Pharmacokinetics of etonogestrel released from the contraceptive implant Implanon

Pilot study of a novel, alternative subdermal scapular insertion site for the etonogestrel contraceptive implant

OBJECTIVES

To assess the pharmacokinetics and pharmacodynamics of the etonogestrel (ENG) contraceptive implant when inserted at an alternative scapular site.

STUDY DESIGN

We conducted a pilot study of healthy, reproductive-age females who underwent subdermal insertion of an ENG implant over the inferior edge of the nondominant scapula (scapular insertion). We measured serum ENG levels over 1 year at nine time points. Participants completed questionnaires on insertion site and bleeding side effects. We collected photographs and video recordings of insertion and removal techniques.

RESULTS

We enrolled five participants (as prespecified), their median age was 26.0 years (range: 19.6-30.3), and median body mass index was 25.0 kg/m2 (range: 22.0-28.0). All serum ENG concentrations remained >90 pg/mL and were within the range of published data for arm insertion of ENG implant at all time points. The mean serum ENG level was 511.7 pg/mL (±168.2) at 1 week and 136.6 pg/mL (±21.8) at 12 months. During the first week after insertion, four of five participants noted insertion site pain with a median pain score of 2 (range 1-3), but all noted resolution by week two. Participants reported variable bleeding patterns consistent with standard ENG implant placement. At the end of the study, all participants reported satisfaction with the implant and would recommend scapular insertion to a friend.

CONCLUSIONS

Scapular insertion of the ENG contraceptive implant has similar pharmacokinetics to arm insertion over 1 year of use. This novel, alternative site was well tolerated and demonstrated similar bleeding side effects to standard arm insertion.

IMPLICATIONS

Subdermal scapular insertion of the etonogestrel contraceptive implant demonstrated similar pharmacokinetics to arm insertion over 1 year of use. Our pilot data support scapular insertion as an alternative site for ENG contraceptive implants, which could be beneficial for certain patient populations.

Reversible Control of Reproduction In Queens: Mastering the use of reproductive drugs to manipulate cyclicity

BACKGROUND

The literature is full of papers reporting side effects of progestogens in cats; however, they are, in fact, safe drugs, as discussed in this article. Gonadotropin-releasing hormone (GnRH) agonists and melatonin are additionally a practical solution for controlling cyclicity in queens, but they also have some contraindications and need to be used carefully.

CLINICAL RELEVANCE

Mastering the use of reproductive drugs allows feline practitioners to handle many more clinical situations than can be solved using surgery. It is not necessary to be a specialist in reproduction to be able to halt cyclicity in a valuable breeding queen using hormones.

EQUIPMENT AND TECHNICAL SKILLS

A sound knowledge of appropriate dosages and criteria for patient selection for all reproductive drugs currently used in feline reproduction is the best guarantee of owner satisfaction and of ensuring the queen's health. Availability of a serum progesterone assay, either in-house or via an external laboratory, is also important, in order to confirm a queen is at an appropriate stage of the reproductive cycle for treatment.

AUDIENCE

This article is aimed principally (but not exclusively) at veterinarians working with cat breeders and whose clientele is increasingly interested in alternative methods of controlling reproduction in pet queens. Surgery is no longer the only choice, and practitioners who manage to keep abreast of new developments will be able to address clients' needs in a modern, professional way.

EVIDENCE BASE

This review draws on a vast body of scientific evidence-based literature. Previously, personal (and sometimes misinformed) opinions, such as the proposed dangerous side effects of progestogens, have been perpetuated in the scientific literature. The papers cited in this review have therefore been carefully scrutinised to distinguish reliable information based on controlled studies from non-evidence-based information.

Contraceptive implant use duration is not associated with breakthrough pregnancy among women living with HIV and using efavirenz: a retrospective, longitudinal analysis

Introduction

Contraceptive implants containing etonogestrel and levonorgestrel have emerged as popular contraceptive options among women in areas of high HIV burden in sub‐Saharan Africa. However, recent pharmacokinetic data have shown drug–drug interactions between implants and efavirenz‐containing antiretroviral therapy (ART), reducing the effectiveness of the implants. Here, we evaluated pregnancy incidence in 6‐month intervals following implant initiation among women using efavirenz and contraceptive implants to assess whether the risk of breakthrough pregnancy is higher after specific periods of implant use.

Methods

We used data from a retrospective longitudinal analysis of women living with HIV ages 18–45 years in western Kenya who attended HIV‐care facilities between 2011 and 2015. We used Cox proportional hazard models to compute hazard ratios (HRs) for breakthrough pregnancy by implant type and ART regimen. Depending on the model, we adjusted for socio‐demographic and clinical factors, programme, site and interaction between calendar time and ART regimen. We utilized inverse probability weights (IPWs) to account for three sampling phases (electronic medical record [EMR], chart review and phone interview) and calculated overall parameter estimates.

Results

Women contributed 14,768 woman‐years from the largest sampling phase (EMR). The median age was 31 years. Women used etonogestrel implants for 26–69% of the time and levonorgestrel implants for 7–31% of the time, depending on the sampling phase. Women used efavirenz, nevirapine or no ART for 27–33%, 40–46% and 15–26% of follow‐ups, respectively. When combining sampling phases, there was little evidence to suggest that the relative hazard of pregnancy among efavirenz‐containing ART users relative to nevirapine‐containing ART changed with length of time on implants: IPW‐adjusted HR of 3.1 (CI: [1.5; 6.4]) at 12 months, 3.4 (CI: [1.8; 6.3]) at 24 months, 3.8 (CI: [1.9; 7.7]) at 36 months and 4.2 (CI: [1.6; 11.1]) at 48 months (interaction p‐value = 0.88). Similarly, no significant change in HRs over time was found when comparing women not using ART to nevirapine‐containing ART users (interaction p‐value = 0.49).

