Induction of ethinylestradiol and levonorgestrel metabolism by oxcarbazepine in healthy women

In vitro assessment of the potential for dolutegravir to affect hepatic clearance of levonorgestrel

Objectives:

The World Health Organization recommends that all countries adopt dolutegravir-based antiretroviral therapy as the preferred regimen for all individuals living with HIV. Levonorgestrel is a commonly used hormonal contraceptive, which undergoes drug–drug interactions with some antiretrovirals, but the potential interaction between dolutegravir and levonorgestrel has not been examined. We aimed to evaluate cytochrome P450 (CYP)-mediated levonorgestrel metabolism and quantify the effects of dolutegravir on levonorgestrel apparent intrinsic clearance (CL_int.app.) and CYP gene expression.

Methods:

In vitro CYP-mediated CL_int.app. of levonorgestrel was quantified using a recombinant human CYP (rhCYP) enzyme system. A primary human hepatocyte model of drug metabolism was used to assess the effects of dolutegravir on (1) levonorgestrel CL_int.app., using liquid chromatography-tandem mass spectrometry, and (2) the expression of specific CYP enzymes, using quantitative real-time polymerase chain reaction.

Results:

Levonorgestrel clearance was mediated by multiple rhCYPs, including rhCYP3A4. Under control conditions, levonorgestrel CL_int.app. was 22.4 ± 5.0 μL/min/10⁶ hepatocytes. Incubation with 43.1 nM of unbound dolutegravir elevated levonorgestrel CL_int.app. to 31.4 ± 7.8 μL/min/10⁶ hepatocytes (P = 0.168), while 142.23 nM increased levonorgestrel CL_int.app. to 37.0 ± 2.9 μL/min/10⁶ hepatocytes (P = 0.012). Unbound dolutegravir ≥ 431 nM induced expression of CYP3A4 (≥ two-fold) in a dose-dependent manner, while 1.44 μM of unbound dolutegravir induced CYP2B6 expression 2.2 ± 0.3-fold (P = 0.0004).

Conclusions:

In summary, this in vitro study suggests that dolutegravir has the potential to increase hepatic clearance of levonorgestrel by inducing both CYP3A and non-CYP3A enzymes. The observed in vitro dolutegravir–levonorgestrel drug–drug interaction should be further examined in clinical studies.

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.

Contraceptive vaginal ring reduces lamotrigine levels

OBJECTIVE

The objective of the study was to describe the effect of the vaginal ring and transdermal patch on lamotrigine serum levels in women with epilepsy.

BACKGROUND

Previous studies demonstrate that oral hormonal contraceptives containing synthetic estrogen increase lamotrigine clearance through induction of glucuronidation. This leads to variable lamotrigine serum concentrations throughout monthly cycles in women who are on combined oral contraceptives (COCs). The effects of estrogen-containing nonoral hormonal contraceptive methods, including the vaginal ring and transdermal patch, on lamotrigine pharmacokinetics are not well described.

METHODS

Retrospective chart review was performed to identify serum lamotrigine levels drawn from women with epilepsy while on the active phase of vaginal ring or transdermal patch and while off contraception. Wilcoxon signed-rank tests for paired data were used to compare the difference in dose-corrected lamotrigine concentration in plasma between values while on hormonal contraception to those while off contraception in patients using a vaginal ring.

RESULTS

Six patients were using the vaginal ring, and one patient was using the transdermal patch. Lamotrigine dose-corrected concentrations were decreased during the active phase of the vaginal ring compared with concentrations during the period off contraception (p = .04). There was one patient without a decrease in concentration, but the other five patients on the vaginal ring had a decrease in dose-corrected lamotrigine concentration ranging from 36 to 70% while on the vaginal ring. Similarly, one patient using the transdermal patch had a decrease of 37% in dose-corrected lamotrigine concentration while on the patch.

CONCLUSIONS

The findings support that the vaginal ring contraceptive method decreases lamotrigine concentrations during the active phase of treatment. This has important implications for contraceptive counseling and maintaining therapeutic levels in women of childbearing age with epilepsy.

