inflammatory disease. The present study was composed of 20 IUD seekers in whom ROI and RNI were studied before insertion of Cu IUD and then at 1, 4, and 12 weeks afterward. ROI showed a rise after insertion, whereas RNI showed a steady decline. Hence, it is presumed that the rise in ROI could be responsible for both the bactericidal effect of Cu IUD and also for the fall in RNI.

Normalized activated protein C ratio itself not associated with increased risk of venous thromboembolism

Recently, discussions focused on the question whether acquired activated (APC) resistance is a clue to the observed association between venous thromboembolism (VTE) risk and oral contraceptive (OC) use, especially with the so-called third-generation OC. The objective of our study was to check the validity of acquired APC resistance regarding VTE risk in a case-control study. Sixty-seven women with confirmed VTE diagnosis (n = 67) were consecutively ascertained in primary health care settings, interviewed and blood samples taken (at the earliest 6 months after VTE). Cases were age-matched to 290 population controls. Acquired APC resistance was measured as normalized APC ratio (APCRN). The effect of APC on tissue factor initiated thrombin generation was measured in plasma using alpha 2-macroglobulin attached thrombin activity as an endpoint. Higher risk (odds) ratio with 95% CI) of VTE for carriers of heterozygote Factor V Leiden mutation was confirmed [OR = 2.72 (CI:1.51-4.92)]. However, there is no association between VTE and the level of APCRN OR 0.65 (CI:0.35-1.22). We conclude that acquired APC resistance, measured with a tissue factor initiated test, is unlikely to have a direct association to the clinical outcome of venous thromboembolism.

Can oral contraceptive steroids influence the elimination of nifedipine and its primary pryidine metabolite in humans?

OBJECTIVE

To investigate the influence of oral contraceptives on cytochrome P450 3A4 (P450NF) activity.

METHODS

In 23 healthy women, the pharmacokinetics of nifedipine and its main metabolite dehydronifedipine in plasma were assessed after a single oral dose, prior to and after intake of one of two oral contraceptive formulations, one containing 2 mg dienogest and 0.03 mg ethinylestradiol (group A) and the other containing 0.125 mg levonorgestrel and 0.03 mg ethinylestradiol (group B).

RESULTS

While the intake of two oral contraceptives for 21 days did not influence the plasma concentration-time curve of unchanged nifedipine, mean AUC0-23.5 h and the mean Cmax values of dehydronifedipine were significantly lower in both groups tested/(24% in group A and 25% in group B). This observation may indicate a reduced formation rate of metabolites and reflects an inhibition of cytochrome P450 3A4 activity. The activation of the same or other metabolic degradation mechanism(s) could explain this result.

CONCLUSION

The investigation presented demonstrates the importance of metabolite measurement when in vivo studies are undertaken to investigate different influences on drug metabolizing ability.

Effect of desogestrel-containing oral contraceptives on vascular reactivity and catecholamine levels

The modifications induced by new oral contraceptives (OC) on blood pressure, great vessel vascular reactivity by color Doppler, and catecholamine levels were investigated. Young healthy women not taking OC (n = 22; controls) or receiving, for > or = 6 months, OC containing desogestrel with either 30 micrograms (n = 14) or 20 micrograms of EE (n = 8) were enrolled. Blood pressure measured at rest in supine position was similar between controls and OC users. The pulsatility index (PI), an indirect index of resistance to blood flow, of axillary artery was significantly higher (p < 0.05) in 30 micrograms than in 20 micrograms EE OC users or controls. A similar trend, albeit not significant, was observed for the internal carotid artery PI. Norepinephrine (p < 0.01) and dopamine (p < 0.05) but not epinephrine levels, were lower in 30 micrograms EE OC users than in 20 micrograms EE OC users or controls. Thus, both 20 micrograms and 30 micrograms EE OC had no negative effect on blood pressure, but the 30 micrograms EE OC tended to increase great vessel resistance to blood flow, independently of catecholamine levels.

Effect of two oral contraceptives containing ethinyl estradiol and gestodene or norgestimate on different lipid and lipoprotein parameters

The effect of a triphasic oral contraceptive containing ethinyl estradiol and gestodene (EE/GSD) on various lipid and lipoprotein parameters was compared with that of a monophasic formulation containing 35 micrograms ethinyl estradiol and 250 micrograms norgestimate (EE/NGM). Blood samples were collected from 46 women on days 2, 11, and 21 of the preceding control cycle and of the third, sixth, and twelfth treatment cycles. There was no significant difference between formulations with regard to the influence on any measured parameter. As compared with controls, a significant increase was observed in the plasma levels of total triglycerides (24-78%), total phospholipids (7-20%), very low density lipoprotein (VLDL) triglycerides (61-76%), VLDL-phospholipids (14-60%), low density lipoprotein (LDL) triglycerides (8-35%), LDL-phospholipids (28-30%), high density lipoprotein (HDL) cholesterol (8-16%), HDL 3-cholesterol (11-20%), HDL-triglycerides (17-66%), HDL-phospholipids, HDL 3-phospholipids (7-11%), apolipoprotein (apo) A-I (5-20%) and apo A-II (10-40%) during treatment with both formulations. In contrast, the LDL-cholesterol levels were significantly decreased. These changes in lipid metabolism appear to reflect a predominance of the effect of the estrogen component. The results indicate that both low dose oral contraceptives containing different progestins and different amounts of EE do not exert a deleterious effect on lipoprotein metabolism, as high HDL-cholesterol and low LDL-cholesterol levels are known as low risk factors of cardiovascular disease. In contrast to endogenous hypertriglyceridemia, an EE-induced rise in triglyceride levels does not appear to increase cardiovascular risk if LDL is not increased.

A randomized cross-over study on various hormonal parameters of two triphasic oral contraceptives

The effect of two triphasic oral contraceptives (Triquilar [TRQ] and Trisiston [TRS]) containing ethinyl estradiol (EE) and levonorgestrel (LNG) on various hormonal parameters was investigated in 26 women during a cross-over study. TRS consisted of 0.03 mg EE + 0.05 mg LNG (six tablets), 0.04 mg EE + 0.075 mg LNG (six tablets), and 0.03 mg EE + 0.15 mg LNG (nine tablets), whereas TRQ was different in the second phase (five tablets) and third phase (10 tablets). Blood samples were taken on days 6, 11, 21, and 28 of the control and washout cycles and the third treatment cycle. Both formulations inhibited ovulation reliably and decreased the serum levels of gonadotropins, free testosterone, and dehydroepiandosterone sulfate in a time-dependent manner, whereas estradiol and testosterone were already suppressed on day 6, indicating a direct suppressive effect on ovarian steroid synthesis. Prolactin, which rose sporadically in some women, was not significantly changed. In contrast, the levels of sex hormone binding globulin, corticosteroid binding globulin, and cortisol were significantly elevated by 100%. During the hormone-free interval of 7 days, all parameters returned at least partly to baseline. There was no significant difference between the effects of both formulations. The results suggest the possibility of a direct inhibitory effect of contraceptive steroids on ovarian steroid synthesis.