Conclusions

We did not find evidence to suggest implants being more fallible from drug–drug interactions with efavirenz at later time intervals of implant use. Thus, we would not recommend shortening the duration of implant use or replacing implants sooner when concomitantly used with efavirenz.

Alternative Insertion Site of Nexplanon: Description of a Case Report and Systematic Review of the Literature

The etonogestrel (ENG) implant is among the most effective reversible contraceptives. It can be a good option for patients with different chronic diseases due to no clinically significant effects on lipid metabolism or liver function. Some limitations in the use of this type of device are represented by social and psychiatric disorders, where the easy accessibility of the device becomes a negative feature. In these patients several cases of self-removal or damage to the device have been reported. We report the successful insertion of the Nexplanon^® device into the scapular region in a young woman with a chronic psychiatric disorder. To verify the presence in the literature of other possible implantation sites, we performed a systematic review of the literature on Pubmed, Google scholar and Scopus from 2000 to 2021 using different combinations of the following terms: (Nexplanon), (contraceptive implant), (insertion). Two manuscripts with three cases were detected. Nexplanon^® was implanted in the upper back. In all cases, there were no complications during the insertions and the follow up demonstrated no side effects with contraceptive efficacy. Our report and review is a further confirmation that the scapular region can become a valid insertion site, maintaining good efficacy and safety of the subcutaneous device.

Variability in repeat serum etonogestrel concentrations among contraceptive implant users during the steady-release pharmacokinetic period

OBJECTIVE

To assess the variability of repeated measurements of serum etonogestrel concentration among contraceptive implant users.

STUDY DESIGN

We measured 3 consecutive serum etonogestrel concentrations, drawn weekly, in women using etonogestrel implants for 12 to 36 months. We used a repeated measures test to evaluate differences.

RESULTS

Among 20 participants, repeat serum etonogestrel concentrations did not differ from initial measurements (Friedman's test, p = 0.95). Mean serum etonogestrel concentrations had similar 95% confidence intervals at each time point: (134.09, 201.46), (135.08, 237.46), and (132.66, 192.45).

CONCLUSION

We confirm that single-time measurements of serum etonogestrel concentration are acceptable pharmacokinetic outcomes for etonogestrel implant studies.

IMPLICATIONS

Pharmacokinetic studies of the etonogestrel contraceptive implant assume single-time measurements are stable steady-state estimates based on small studies using older analysis methods. Our repeated measures study using modern liquid-chromatography mass-spectrometry analysis methods provides updated support for single-time pharmacokinetic measurements among etonogestrel implant users.

Extending drug release from implants via transcutaneous refilling with solid therapeutics

Long-acting (LA) implantable drug delivery systems (IDDS) offer an effective approach for the management or prevention of chronic conditions by sustained parenteral therapeutic administration. LA IDDS can and improve adherence to treatment regimens by minimizing dosing frequency. However, their clinical deployment is challenged by factors such as poor drug loading capacity, which limit their lifespan and require repeated surgical replacement for continued therapy. To address these challenges, and by leveraging previous work on nanofluidic systems, a reservoir-based IDDS that enables transcutaneous refilling of solid drug formulations through minimally invasive needle injection is presented. With thousand-fold higher drug loading efficiency, the implant affords minimal volume and aspect ratio suitable for discrete subcutaneous deployment. Key parameters for clinical acceptability, namely implant safety, access port robustness, and refilling method were systematically evaluated. The implant and refilling procedure are studied in rats and nonhuman primates with therapeutics used clinically for type 2 diabetes and human immunodeficiency virus (HIV) pre-exposure prophylaxis (PrEP). The ability to extend drug release and maintain equivalent pharmacokinetics (PK) profiles pre- and post-drug refilling is demonstrated. This technology presents a clinically viable LA approach to prolong drug release for lifelong prevention or management of chronic conditions.

Interactions between etonogestrel-releasing contraceptive implant and 3 antiretroviral regimens

OBJECTIVES

Long-acting reversible contraceptives are effective contraceptives for women with HIV, but there are limited data on etonogestrel implant and antiretroviral therapy pharmacokinetic drug-drug interactions. We evaluated etonogestrel/antiretroviral therapy drug-drug interactions, and the effects of etonogestrel on ritonavir-boosted-atazanavir, ritonavir-boosted-lopinavir, and efavirenz pharmacokinetics.

STUDY DESIGN

We enrolled postpartum women using etonogestrel implants and receiving ritonavir-boosted-atazanavir, ritonavir-boosted-lopinavir, or efavirenz-based regimens between 2012 and 2015. Etonogestrel implants were inserted 2 to 12 weeks postpartum. We performed pharmacokinetic sampling pre-etonogestrel insertion and 6 to 7 weeks postinsertion. We measured antiretroviral concentrations pre and postetonogestrel insertion, and compared etonogestrel concentrations between antiretroviral regimens. We considered a minimum serum etonogestrel concentration of 90 pg/mL adequate for ovulation suppression.

RESULTS

We collected pharmacokinetic data for 74 postpartum women, 22 on ritonavir-boosted-atazanavir, 26 on ritonavir-boosted-lopinavir, and 26 on efavirenz. The median serum concentrations of etonogestrel when co-administered were highest with etonogestrel/ritonavir-boosted-atazanavir (604 pg/mL) and etonogestrel/ritonavir-boosted-lopinavir (428 pg/mL), and lowest with etonogestrel/efavirenz (125 pg/mL); p < 0.001. Minimum concentration (C_min) of ritonavir-boosted-atazanavir and ritonavir-boosted-lopinavir were lower after etonogestrel implant insertion, but overall exposure, predose concentrations, clearance, and half-lives were unchanged. We found no significant change in efavirenz exposure after etonogestrel insertion.

