Effect of long-term use of Norplant implants on haemostatic function

Evaluation of haemostatic function in Nigerian Norplant acceptors after 12 months of use

A total of 55 non-breastfeeding informed volunteers were recruited into a prospective longitudinal study from a family planning clinic between September and December 2002. Blood samples were collected at pre-treatment and at 3, 6 and 12 months follow-up, for packed cell volume, platelet count, prothrombin and activated partial thromboplastin time. Statistical analysis was with paired t-tests. The level of significance was set at 5%. Each subject received a menstrual calendar to chart all bleeding and spotting events. The mean age and weight of acceptors were 32.5 +/- 6.1 years and 63.6 +/- 9.6 kg, respectively. Mean packed cell volume (PCV) was 35.2 +/- 2.9% at pre-insertion. This rose to significant mean +/- SD values of 36.5 +/- 3.1%; p<0.05, 38.5 +/- 2.8%; p<0.0001 and 38.4 +/- 3.6%; p<0.0001 at 3, 6 and 12 months, respectively when compared with the pre-insertion mean value. The mean values of the platelet count showed no significant change at 3 months (238,448 +/- 68,618 mm(3); p>0.9), compared with pre-treatment value (240,545 +/- 96,769 mm(3)). There was a significant reduction in mean concentration at 6 months (p<0.009; 191,364 +/- 55,531 mm(3)) and at 12 months (p<0.003; 202,773 +/- 81,544 mm(3)) follow-up. The prothrombin and the partial thromboplastin time did not show significant change over their pre-insertion mean values of 12.0 +/- 1.1 s and 36.9 +/- 2.9 s, respectively. At 12 months, 79.5% (35) of the users reported an abnormal menstrual pattern, which included 54.5% (24) reduced bleeding pattern, 20.5% (9) increased bleeding and 4.5% (2) of combination of patterns. Only 20.5% (9) had a normal menstrual pattern. The continuation rate was 98%, as one user discontinued because of headaches. Norplant (the registered trademark of the Population Council for levonorgestrel subdermal implants) had an effect on the bleeding pattern - mainly reduced bleeding. The increase packed cell volume is beneficial in preventing anaemia. There was no detrimental effect as a result of the reduced but normal platelet count and users were not predisposed to clotting abnormalities.

Risks and benefits, advantages and disadvantages of levonorgestrel-releasing contraceptive implants

Levonorgestrel-releasing implants are long acting contraceptives, approved for 5 years of continuous use. Two marketed systems, the six capsule Norplant use of tradenames is for product identification purposes only and does not imply endorsement. and the two rod Jadelle, have essentially equal rates of drug release, pregnancy and adverse events over 5 years of use. Randomised clinical trials and controlled cohort observations indicate that for the first 3 years, when pregnancy rates are at or almost zero, no other contraceptive system is more effective, although etonogestrel implants provide equal effectiveness. Annual pregnancy rates rise in the fifth year of continuous use but remain below 1 per 100 women. Annual pregnancy rates of Norplant users remain below 1 per 100 throughout 7 years of continuous use. Levonorgestrel implants provide low progestogen doses; 40-50 microg/day at 1 year of use, decreasing to 25-30 microg/day in the fifth year. Serum levels of levonorgestrel at 5 years are 60-65% of those levels measured at 1 month of use. Adverse effects with levonorgestrel implants are similar to those observed with progestogen only and combined oral contraceptives. Risks of ectopic pregnancy, other pregnancy complications and pelvic inflammatory disease are reduced in comparison with those of women using copper or non-medicated intrauterine devices. Risks of developing gallbladder disease and hypertension or borderline hypertension, although small, are about 1.5 and 1.8 times greater, respectively, in women using levonorgestrel implants than in women not using hormonal contraception. Other serious diseases have not been found to occur significantly more frequently in levonorgestrel implant users than in women not using hormonal contraception. The great majority of levonorgestrel implant users experience menstrual problems, but serious bleeding problems are not more frequent than in controls. Other health problems reported more frequently by levonogestrel implant users than by women not using hormonal contraception in a study of 16000 women included skin conditions, headache, upper limb neuropathies, dizziness, nervousness, malaise, minor visual disturbances, respiratory conditions, arthropathies, weight change, anxiety and non-clinical depression. Clinical depression is not more frequent in women using implants compared with those not using hormonal contraception (i.e. using intrauterine devices, sterilisation). Removal problems occur less frequently with Jadelle than with Norplant. The mean removal time for Jadelle is half that of Norplant. Levonorgestrel implants in nationally representative scientific samples, in randomised trials, and in controlled cohort studies have continuation rates as high as or higher than any other reversible contraceptive over a duration of 5 years. This would imply that the satisfaction women derive from the contraceptive effectiveness of levonorgestrel implants greatly outweighs the dissatisfaction that may accompany menstrual disturbances and other adverse effects associated with implants.