The effects on mortality of the use of combined oral contraceptives

OBJECTIVE

To assess, using a computerised model, the effects on mortality of the use of combined oral contraceptives (COCs).

DESIGN

Two hypothetical cohorts of one million women each, identical except for their use of contraception. The impact of COC use was explored by applying, to each cohort, death rates which were adjusted according to a series of assumptions about the risks associated with COC use. The model also explored the effects of a number of different patterns of COC use.

SETTINGS AND SUBJECTS

Women aged 16, followed through to ages 50 and 75, exposed to 1994 UK death rates.

MAIN OUTCOME MEASURES

Numbers of deaths from various cancers and cardiovascular diseases attributable to COC use.

RESULTS

Based on the standard pattern of use, there were 1.7 per cent more deaths in the COC cohort to age 50. The important effects on mortality of different patterns of use and of different assumptions about risks in ex-users were illustrated.

CONCLUSIONS

The results confirm the findings of earlier work and provide some reassurance about the likely adverse effects of COC use.

Gabapentin does not interact with a contraceptive regimen of norethindrone acetate and ethinyl estradiol

Anticonvulsants that induce hepatic metabolism increase clearance of oral contraceptive hormones and thereby cause contraceptive failure. Gabapentin is not metabolized in humans and has little liability for causing metabolic-based drug-drug interactions. In healthy women receiving 2.5 mg norethindrone acetate and 50 microg ethinyl estradiol daily for three consecutive menstrual cycles, concurrent gabapentin administration did not alter the steady-state pharmacokinetics of either hormone. Thus, gabapentin is unlikely to cause contraceptive failure.

Metabolic interrelationships, cardiovascular disease, and sex steroids

Future studies of the pharmacodynamics of oral contraceptives should encompass interactions between various areas of physiology rather than concentrate on single metabolic processes. Changes in one area of metabolism may affect other areas. Insulin plays a central role in metabolic control and, in addition to profound effects on carbohydrate and lipid metabolism, also affects the hematological system. Insulin has been proposed as a major physiological regulator of plasminogen activator inhibitor, and hyperinsulinemia is associated with increased blood coagulability and decreased fibrinoloysis. There is a close relationship between insulin and triglyceride metabolism, and this may affect factor VII activity in blood. There are many interactions between lipid metabolism and hematological factors. The apoprotein of lipoprotein (a) is structurally similar to plasminogen. Tissue factor pathway inhibitor, a regulator of coagulation, circulates in blood bound to LDL and HDL. Some fatty acids may act as a contact surface for activation of hematological factors. Dietary factors also need to be considered. Changes not only in the quantity but also in the composition of dietary fat influence lipid metabolism and also blood levels of a number of hematological factors. Other aspects of pharmacodynamic studies that require consideration and other factors that affect metabolic interrelationships are discussed.

Effects of oral contraceptives on free fatty acid metabolism in women

These studies examined whether women using oral contraceptives have abnormalities in free fatty acid (FFA) metabolism compared with women not using oral contraceptives. Plasma palmitate kinetics ([3H]palmitate) were measured at rest, following glucose ingestion, and during epinephrine infusion in 13 oral contraceptive users and 13 matched women not using oral contraceptives. Oral contraceptive users had significantly greater plasma triglyceride concentrations and glucose responses to oral glucose tolerance testing. No differences in basal (2.1 +/- 0.1 v 1.8 +/- 0.2 micromol x kg fat-free mass x FFM(-1) x min[-1]), glucose-suppressed (0.6 +/- 0.1 v 0.5 +/- 0.1 micromol x kg FFM(-1) x min[-1]), or epinephrine-stimulated (3.3 +/- 0.1 v 3.6 +/- 0.2 micromol x kg FFM(-1) x min[-1]) palmitate flux were detected between women using and not using oral contraceptives. The respiratory quotient (RQ) also was not different between groups. We conclude that the increase in plasma triglycerides and the mild glucose intolerance seen with oral contraceptive use is not associated with significant abnormalities of FFA metabolism.

Safety evaluation of modern oral contraceptives. Effects on lipoprotein and carbohydrate metabolism

An ideal oral contraceptive should either be neutral as regards metabolic risk markers for arterial disease or should only change them in directions that would be expected to reduce risk. Depending on their formulation, modern low dose oral contraceptives affect systems such as hemostasis, lipoprotein metabolism, and glucose and insulin metabolism. Some of these actions would be expected to decrease the risk of arterial disease and some might be expected to increase risk. Despite these associations there is at present no justification for widespread metabolic screening as a strategy to further improve oral contraceptive safety. Recent developments in atherosclerosis research support the introduction of progestogens such as desogestrel that allow the estrogenic increase in high density lipoprotein levels to persist and that may cause less of an elevation in plasma insulin responses to glucose. The predicted benefit of these formulations in terms of arterial disease is difficult to demonstrate in an epidemiological setting because of the rarity of the disease in young women.

The risks of venous thromboembolic disease among German women using oral contraceptives: a database study

This study investigated the risk of venous thromboembolic disease (VTE) between second and third generation combined oral contraceptives, using the German MediPlus database of patient records. Women studied included 42 patients between the ages of 18 and 49 years, with a diagnosis of VTE treated with an anticoagulant, who were exposed to an oral contraceptive (OC). Four controls per patient (168), matched by year of birth and exposure to an OC on the even day, were identified. More women were users of second generation than third generation OC, and none were using progestogen-only pills. There was no significant difference between patients and control subjects with respect to the type of OC used on the event day (unadjusted odds ratio for third versus second generation users was 0.77; 95% confidence interval [CI] 0.38-1.57). There was no significant age difference between second and third generation users among patients or control subjects. Between January 1 and the event date, there was no significant difference between the patients and control subjects in terms of the number of oral contraceptive prescriptions, number of consultations for psychotherapeutic complaints, or mixed physical and psychotherapeutic consultations; however, patients did demonstrate significantly more consultations for purely physical complaints compared with control subjects (p < 0.0001). There were no significant consultation differences between patients with pulmonary emboli (n = 6) and other VTE patients (n = 36). No significant differences with respect to VTE risk between users of second and third generation oral contraceptives were found in this study. Consultations (physical) for patients were higher than for control subjects before the VTE event. If consultation rate relates to the general health status of a person, this might indicate that VTE risk is higher among women of poorer health, but that this is not related to the type of progestogen in the oral contraceptive that they use.