CONCLUSIONS

Unlike efavirenz, ritonavir-boosted-atazanavir and ritonavir-boosted-lopinavir were not associated with significant decreases in etonogestrel concentrations. Efavirenz was associated with a significant decrease in etonogestrel concentrations.

IMPLICATIONS

The findings demonstrate no interactions between etonogestrel and ritonavir-boosted-lopinavir or ritonavir-boosted-atazanavir, but confirm the decreased efficacy of etonogestrel with efavirenz-based antiretrovirals. This information should be used to counsel women with HIV who desire long-acting reversible contraceptives.

Pharmacokinetics, metabolism and serum concentrations of progestins used in contraception

Many different forms of hormonal contraception are used by millions of women worldwide. These contraceptives differ in the dose and type of synthetic progestogenic compound (progestin) used, as well as the route of administration and whether or not they contain estrogenic compounds. There is an increasing awareness that different forms of contraception and different progestins have different side-effect profiles, in particular their cardiovascular effects, effects on reproductive cancers and susceptibility to infectious diseases. There is a need to develop new methods to suit different needs and with minimal risks, especially in under-resourced areas. This requires a better understanding of the pharmacokinetics, metabolism, serum and tissue concentrations of progestins used in contraception as well as the biological activities of progestins and their metabolites via steroid receptors. Here we review the current knowledge on these topics and identify the research gaps. We show that there is a paucity of research on most of these topics for most progestins. We find that major impediments to clear conclusions on these topics include a lack of standardized methodologies, comparisons between non-parallel clinical studies and variability of data on serum concentrations between and within studies. The latter is most likely due, at least in part, to differences in intrinsic characteristics of participants. The review highlights the importance of insight on these topics in order to provide the best contraceptive options to women with minimal risks.

A pharmacokinetic and pharmacogenetic evaluation of contraceptive implants and antiretroviral therapy among women in Kenya and Uganda

OBJECTIVES

To evaluate pharmacokinetics and pharmacogenetics of contraceptive implant progestin concentrations in HIV-positive women initiating efavirenz (EFV)-containing or nevirapine (NVP)-containing antiretroviral therapy (ART).

DESIGN

We analyzed stored samples from women self-reporting implant use in the Partners PrEP Study.

METHODS

Plasma samples collected every 6 months were analyzed for levonorgestrel and etonogestrel concentrations. Progestin concentrations from samples collected after ART initiation were compared with pre-ART concentrations for intraindividual comparisons. We used adjusted linear mixed models to compare hormone concentrations between individuals on EFV and NVP to a no ART group. We then evaluated whether possessing certain alleles with known or possible influences on EFV, NVP, or progestin metabolism were associated with changes in progestin concentrations or modified the association between ART use and progestin concentrations.

RESULTS

Our analysis included 11 women who initiated EFV, 13 who initiated NVP, and 36 who remained ART-naive. In the EFV group, the adjusted geometric mean ratio (aGMR) of levonorgestrel was 0.39 [90% confidence intervals (0.31, 0.49); P < 0.001] and the etonogestrel aGMR was 0.51 (0.34, 0.76; P = 0.006) compared with the control group. No difference was observed in the NVP group compared with controls [levonorgestrel 0.93 (0.74, 1.18); P = 0.64; etonogestrel 1.07 (0.77, 1.50); P = 0.73]. Possession of four allele variants were found to result in further reductions in progestin concentrations among those receiving EFV.

CONCLUSION

Concomitant use of EFV significantly reduces levonorgestrel or etonogestrel concentrations by 61 and 49%, respectively, compared with no ART use. We also report allelic variants in hepatic enzymes that influenced the extent of the observed drug-interaction between progestins and EFV.

Relationship between patient characteristics and serum etonogestrel concentrations in contraceptive implant users

OBJECTIVE

To determine whether serum etonogestrel concentrations in contraceptive implant users are associated with certain individual patient characteristics.

STUDY DESIGN

We enrolled reproductive-age women using etonogestrel contraceptive implants between 12-36 months duration and measured a single serum etonogestrel concentration. Participants also completed a questionnaire about demographics.

RESULTS

We enrolled 350 participants; median age was 22.5 years (range 18.0-39.1), median months of implant use was 26.0 (range 12.0-36.0), and median body mass index was 25.7 kg/m² (range 18.5-52.0). Our study population was primarily white/Caucasian (46.6% [163/350]) and Hispanic/Latina ethnicity (51.4% [180/350]). The median serum etonogestrel concentration was 137.4 pg/ml and etonogestrel concentrations varied 12.4 fold in the population (range 55.8-695.1 pg/ml). Using forward stepwise linear regression, months of implant use (β=-1.74, p<.001) and body mass index (β=-3.10, p<.001) were both significantly associated with decreased serum etonogestrel concentration with Black/African American race as a positive effect modifier (β=18.24, p=.099); R-squared for the model=0.13.

CONCLUSIONS

Individuals demonstrated a wide variability in serum etonogestrel concentrations, which can potentially affect side-effect profiles and efficacy. Increasing body mass index and longer duration of implant use were associated with small decreases in serum etonogestrel concentrations, while self-reported Black/African American race was associated with a non-significant increase. Despite these findings, most of etonogestrel variability was unaccounted for, suggesting that other clinical, pharmacologic, and genetic factors contributing to variability in etonogestrel concentrations remain to be determined.

IMPLICATIONS

Although increases in body mass index are associated with lower etonogestrel levels in contraceptive implant users, the majority of women will maintain serum concentrations that consistently suppress ovulation. Furthermore, certain patient characteristics can only explain a small portion (13%) of the variability in serum etonogestrel levels among contraceptive implant users.

