The effect of carbamazepine on etonogestrel concentrations in contraceptive implant users

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.

Depot medroxyprogesterone acetate concentrations in patients with and without the use of antiseizure medications

OBJECTIVES

To measure plasma concentrations of medroxyprogesterone acetate (MPA) in users with epilepsy treated with antiseizure medications and compare these to MPA concentrations in those without epilepsy.

STUDY DESIGN

For this multisite cross-sectional study, we obtained a single blood sample from those with epilepsy treated with various antiseizure medications (n = 18) within the week before their next depot medroxyprogesterone injection. Among the participants without epilepsy (n = 20), 10 similarly were scheduled within the week prior to the next injection, and 10 were scheduled at earlier intervals to attempt to balance the time intervals between groups. MPA concentrations were determined by a validated assay.

RESULTS

MPA concentrations were similar among those with epilepsy and controls and between groups with and without the use of enzyme-inducing medications. The lowest MPA concentrations, under 0.07 ng/mL, were observed among two of eight using enzyme-inducing antiseizure medications, one of 10 using noninducing medications, and one of 19 controls had concentrations below 0.2 ng/mL.

CONCLUSIONS

In this exploratory study, lower MPA concentrations in some participants using enzyme-inducing antiseizure medications suggest a potential interaction that could reduce depot medroxyprogesterone efficacy.

The effect of rifampin on serum etonogestrel concentrations and biomarkers of ovulation among contraceptive implant users: A pharmacokinetic and pharmacodynamic study

OBJECTIVES

Rifampin, a strong CYP3A inducer, is the gold standard for evaluating CYP3A-mediated drug-drug interactions. We aimed to evaluate the pharmacokinetic and pharmacodynamic effects of a short course (2 weeks) of rifampin on serum etonogestrel (ENG) concentrations and serologic measures of ovarian activity (endogenous estradiol [E2] and progesterone [P4]) among ENG implant users.

STUDY DESIGN

We enrolled healthy females using ENG implants for 12 to 36 months. We measured baseline serum ENG concentrations using a validated liquid chromatography mass-spectrometry assay and baseline E2 and P4 concentrations using chemiluminescent immunoassays. After 2 weeks of rifampin 600 mg daily, we repeated ENG, E2, and P4 measurements. We compared pre- and post-rifampin serum measurements using paired Wilcoxon signed-rank tests.

RESULTS

Fifteen participants completed all study procedures. Participants' median age was 28.2 years (range 21.8-34.1), median body-mass index was 25.2 kg/m2 (range 18.9-37.3), and median duration of implant use was 22 months (range 12-32). All participants experienced significant decreases from baseline ENG concentrations (median 164.0 pg/mL [range 94.4-265.0]) to post-rifampin measurements (median 47.8 pg/mL [range 24.7-82.8]) (p < 0.001). Serum E2 concentrations also significantly increased with rifampin exposure (median 73 pg/mL vs 202 pg/mL, p = 0.003); increases in serum P4 concentrations were not statistically significant (p = 0.19). Three participants (20%) experienced increased luteal activity, with one presumptively ovulating post-rifampin (P4 = 15.8 ng/mL).

CONCLUSIONS

With only short exposure to a strong CYP3A inducer, ENG implant users experienced clinically significant decreases in serum ENG concentrations that led to changes in biomarkers indicative of waning suppression of ovulation.

IMPLICATIONS

Even a short, 2-week course of treatment with rifampin places etonogestrel contraceptive implant users at risk for decreased contraceptive efficacy. Clinicians should counsel patients using etonogestrel implants considering any duration of rifampin therapy on the need for backup nonhormonal contraception or the use of an intrauterine device to avoid unintended pregnancies.

Preventive Approaches in Women's Neurology: Prepartum, Pregnancy, and Postpartum

Women's neurology is the subspecialty within neurology concerned with the distinct healthcare needs of women. In this article, we review current literature and expert management strategies regarding disease-specific neurologic concerns of women, with an emphasis on issues related to contraception, pregnancy, and lactation. Health conditions that we discuss in this article include epilepsy, headache, stroke, multiple sclerosis, and Chiari I malformation. Current findings on neurologic disease in women suggest that many women with neurologic disease can safely manage their disease during pregnancy and have healthy children, though pregnancy planning is important in many conditions to mitigate risks and effective contraceptive management is important when pregnancy prevention is desired.