Dimeric inhibin serum values as markers of ovarian activity in pill-free intervals

Levels of inhibin A and B as well as other hormones in serum samples obtained during the pill-free interval in women taking combined oral contraceptives (OC) were measured to asses the extent of ovarian activity during that period. Type of pill and day of pill-free interval were recorded during routine gynecologic check-ups, if patients were in the pill-free period and had taken their pills regularly in the previous cycle. In addition to inhibin A and B, serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), and progesterone were also quantified. Inhibin B levels rise significantly in parallel with rising levels of FSH, LH, and E2. Progesterone levels were completely suppressed and inhibin A levels rose slightly but insignificantly. Inhibins are sensitive biochemical markers of ovarian activity in pill-free intervals.

Factor V Leiden mutation and the risks for thromboembolic disease: a clinical perspective

BACKGROUND

A single point mutation in the gene coding for coagulation factor V results in a form of factor Va that is resistant to degradation by activated protein C and leads to a relative hypercoagulable state. This mutation, factor V Leiden, is found in 4% to 6% of the U.S. population.

PURPOSE

To review clinical data on factor V Leiden mutation, with emphasis on prevalence of and risks for thromboembolism and implications for screening and management.

DATA SOURCES

A MEDLINE search of the English-language literature published between 1993 and April 1997 and an extensive bibliography review.

STUDY SELECTION

Case-control and prospective cohort studies were reviewed if clinical features of thromboembolic disease associated with factor V Leiden mutation or resistance to activated protein C were presented. Original research articles were reviewed if they addressed the identification of the laboratory abnormality of activated protein C or factor V Leiden mutation. Case reports and case series were reviewed when no analytic data were available.

DATA EXTRACTION

Review of the identified articles.

DATA SYNTHESIS

Factor V Leiden mutation is associated with three- to sixfold increases in risks for primary and recurrent venous thromboembolism, especially in patients without transient risk factors, such as surgery or trauma. Risks for venous thromboembolism in genetically affected persons are substantially higher among patients with coexistent predispositions for thrombosis, such as advanced age, use of oral contraceptives, hyperhomocystinemia, and deficiencies of protein C and protein S. Factor V Leiden mutation does not seem to increase risks for arterial thrombosis. Whether patients with the mutation would benefit from more intense or prolonged anticoagulation is unknown.

CONCLUSIONS

The presence of factor V Leiden mutation predisposes patients to venous thromboembolism, but screening for this disorder is of uncertain utility. Decisions about whether to screen for the mutation will depend on the results of clinical trials designed to evaluate the benefit-to-risk ratio of long-term anticoagulation in the secondary prevention of venous thromboembolism in patients with resistance to activated protein C.

Haemostatic changes and the oral contraceptive pill

Oral contraceptives have been linked to an increased incidence of thrombovascular disease. This may be mediated by their effects on the haemostatic system. An increase in the activity of coagulation Factors VII, X and fibrinogen occur with pill usage. Increased Factor VII levels are dependent on both the oestrogen and progestogen component of the oral contraceptive. A reduction in antithrombin III levels has also been observed in some but not all studies. Increased fibrinolysis has also been shown in oral contraceptive users which should balance the changes in the coagulation pathway. The increase in fibrinolytic potential is thought to be due to a decrease in the levels of plasminogen activator inhibitor I combined with an increase in the levels of plasminogen; tissue plasminogen activator antigen is decreased in most studies. The increased levels of endpoints of coagulation and fibrinolysis in pill users indicate that enhanced activity of both systems is occurring in vivo. The increased coagulation activity appears to be balanced by the rise in fibrinolytic activity, so preserving haemostatic balance. Enhanced platelet activity has also been shown in women taking oral contraceptives. Thrombus formation can result, however, when local vascular wall damage exists, or when other risk factors for thrombo-embolism, such as older age and smoking, coexist and create a local activation resulting in a thrombus. In these situations, the small differences in levels of coagulation factors in women taking different oral contraceptive formulations may be important. Pills containing the lowest doses of oestrogen (20 micrograms ethinyloestradiol) have shown the least changes in haemostatic factors. The progestogen component of the pill modifies the effect of oestrogen on the haemostatic system.

The pill and thrombosis: epidemiological considerations

The oral contraceptive is one of the most widely taken medications in the healthy population. The clinically important side-effects are venous and arterial thrombosis. Accurate estimates of incidence of these side-effects have proven to be difficult. Diagnostic modalities for thrombosis are sub-optimal and the problems of study methodology, primarily a reliance on non-experimental studies, have limited the ability to define the attributable risk of thrombosis from oral contraception. Pharmacological attempts to further decrease venous thrombotic side-effects by the use of third-generation oral contraceptives have failed. This places a greater emphasis on the selection of patients to help avoid giving medication to those patients with underlying thrombotic risk factors. An example of this approach has been the clear confirmation of the adverse effects of cigarette smoking and arterial thrombosis in oral contraceptive users. At the biochemical level, hypercoagulability testing may be useful. Screening for high-frequency prothrombotic abnormalities, such as the Factor V Leiden genotype, represents an important addition to the process by which patients are selected, and may be prototypic of further advances.

A comparative randomized trial on the impact of two low-dose oral contraceptives on ovarian activity, cervical permeability, and endometrial receptivity

In a double-blind randomized study, the suppression of ovarian activity and anti-conceptive effects on the cervix and endometrium were assessed during administration of two low-dose monophasic oral contraceptives (20 micrograms ethinyl estradiol [EE], 500 micrograms norethisterone--Eve 20 [Grünenthal, Aachen, Germany]; 20 micrograms EE, 150 micrograms desogestrel --Lovelle [Organon, Munich, Germany]). One hundred eighteen healthy women (ages: 18-35 years) were studied in 10 investigation centers during medication with either Eve 20 (n = 59) or Lovelle (n = 59). During three treatment cycles, ovarian activity was evaluated by sonographic determination of follicle-like structures (FLS) and by simultaneous assessment of serum endocrine profiles (gonadotropins LH and FSH, ovarian steroids estradiol [E2] and progesterone [P]). While on either treatment, no ovarian activity (as judged by no FLS and/or reduced sex steroid levels) was found in 90.8% (Eve 20) and 97.2% (Lovelle) of all investigated cycles. Follicular activity or cyst formation were detected in 18 of 173 cycles (Eve 20) and in 5 of 175 cycles (Lovelle), respectively. Gonadotropin levels were suppressed (LH < 6 IU/L, FSH < 8 IU/L) in most treatment cycles (Eve 20 76.6% vs. Lovelle: 84.8%). Serum E2 concentrations exceeding 0.1 nmol/L indicated residual follicular activity in 19.3% (Eve 20) versus 12.2% (Lovelle) of all cycles. An estimated by serum P levels over 5 nmol/L, ovulation had presumably occurred in 4.1% (Eve 20) versus 2.9% (Lovelle) of treatment cycles. However, when the sonographical and endocrinological data were combined, no ovulation was documented in any pill cycle. The quality and quantity of the cervical mucus was found to be minimal in the majority of women. Moreover, the endometrial layer was determined to be low by ultrasound during most pill cycles, indicating equally strong suppressive effects on endometrial receptivity by the two contraceptives. These observations suggest that ovarian activity is suppressed in the majority of cycles during use of low-dose contraceptives. This effect may mainly be medicated by pronounced suppression of serum gonadotropin levels. Strong anti-conceptive effects of these formulations on both cervical permeability and endometrial receptivity are additional factors ensuring the contraceptive efficacy of these formulations.