Effects of etonogestrel implant on quality of life, sexual function, and pelvic pain in women suffering from endometriosis: results from a multicenter, prospective, observational study

PURPOSE

Progestins are successfully employed as treatment for endometriosis. Our study evaluates the effects of the etonogestrel (ENG) implant on pelvic pain, quality of life, and sexual function in women requiring long-term reversible contraception and presenting ovarian cysts of probable endometriotic origin.

METHODS

We enrolled 25 women asking for contraception with the ENG implant and presenting a cyst with the ultrasound features of an endometrioma and pain symptoms. Patients were interviewed on pain symptoms (dysmenorrhea, dyspareunia, dyschezia, and dysuria) using a VAS score (0-10), on quality of life (QoL) using the Short Form-36 questionnaire, and on sexual activity using the Female Sexual Function Index (FSFI) questionnaire before inserting the implant (T0) and after 6 (T1) and 12 months (T2).

RESULTS

We found a significant decrease in dysmenorrhea and dyspareunia VAS scores comparing baseline scores to 6 and 12 months. After 12 months, the bodily pain, general health, vitality, social functioning, and mental health domains of the QoL score were significantly improved. The total FSFI score results increased in comparison with baseline both at 6 and 12 months. In particular, we highlighted a significant improvement in desire, satisfaction, and pain domains already at 6 months; the arousal domain improved only after 12 months. Finally, mean diameters of endometrioma-like cysts were not changed after 12 months of treatment.

CONCLUSIONS

Etonogestrel implants seem to be able to reduce pelvic pain, improve sexual function, and quality of life in patients with ovarian cysts suspected of endometriotic origin.

Long acting systemic HIV pre-exposure prophylaxis: an examination of the field

Oral pre-exposure prophylaxis for the prevention of HIV-1 transmission (HIV PrEP) has been widely successful as demonstrated by a number of clinical trials. However, studies have also demonstrated the need for patients to tightly adhere to oral dosing regimens in order to maintain protective plasma and tissue concentrations. This is especially true for women, who experience less forgiveness from dose skipping than men in clinical trials of HIV PrEP. There is increasing interest in long-acting (LA), user-independent forms of HIV PrEP that could overcome this adherence challenge. These technologies have taken multiple forms including LA injectables and implantables. Phase III efficacy trials are ongoing for a LA injectable candidate for HIV PrEP. This review will focus on the design considerations for both LA injectable and implantable platforms for HIV PrEP. Additionally, we have summarized the existing LA technologies currently in clinical and pre-clinical studies for HIV PrEP as well as other technologies that have been applied to HIV PrEP and contraceptives. Our discussion will focus on the potential application of these technologies in low resource areas, and their use in global women's health.

Current understanding on pharmacokinetics, clinical efficacy and safety of progestins for treating pain associated to endometriosis

INTRODUCTION

Endometriosis is a chronic estrogen and progestogen responsive inflammatory disease associated with pain symptoms and infertility. The medical therapy of endometriosis aims to induce decidualization within the hormonally dependent ectopic endometrium, and it is often administered to ameliorate women' pain symptoms or to prevent post-surgical disease recurrence. A variety of progestins have been used in monotherapy for the medical management of women with endometriosis. Areas covered: This review aims to offer the reader a complete overview of pharmacokinetic (PK) and clinical efficacy of progestins for the treatment of endometriosis. Expert opinion: Each progestin has a distinct PK parameters and pharmacodynamics affinity not only for progesterone receptor, but also for other steroid receptors, such as estrogen, androgen, and glucocorticoid. Moreover, progestins can also be delivered in different formulations. All these characteristics influence their final biological effect. Randomized, controlled, non-blinded studies support the use of oral progestin-only treatment for pelvic pain associated with endometriosis. Currently, the only two progestins approved by Food and Drug Administration (FDA) for the treatment of endometriosis are norethindrone acetate (NETA) and depot medroxyprogesterone acetate (DMPA).

Hormonal Contraception and HIV-1 Acquisition: Biological Mechanisms

Access to effective affordable contraception is critical for individual and public health. A wide range of hormonal contraceptives (HCs), which differ in composition, concentration of the progestin component, frequency of dosage, and method of administration, is currently available globally. However, the options are rather limited in settings with restricted economic resources that frequently overlap with areas of high HIV-1 prevalence. The predominant contraceptive used in sub-Saharan Africa is the progestin-only three-monthly injectable depot medroxyprogesterone acetate. Determination of whether HCs affect HIV-1 acquisition has been hampered by behavioral differences potentially confounding clinical observational data. Meta-analysis of these studies shows a significant association between depot medroxyprogesterone acetate use and increased risk of HIV-1 acquisition, raising important concerns. No association was found for combined oral contraceptives containing levonorgestrel, nor for the two-monthly injectable contraceptive norethisterone enanthate, although data for norethisterone enanthate are limited. Susceptibility to HIV-1 and other sexually transmitted infections may, however, be dependent on the type of progestin present in the formulation. Several underlying biological mechanisms that may mediate the effect of HCs on HIV-1 and other sexually transmitted infection acquisition have been identified in clinical, animal, and ex vivo studies. A substantial gap exists in the translation of basic research into clinical practice and public health policy. To bridge this gap, we review the current knowledge of underlying mechanisms and biological effects of commonly used progestins. The review sheds light on issues critical for an informed choice of progestins for the identification of safe, effective, acceptable, and affordable contraceptive methods.