The effect of carbamazepine, which increases oestrogen destruction, on the endometriotic implants; an experimental rat model

We planned this experimental study to investigate the effect of carbamazepine (CMZ) on the endometriotic implants. Rats were randomised into four groups after endometriosis surgery. Drinking water was given to the sham group, 0.2 mg/kg oestradiol valerate (EV) to the EV group, 100 mg/kg/day CMZ to the CMZ group, and 0.2 mg/kg EV and 100 mg/kg/day CMZ to the EV-CMZ group. The endometrium of the rats using CMZ stained more intensely with cytochrome P450-3A4 (CYP3A4) enzyme. No endometrial hyperplasia was found in these rats. Endometriotic implants weight was found to be higher in these rats. There was no difference between the groups in terms of staining of the endometriotic implants with CYP3A4 enzyme. Endometriotic implants were less stained with the CYP3A4 enzyme than the endometrium. According to our results, CMZ does not increase the destruction of oestrogen in the endometriotic implants, unlike the endometrium. It may even cause the lesion to enlarge.Impact statementWhat is already known on this subject? Endometriosis is an oestrogen-dependent, progressive disease. Carbamazepine (CMZ) is known to increase oestrogen degradation by activating the cytochrome P450-3A4 (CYP3A4) enzyme. CMZ can be used in the treatment of endometriosis because it increases oestrogen breakdown in tissues.What do the results of this study add? CMZ can protect the endometrium against hyperplasia by increasing the amount of CYP3A4 enzyme in the endometrium. This effect could not be demonstrated in the endometriotic implants. The presence of CYP3A4 enzyme less in the endometriotic implants than in the endometrium may explain this situation. In addition, the fact that CMZ does not increase the enzyme in the endometriotic implants may contribute to this situation.What are the implications of these findings for clinical practice and/or further research? CMZ may not be a suitable alternative in the treatment of endometriosis. However, it may protect against endometrial hyperplasia. Clinical studies are needed for this effect.

Society of Family Planning Clinical Recommendation: Extended Use of Long Acting Reversible Contraception

In this clinical recommendation, we review the evidence supporting the use of the copper intrauterine device, levonorgestrel intrauterine devices and etonogestrel subdermal implant beyond the Food and Drug Administration approved duration of use for contraception (extended use). Clinicians should discuss effectiveness as well as other clinical considerations with patients to allow them to make contraceptive decisions that support their reproductive goals and clinical needs. Extended use of long acting reversible contraception may be a safe, effective and desirable option for many patients.

Etonogestrel contraceptive implant failure in a woman taking rifampin: a case report

Background

The etonogestrel subdermal implant is the most efficacious hormonal contraceptive currently available and provides 99.7% effective contraception. However, similar to other hormonal contraception, its effectiveness is compromised with the use of cytochrome P450 inducing drugs resulting in an unplanned pregnancy. Despite this risk, little is known about the outcome of concomitant use of rifampin and contraceptive implants.

Case presentation

A 24-year-old woman was provided with an etonogestrel implant in September 2018. In July 2020, she was started with rifampin based anti-tuberculosis for tuberculosis of the lymph nodes. In December 2020, she presented to the family planning clinic of St. Paul’s Hospital Millennium Medical college with a diagnosis of failed implant and second-trimester pregnancy at a gestational age of 19 weeks. The etonogestrel implant was removed and the patient was linked to antenatal care follow up.

Conclusion

Concomitant use of hepatic cytochrome P450 enzyme-inducing medications with certain hormonal contraceptives may reduce effectiveness resulting in unintended pregnancy. Women should be given detailed counseling about the potential for drug interactions and a multidisciplinary approach with consultation or referral to reproductive health specialists is crucial for optimal management of women who are at increased risk of contraceptive failure and unintended pregnancy.