Metabolic effects of implantable steroid contraceptives for women

The metabolic impact of progestin-only contraceptives is less than that of combined oral contraceptives. Subdermal contraceptive implant systems that provide a sustained release of low levels of progestins are now becoming widely available. This review evaluates the metabolic effects of currently available products that release the progestins levonorgestrel (Norplant, Jadelle, and their Chinese equivalents); etonogestrel (Implanon); nomegestrol acetate (Uniplant); and Nestorone, formally called ST-1435 (Nestorone implant/Elcometrine). Data on liver, kidney, and renal function; carbohydrates and insulin release; hemostasis; blood pressure; and lipids are considered. The metabolic effects reported for these methods as a whole were minimal. Any changes were generally within the normal range for the populations studied and, therefore, are unlikely to be of clinical significance. However, all published studies have been conducted in healthy populations of women. To inform clinical practice, the field would be well served to have additional empiric data from well-designed, well-implemented, and well-reported trials in women who are deemed to be at elevated risk for certain diseases including cardiovascular disease and diabetes.

Implantable contraception

Although levonorgestrel contraceptive implants have been available for over 15 years, innovations have only recently led to a wider choice. These new implants offer easier insertion and removal and other advantages depending on the type of progestin. Implants prevent pregnancy by several mechanisms, including inhibition of ovulation and luteal function and alteration of cervical mucus and the endometrium. The high efficacy and ease of maintenance make implants an ideal contraceptive for many women, including adolescents, a population that uses implants infrequently but reports high satisfaction. Implants are appropriate for women who are breastfeeding, who have contraindications to estrogen, or who have diseases such as diabetes, hypertension, sickle cell anemia, or an HIV infection because implants have few metabolic or hematologic effects. Long-term use has not been associated with a decrease in BMD and generally leads to increased blood levels and iron stores. Women who wish to space their pregnancies appreciate the nearly immediate onset of action with insertion and the rapid termination of all effects with removal. All types of implants lead to menstrual changes and other side effects in some women. Adverse effects that occur in implant users more than the general population include headaches and acne. Women must be thoroughly counseled regarding the potential for menstrual alteration, side effects, and sexually transmitted infections if they do not use condoms. Despite their initial high cost, implants are a cost-effective method over several years, even when discontinued before the life of the implant.

A prospective study on the effects of reformulated 2-rod Norplant implant on haemostasis after five years of use

OBJECTIVE

To evaluate the long-term effects of the new reformulated 2-rod Norplant implant on haemostasis in a prospective group of subjects who have completed 5 years of use.

METHODS

Data from 11 women who have completed 5 years' use of the new reformulated 2-rod subdermal implant from the original 16 women who were recruited and randomized to receive this new improved implant in a comparative study were analysed. Clinical assessment and serial blood sampling were done prior to insertion of implant and after 1, 3, 12, 18, 24, 36, 48 and 60 months of implant use. Each subject served as its own control and Analysis of Variance with Student-Newman-Kuels test was used for statistical analysis. The following parameters were determined: plasminogen activators (t-PA, u-PA), plasminogen activator inhibitor-1 (PAI-1), D-dimer, beta-thromboglobulin (beta-TG), thrombin-antithrombin (TAT)-complex, fibrinogen, Factor VII, platelets, haematocrit and haemoglobin levels.