Elbasvir/grazoprevir in women with hepatitis C virus infection taking oral contraceptives or hormone replacement therapy

Introduction

Some direct-acting antiviral regimens for hepatitis C virus (HCV) infection pose safety or efficacy concerns if coadministered with drugs containing ethinyl estradiol. The present analysis was conducted to examine the impact of concomitant oral contraceptive pills (OCP) or hormone replacement therapy (HRT) during treatment with elbasvir (EBR)/grazoprevir (GZR) in women with HCV genotype (GT)1 or GT4 infection.

Methods

This is a post hoc, integrated retrospective analysis of female participants with HCV GT1 or GT4 infection who received EBR 50 mg/GZR 100 mg once daily for 12 weeks in phase 2/3 clinical trials. The primary end point was sustained virologic response at 12 weeks after therapy completion (SVR12). For this analysis, participants were stratified according to whether they received OCP or HRT during the original treatment study.

Results

A total of 1,022 women with HCV GT1 or GT4 infection were included (receiving OCP/HRT, n=81; not receiving OCP/HRT, n=941). Most participants receiving OCP/HRT were treatment-naive (79%), noncirrhotic (91.4%), and aged >35 years (71.6%). SVR12 rates were similar in women receiving OCP/HRT and those not receiving OCP/HRT (95.1% vs 96.3%). SVR12 rates remained high across all subgroups within the population receiving OCP/HRT: SVR12 rates were 94.6%, 100%, and 100% in participants with GT1a, GT1b, and GT4 infection, and all women aged 18-35 years achieved SVR (21/21). Treatment-related adverse events occurred in 40.7% (33/81) and 30.1% (283/941) of women receiving and those not receiving OCP/HRT, respectively.

Conclusion

The efficacy and safety of EBR/GZR administered for 12 weeks was similar in women receiving OCP/HRT and those not on OCP/HRT. These data indicate that EBR/GZR can be safely used for the treatment of HCV GT1 or GT4 infection in women receiving concomitant OCP/HRT.

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.

Risk-Benefit Assessment of Ethinylestradiol Using a Physiologically Based Pharmacokinetic Modeling Approach

Current formulations of combined oral contraceptives (COC) containing ethinylestradiol (EE) have ≤35 μg due to increased risks of cardiovascular diseases (CVD) with higher doses of EE. Low‐dose formulations however, have resulted in increased incidences of breakthrough bleeding and contraceptive failure, particularly when coadministered with inducers of cytochrome P450 enzymes (CYP). The developed physiologically based pharmacokinetic model quantitatively predicted the effect of CYP3A4 inhibition and induction on the pharmacokinetics of EE. The predicted C_max and AUC ratios when coadministered with voriconazole, fluconazole, rifampicin, and carbamazepine were within 1.25 of the observed data. Based on published clinical data, an AUC_ss value of 1,000 pg/ml.h was selected as the threshold for breakthrough bleeding. Prospective application of the model in simulations of different doses of EE (20 μg, 35 μg, and 50 μg) identified percentages of the population at risk of breakthrough bleeding alone and with varying degrees of CYP modulation.

Eslicarbazepine acetate in epilepsies with focal and secondary generalised seizures: systematic review of current evidence

INTRODUCTION

Eslicarbazepine acetate (ESL) is a third-generation antiepileptic drug (AED) approved for adjunctive treatment in adults, children, and adolescents with focal-onset seizures. Recently ESL was approved for initial monotherapy in adults. The intention of this article is to review current evidence for ESL and to summarise its pharmacological profile in comparison to other AEDs of the dibenzazepine group. Areas covered: We performed a systematic literature search in electronic databases (MEDLINE database, Cochrane Central Register of Controlled Trials, Excerpta Medica dataBASE) using a combined search strategy including the following keywords: eslicarbazepine, epilepsy and seizure. The search was performed from 2000 until December 2017. Using a standardised assessment form, information on the study design, methodological framework, data sources and efficacy and adverse events attributed to ESL were extracted from each publication and systematically reported. Expert commentary: ESL is an effective, safe and well tolerated third-generation AED for the treatment of focal epilepsies. During therapy, especially serum sodium levels and possible interactions with other substances have to be monitored. As of yet, long-term experience is still needed to make severe late-occurring adverse events unlikely and to obtain data regarding its use in pregnancy.