The effect of oral contraceptive agents on the basal metabolic rate of young women

The use of oral contraceptive agents by women may be a factor that contributes to the observed inter-individual variability in the BMR. We, therefore, measured the BMR, body build and composition in two groups of young women and also assessed their self-reported level of physical activity. One group had been using oral contraceptive agents for a period of 6 months or more (OCA, n 24), while the other group had never used oral contraceptives (NOCA, n 22). There were no significant differences in age, body build or composition. The absolute BMR in the groups were not significantly different when compared using an unpaired t test (OCA: 5841 (SD 471) v. NOCA: 5633 (SD 615) kJ/d). However, using an analysis of covariance, with either body weight or a combination of fat and fat free mass as covariates, the OCA group had a BMR almost 5% higher than that of the NOCA group (OCA: 5871 v. NOCA: 5601 kJ/d; P = 0.002). When those subjects with high self-reported levels of physical activity were excluded, the difference in BMR between the two groups persisted (P = 0.001). An ANOVA of oral contraceptives use and phase of menstrual cycle showed significant differences in BMR with use of oral contraceptives (P = 0.004) but no difference in BMR between phases of the menstrual cycle. In conclusion, the use of oral contraceptive agents deserves consideration when conducting and analysing data from studies on energy metabolism in young women, as it results in a significantly higher BMR.

Estrogen and progestin components of oral contraceptives: relationship to vascular disease

Recently, new information has been published about: a) the relationship between combination oral contraceptives (OCs), estrogen dose, cigarette smoking, and the risk of myocardial infarction (MI) and stroke; and b) the effect of different progestins on the risk of venous thromboembolism (VTE). We review the epidemiologic data. Regardless of age, in the absence of smoking, use of sub-50 micrograms OCs is not associated with any meaningful increase in risk of MI or stroke. If the small, statistically nonsignificant elevations in risk for these diseases are assumed (for the sake of argument) to be causal, then the incidence of MI and stroke associated with use of OCs containing less than 50 micrograms ethinyl estradiol (EE) would be approximately 2 per 100,000 per year. For women less than 35 years of age who do not smoke or do not have a history of hypertension, the risk would be even lower. Any woman over the age of 35 who smokes should be advised to use a non-estrogen or nonhormonal contraceptive. There are now two reports, from jick et al. and Lewis et al., that demonstrate that the relative risk of MI is certainly no greater for users of OCs containing desogestrel or gestodene than for users of OCs containing older progestins. In fact, both show reduced relative risks for the newer progestins compared to the older ones. With respect to progestins, four recent epidemiologic studies have indicated a twofold increased risk of nonfatal VTE with use of OCs containing desogestrel or gestodene compared with levonorgestrel. A fifth report, which showed an increased relative risk for norgestimate, is based on use among only 19 cases and 31 controls and is not statistically significant. As the authors themselves caution and as subsequent follow-up analyses and editorials conclude, these studies do not provide evidence for a cause-and-effect relationship between OCs containing desogestrel or gestodene, and VTE. The recommendation with respect to desogestrel- and gestodene-containing OCs is that no change in prescribing practices is warranted for either current or new-start patients. There is a growing body of evidence demonstrating that OCs containing 30 or 35 micrograms of EE have lower risks of MI, stroke, and VTE than higher dose OCs. However, there is no epidemiologic study that demonstrates a greater risk of vascular events among women using OCs containing 30 or 35 micrograms EE compared with preparations containing 20 micrograms EE. Users of sub-50 micrograms OCs of any age have no clinically meaningful increase in incidence of MI or stroke compared with non-OC users. This is also true for smokers under the age of 35 years who use OCs. However, smokers over the age of 35 years who use OCs still have an unacceptably high incidence rate of MI and stroke and should not use combination OCs. Sub-50 micrograms OCs of all types are associated with a small excess risk of VTE, about 15 per 100,000 events per year. Until there is biologic explanation of the twofold greater risk of VTE in users of OCs containing desogestrel or gestodene compared with users of those containing older progestins, this association should not be accepted as one of cause and effect.

Influence of oral contraceptive use and cigarette smoking, alone and together, on antipyrine pharmacokinetics

The pharmacokinetics of antipyrine following a single 1-g intravenous dose was determined in 63 healthy women. Subjects were divided into 4 groups as follows: 1) cigarette smokers using low-dose oral contraceptives (n = 15); 2) nonsmokers using low-dose oral contraceptives (n = 12); 3) cigarette smokers not using oral contraceptives (n = 10); and 4) controls, neither cigarette smokers nor oral contraceptive users. Plasma antipyrine concentrations during 24 to 48 hours after dosage were measured by high-performance liquid chromatography. Mean kinetic variables in the nonsmoking, non-oral contraceptive using control group were: volume of distribution, 37.7 L; elimination half-life, 13.2 hours; and clearance, 34.4 mL/min. In cigarette smoking, non-oral contraceptive users versus controls, elimination half-life was reduced (8.0 vs. 13.2 hours, P < 0.05) and clearance increased (56.0 vs. 34.4 mL/min, P < 0.05). In nonsmoker oral contraceptive users, the reverse was true (elimination half-life was significantly increased: 16.6 vs. 13.2 hours, P < 0.05; and clearance was significantly decreased: 24.8 vs. 34.4 mL/min, P < 0.05). In smokers who were using oral contraceptives, values were not significantly different from controls (elimination half-life, 11.2 hours; clearance, 39.5 mL/min). Volume of distribution did not differ among the four groups. Thus the opposing effects on antipyrine clearance of the induction of metabolism by cigarette smoking and the inhibition due to low dose oral contraceptive use in effect negate each other when combined in humans.

