Plasma levels of levonorgestrel in women during longterm use of norplants

Levonorgestrel plasma levels were determined by a specific radioimmunoassay in a group of 110 women at various intervals between 1 and 60 months following implantation of six silastic capsules containing levonorgestrel (Norplant). The implants were placed subdermally in the anterior aspect of the forearm. Blood samples were taken twice a week for six consecutive weeks in each subject. Blood drawn from the antecubital vain ipsilsteral to the implant site contained two to three times more levonorgestrel than contralateral samples. Average systemic plasma levels represented by contralateral samples ranged from 0.35 0.03 to 0.29 0.02 ng/ml (Mean ± S.E.) in the first and fifth year, respectively. The difference between these values is statistically significant at the 5% level. The results of the regression analysis of individual levels suggest that the decline observed throughout the first five years is mainly due to an early decrease taking place in the first two years. When the sampling period was repeated in the same subjects two or three times 10 to 24 months apart, no significant difference was found, A significant negative correlation was found between plasma levonorgestrel levels and body weight and body surface. The data indicate that the contraceptive efficacy of Norplants during the first five years of use is associated with sustained release of levanorgestrel and is in keeping with the estimated life span of Norplants of seven years.     

Bleeding pattern, outcome of accidental pregnancies and levonorgestrel plasma levels associated with method failure in Norplant implants users

The aim of this study was to characterize the bleeding pattern, the outcome of pregnancies and the levonorgestrel plasma levels associated with method failures in Norplant implants users. Nineteen pregnancies are reported in 458 woman and 21,589 woman-months observed during the first eight years of Norplant use. Pregnancy rates increased slightly during the first six years of use, attaining a Pearl Index above three thereafter. All women who became pregnant had experienced a regular bleeding pattern in the six months preceding conception. Levonorgestrel plasma levels observed at different intervals before conception and during the conceptional cycle were similar to those observed in non-pregnant women at comparable intervals after Norplant insertion. The nineteen pregnancies ended in thirteen term deliveries, one premature delivery, three abortions and two ectopic pregnancies. No abnormalities were found in the infants. The two ectopic pregnancies are the only ones reported for Norplant users in The Population Council studies. The overall incidence is less than 0.8 per 1000 woman-years.     

Effects of a subdermal levonorgestrel contraceptive implant (Norplant) on serum cholesterol, triglycerides, ALT and AST in Iranian women

BACKGROUND: To evaluate the effects of Norplant (36 mg of levonorgestrel, six capsules) on serum cholesterol, triglycerides, alanine transaminase (ALT) and aspartate transminase (AST), we enrolled 465 healthy women from Zahedan, Iran, into a longitudinal study. MATERIALS AND METHODS: Blood samples were collected after an overnight fast before implant insertion and after 3, 6, 9 and 12 months of use. RESULTS: Total cholesterol and triglyceride levels did not significantly change during Norplant use. Although there were statistically significant increases in ALT and AST levels during Norplant use, the values were within the reference range.     

Immediate postabortal contraception with Norplant: levonorgestrel, gonadotropin, estradiol, and progesterone levels over two postabortal months and return of fertility after removal of Norplant capsules

Six Silastic levonorgestrel-releasing capsules, Norplant, were introduced subcutaneously into the ventral aspect of the left forearm or upper arm of thirteen patients immediately after first trimester pregnancy termination. Blood samples were taken twice a week over two months after abortion and from one subject over one month after removal of Norplant capsules. Plasma concentrations of levonorgestrel were measured by radioimmunoassay and the effects of treatment on pituitary and ovarian function were determined by assaying plasma concentrations of LH, FSH, estradiol and progesterone. If removal of Norplant capsules took place because of planning pregnancy, the subjects were asked to inform us if they had become pregnant. During the first month after abortion the mean levonorgestrel concentration (489 pg/ml) was statistically significantly higher than during the second month (237 pg/ml). The mean estradiol values fell to prefollicular levels within four days, remaining a little suppressed. The mean progesterone concentrations were below 2 ng/ml three days after abortion. Three subjects had a transient increase in plasma progesterone concentrations nine days after abortion. Thereafter no ovulatory progesterone concentrations were seen. The LH concentrations ranged within normal values of the follicular phase and FSH values were just beneath the lower limit of follicular phase FSH values, apart from a few peaks, indicating mild suppression. After removal of Norplant capsules, progesterone concentrations increased to ovulatory levels fifteen days after removal. The Norplant capsules were removed from two subjects because of planning pregnancy and they delivered healthy babies 9.5 and 12.5 months after removal.     