Unscheduled vaginal bleeding with progestin-only contraceptive use

Nearly 20% of women using contraception are using progestin-only contraception, including progestin-only pills, depot-medroxyprogesterone acetate, subdermal etonogestrel implants, and levonorgestrel intrauterine devices. This number will continue to grow with the increased provision of long-acting reversible contraception. Although overall satisfaction among women using progestin-only contraception is high, dissatisfaction and discontinuation may be associated with unscheduled bleeding and spotting. The exact etiology of irregular bleeding associated with progestin-containing contraceptives is not completely understood, yet several mechanisms have been suggested. Several therapies targeting these mechanisms have been evaluated with mixed results. This paper will review the physiology and management of unscheduled bleeding with progestin-containing contraceptives.

Extended use up to 5 years of the etonogestrel-releasing subdermal contraceptive implant: comparison to levonorgestrel-releasing subdermal implant

STUDY QUESTION

Is it possible to extend the use of the 3-year one-rod etonogestrel (ENG)-releasing subdermal contraceptive implant to 5 years?

SUMMARY ANSWER

The extended use of the one-rod ENG-releasing subdermal contraceptive implant showed 100% efficacy in years 4 and 5.

WHAT IS KNOWN ALREADY

The initial regulated trials on the ENG-releasing subdermal contraceptive implant conducted in the 1990 s were designed to measure cumulative 3-year efficacy. The ENG-implant has both well established safety and efficacy for up to 3 years. Pharmacokinetic data on ENG show high levels at 3 years and some previous clinical research confirms efficacy beyond the current approved duration of 3 years. Today, many women, because the labeled duration has been reached, have the ENG implant removed at 3 years, increasing costs, inconvenience and risks.

STUDY DESIGN SIZE, DURATION

For the first 3 years, this study was an open-label, multi-centre randomized trial comparing the 3-year ENG implant to the 5-year levonorgestrel (LNG)-releasing implant. After 3 years, a subset of 390 ENG participants, consented to extended use. We compared efficacy, side effects and removal procedures of both implants. We used Kaplan–Meier (K–M) analysis. We included an observational cohort of copper intrauterine device (IUD) users as non-users of hormonal contraceptive method for comparative purposes.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study took place in family planning clinics in seven countries worldwide. Women were enlisted after an eligibility check and informed consent, and 1328 women were enrolled: 390, 522 and 416 in the ENG-implant, LNG-implant and IUD groups, respectively.

MAIN RESULTS AND THE ROLE OF CHANCE

Over 200 women used the ENG implant for at least 5 years. No pregnancies occurred during the additional 2 years of follow up in the ENG or LNG implant group. The overall 5-year K–M cumulative pregnancy rates for ENG- and LNG- implants were 0.6 per 100 women-years (W-Y) [95% confidence interval (CI): 0.2–1.8] and 0.8 per 100 W-Y [95% CI: 0.2–2.3], respectively. Complaints of bleeding changes were similar; however, ENG-users were more likely than LNG-users to experience heavy bleeding (p < 0.05). The median duration of the implant removal procedure was 64 seconds shorter for the one-rod ENG-implant (inter-quartile range (IQR) = 30.5, 117.5) compared to the two-rod LNG product (IQR = 77.0, 180.0). The 2-year rate for pregnancy in the IUD group compared with the two implant groups combined was 4.1 per 100 W-Y [95% CI: 2.5–6.5].

LIMITATIONS, REASONS FOR CAUTION

Few women were ≤19 years old or nulligravida. Although there was no weight limit for enrolment in the study, the number of women ≥70 kg were few.

WIDER IMPLICATIONS OF THE FINDINGS

The results from this study corroborate previous evidence showing high contraceptive efficacy through 4 years for the ENG-implant. Data through 5 years are a novel contribution and further proof of the product's capability to provide safe and effective contraception that rivals the current 5-year LNG-subdermal implant. The findings provide valuable information for policy makers, family planning programmers and clinicians that the ENG-releasing subdermal implant is still highly effective up to 5 years after insertion. Compared to previous efforts, our study population was geographically diverse and our study had the highest number of participants completing at least 5 years of use.

TRIAL REGISTRATION

The trial was registered as ISRCTN33378571.

STUDY FUNDING/COMPETING INTEREST(S)

The contraceptive devices and funds for conduct of the study were provided by the United Nations Development Programme/United Nations Population Fund/World Health Organization (WHO)/UNICEF/World Bank Special Programme of Research, Development and Research Training in Human Reproduction (HRP), Department of Reproductive Health and Research (RHR), WHO. This report contains the collective views of an international group of experts, and does not necessarily represent the decisions or the stated policy of the WHO. All stated authors have no conflict of interest, except Dr Hubacher who reported grants from United States Agency for International Development, during the conduct of the study; other from Advisory Boards (Teva, Bayer, OCON), outside the submitted work.

Pharmacokinetic and pharmacodynamic drug interactions between antiretrovirals and oral contraceptives

More than 50 % of women living with HIV in low- and middle-income countries are of reproductive age, but there are limitations to the administration of oral contraception for HIV-infected women receiving antiretroviral therapy due to drug-drug interactions caused by metabolism via the cytochrome P450 isoenzymes and glucuronidation. However, with the development of newer antiretrovirals that use alternative metabolic pathways, options for contraception in HIV-positive women are increasing. This paper aims to review the literature on the pharmacokinetics and pharmacodynamics of oral hormonal contraceptives when given with antiretroviral agents, including those currently used in developed countries, older ones that might still be used in salvage regimens, or those used in resource-limited settings, as well as newer drugs. Nucleos(t)ide reverse transcriptase inhibitors (NRTIs), the usual backbone to most combined antiretroviral treatments (cARTs) are characterised by a low potential for drug-drug interactions with oral contraceptives. On the other hand non-NRTIs (NNRTIs) and protease inhibitors (PIs) may interact with oral contraceptives. Of the NNRTIs, efavirenz and nevirapine have been demonstrated to cause drug-drug interactions; however, etravirine and rilpivirine appear safe to use without dose adjustment. PIs boosted with ritonavir are not recommended to be used with oral contraceptives, with the exception of boosted atazanavir which should be used with doses of at least 35 µg of estrogen. Maraviroc, an entry inhibitor, is safe for co-administration with oral contraceptives, as are the integrase inhibitors (INIs) raltegravir and dolutegravir. However, the INI elvitegravir, which is given in combination with cobicistat, requires a dose of estrogen of at least 30 µg. Despite the growing evidence in this field, data are still lacking in terms of large cohort studies, randomised trials and correlations to real clinical outcomes, such as pregnancy rates, in women on antiretrovirals and hormonal contraception.