Mechanisms of action of intrauterine devices

The major effect of all intrauterine devices (IUD) is to induce a local inflammatory reaction in the endometrium whose cellular and humoral components are released into the uterine cavity. This inflammatory reaction has a variable effect on the reproductive strategy of the species studied. For example, this foreign body reaction can be localized within the uterus of rodents; and in farm animals it can have striking extrauterine effects. Thus, the action of IUDs in humans cannot be discerned from animals. In humans, copper ions released from Cu-IUDs enhance the inflammatory response and reach concentrations in the luminal fluids of the genital tract that are toxic for spermatozoa and embryos. In women using the IUD, the entire genital tract seems affected, at least in part, because of luminal transmission of the fluids that accumulates in the uterine lumen. This affects the function or viability of gametes, decreasing the rate of fertilization and lowering the chances of survival of any embryo that may be formed, even before it reaches the uterus. Studies on the recovery of eggs from women using IUDs and from women not using contraception show that embryos are formed in the tubes of IUD users at a much lower rate compared with nonusers. This is believed to be the major action of IUDs. Therefore, the common belief that the major mechanism of action of IUDs in women is through destruction of embryos in the uterus (i.e., abortion) is not supported by the available evidence. In Cu-IUD users, it is likely that few spermatozoa reach the distal segment of the fallopian tube, those that encounter an egg may be in poor condition. Thus, the few eggs that are fertilized have little chance for development and their possibility for survival in the altered tubal milieu become worse as they approach the uterine cavity.

Ovarian activity during regular oral contraceptive use

The aim of this study was to assess whether during regular OC use ovarian activity might lead to ovulation, as assessed by ultrasound (US) evaluation of follicular growth and blood levels of 17-beta-estradiol and progesterone. A total of 51 healthy women with normal menstrual cycles (28 +/- 3 days) and no gynecological symptoms were recruited. A total of 22 patients were given a triphasic OC pill containing 35 mg ethinyl estradiol (EE) and 50 mg desogestrel (DSG) in the first seven tablets; 30 mg EE and 100 mg DSG in tablets 8 to 14, and 30 mg EE and 150 mg DSG in tablets 15 to 21; 29 patients received one of two OC pills, both containing 20 mg EE plus 150 mg DSG (15 patients) or 75 mg of gestodene (14 patients). A total of 86 cycles were monitored: 51 during the 3rd-4th cycle and 35 during the 6th-8th cycle of OC treatment. Follicular-like structures were observed in nine patients. The frequency of follicular-like structures was similar during the 3rd-4th cycle (9%) and during the 6th-8th cycle (11%). There was no relationship between follicular growth and blood levels of E2 and progesterone, which always appeared suppressed. In conclusion, the results of this study suggest that during OC use (even with low dose of ethinyl estradiol), a little ovarian activity may be present without ovulation.

Lack of interaction between orlistat and oral contraceptives

OBJECTIVES

Orlistat, a potent and selective inhibitor of gastrointestinal lipases, is designed for the treatment of obesity. A double-blind, randomised, placebo-controlled, 2-way crossover study investigated the possible influence of orlistat on the ovulation-suppressing action of combination oral contraceptives (OC).

METHODS

After an 8-day run-in prior to the first of two consecutive menstrual cycles (Day 1 was the first day of menstruation), two groups of 10 healthy women, 20-27 years of age and on a stable regimen with OCs, received either 120 mg orlistat t.i.d. or placebo t.i.d. on Days 1-23 of the first cycle, and, separated by a placebo washout period on Days 24-28, the alternative treatment on Days 1-23 of the second cycle. In both cycles, serum luteinizing hormone (LH) was measured on Days 12-16 and progesterone on Days 12, 16, 19-23.

RESULTS

The geometric means of time averaged concentrations (Days 12-16 for LH and Days 19-23 for progesterone) in the cycles with orlistat and placebo, respectively, and the one-sided 95% confidence region for the mean in the cycle with orlistat were 1.92, 2.03 and < 2.23 IU 1-1 for LH and 0.147, 0.145 and < 0.176 micrograms 1-1 for progesterone. The one-sided 95% confidence region for the ratio (orlistat/placebo) of geometric means was < 1.06 for LH and < 1.11 for progesterone.

CONCLUSION

During normal ovulation the peak serum concentration of LH is above 30 IU 1-1 around Day 14 of the cycle, and that of progesterone exceeds 3 micrograms 1-1 around Day 21. The 95% confidence regions for the means, as well as all individual concentrations, were below these limits. It was concluded that orlistat did not influence the ovulation suppressing action of oral contraceptives.

The role of triphasic levonorgestrel in oral contraception: a review of metabolic and hemostatic effects

Epidemiological studies suggesting a possible association between the use of combined oral contraceptives and an increased risk of cardiovascular disease have led to extensive investigations into the effect of oral contraceptives on lipid and carbohydrate metabolism, and on hemostasis. Since this association was originally suggested, the steroid dose in oral contraceptives has been significantly reduced and new progestogens have been developed. Also, triphasic formulations have been introduced which offer a well-balanced estrogen/progestogen ratio, allowing a further reduction in the progestogen dose per cycle, and thus helping to minimize unwanted metabolic and hemostatic effects. The metabolic interactions of triphasic levonorgestrel, the first triphasic formulation to be introduced, have received particular attention. Lipid metabolism appears to be largely unaffected by triphasic levonorgestrel, most studies reporting no significant change in high- (HDL-C) or low-density lipoprotein-cholesterol (LDL-C) levels. Several studies have reported a decrease in the lipoprotein subfraction HDL2-C levels, but in most cases measurements of the LDL-C/HDL-C and apolipoprotein A-1/B ratios reveal no clinically significant effects. Concerning lipids, most studies suggest that triphasic levonorgestrel has less metabolic impact than the monophasic formulation. In common with all currently available oral contraceptives, triphasic levonorgestrel appears to have some effect on carbohydrate metabolism. The study results vary, however; some investigators have found an impairment of glucose tolerance, whereas others have not detected any significant effect. Compared with lipid and carbohydrate metabolism, fewer studies have investigated the effect of triphasic levonorgestrel on hemostasis. In common with all estrogen-containing oral contraceptives, levonorgestrel appears to stimulate some procoagulant activity, elevating the levels of factors VII and X, and fibrinogen. However, the effect of triphasic levonorgestrel appears to be balanced, with most studies reporting a corresponding increase in anti-coagulant-fibrinolytic activity. Although most of the studies reviewed here reported some statistically significant metabolic interactions, many authors comment that the changes are probably not clinically relevant in terms of an altered risk of cardiovascular disease. The true risk of vascular disease associated with modern low-dose oral contraceptives remains to be confirmed when sufficient epidemiological data eventually become available.