Sodium Channel Blockers in the Treatment of Epilepsy

Sodium channel blockers have been the mainstay of the pharmacological management of focal and generalised tonic-clonic seizures for more than 70 years. The focus of this paper will be on phenytoin, carbamazepine, lamotrigine, oxcarbazepine, rufinamide, lacosamide and eslicarbazepine acetate. All these antiepileptic drugs have similar efficacy and share similar dose-dependent, adverse effect profiles, although phenytoin, carbamazepine and oxcarbazepine are more likely to cause idiosyncratic reactions than the others. With the exception of lamotrigine, rufinamide and lacosamide, all are enzyme inducers and most are minor teratogens; although data on teratogenicity are sparse with lacosamide and eslicarbazepine acetate. There is increasing evidence that these drugs differ mechanistically, with the newer agents, lacosamide and eslicarbazepine acetate, having their major pharmacological effect on the slow inactivation state of the sodium channel, which may be associated with better tolerability at higher dosage, although hard evidence in support of this observation is currently not available. Rufinamide is licensed only for Lennox-Gastaut syndrome in children aged 4 years and above. There is a move away from using enzyme inducers, particularly phenytoin and carbamazepine, in everyday clinical practice. There seems little doubt, however, that some sodium channel blockers will have an enduring place in the management of epilepsy well into the 21st century.

Folic acid use by women with epilepsy: Findings of the Epilepsy Birth Control Registry

PURPOSE

To determine the prevalence and predictors of folic acid (FA) use by women with epilepsy (WWE) at risk of unintended pregnancy.

METHODS

These retrospective data come from the Epilepsy Birth Control Registry (EBCR) web-based survey of 1144 WWE in the community, 18-47years, who provided demographic, epilepsy, AED, contraception, pregnancy, healthcare visits and FA data. We report prevalence and predictors of FA use in relation to risk of pregnancy (not at risk, at risk, seeking pregnancy, pregnant), demographics, seizure types and AED and contraception categories.

RESULTS

368 (47.6%) of the 773 WWE at risk of unintended pregnancy in the EBCR took FA supplement. Being at risk was a significant predictor in comparison to WWE not at risk (OR=1.464 [1.103-1.944], p=0.008). In comparison to WWE at risk, FA use trended greater for WWE actively seeking pregnancy (29/47, 61.7% v 368/773, 47.6%; p=0.0605) and was greater for pregnant WWE (17/19, 89.5% v 368/773, 47.6%; p=0.0007). Demographic predictors for WWE at risk were race (p=0.003), education (p=0.012) and income (0.043) with significantly greater FA use by Caucasians than minorities and direct correlations between FA use and levels of education and household income. Seizure type, AED use, category and dosage, polytherapy and contraceptive category were not predictors. A healthcare provider visit during the year prior to the survey was not a predictor. Prevalence of FA use was similar following visits with gynecologists - 51.7%, neurologists - 48.7% and primary care - 48.6%. FA supplementation by prescription was greater for WWE at risk on AED versus no AED (190/355, 53.5% v 3/13, 23.1%; p=0.045).

CONCLUSION

Low prevalence of preconception FA use may reflect a need for more education. In addition, further research is needed to provide definitive evidence that FA reduces congenital malformations in the offspring of WWE.

Development and validation of a reversed-phase HPLC method for licarbazepine monitoring in serum of patients under oxcarbazepine treatment

Licarbazepine is the pharmacologically active metabolite of oxcarbazepine, a drug indicated for the treatment of partial seizures and bipolar disorders. Several HPLC methods have been developed thus far but there is lack of control for interferences from antipsychotic drugs. The aim of the present study was to develop a simple, low-cost and reliable HPLC-UV method for the determination of licarbazepine in human serum in the presence of co-administered antiepileptic, antipsychotic and commonly prescribed drugs. Sample preparation consisted of a single protein precipitation step with methanol. Separation lasted ~9 min on a reversed-phase C₁₈ column using a mobile phase composed of 50 mm sodium-dihydrogen-phosphate-monohydrate/acetonitrile (70:30, v/v) delivered isocratically at 0.9 mL/min and 30°C. Wavelength was 210 nm and calibration curve was linear with r² 0.998 over the range 0.2-50.0 μg/mL. Coefficient of variation was <5.03% and bias <-4.92%. Recovery ranged from 99.49 to 104.52% and the limit of detection was 0.0182 μg/mL. No interferences from the matrix or from antiepileptic, antipsychotic and commonly prescribed drugs were observed. The method was applied to serum samples of patients under oxcarbazepine treatment and proved to be a useful tool for the therapeutic drug monitoring of licarbazepine during monotherapy or adjunctive treatment of seizures or affective disorders.