Effect of Topiramate on Serum Etonogestrel Concentrations Among Contraceptive Implant Users

OBJECTIVE

To evaluate topiramate and etonogestrel pharmacokinetic interactions in contraceptive implant users.

METHODS

We conducted a prospective, noninferiority study with healthy women using etonogestrel implants continuously for 12-36 months. We measured baseline serum etonogestrel concentrations and then began a 6-week titrated topiramate regimen to standard migraine (100 mg/day) and epilepsy (400 mg/day) dosages. We repeated serum etonogestrel concentrations at 3 weeks (100 mg/day), 4 weeks (200 mg/day), and 6 weeks (400 mg/day) of topiramate therapy. We measured etonogestrel using a validated liquid chromatography-tandem, mass-spectrometry assay and tested for noninferiority (less than 30% decrease) in serum etonogestrel concentrations from baseline.

RESULTS

We enrolled 48 total participants; 32 completed 3 weeks, 31 completed 4 weeks, and 27 completed all follow-up visits. Participants' median age was 25.3 years (range 18.3-37.2), median body mass index (BMI) was 25.5 kg/m2 (range 18.7-42.2), and median duration of implant use was 24 months (range 12-36). Median etonogestrel concentrations were 142 pg/mL (range 76.2-771) at baseline, 126 pg/mL (range 72.4-585) at 3 weeks, 119 pg/mL (range 65.6-542) at 4 weeks, and 105 pg/mL (46.2-859) at 6 weeks. The 95% CIs for mean percent change in serum etonogestrel concentrations from baseline were [-37.3%+16.9%], [-45.4%+5.2%], and [-66.8%+24.8%] at 3 weeks, 4 weeks, and 6 weeks, respectively. Excluding one participant who had a serum etonogestrel concentration less than 90 pg/mL at baseline, 30.8% of participants (8/26, 95% CI 14.3-51.8%) had a serum etonogestrel concentration less than 90 pg/mL at 6 weeks.

CONCLUSION

Though only a mild enzyme-inducing antiepileptic drug, concomitant topiramate use led to inferior serum etonogestrel concentrations among implant users, with a significant proportion reaching etonogestrel concentrations below the threshold for ovulatory suppression when taking antiepileptic dosages of topiramate.

FUNDING SOURCE

This study was primarily funded through an Investigator-Initiated Study grant from Merck Sharp & Dohme Corp [MISP#57073]. This work was also supported by NIH/NCATS CTSA Grant Number UL1 TR001082 and NICHD K12 Women's Reproductive Health Research Scholar Program (grant number 5K12HD001271-18).

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT03335163.

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.

Carbamazepine protects the endometrium against negative effects of estrogen in rats

Carbamazepine (CMZ) increases estrogen metabolism by inducing cytochrome P450 (CYP3A4). We investigated whether CMZ is protective against endometrial hyperplasia (EH). We used 32 female Wistar albino rats divided into four equal groups: the control group received drinking water, the estradiol valerate (EV) group was given EV, the CMZ group was given CMZ, and the EV + CMZ group was given both EV and CMZ. After 30 days the uteri of the rats were removed and serum estrogen and progesterone levels were measured, and endometrial tissue characteristics were evaluated. CYP3A4 expression was assessed using immunohistochemistry. Serum estrogen levels were lowest in the EV group and highest in the CMZ group. Serum progesterone levels were similar among all groups. Glandular density, a proxy measure of EH, was highest in the EV group and lowest in the EV + CMZ group. EH was detected in six of eight rats (75%) in the EV group and two of eight rats (25%) in the EV + CMZ group. Immunohistochemical staining revealed no significant difference in CYP3A4 expression among the four groups. CMZ reduced the negative effect of high dose estrogen that is not balanced by progesterone on the endometrium in rats. The effect likely is probably due to the CYP3A4 enzyme activator effect. CMZ may be protective against EH in high risk women, although confirmation is required.

A Pharmacoepidemiologic Approach to Evaluate Real-world Effectiveness of Hormonal Contraceptives in the Presence of Drug-drug Interactions

Accurate estimation of conception is critical in the assessment of the effects of drugs used during pregnancy or to prevent pregnancy. In a novel application, we studied the effectiveness of oral contraceptives (OCs), where misclassification of conception relative to OC exposure may obscure effect estimates.