Levonorgestrel plasma levels during continuous administration with different models of subdermal implants

Plasma concentrations of levonorgestrel were determined in women using subdermal levonorgestrel implants. One group had 6 Silastic capsules (NORPLANT), one group had 4 and one group had 6 covered Silastic rods for variable lengths of time. Levonorgestrel concentrations remained constant around 0.4 ng/ml up until 6 years of use in the Norplant group. The observation period was shorter for the covered rods; plasma concentrations were, however, constant around 0.55 ng/ml and 0.70 ng/ml for 3.5 years with the 4 rods and 6 covered rods, respectively. The difference in mean levonorgestrel concentrations between the three groups were statistically significant (p less than 0.0005). Plasma levels of levonorgestrel were twice to three times higher in blood obtained from the arm with the implants compared to the levels found in the other arm. The application of a tourniquet for variable periods before blood sampling did not influence the plasma concentrations of levonorgestrel.     

Androgen levels in women using Norplant implants

Plasma concentrations of sex hormone binding globulin (SHBG), testosterone, free testosterone, androstenedione (A4) and levonorgestrel were studied in 17 women before and during use of two levonorgestrel covered rods resulting in identical plasma concentrations of levonorgestrel as Norplant implants. There was a highly significant decrease in SHBG during treatment. Total testosterone and A4 also decreased significantly. Free testosterone remained unchanged. Diurnal variations were found to occur for A4, total and free testosterone, but not for SHBG or levonorgestrel. Moreover, plasma concentrations of testosterone, free testosterone, levonorgestrel and SHBG were measured in a second group of 88 women participating in a clinical study on Norplant implants, who at the one year follow-up visit either denied or claimed to have developed increased facial acne during treatment. There was no difference regarding SHBG, total testosterone, free testosterone or levonorgestrel between the groups of women with and without facial acne. However, the women in the group noticing increased acne during treatment, reported significantly more often to have had acne before treatment compared to the women who did not notice increased acne during treatment. It is concluded that treatment with Norplant implants does not result in increasing plasma levels of androgens.     

Enhanced metabolism of levonorgestrel during phenytoin treatment in a woman with Norplant implants

A 26-year-old woman, treated with phenytoin for 10 years because of epilepsy, had Norplant subdermal implants inserted after a legal abortion. She became pregnant again after nine months of Norplant use. Her plasma levonorgestrel (LNG) levels were followed during one month during phenytoin treatment and then later during one month after discontinuation of phenytoin. During phenytoin treatment, plasma LNG levels were markedly below the levels found in healthy women with Norplant. There was a pronounced, statistically significant increase in plasma LNG levels after discontinuation of phenytoin. The plasma levels of sex hormone binding globulin were markedly above those found in normal healthy women during treatment with phenytoin and decreased significantly after cessation of phenytoin. The effects on the pharmacokinetics of LNG were reflected by effects on the menstrual cycle. During phenytoin treatment, the woman had regular ovulatory menstrual cycles. After cessation of phenytoin, her cycles became irregular and during the study period of one month, no signs of ovulation were found. It is concluded that treatment with phenytoin during use of Norplant subdermal implants enhances the metabolism of LNG to an extent where the contraceptive efficacy is endangered.     

A five-year clinical evaluation of NORPLANT contraceptive subdermal implants in Bangladeshi acceptors

A non-comparative study of the Norplant contraceptive subdermal implant system was conducted in Dhaka, Bangladesh. The study was designed to evaluate the contraceptive efficacy, safety and overall acceptability of Norplant implants. Six hundred women were enrolled in the clinical trial, which began in 1985 at three study sites. Follow-up visits were scheduled at 1, 3, and 6 months after Norplant implant insertion, and every six months thereafter until removal or at the end of five years. There were no post-insertion pregnancies during Norplant implant use in this study. After five years of Norplant implant use, there was no clinically significant change in body weight, systolic or diastolic blood pressure. Less than 3% of the women ever reported having any significant medical problems such as migraine, respiratory or cardiac problems during the study. The gross cumulative continuation rate was 41.2 per 100 women at the end of five years. The two most frequently reported reasons for discontinuation during the study were menstrual problems and desired pregnancy. Of the women who completed the five-year user satisfaction questionnaire, the majority of the women (86.3%) planned to continue using contraception after study completion. Of these women, approximately one-third said they planned to use another Norplant set. The findings presented suggest that the Norplant system is a highly effective, safe and acceptable method among Bangladeshi women.     