RESULTS

No significant change was observed for t-PA levels in prolonged implant use. u-PA antigen showed a significant decrease whilst D-dimer were significantly elevated at only 24 months of implant use compared to pre-implant level. PAI-1 levels were not significantly changed but fibrinogen and FVII levels increased at 36 months and 42 months of use with enhanced platelet activation shown by beta-TG levels at 24 months. Platelet numbers were not affected by prolonged implant use. Haemoglobin concentration and haematocrit level showed significant fluctuations and then return to pre-implant level by 54 and 60 months.

CONCLUSION

Enhanced fibrinolysis with platelet activation at 24 months of implant use were seen during the 60 months of 2-rod reformulated Norplant implant use. Hypercoagulable state was not observed although fibrinogen and FVII levels remain above the pre-implant levels as coagulation activation was not enhanced. The increased haemoglobin and haematocrit levels seen indicate enhanced bone marrow activity. There was no association between the use of reformulated 2-rod Norplant implant over 60 months of use and prothrombotic state.

Effects on the hemostatic system and liver function in relation to Implanon and Norplant. A prospective randomized clinical trial

In this prospective randomized clinical trial, two long-term contraceptive implants were studied with respect to hemostasis and liver function in 86 healthy young women. The two implants used were Implanon, containing the progestagen etonogestrel (the biologically active metabolite of desogestrel) and Norplant, the implant containing the progestagen levonorgestrel. The results of the trial showed that both implants had similar small effects on the hemostatic system that are not suggestive of a tendency towards thrombosis. The effect on liver function was characterized by increases in total bilirubin and gamma-glutamyl transferase and decreases in alanine aminotransferase and aspartate aminotransferase.

Blood coagulation and oral contraceptives. A critical review

The use of oral contraceptives is associated with altered plasma concentrations of many components of the coagulation and fibrinolysis system, increased plasma levels of markers indicating in vivo coagulation and fibrinolysis, and a modified response to challenge tests both in vivo and in vitro. None of these effects seems to be specific for users of oral contraceptives and none was found uniformly in all users. The predictive value of each of these effects, or even of certain combinations of tests, for the prediction of venous thrombosis is low. There is no established way to assess the "thrombogenicity" of particular pills. The individual susceptibility, however, to develop venous thrombosis varies considerably. Recently, several congenital abnormalities of the hemostatic system have been found that are associated with an increased risk of venous thrombosis in general. The risk associated with the use of oral contraceptives appears to act synergistically with some of these thrombophilic conditions. Although the prevalence of these congenital predispositions varies among different populations, screening for these conditions is not feasible: negative results would not exclude the occurrence of about two-thirds of oral contraceptives-associated thromboses and positive results are likely to be disregarded because of their poor predictive value. Future research has to evaluate the role of a more targeted screening strategy aiming at women with risk factors such as a positive personal or family history of venous thromboembolism.

Norplant consensus statement and background review

This review has highlighted the attributes of a very important new method of contraception. The signatories to this document agree that, with the provision of appropriate information and instruction for the user, Norplant is a good contraceptive choice to be made available worldwide in family planning programs that have the resources for appropriate training and counseling. The signatories to this document are acting in their own personal capacity and not as representatives of any particular organization.

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.

Immunohistochemical staining of von Willebrand factor in endometrium of women during the first year of Norplant implants use

The mechanisms responsible for Norplant implants-induced menstrual irregularities remain poorly understood. It is unclear whether local changes in endometrial haemostasis are involved. The aim of the present study was to examine the immunohistochemical staining for von Willebrand factor (vWF) in endometrial biopsies taken from 37 women exposed to Norplant implants for 3-12 months and to compare it with 73 controls at various phases of the normal menstrual cycle. The vWF staining intensity was quantified by subjective scoring and by objective computerised colour image analysis. Results from the Norplant implants group were additionally correlated with their bleeding patterns, endometrial histology, and plasma oestradiol (E2) and progesterone (P4) levels. No differences were found between control and Norplant implants subjects in the localization of vWF staining, which was specifically confined to the endothelium of endometrial blood vessels. vWF staining intensity in Norplant implants endometrium was significantly lower than in controls during mid cycle, and reached a mean (+/- SE) level (subjective staining score 2.05 +/- 0.13, n = 37) in the range of the early proliferative and mid secretory phase normal endometrium; nevertheless, it remained significantly higher than that of menstrual and late secretory phase normal endometrium. No significant variations in vWF staining could be related to either the histology of the endometrium or the bleeding pattern of the users. Correlation of vWF staining with either serum E2 or serum P4 prior to biopsy, or to the number of days of Norplant implants exposure revealed no significant relationships. However, vWF staining was positively correlated (r = 0.419, P < 0.01) to the number of bleeding/spotting days within a 90-day reference period prior to biopsies being taken. These results demonstrate that there are major differences in the mechanism responsible for normal menstruation and Norplant implants-induced intermenstrual bleeding and spotting, and show that menstrual disturbances associated with the use of Norplant implants are unlikely to be due to changes in vWF levels in endometrial endothelial cells.