Current strategies for endometriosis management

Endometriosis is a common gynecologic disorder that persists throughout the reproductive years. Although endometriosis is a surgical diagnosis, medical management with ovarian suppression remains the mainstay of long-term management with superimposed surgical intervention when needed. The goal of surgery should be excision or ablation of all visible disease to minimize risk of recurrence and need for repeat surgeries. When infertility is the presenting symptom, surgical therapy in addition to assisted reproductive technology can improve chances of conception; however, the treatment approach depends on stage of disease and other patient characteristics that affect fecundity.

New trends of progestins treatment of endometriosis

The management of endometriosis with OC or progestins is generally safe, effective and well-tolerated and should constitute the first line of medical treatment in symptomatic patients who do not want to have children. Progestins, synthetic progestational agents, have been used in the management of symptomatic endometriosis both as primary therapy and as an adjunct to surgical time. A variety of oral agents have been employed in this regard and investigators have demonstrated differing degrees of benefit. The lack of a standardized instrument to evaluate painful symptoms makes comparative analysis more difficult. Concern about efficacy and side effect has pushed the research on the development of new well-tolerated drugs and to develop new administration routes to minimize general side effects. Aim of the present review is to present the results of clinical studies on new trends of progestins in the treatment of endometriosis.

Nexplanon: the new implant for long-term contraception. A comprehensive descriptive review

Nexplanon(®) is a new long-term reversible contraception method. The current review is aimed to analyze the published data concerning the contraceptive effectiveness of Nexplanon(®) and its effects on reproductive function. Pharmacological properties and technical procedures of insertion and removal, as well as the efficacy and safety data available, were discussed. Possible strategies for treating Nexplanon(®)-related bleeding were also described. With regard to the future research and the future scientific developments of contraceptive implants, the possible use of Nexplanon(®) wide-ranging for the symptomatic treatment of endometriosis and premenstrual syndrome (PMS) were considered. Finally, it was defined in which women the use of Nexplanon(®) is indicated and in which it is contra-indicated.

Bioequivalence and x-ray visibility of a radiopaque etonogestrel implant versus a non-radiopaque implant: a 3-year, randomized, double-blind study

BACKGROUND

The etonogestrel (ENG)-releasing implant is a subdermal progestogen-only contraceptive that provides coverage for up to 3 years. This long-acting hormonal contraceptive has been available in Europe since 1998 and in the US since 2006. To date, localization of non-palpable implants at insertion and before removal has been dependent on ultrasound or magnetic resonance imaging by an experienced clinician. To facilitate localization in rare cases of non-palpable implants using widely available equipment without the need for a specialist, a radiopaque ENG implant has been developed that is detectable by two-dimensional x-ray imaging.

OBJECTIVE

This study aimed to establish whether the radiopaque ENG implant is bioequivalent in situ compared with the original non-radiopaque ENG implant, and to assess x-ray visibility of the radiopaque ENG implant.

METHODS

This was a 3-year, randomized, double-blind, parallel-group study carried out in nine international clinical trial centres. Women aged 18-40 years at the time of screening, with menstrual cycles of a usual length of 24-35 days and a body mass index of between ≥18 and ≤29 kg/m(2) were included. Women were assigned to either the radiopaque or non-radiopaque ENG implant in a 1 : 1 ratio via a block randomization by centre. Bioequivalence testing was performed based on the peak ENG concentration (C(max)), and the area under the curve (AUC) for ENG at 6, 24 and 36 months (AUC(6 mo), AUC(24 mo) and AUC(36 mo)) after insertion. For this purpose, blood sampling for pharmacokinetic determination was performed prior to insertion and for up to 3 years afterwards. Bioequivalence was defined as the 90% confidence interval (CI) of the ratio radiopaque implant/non-radiopaque implant of the geometric means (GMR) within the acceptance range of 0.80-1.25. x-Ray visibility was assessed by two-dimensional x-ray imaging after insertion and before removal of the implant.

RESULTS

The pharmacokinetic profiles of ENG indicated that the radiopaque and non-radiopaque implants were bioequivalent with respect to the geometric mean of C(max) (GMR 1.06; 90% CI 0.91, 1.23), AUC(6 mo) (GMR 1.00; 90% CI 0.91, 1.10), AUC(24 mo) (GMR 0.98; 90% CI 0.88, 1.10) and AUC(36 mo) (GMR 1.00; 90% CI 0.89, 1.11). The radiopaque ENG implant was clearly visible in 50 out of 52 women after insertion and in all 52 women before removal, whereas none of the non-radiopaque implants were visible.

CONCLUSION

The radiopaque ENG implant is bioequivalent in situ compared with the original non-radiopaque ENG implant and is clearly visible using x-ray imaging.

CLINICAL TRIALS REGISTRATION

Registered as ClinicalTrials.gov identifier NCT00620464.

Pharmacokinetics of the etonogestrel contraceptive implant in obese women

OBJECTIVE

We sought to examine the pharmacokinetics and acceptability of the etonogestrel contraceptive implant in obese women.