Blood pressure rhythm and endocrine functions in normotensive women on oral contraceptives

DESIGN AND METHODS

Twenty-four hour blood pressure profiles were determined by non-invasive ambulatory blood pressure measurements in young normotensive women during the follicular and luteal phases of the menstrual cycle. Forty women participated, 20 of whom were on oral contraceptives (ethinyl-ethylestradiol 0.03 mg + levonorgestrel 0.15 mg) and 20 of whom were age- and weight-matched control individuals not on oral contraceptives. Data on systolic and diastolic blood pressure and heart rate were analyzed in each case by linear and rhythm analysis. Urine was collected day and night on each occasion on which ambulatory blood pressure measurements were recorded.

RESULTS AND CONCLUSION

Daytime, night-time, and 24 h mean systolic and diastolic blood pressure and heart rate did not depend on the cycle phase. The nocturnal fall in blood pressure was preserved in both groups and during both phases. Rhythm analysis by partial Fourier series showed that, of 240 individual 24 h blood pressure profiles, only 12 (5%) did not exhibit a significant circadian rhythm. Linear and rhythm analyses revealed that during both phases of the menstrual cycle systolic and diastolic blood pressure were significantly higher throughout the 24 h, especially during the night, in women taking oral contraceptives. During both phases of the menstrual cycle urinary aldosterone excretion was significantly higher in women taking oral contraceptives. This increase could contribute to the night-time blood pressure elevations caused by oral contraceptives. The results suggest a modulating influence of sex steroids on the circadian blood pressure profile even in normotensive healthy volunteers.

[Pharmacology of oral contraceptives]

Oral contraceptives include two types of steroids; ethinyl-estradiol as the main estrogenic component which dose vary from 20 to 50 micrograms per tablet (mostly 30 to 35 micrograms) and progestins essentially derivatives of 19 nortestosterone. Derivatives of 19 norprogesterone such as nomegestrol acetate or ST 1435 are not used as oral contraceptives but are being evaluated through parenteral administration, e.g. implants or transdermal systems. The assessment of the pharmacological properties of these progestins indicate a high antigonadotropic and a high antiestrogenic properties for levonorgestrel and for the newer gestagens as well. Therefore very low doses are being used in the current oral contraceptives. However, there is a lower margin of security with the low dose contraceptives than with previous standard combinations and especially when concomitant medications are ingested such as enzyme-inducing agents. Selection of contraceptive methods should be discussed when specific co-medications are necessary.

Pharmacokinetics of centchroman in healthy female subjects after oral administration

The pharmacokinetics of centchroman, a non-steroidal antifertility agent, were assessed in serum of eleven healthy female subjects after a single 30 mg oral dose. Maximum serum concentration (Cmax) of 55.53 (s.d., 15.45) microgram/L was attained at 5.18 (s.d., 1.78) h after oral administration. The concentration-time profile was best described by a two-compartment open model with bi-exponential disposition functions. The mean terminal elimination half-life (t1/2) was 165 (s.d., 49) h with a clearance of 6.17 (s.d., 1.67) L/h and volume of distribution of 1420 (s.d., 478) L. Comparison of the pharmacokinetic parameters of this study with those obtained after a single 60 mg oral dose did not show statistically significant differences in the rate of absorption, distribution and elimination. The Cmax and AUC0-infinity were dose-dependent. Thus, the absorption and disposition of centchroman are of first-order, reproducible and dose-dependent.

Relationships between blood pressure, oral contraceptive use and metabolic risk markers for cardiovascular disease

Data from a previous study, designed to compare metabolic risk markers for cardiovascular disease in non-users and oral contraceptive (OC) users, were analysed to evaluate the influence of OC composition on blood pressure. Healthy, female volunteers (1189 women) either not using OC (non-users) or currently using one of six different combined formulations (users) were compared. Combinations studied contained 30-40 micrograms ethinyl estradiol combined with the progestins levonorgestrel, norethindrone (at two and three different doses, respectively) or desogestrel. After statistical standardisation to account for the significantly greater age of the non-users and longer duration of OC use amongst the levonorgestrel combination users, mean blood pressure was higher, compared with non-users, in users of monophasic or triphasic levonorgestrel combinations (systolic: +4.3 mmHg (p < 0.001) and +2.7 mmHg (p < 0.001), respectively; diastolic: +2.6 mmHg (p < 0.001) and +2.3 mmHg (p < 0.05), respectively). Blood pressures in users of monophasic norethindrone and desogestrel combinations were not significantly raised and there was no increase in the proportion of women with abnormal values. Diastolic and systolic blood pressures were positively associated with oral glucose tolerance test insulin response (r = 0.11 (p < 0.01) and r = 0.15 (p < 0.001), respectively) in users but not in non-users. Currently used OC containing norethindrone or desogestrel progestins have little impact on blood pressure. Their correlated reduction in impact on insulin concentrations, though small, suggests common mechanisms through which OC affect blood pressure and insulin.

Lack of effect of gender and oral contraceptive steroids on the pharmacokinetics of (R)-ibuprofen in humans

The effects of gender and oral contraceptive steroids on the pharmacokinetics of (R)-ibuprofen were studied in groups of healthy adult males, females and oral contraceptive steroid (OCS) using females. The values of AUC, CLpo, t1/2 and Vss, app did not differ significantly between the groups. Similarly, the percentage unbound of (R)-ibuprofen in pooled plasma from the three groups was not statistically different. Since chiral inversion is the major determinant of (R)-ibuprofen clearance in humans, it may be inferred from these data that gender and OCS have little or no effect on conversion of (R)-ibuprofen to the pharmacologically active S-enantiomer. Moreover, it is unlikely that hormonal factors influence the activity of the human hepatic long-chain fatty-acid:CoA ligase, the enzyme mediating the rate limiting step of (R)-ibuprofen inversion.

Effects of a new oral contraceptive containing an antimineralocorticoid progestogen, drospirenone, on the renin-aldosterone system, body weight, blood pressure, glucose tolerance, and lipid metabolism

Combined hormonal oral contraceptives (OCs) may lead to a mild rise in blood pressure and body weight. In rare instances, large increments in blood pressure are measured. We investigated the effect of a combination of ethinyl estradiol (EE) plus a progestogen with antimineralocorticoid, i.e. natriuretic, properties [Drospirenone (DRSP)] on body weight, blood pressure, the renin-aldosterone system, atrial natriuretic factor, plasma lipids, and glucose tolerance. It is anticipated that this will lead to the development of an OC that does not raise body weight or blood pressure. Four groups of 20 women each received 30 micrograms EE plus 3 mg DRSP (group A), 20 micrograms EE plus 3 mg DRSP (group B), 15 micrograms EE plus 3 mg DRSP (group C), and, as a control OC, 30 micrograms EE plus 150 micrograms levonorgestrel (Microgynon, Schering; group D) for 6 months. During the OC-free control cycles before and after treatment and throughout treatment, the target parameters were measured. Between the pretreatment cycle and the sixth treatment cycle, mean body weight fell by 0.8 to 1.7 kg in groups A, B, and C (P < 0.05 vs. D), whereas it rose by 0.7 kg in group D. Systolic and diastolic blood pressures fell by 1-4 mm Hg in groups A, B, and C (significant for A and C vs. D) and increased by 1-2 mm Hg in group D. Renin substrate rose equally in all groups (P < 0.05), whereas PRA and plasma aldosterone rose significantly only in the DRSP groups, presumably due to sodium loss. In the DRSP groups, high density lipoprotein cholesterol rose (P < 0.05), in contrast to group D. Low density lipoprotein cholesterol fell slightly (P > 0.05), whereas triglyceride levels showed a stronger increase in the DRSP groups (P < 0.05) than in group D. All groups attained good cycle control; group A had the best. Side-effects were minimal. To our knowledge, this is the first report on a combined OC that leads to a small decrease in body weight and blood pressure. It may be especially beneficial for women susceptible for a gain in weight and a rise in blood pressure.