Effect of Implanon and Norplant subdermal contraceptive implants on serum lipids--a randomized comparative study

The objective of this study was to assess the possible differences in effects of Implanon (etonogestrel 68 mg, single-rod) and Norplant (levonorgestrel 36 mg, six capsules) implants on serum lipids over 2 years of use. In this 2-year open randomized study of 80 implant acceptors, selected serum lipids were tested before implant insertion and at 6, 12 and 24 months after implant insertion. The lipid parameters evaluated were: total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides, apolipoprotein A-I and apolipoprotein B. During the 2 years, the serum lipid pattern in the Implanon users was not significantly different from that of the Norplant users. There was slight decrease in HDL-C levels in both the groups but there were no significant changes in the HDL/TC ratio and the HDL/LDL ratio. Although it was statistically significant, the magnitude of decrease in HDL-C from preinsertion levels in Implanon users was only 5.8% at the end of 2 years.     

Norplant contraceptive implants: rods versus capsules

Norplant contraceptive implants are silastic implants containing levonorgestrel. When placed subcutaneously in the medial aspect of the upper arm, they release low levels of levonorgestrel in a constant manner over an extended period of time. Comparative studies of two silastic rods versus six capsules containing levonorgestrel were studied in 250 subjects for 4,464 months of use. Only one pregnancy occurred during the study. Side effect patterns were similar in both groups; the major side effect being irregular uterine bleeding. The bleeding, however, was well tolerated by subjects in both groups and discontinuation rate was very low. The two-rod system offers the advantages of easier insertion technique and shorter insertion time as well as ease of removal as compared to the six-capsule system. Norplant contraceptive implants offer a highly effective means of contraception which is particularly suited for women who are concerned about failure and compliance with oral contraceptives. This type of contraception should become well accepted, not only in underdeveloped countries, but in developed countries as well.     

Plasma levels of levonorgestrel and free levonorgestrel index in women using NORPLANT implants or two covered rods (NORPLANT-2)

Plasma levels of levonorgestrel, sex hormone binding globulin (SHBG) and estradiol were studied during four years in 283 healthy women using either NORPLANT implants or two covered rods (NORPLANT-2). The women were randomized to use either type of implant. Both implant systems have previously been shown to have similar release rates of levonorgestrel. In both groups plasma levels of levonorgestrel decreased throughout the study, and there were no statistically significant differences between the two groups in mean plasma levels of levonorgestrel. During the study 8 women became pregnant. All pregnancies but one occurred after 35 months of implant use and only in women using the covered rods. No significant differences were seen between the women who became pregnant and the rest of the group using two covered rods with respect to plasma levels of levonorgestrel. SHBG capacity tended to be somewhat higher in women using the two covered rods. As levonorgestrel is to a great extent bound to SHBG, and in that form not biologically active, a "free levonorgestrel index" was calculated as a ratio between levonorgestrel and SHBG. This index was significantly lower in users of two covered rods than in users of NORPLANT implants at 1, 12 and 48 months of use. Women who became pregnant had significantly lower "free levonorgestrel index" than had the rest of the group. It is postulated that the difference in "free levonorgestrel index" between users of the two implant systems reflect differences in release rate, the covered rods having a lower release rate of levonorgestrel than NORPLANT throughout the observation period. It is concluded that "free levonorgestrel index" is a better parameter than levonorgestrel plasma levels to describe implant function, and to discriminate women who are at risk of pregnancy.     

Plasma levonorgestrel and progesterone levels in women treated with silastic covered rods containing levonorgestrel

Levonorgestrel and progesterone plasma levels were measured in women bearing levonorgestrel subdermal implants. Two groups using four or six levonorgestrel covered rods and one group of non-hormonal contraceptors were compared. Blood samples were drawn twice a week for six consecutive weeks at different intervals after treatment administration.

The mean levonorgestrel levels (X ± S.D.) observed in the four rods group was .49 ± .13 ng/ml in the first year and decreased to .34 ± .06 in the fifth year of treatment. The mean values observed in the six rods group were .70 ± .15 ng/ml in the second year and .43 ± .11 in the sixth year. The levonorgestrel plasma levels were slightly above those found with NORPLANT^R implants in the four rods group and well above it in the six rods group.