Effect of norethisterone acetate on serum lipid and lipoprotein parameters as well as on blood coagulation in female monkeys (M. fascicularis)

The effects of daily oral administration of a high dose of 10 mg norethisterone acetate (NET-Ac.)/kg/day over 14 weeks on serum lipid and lipoprotein parameters as well as on blood coagulation were investigated in female monkeys (M. fascicularis). Measurements of lipids and lipoprotein cholesterol were performed in weeks--5 and -1 before treatment and in weeks 4, 8 and 12 after treatment. In addition, various blood coagulation and fibrinolytic parameters were determined in weeks 11-14 after treatment with NET-Ac. Furthermore, the serum levels of norethisterone (NET) were determined in order to monitor the real systemic compound exposure and revealed that Cmax and AUC (0-3 h) values reached for norethisterone in this experiment in monkeys were about 25 times higher than those obtained after an oral contraceptive dose of NET-Ac. in women. The results of lipid and lipoprotein cholesterol determinations showed decreases in serum total lipids, phospholipids, triglycerides and total cholesterol associated with similar decreases in HDL-, LDL- and VLDL-cholesterol fractions after NET-Ac.-treatment in monkeys. These effects were observed from week 4 onwards and maintained their magnitude up to week 12 after treatment. Since both HDL- and LDL-cholesterol fractions decreased, the HDL/LDL-ratio remained almost unchanged. Thus, the results obtained in this study after high-dose treatment with NET-Ac. in monkeys did not indicate any changes of lipid and lipoprotein parameters which in humans are supposed to be associated with an increased risk of cardiovascular lesions, namely a decrease in HDL- and increase in LDL-cholesterol fractions. The results of blood coagulation and fibrinolytic parameters showed increased antithrombin-III and plasminogen levels besides minor changes in other parameters, thus indicating that NET-Ac.-treatment does not contribute to an increased risk of cardiovascular thrombotic events in the cynomolgus monkey.

Evaluation of hemostatic function following Norplant implant removal

Norplant implant use in Singapore showed a decrease in vitamin K-dependent Factors II, V, VII and reduction in fibrinolytic activity at the end of 5 years of use. Increased platelet numbers and accelerated platelet aggregation were also found throughout the 5 years of Norplant use. It thus appears that unlike the combined pill, prolonged Norplant use does not activate the coagulation system and does not enhance a state of hypercoagulation. On removal of the Norplant implants at the end of 5 years, the significant changes seen in hemostatic function observed with Norplant use remained.

Effect of Norplant-2 rods on liver, lipid and carbohydrate metabolism

The effect of Norplant-2 rods on liver, lipid and carbohydrate metabolism was evaluated in 100 women using Norplant-2 rods. Besides a significant increase in serum bilirubin, there was no other obvious evidence to suggest any possible hepatocellular dysfunction with the use of Norplant-2 rods. As regards lipid metabolism, decreases in total triglycerides, cholesterol and LDL-cholesterol and HDL-cholesterol were initially seen. These parameters returned to their preinsertion mean at the end of five years. As a result, the value of the HDL-cholesterol/total cholesterol - HDL-cholesterol and LDL-cholesterol/HDL-cholesterol ratios remained around their preinsertion value at the end of five years. All this appears to indicate that the use of Norplant-2 rods is not directly contributory to cardiovascular risk. The use of Norplant-2 rods was not associated with any significant effect on carbohydrate metabolism.