Comparison of contraceptive failures associated with CYP3A4-inducing drug-drug interactions by route of hormonal contraceptive in an adverse event reporting system

Objective

To estimate associations between contraceptive failures and concomitant CYP3A4-inducing medications by route of administration.

Study design

Comparison of unintended pregnancy outcomes within U.S. Food and Drug Administration's Adverse Event Reporting System by couse of CYP3A4-inducing drugs and route of administration for levonorgestrel and etonogestrel/desogestrel.

Results

Among 14,504 levonorgestrel case reports, the reporting odds ratio (ROR) was increased for oral (ROR = 4.2 [3.0–5.7]), implants (ROR = 8.0 [5.8–11.0]), but not intrauterine (ROR = 0.9 [0.6–1.3]) levonorgestrel products. For 9348 etonogestrel/desogestrel case reports, oral and vaginal products were not associated with contraceptive failure. Etonogestrel containing implants (ROR = 4.9 [4.1–5.9]) were associated with increased contraceptive failure.

Conclusion

Levonorgestrel containing combination oral products and implants containing levonorgestrel or etonogestrel were prone to CYP3A4-inducing drug-drug interactions that may increase contraceptive failures.

Implications

The progestin components of hormonal contraceptives are susceptible to drug-drug interactions, but this susceptibility is influenced by route of administration. This study provides evidence from an Adverse Event Reporting System that CYP3A4-inducing medications increase the risk of unintended pregnancy for oral and implant contraceptives but not intrauterine or vaginal devices.

Adolescents and long-acting reversible contraceptives: beyond the basics

PURPOSE OF REVIEW

The current article explores some of the more complex subtopics concerning adolescents and long-acting reversible contraceptives (LARC).

RECENT FINDINGS

Recent research has highlighted ways in which LARC provision can be optimized in adolescents and has identified gaps in adolescent LARC access and utilization.

SUMMARY

Contraceptive counseling for adolescents should be patient-centered, not necessarily LARC-first, to avoid coercion. There are increasing applications for the noncontraceptive benefits of LARC for several unique patient populations and medical conditions.

Gynecologic Management of Adolescents and Young Women With Seizure Disorders: ACOG Committee Opinion, Number 806

Seizure disorders frequently are diagnosed and managed during adolescence; therefore, obstetrician-gynecologists who care for adolescents should be familiar with epilepsy and other seizure disorders, as well as antiepileptic drugs. Patients diagnosed with seizure disorders during childhood may have increased seizure activity with puberty and menarche due to the neuroactive properties of endogenous steroid hormones. Compared with patients without epilepsy, patients with epilepsy are more likely to experience anovulatory cycles, irregular menstrual bleeding, and amenorrhea. Although hormonal suppression should not be initiated before puberty or menarche, prepubertal counseling may be appropriate, and obstetrician-gynecologists may work with young patients and their families to develop a plan to initiate with menarche. Additionally, obstetrician-gynecologists should be aware of any medication changes, including antiepileptics, for adolescent patients with seizure disorders. Research on hormonal therapy for the treatment of epilepsy is scant; however, the anticonvulsant properties of various progestins have been explored as potential treatment. There is no conclusive evidence that combination hormonal contraception increases epileptic seizures, and epilepsy itself poses no increased risk of an adverse outcome for those using combined oral contraceptive pills, the contraceptive patch, or a contraceptive ring. Because many antiepileptic drugs are teratogenic, discussing sexual health with and providing effective contraceptive choices to this population is critical. Obstetrician-gynecologists should work with patients with seizure disorders to develop a plan when pregnancy occurs.

A pilot study on the effect of isotretinoin on serum etonogestrel concentrations in contraceptive implant users

OBJECTIVE

To explore the pharmacokinetic interaction between isotretinoin, a cytochrome P-450 (CYP) inducer and potent teratogen, and the etonogestrel contraceptive implant.