The highest plasma progesterone value found in each sampling period was above 9 nmol/l in 7 (14%) out of 50 subjects in the four rods group, in 2 (4.3%) out of 47 subjects in the six rods group and in all the 49 control women. In 4 out of the 7 subjects from the 4 rods group and in the two subjects from the 6 rods group, the highest progesterone value was preceded and followed by values lower than 6 nmol/l. It was concluded that the progesterone levels were seldom compatible with the occurrence of ovulation in women treated with four or six levonorgestrel covered rods which release an estimated daily dose of 70 and 105 ug, respectively.     

IMAP statement on Norplant subdermal contraceptive implant system

The Norplant implant system consists of 6 silastic capsules which deliver levonorgestrel to protect against pregnancy over 5 years. Clinical trials were conducted in 46 countries. The 5-year cumulative pregnancy rate is 3.9%. Norplant's efficacy falls as weight increases. Its failure rate is lower than that of combined oral contraceptives and most IUDs. Counseling is linked to acceptability. Medical personnel should be trained in counseling potential Norplant acceptors. They must undergo formal training in insertion and removal of Norplant. The first year and fifth year continuation rates are 75-90% and 25-78%, respectively. Bleeding irregularities are the main reason for discontinuation and the most commonly reported side effects. Levonorgestrel changes the cervical mucus and suppresses ovulation and the endometrium. Toxicological and teratological data on levonorgestrel and silastic show that Norplant is safe. It appears that Norplant does not cause any major pathological changes in the endometrium, liver, kidney, and adrenal and thyroid glands. Levonorgestrel in Norplant is linked to a slight increase in serum glucose levels which are not of significant consequence. Its effects on lipids and lipoproteins are not clear. Fertility returns to Norplant users shortly after removal. The return to fertility pattern basically matches that of other methods. Contraindications of Norplant use are confirmed or suspected pregnancy, previous ectopic pregnancy, breast cancer, cancer of the genital tract, cerebrovascular or coronary artery disease, acute liver disease, and undiagnosed abnormal genital bleeding. Norplant should be inserted subdermally in the upper arm during the first 7 days after menstruation begins. The capsules must be removed after 5 years if pregnancy is to be avoided. Before family planning programs provide Norplant, managers should make sure the staff is adequately prepared. Health personnel, counselors, potential users, and the public need informational materials on Norplant.     

CLa长效避孕埋植剂体外溶出度质量标准的研究

本文采用高效液相色谱法,色谱分离柱为Rp-18.7μ,4.6×250mm,流动相为甲醇:水(80/20V/V),紫外检测波长240nm。以国际Norplant Ⅰ型埋植剂为对照,利用外标法测定国产CLa埋植剂7个批次平行14套样品的体外溶出度。实验方法将CLa埋植剂在重蒸水中连续浸泡3天,(水浴温度37℃±1℃),每24小时更换溶剂,测每天溶液中,左旋18甲基炔诺酮(LNG)的浓度。以第三天溶液中LNG((?)±2SD),制定出CLa埋植剂体外溶出度的质量控制范围50.0～70.0μg/6支·日。该法简便准确,结果可靠,完全可适用于国产CLa埋植剂溶出度的质量监控。     

国产皮下埋植剂多中心研究

目的:评价两种国产皮下埋植剂的避孕效果、副反应和继续使用率。方法:分两期进行。第一期为国产Ⅰ型、Ⅱ型皮下埋植剂与Norplant进行前瞻性临床对比研究,各100例,共300例。第二期为国产皮下埋植剂扩大临床应用,接受合格对象Ⅰ型999例,Ⅱ型998例,共1997例。随访5年。结果:5年随访率为99.5％。第一期国产Ⅰ型、Ⅱ型皮下埋植剂和Norplant的5年累计妊娠率分别为0/百妇女、1.0/百妇女、0/百妇女,5年继续使用率分别为77％、80％、80％,差异均无统计学意义(P>0.05)。主要副反应为月经紊乱,月经卡分析显示3种埋植剂的出血模型相似。第二期国产Ⅰ型、Ⅱ型皮下埋植剂5年累计妊娠率分别为0.20/百妇女,2.10/百妇女,5年继续使用分别为84.47％、82.28％。使用埋植剂6个月Ⅰ型和Ⅱ型月经问题主诉发生率分别为50.88％、57.16％,差异有显著意义(P<0.01),但随着使用时间延长,月经紊乱主诉发生率逐渐下降,两组间无差异。结论:5年研究表明两种国产皮下埋植剂的避孕效果、副反应发生率和继续使用率与Norplant相似,也是一种高效,长效的避孕制剂。国产皮下埋植剂Ⅱ型使用至第5年避孕失败率明显增加,建议国产Ⅱ型皮下埋植剂使用期限在3～4年为好。     