Twelve years of clinical experience with an oral contraceptive containing 30 micrograms ethinyloestradiol and 150 micrograms desogestrel

The clinical experience with a combined oral contraceptive (COC) containing 150 micrograms desogestrel and 30 micrograms ethinylestradiol is reviewed. Fourteen clinical trials have been reported involving over 44,000 women for more than 190,000 cycles. None of the 17 pregnancies which occurred (overall Pearl Index 0.12) were due to method failure. The incidences of breakthrough bleeding and spotting after 6 treatment cycles varied from 0.1-6.0% and 2.8-11% of subjects, respectively, and at this time they were not significantly different from pretreatment in most trials. About 90% of subjects maintained regular cycles. The incidence of subjective side effects (approximately 5% for headache, 4% for breast tenderness, 2% for nausea) was low. No significant changes occurred in body weight or blood pressure. In all trials, the COC was well accepted and the rates of discontinuation were similar to those in other COC trials. Pharmacodynamic effects have been widely investigated. There were no significant changes in glucose metabolism or in haematological factors except for possibly minor increases in factors VII and X, fibrinogen and plasminogen. Over thirty studies of the effect of the COC on lipid metabolism have been published; significant increases occur in serum triglycerides, HDL-C and apoprotein A1. SHBG concentrations increase 2-3 fold with a consequent decrease in the levels of free testosterone. This effect can be particularly important therapeutically in women with hyperandrogenic skin disorders and 14 trials in women with these disorders have demonstrated significant clinical improvement with the COC. The findings from the various trials show the COC to be effective and acceptable with no adverse metabolic effects.

Serum distribution of two contraceptive progestins: 3-ketodesogestrel and gestodene

A cross-over study of two oral contraceptive formulations, containing 30 micrograms ethinylestradiol in combination with 150 micrograms desogestrel (Marvelon) or 75 micrograms gestodene (Femovan), has been performed to compare the serum distribution and pharmacokinetics of gestodene and the active metabolite of desogestrel, namely 3-ketodesogestrel. Serum concentrations of both sex hormone-binding globulin (SHBG) and corticosteroid-binding globulin (CBG) were also measured and were increased more than 3-fold and 2-fold, respectively, on day 21 of the treatment cycle, with no statistically significant difference between treatment groups. In addition, 35 days after ingestion of either oral contraceptive had ceased, the serum SHBG and CBG concentrations were similar to the pretreatment values. During treatment cycles, increased serum SHBG levels were associated with a redistribution of 3-ketodesogestrel and gestodene such that the non-protein-bound (NPB) and albumin-bound fractions were reduced in concert with an increase in the relative proportions bound to SHBG. The proportion of gestodene bound to SHBG was consistently higher than that observed for 3-ketodesogestrel, and this undoubtedly reflects the higher affinity of SHBG for gestodene (Kd = 1.2 nM at 37 degrees C) when compared to 3-ketodesogestrel (Kd = 4.7 nM at 37 degrees C). It also probably accounts, in part, for the much higher total serum levels of gestodene (8.58 nmol/L) when compared to 3-ketodesogestrel (2.37 nmol/L) during the treatment cycles. Consequently, the absolute amounts of NPB, non-SHBG-bound, and SHBG-bound gestodene are significantly higher than those measured for 3-ketodesogestrel. It is concluded that ethinylestradiol-induced increases in serum SHBG levels during treatment with Marvelon or Femovan, influenced the distribution and total amount of 3-ketodesogestrel and gestodene in serum, respectively, and that this, combined with the higher affinity of SHBG for gestodene, results in a greater amount of bioavailable gestodene compared to 3-ketodesogestrel, despite the smaller dose of gestodene administered.

Hemostatic and metabolic effects of lowering the ethinyl-estradiol dose from 30 mcg to 20 mcg in oral contraceptives containing desogestrel

The metabolic and hemostatic effects of two oral contraceptives containing 150 mcg desogestrel and 20 mcg ethinyl-estradiol (EE) (MERCILON) or 30 mcg EE (MARVELON) were compared in order to examine the effect of reducing the EE dose in contraceptive pills. Forty-nine women participated in this randomized study during 6 cycles. In both groups, there was a significant increase in triglycerides, HDL-cholesterol and apoprotein A1; the same increase was observed for SBP and CBG. Slight and transient variations of fasting blood glucose levels were seen in the 30 mcg EE group and in the two groups for fasting insulin levels. The increase in renin substrate was significantly higher with the 30 mcg EE than with the 20 mcg EE pill. In both groups, plasminogen increased significantly, but antithrombin III, total and free protein S and fibrinogen decreased significantly only in women taking the 30 mcg EE pill, whereas there was no significant change in the 20 mcg EE group. Reducing the dose of EE in oral contraceptives from 30 mcg to 20 mcg minimizes their impact on renin substrate and hemostatic parameters.

Rheumatoid arthritis, the contraceptive pill, and androgens

Evidence is accumulating that low androgen concentrations are a cause of rheumatoid arthritis. This would explain a number of established features of the epidemiology of the disease. These include: (a) the variation of disease activity with pregnancy; (b) the variation of age at onset by sex; (c) the variation by sex with HLA-B15; (d) the association with bone mineral density; and (e) the differing time trends in incidence rates by sex. It is argued, moreover, that if one makes a plausible assumption--namely, that women who choose oral contraceptives have high androgen concentrations at the time they first make this choice--then an explanation becomes available for the confusion about the relation between rheumatoid arthritis and oral contraception. Grounds are adduced for that assumption. If this line of reasoning is substantially correct it also has implications for the relations between rheumatoid arthritis and smoking and consumption of alcohol.

Single- and multiple-dose pharmacokinetics of a low-dose oral contraceptive in women with chronic renal failure undergoing peritoneal dialysis

OBJECTIVE

Our purpose was to compare the pharmacokinetic parameters of oral administration of a 35 micrograms ethinyl estradiol, 1 mg norethindrone pill in peritoneal dialysis patients and normal women.