STUDY DESIGN

We developed and validated a plasma etonogestrel concentration assay and enrolled 13 obese (body mass index ≥30) women and 4 normal-weight (body mass index <25) women, who ensured comparability with historical controls. Etonogestrel concentrations were measured at 50-hour intervals through 300 hours postinsertion, then at 3 and 6 months to establish a pharmacokinetic curve.

RESULTS

All obese participants were African American, while all normal-weight participants were white. Across time, the plasma etonogestrel concentrations in obese women were lower than published values for normal-weight women and 31-63% lower than in the normal-weight study cohort, although these differences were not statistically significant. The implant device was found highly acceptable among obese women.

CONCLUSION

Obese women have lower plasma etonogestrel concentration than normal-weight women in the first 6 months after implant insertion. These findings should not be interpreted as decreased contraceptive effectiveness without additional considerations.

Efficacy and safety of long-acting reversible contraception

Long-acting reversible contraception (LARC) includes intrauterine devices (IUDs) and the subdermal implant. These methods are the most effective reversible methods of contraception, and have the additional advantages of being long-lasting, convenient, well liked by users and cost effective. Compared with other user-dependent methods that increase the risk of noncompliance-related method failure, LARC methods can bring 'typical use' failure rates more in line with 'perfect use' failure rates. LARC methods are 'forgettable'; they are not dependent on compliance with a pill-taking regimen, remembering to change a patch or ring, or coming back to the clinician for an injection. LARC method failure rates rival that of tubal sterilization at <1% for IUDs and the subdermal implant. For these reasons, we believe that IUDs and implants should be offered as first-line contraception for most women. This article provides a review of the LARC methods that are currently available in the US, including their effectiveness, advantages, disadvantages and contraindications. Additionally, we dispel myths and misconceptions regarding IUDs, and address the barriers to LARC use.

Etonorgestrel concentrations in morbidly obese women following Roux-en-Y gastric bypass surgery: three case reports

BACKGROUND

Pregnancy should be avoided for 12 to 18 months after Roux-en-Y gastric bypass (RYGB) surgery. The etonorgestrel (ENG)-releasing implant (Implanon®) may represent a safe and effective contraceptive method in morbidly obese women who are candidates for bariatric surgery. In addition, the subcutaneous delivery of steroid is unaffected by malabsorptive surgery.

METHODS

Three cases of young women with ENG-releasing implant are reported. The device was inserted 1-2 months prior to RYGB.

RESULTS

Their initial weights were 130 to 176 kg, and the mean weight loss was 33.6 kg at 6 months. The concomitant serum ENG concentrations decreased currently with weight loss but remained above the minimum concentration required for effective contraceptive effect of the implant for at least 6 months following RYGB (average, 170 pg/mL). The concentrations observed before weight loss were lower than in normal-weight women, but decreases in ENG concentrations following implant insertion were similar.

CONCLUSION

These unique data in morbidly obese women highlight the need for further pharmacokinetic studies of contraceptive agents in obese women during weight loss.

Clinician satisfaction and insertion characteristics of a new applicator to insert radiopaque Implanon: an open-label, noncontrolled, multicenter trial

BACKGROUND

The etonogestrel (ENG) implant Implanon is a progestin-only contraceptive that provides effective contraception for up to 3 years. A new radiopaque ENG implant has been developed to extend the diagnostic modalities of Implanon and a next-generation applicator (NGA) was designed to facilitate correct subdermal insertion of Implanon.

STUDY DESIGN

In this open-label study, 23 investigators, experienced and inexperienced with Implanon, performed 301 insertions of the new radiopaque implant using the NGA. Primary outcome measurements were obtained from clinician satisfaction questionnaires completed after the 4th, 8th and 12th insertions. Additionally, insertion characteristics and X-ray visibility were assessed.

RESULTS

Almost all investigators were satisfied with the NGA from the first insertion onward, and all were satisfied or very satisfied after 12 insertions. The most frequently reported advantages included ease of use, one-handed action and fast insertion time; 2% of insertions were considered difficult in skin puncturing and/or sliding the needle subdermally. Three incorrect insertions occurred due to noncompliance with instructions. All assessed implants were visible on plain X-ray imaging.

CONCLUSIONS

The NGA was well accepted by investigators with or without prior experience with Implanon. The results stressed the importance of correctly following implant insertion instructions.

Examining the efficacy, safety, and patient acceptability of the etonogestrel implantable contraceptive

Contraceptive implants provide long-acting, highly effective reversible contraception. The etonogestrel implant (ENG implant) is a single rod implant that offers three years of efficacy. The ENG implant was designed to provide contraceptive efficacy by inhibiting ovulation and Pearl Index scores reported for this method are similar to other long-acting reversible contraception as well as similar to sterilization. The implant has been shown to be safe during breast feeding and may improve symptoms of dysmenorrhea and endometriosis. Irregular bleeding patterns can be expected with the device's use and should be addressed in order to decrease rates of discontinuation.

Removal of etonogestrel contraceptive implants in the operating theater: report on 28 cases

OBJECTIVES

We describe removal procedures for etonogestrel contraceptive implants in the operating theater. In addition, we discuss the management of removal of contraceptive implants that are difficult to palpate or are impalpable.

DESIGN

We conducted a retrospective single-center case series analysis of Implanon removals conducted at a university hospital between January 2002 and April 2005.

MATERIALS AND METHODS

We analyzed case notes for 28 patients who had their contraceptive implant removed in the operating theater.

RESULTS

Intermenstrual bleeding was the principal reason for removal (52.4%). Ten patients already had one attempted removal of their implant. Preoperative ultrasound localized the implant in all cases. Half of the removals were done under local anesthetic, with three cases progressing to general anesthesia (11%). Thirty percent of the implants had migrated from their initial implantation, 37% were in intramuscular tissue and 11% were in the humeral neurovascular sheath. The only postoperative complications were one small seroma and transient paresthesia in the territory of the ulnar nerve. The implant was not found in one case.