Health and growth of infants breastfed by Norplant contraceptive implants users: a six-year follow-up study

The objective of the study was to evaluate safety to infants whose mothers used Norplant levonorgestrel implants during breastfeeding. A nonrandomized clinical trial design was used. Participants were 220 and 222 healthy breastfed infants of mothers initiating use of Norplant or T-Cu IUD, respectively, at 55 days to 60 days postpartum. Infants were followed from birth through age 6 years. Breastfeeding pattern, infant growth, and disease events were recorded monthly in the first year, three-monthly in the second, and annually thereafter. Most mothers continued use of Norplant (96.4%) and T-Cu (94.1%) during lactation, and 2140 months of infant exposure to levonorgestrel were accumulated. Breastfeeding pattern and infants growth, from admission through age 6 years, were similar in both groups. In the first year, breastfed infants in the Norplant group had higher incidence rates (p < 0.05) of mild episodes of respiratory infections (adjusted RR 1.17, CI 1.08-1.27), skin conditions (adjusted RR 1.46, CI 1.20-1.79), and eye infections (unadjusted RR 1.49, CI 1.03-2.18) than the control group. Later on, a higher proportion of infants in the T-Cu group showed neurological conditions. Although breastfeeding patterns and infant growth is not affected by Norplant use during lactation, the effect on infants' health of steroidal contraception should be further evaluated.     

长效避孕皮下埋植剂对生育妇女骨质的影响

为探讨长期缓释单孕激素对妇女骨代谢的影响,测定使用国产Ⅰ、Ⅱ型长效避孕皮下埋植剂和Norplant 3年以上妇女的骨密度及骨代谢指标。采用回顾、设对照组的研究方法,测定123例妇女骨密度(BMD)及其骨代谢指标血钙(Ca)、磷(P)、碱性磷酸酶(ALP)、骨钙素(BGP)、血清雌激素(E_2),尿钙(Ca)、尿肌肝(Cr)和尿羟脯氨酸(HYP)等。结果表明国产Ⅰ、Ⅱ型和Norplant组妇女骨峰值形成期(30～40岁)使用皮埋剂的三组妇女平均E_2水平有不同程度降低,但均在正常低限水平内,与对照组间无差别。除对照组外三组妇女平均E_2水平与BMD之间不呈线性关系;Norplant组妇女BMD和Ca/Cr、HTP/Cr的变化说明骨吸收过程增强。使用国产Ⅰ、Ⅱ型皮埋剂和Norplant妇女3年后平均E_2水平在正常低水平上波动,未造成BMD的变化及其它骨代谢指标的明显变化;三组皮埋剂妇女骨峰值形成期(30～40岁),骨密度处于正常水平范围。长效LNG缓释皮埋剂对育龄妇女在骨代谢方面是安全的。     

NorplantR contraceptive subdermal implants: Two-year experience in Singapore

Norplant contraceptive implants are Silastic containing levonorgestrel implants. This study describes our two-year experience with 100 acceptors of Norplant implants in Singapore. No pregnancies occurred during the first two years of use. Desire for planned pregnancy and disruption of menstrual rhythm were the two main reasons for twenty implant removals during the two years. The continuation rate at the end of two years was 79%. The post-removal conception rate in women desiring pregnancy was 90% at the end of one year. It thus appears that the Norplant contraceptive system offers a highly effective, acceptable, reversible and safe method of contraception.     

Free levonorgestrel index and its relationship with luteal activity during long-term use of Norplant implants

Levonorgestrel serum levels and sex hormone binding globulin (SHBG) were measured in 82 women during different years of use of Norplant implants. The ratio between levonorgestrel and SHBG was calculated as an indicator of the free biologically active fraction of levonorgestrel (free levonorgestrel index, FLI). These parameters were then correlated with the presence of luteal activity, as determined by progesterone levels above 9.6 nmol/L, in a sampling run of 10 samples taken twice a week for five consecutive weeks. Levonorgestrel serum levels remained constant around 1.0 nmol/L during the five-year period. SHBG levels were below normal for the first 18 months of use, returning to normal levels during the last three years of use. The FLI in the first two years was significantly higher than that observed in the later years. The frequency of cycles with luteal activity was 12% during the first 2 years, increasing to 44% in the latter years, when FLI levels were lower.Our results suggest that the changes in SHBG and consequently in the free biologically active fraction of levonorgestrel may largely account for the differences in degree of ovarian suppression observed between the first two years of use of Norplant implants and the latter three, even in the absence of a significant variation in total levonorgestrel concentrations.