STUDY DESIGN

A single-dose study was performed with five patients and four controls, followed by a multiple-dose study with five subjects in each group. Pharmacokinetic parameters were calculated by noncompartmental analysis and statistical analysis performed with Mann-Whitney U testing.

RESULTS

There is no difference in the pharmacokinetic parameters for norethindrone in peritoneal dialysis patients compared with normal women. During multiple dosing an increased area under the concentration curve and decreased apparent oral clearance was observed for ethinyl estradiol in peritoneal dialysis patients compared with normal women.

CONCLUSION

Peritoneal dialysis patients have decreased apparent oral clearance of ethinyl estradiol, leading to slightly higher serum concentrations compared with women with normal renal function. The clearance of norethindrone is the same in peritoneal dialysis patients and normal women.

FDA requirements for nonclinical testing of contraceptive steroids

Written guidelines for the preclinical testing of contraceptive steroids have not been revised since 1968 despite the fact that many important changes have been implemented by the FDA's Division of Metabolism and Endocrine Drug Products. This paper describes the new preclinical testing requirements and the rationale for their implementation.

Existence of multiple peaks in plasma ethinyl estradiol and norethindrone after oral administration of a contraceptive pill

Previous measurements of plasma ethinyl estradiol (EE2) and norethindrone (NE) over 24 h after oral administration of a contraceptive pill have demonstrated a single steroid peak occurring 1-2 h after pill ingestion, with a gradual decline over the next 22 h. In the present study plasma concentrations of EE2 and NE were measured 0, 0.5, 0.75, 1, 2, 4, 12, and 24 h after oral ingestion of a contraceptive pill containing 35 micrograms EE2 and 1 mg NE at 0, 3, 6, and 9 months of use in 58 normal healthy women. Contrary to previous reports, analysis of the 464 steroid curves (58 subjects x 4 time periods x 2 steroids) revealed the presence of multiple hormone peaks. Two peaks of EE2 were identified in 44.8% of women during the first pill cycle and in 75.9%, 55.2%, and 67.2% of women after 3, 6, and 9 months of pill use. Two hormone peaks of NE were observed in 29.3% of women during the first cycle and in 36.2%, 50%, and 44.8% at 3, 6, and 9 months, respectively. Existence of these multiple peaks at the frequency observed has not previously been reported. Further quantification of the frequency and magnitude of these peaks could be helpful in explaining differences in biological responses associated with pill use.

Contact factor proteases and the complexes formed with alpha 2-macroglobulin can interfere in protein C assays by cleaving amidolytic substrates

Plasma from women taking combined oral contraceptives and cold-activated plasma contain proteases which cleave chromogenic substrates in protein C assays in the absence of protein C activators such as Protac. This spontaneous activity makes a background substraction necessary and makes protein C (PC) assays less accurate. We investigated two commonly used substrates < Glu-Pro-Arg-pNA (S-2366) and 2AcOH.H-D-Lys(Cbo)-Pro-Arg-pNA (PC substrate) and found that cold-activated normal and protein C-deficient plasmas gave absorbance values up to 300 times higher than buffer blanks. FXIa cleaves these substrates but activity was not blocked by corn or lima bean trypsin inhibitors, soy bean trypsin inhibitor (SBTI), hirudin or epsilon-amino-n-caproic acid (EACA). Kaolin activation of normal, FXI, FIX, FVIII, FVII and protein C-deficient, but not of FXII or prekallikrein (PKK)-deficient plasmas led to cleavage of chromogenic substrate for protein C. The protein C substrates were cleaved by purified kallikrein and alpha- and beta-FXIIa. Immunoabsorption with alpha 2-macroglobulin (alpha 2M) antibodies removed 60% of the alpha 2M and 70% of the activity on PC Substrate. Gel filtration of normal plasma on Sephadex G-150 gave a single peak of protein C activity and antigen in the included volume. After cold activation of the fractions, a second protein C-like peak appeared in the void volume, but with no detectable protein C antigen. This peak coincided with alpha 2M (chromogenic and ELISA) and plasma kallikrein (S-2302), but FXII (measured with a substrate insensitive to kallikrein) eluted separately.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of oral contraceptives on plasma beta-endorphin and corticotropin at rest and during exercise

Concentrations of immunoreactive beta-endorphin and corticotropin in plasma were studied in 27 healthy physically active women at rest and after the exercise test on a treadmill requiring 60% and 90% of the maximal oxygen consumption. Eleven of the subjects were on a combination-type of oral contraceptive pills, and the remaining 16 did not use any pills. Plasma immunoreactive beta-endorphin levels at rest were higher in pill non-users than in pill users. Corticotropin levels at rest did not differ between the pill users and non-users. After the 60% exercise test a slight increase was found in the concentrations of corticotropin and beta-endorphin in the pill non-users but not in the pill users. In the 90% exercise test, plasma beta-endorphin and corticotropin levels increased significantly in both groups. We conclude that the use of oral contraceptives may elevate the threshold of the intensity of exercise required to increase beta-endorphin and corticotropin secretion. Decreased resting concentration of beta-endorphin in pill users can be explained by suppression of normal cyclic ovarian function.

A cross-over study of three oral contraceptives containing ethinyloestradiol and either desogestrel or levonorgestrel

A randomised cross-over trial was performed to compare the pharmacodynamic actions of three low-dose oral contraceptives (OCs): Marvelon (150 micrograms desogestrel (DSG)+ 30 micrograms ethinyloestradiol (EE)), Mercilon (150 micrograms DSG + 20 micrograms EE) and Microgynon (150 micrograms levonorgestrel (LNG) + 30 micrograms EE). None of the OCs produced any significant changes in serum cholesterol, LDL-C and apoprotein B. Triglycerides were increased by the desogestrel OCs but not by Microgynon. The latter however increased the glucose and insulin responses to a glucose tolerance test whereas Marvelon and Mercilon had no effect. HDL-C increased with Marvelon, was unchanged with Mercilon and was decreased with Microgynon. Apoprotein AII was increased by all three OCs but only the DSG OCs increased apoprotein AI. All OCs produced similar increases in caeruloplasmin but the increase in SHBG was much greater with Marvelon and Mercilon than with Microgynon. Testosterone was reduced more with Microgynon than with the DSG OCs. Many of the changes reflect the strong anti-oestrogenic action of LNG on metabolic parameters compared to DSG. Except for the effect on HDL-C, there was little difference between Marvelon and Mercilon on metabolic parameters and this complements the findings from large-scale clinical trials of the two OCs. Mercilon, therefore provides a very satisfactory alternative to Marvelon.