CONCLUSIONS

The removal of an implant that is not palpable or difficult to palpate should take place in the operating theater following localization by ultrasound. Patients must be fully informed about the procedure, including its complications and the risk for failure.

Contraceptive Implants: An Overview and Update

Contraceptive implants are safe, highly effective, and long-term methods of contraception that are widely applicable to any reproductive-aged woman. Implants require minimal user compliance and are cost-effective. The new single-rod system simplifies insertion and removal, making implants more accessible for both providers and patients. Specifically, progestin-only implants are safe options for various women including adolescents, postpartum, breast-feeding, those who are medically complicated, or those who have contraindications to or intolerance of estrogen-containing contraceptives.

Medical eligibility criteria for new contraceptive methods: combined hormonal patch, combined hormonal vaginal ring and the etonogestrel implant

To review evidence on the combined hormonal patch, combined hormonal vaginal ring and the etonogestrel implant, with a focus on safety and effectiveness of use among women with special health conditions, we searched MEDLINE, Pre-MEDLINE and the Cochrane Library for reports published from 1980 through March 2005. Articles eligible for review included 11 on the hormonal patch, nine on the hormonal ring, and 11 on the etonogestrel implant. Limited evidence suggests patch efficacy is lower among women>90 kg. No evidence was identified for vaginal ring use among women with medical conditions. A single small study found that etonogestrel implants had no adverse effects on bone mineral density among women 18-40 years old. Limited evidence also suggests no adverse effects of the etonogestrel implant on lactation parameters or infant development among users enrolled 28 to 56 days postpartum and followed for 4 months.

Safety and efficacy of Implanon™, a single-rod implantable contraceptive containing etonogestrel

OBJECTIVES

The safety and efficacy of a single-rod implantable contraceptive containing etonogestrel (Implanontrade mark) were investigated in a multicenter clinical trial.

STUDY DESIGN

Sexually active American women (N=330) with apparently normal menstrual cycles used the implant for up to 2 years. All subjects recorded bleeding and/or spotting daily in a diary. Safety was assessed through adverse experiences (AEs), laboratory tests and physical and gynecologic examinations.

RESULTS

Total exposure was 474 woman-years (6186 cycles), and 68% of subjects had at least 1 year of exposure. No pregnancies occurred. The most common bleeding pattern observed throughout the study was infrequent bleeding, defined as less than three episodes of bleeding in a reference period (excluding amenorrhea). The least common pattern was frequent bleeding, defined as more than five episodes of bleeding in a reference period. Infrequent, prolonged and frequent bleeding patterns were most common early in the study and declined thereafter. During the 3-month Reference Periods 2-8 (Months 4-24), the incidence of amenorrhea ranged from 14% to 20%. Forty-three subjects (13%) withdrew from the study because of bleeding pattern changes and 76 subjects (23%) discontinued because of other AEs. Other common AEs leading to discontinuation, besides bleeding irregularities, were emotional lability (6.1%), weight increase (3.3%), depression (2.4%) and acne (1.5%). Use of Implanon (etonogestrel subdermal implant, referred to herein as ENG implant) for up to 2 years had no clinically significant effects on laboratory parameters, physical and pelvic examinations, vital signs or body mass index. The average length of time required for ENG implant insertion and that for removal were 0.5 and 3.5 min, respectively, and all the procedures were uncomplicated. The return to normal menstrual cycles and fertility was rapid after removal.

CONCLUSIONS

Implanon is a safe, highly effective and rapidly reversible new method of contraception.

Progestin implants for female contraception

Four different implants, in the form of capsules or covered rods, that release one of the synthetic progestins levonorgestrel, etonogestrel, Nestorone, or Elcometrine and nomegestrol acetate were reviewed. Biocompatible polymers or copolymers of polydimethyl/polymethylvinyl-siloxanes or ethylvinylacetate are used to hold the steroid crystals and to control the rate of release. Once inserted under the skin, these implants release the corresponding steroid continuously over prolonged periods, a process that can be readily interrupted by implant removal. During long-term use of the implant, the released steroid circulates in blood at a fairly stable level. The physical characteristics of the implants, including drug contents and rate of release, serum levels of the progestin during use, and the duration of their effective life are described. Total steroid loads vary in the range of 50 mg to 216 mg; average release rates are in the range of 30-100 ug/day, and effective lives from 6 months to 7 years.

Implanon: a critical review

OBJECTIVE

To evaluate clinical information on Implanon as a long-term method of contraception and, specifically, to review the efficacy and adverse effect profile of Implanon.

DATA SOURCES

A MEDLINE search (from 1966 through June 1999) was performed to retrieve primary and review articles. The search was limited to data on human subjects. Some references were identified through secondary sources.

STUDY SELECTION AND DATA EXTRACTION

Pharmacokinetic and pharmacodynamic studies, and clinical trials assessing the efficacy and safety of desogestrel implants were reviewed. Relevancy and consistency of information was assessed for each trial.

DATA SYNTHESIS

Implanon is the newest contraceptive implant system that has completed worldwide Phase III clinical trials. It is a single rod that contains a core of 68 mg of 3-keto-desogestrel with a membrane of ethylene vinyl acetate. Inhibition of ovulation occurs within one day of implantation, and effective contraception lasts for three years. Fertility returns within one month after implant removal. Insertion and removal by trained medical professionals is simple, and only minor complications have been documented. Adverse effects are mild and primarily consist of abnormal bleeding, weight gain, acne, breast pain, and headache.

CONCLUSIONS

The data on Implanon indicate that it provides effective long-term contraception with limited adverse effects. It appears to be a good addition to the currently available contraceptives.

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.