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Resumen Los niveles séricos de levonorgestrel y de globulina de unión con las hormonas sexuales (SHBG) se midieron en 82 mujeres en differentes períodos de años de utilización de implantes Norplant. La proporción entre el levonorgestrel y la SHBG se calculó como indicador de la fracción libre biológicamente activa del levonorgestrel (índice de levonorgestrel libre-FLI). Estos parámetros se correlacionaron luego con la presencia de actividad lútea, según lo determinado por los niveles de progesterona superiores a 9.6 nmol/L, en una serie de 10 muestras sacadas dos veces por semana durante cinco semanas consecutivas. Los niveles séricos de levonorgestrel permanecieron constantes, a alrededor de 1.0 nmol/L durante todo el período de cinco años. Los niveles de SHBG fueron inferiores a lo normal durante los 18 primeros meses de utilización, retornando a niveles normales durante los tres últimos años de utilización. El FLI durante los dos primeros años fue significativamente superior al observado en los años siguientes. La frecuencia de los ciclos con actividad lútea fue del 12% durante los dos primeros años, aumentando al 44% en los años siguientes, cuando el FLI fue inferior.Nuestros resultados hacen pensar que las modificaciones de la SHBG y, por consiguiente, de la fracción de levonorgestrel biológicamente activa, pueden determinar en gran medida las diferencias en el grado de supresión ovárica observado entre los dos primeros años de utilización de implantes Norplant y los tres últimos, incluso en ausencia de una variación significativa de las concentraciones totales de levonorgestrel.

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Résumé Les taux sériques de lévonorgestrel et de globuline liant les hormones sexuelles (SHBG) ont été mesurés chez 82 femmes à différentes périodes des années d'utilisation des implants Norplant. Le ratio entre le lévonorgestrel et la SHBG a été calculé en tant qu'indicateur de la fraction libre biologiquement active du lévonorgestrel (indice de lévonorgestrel libre-FLI). Ces paramètres ont ensuite été corrélés avec la présence d'activité lutéale, telle que déterminée par les niveaux de progestérone dépassant 9.6 nmol/L, sur une série de 10 échantillons prélevés deux fois par semaine pendant cinq semaines consécutives. Les niveaux sériques de lévonorgestrel sont restés constants, aux alentours de 1.0 nmol/L, durant toute la période de cinq ans. Les niveaux de SHBG étaient inférieurs à la normale pendant les 18 premiers mois d'utilisation et sont redevenus normaux au cours des trois dernières années d'utilisation. Quant au FLI, il était significativement plus élevé durant les deux premières années que celui observé dans les années suivantes. La fréquence des cycles comportant une activité lutéale atteignait 12% pendant les deux premières années, augmentant à 44% pour les années suivantes, lorsque le FLI avait baissé.Nos résultats laissent penser que les modifications de SHBG, et par conséquent de la fraction de lévonorgestrel biologiquement active, détermine sans doute largement les différences dans le degré de suppression ovarienne observé entre les deux premières années de l'utilisation des implants Norplant et les deux années suivantes, même en l'absence d'une variation significative des concentrations totales de lévonorgestrel.

     

Implanon contraceptive implants: effects on carbohydrate metabolism

The objective of the study was to assess the possible differences in effects of Implanon and Norplant implants on carbohydrate metabolism. This is a 2-year open randomized study of 80 implant (Implanon and Norplant) acceptors. Oral glucose tolerance test (OGTT) was performed before implant insertion and at 6, 12, and 24 months after implant insertion. Glycosylated hemoglobin A(1)C was measured in fasting samples and plasma samples during OGTT were tested for glucose and insulin levels. There was a significant increase in the area under the curve for both glucose and insulin during OGTT within each group with increasing duration of use. However, there was no significant change in the fasting plasma glucose values. There was no significant difference in the carbohydrate parameters between the two groups during implant use, except for a minimal but statistically significant rise in fasting glycosylated hemoglobin A(1)C levels at 24 months in the Implanon group. Both implants appear to induce mild insulin resistance but no significant change in serum glucose levels. These alterations in carbohydrate metabolism should have no clinical significance in healthy women.