STUDY DESIGN

We enrolled healthy reproductive-age women initiating isotretinoin and using an etonogestrel implant. We compared serum etonogestrel concentrations at baseline and after four and nine weeks of isotretinoin co-administration using a validated assay.

RESULTS

Among eight implant users, all serum etonogestrel concentrations remained >90 pg/mL during isotretinoin co-administration with no significant changes from baseline (p = 0.25, Friedman's test).

CONCLUSION

In this exploratory study, we found that isotretinoin did not cause serum etonogestrel concentrations to fall below the threshold for ovulatory suppression (<90 pg/mL) among implant users.

IMPLICATIONS

Reproductive-age women treated with isotretinoin require reliable contraception to prevent pregnancies impacted by teratogenic-effects. This small study demonstrates that contraceptive implant users maintained serum etonogestrel concentrations above the threshold for consistent ovulatory suppression during isotretinoin co-administration. The contraceptive implant remains an appropriate option for patients considering isotretinoin therapy.

Treatment of Women With Epilepsy

PURPOSE OF REVIEW

This article provides the latest information to guide practitioners in counseling and treating women with epilepsy.

RECENT FINDINGS

There is an increasing body of literature on the multidirectional effects of sex hormones on seizure frequency and severity and of seizures altering areas of the brain involved in neuroendocrine function. Ongoing pregnancy outcome data from pregnancy registries and meta-analysis of observational studies have provided key information on the safety of using antiseizure medications during pregnancy and the risk to the fetus.

SUMMARY

In treating and counseling women with epilepsy from puberty to menopause, it is important to understand the complex interactions of sex hormones, seizures, and antiseizure medications on reproductive health and pregnancy outcomes.

ACOG Practice Bulletin No. 206: Use of Hormonal Contraception in Women With Coexisting Medical Conditions

Although numerous studies have addressed the safety and effectiveness of hormonal contraceptive use in healthy women, data regarding women with underlying medical conditions or other special circumstances are limited. The U.S. Medical Eligibility Criteria (USMEC) for Contraceptive Use, 2016 (), which has been endorsed by the American College of Obstetricians and Gynecologists, is a published guideline based on the best available evidence and expert opinion to help health care providers better care for women with chronic medical problems who need contraception. The goal of this Practice Bulletin is to explain how to use the USMEC rating system in clinical practice and to specifically discuss the rationale behind the ratings for various medical conditions. Contraception for women with human immunodeficiency virus (HIV) (); the use of emergency contraception in women with medical coexisting medical conditions, including obesity, (); and the effect of depot medroxyprogesterone acetate (DMPA) on bone health () are addressed in other documents from the American College of Obstetricians and Gynecologists.

The need for contraception in patients taking prescription drugs: a review of FDA warning labels, duration of effects, and mechanisms of action

Introduction: This review provides a guide for the rational use of prescription drugs in patients of reproductive age. Areas covered: A comprehensive retrieval of the labels of FDA-approved drugs was performed to identify drugs where the label recommends contraceptive use during and/or after treatment. The acquired data were analyzed and organized into a table. Contraception was recommended or mandated for 268 single-ingredient drugs. These could be divided into four main categories, with many having effects across several categories: 177 drugs required contraception because they were associated with pregnancy loss or stillbirth, 177 drugs were associated with teratogenesis, 136 were associated with non-teratogenic adverse peri- or postnatal effects on the fetus (e.g. low birth weight), and 44 were associated with decreased efficacy of contraception or a change in ovulatory cycle. We also discuss the period of time contraception is required, as well as the known or hypothesized reasons for the reproductive toxicity of these agents. Expert opinion: We have provided a comprehensive overview of the FDA-approved drugs where the warning labels currently stipulate that contraception should be used. Although other references are available for clinicians, this review provides a useful source of information regarding the single-ingredient prescription drugs that may affect the outcome of pregnancy. This information is particularly relevant for researchers, as it provides an overview of the different drugs with reproductive toxicity, and because it highlights the specific needs for future research. In particular, more work (especially epidemiological studies) is needed to clarify the clinical relevance of these findings, most of which were obtained through animal studies.