Predictors of unintended pregnancy in women with epilepsy

Objective:

To determine whether rates of unintended pregnancy in women with epilepsy (WWE) vary by contraceptive category and when stratified by antiepileptic drug (AED) category.

Methods:

These retrospective data come from the Epilepsy Birth Control Registry (EBCR) web-based survey of 1,144 WWE in the community, 18–47 years of age, who provided demographic, epilepsy, AED, contraceptive, and pregnancy data. Participants indicated whether pregnancies were intended or unintended, as well as the type of contraceptive and AED used at conception. We report failure rates relative to the frequency of use of each contraceptive category in the EBCR.

Results:

Most WWE (78.9%) reported having at least one unintended pregnancy; 65.0% of their pregnancies were unintended. Unintended pregnancy was more common among younger, racial minority, and Hispanic WWE. Among reversible contraceptive categories, the intrauterine device had the lowest failure rate. Failure rates varied greatly on systemic hormonal contraception (HC), depending on whether oral or nonoral forms were used and especially in relation to the category of AED with which HC was combined. Oral forms had greater failure rate than nonoral forms. HC combined with enzyme-inducing AEDs had a substantially greater failure rate than HC combined with no AED or any other AED category and in comparison to barrier plus any AED category. Other AED–HC combinations, in contrast, carried lower risks than barrier.

Conclusions:

Unintended pregnancy is common among WWE and may vary by contraceptive category and AED stratification. In view of the important consequences of unintended pregnancy on pregnancy outcomes, these retrospective findings warrant further prospective investigation.

Use of endogenous cortisol 6β-hydroxylation clearance for phenotyping in vivo CYP3A activity in women after sequential administration of an oral contraceptive (OC) containing ethinylestradiol and levonorgestrel as weak CYP3A inhibitors

The present study was undertaken to evaluate the time courses of in vivo cytochrome P450 3A (CYP3A) inhibition in four healthy women after sequential administration of an oral contraceptive (OC) containing ethinylestradiol and levonorgestrel, using 6β-hydroxylation clearance of endogenous cortisol (CLm(6β)) as a new index for CYP3A phenotyping. The 6β-hydroxylation clearance (CLm(6β)) was followed every 2h from 9:00 or 11:00 to 17:00 on days 0 (baseline), 1, 2, 21, and 28 during a single menstrual cycle. The serum concentrations of endogenous estradiol and progesterone were also measured. The time course data of CLm(6β) clearly demonstrated 43-64% inhibition of CYP3A activity in women taking a low daily dose of the OC for 21days. The average CLm(6β) levels that were suppressed by the OC in four women were extremely low (0.60-1.23mL/min) compared with the normal CLm(6β) range (1.5-3.5mL/min) that was obtained from 49 healthy subjects in our previous study. The in vivo inhibitory potencies (43-64%) obtained in this study were stronger than expected from reported in vitro studies (∼20%). Furthermore, it would take at least seven days to return to the baseline activity of CYP3A after discontinuation of the OC. The results presented here should provide important information on the inhibitory effect of OC on the CYP3A activities in women, which are involved in the metabolism of a number of drugs with a narrow therapeutic range.

Drug interactions with the newer antiepileptic drugs (AEDs)--Part 2: pharmacokinetic and pharmacodynamic interactions between AEDs and drugs used to treat non-epilepsy disorders

Since antiepileptic drugs (AEDs) are prescribed to treat various non-epilepsy-related disorders in addition to the fact that patients with epilepsy may develop concurrent disorders that will need treatment, the propensity for AEDs to interact with non-AEDs is considerable and indeed can present a difficult clinical problem. The present review details the pharmacokinetic and pharmacodynamic interactions that have been reported to occur with the new AEDs (eslicarbazepine acetate, felbamate, gabapentin, lacosamide, lamotrigine, levetiracetam, oxcarbazepine, perampanel, pregabalin, retigabine (ezogabine), rufinamide, stiripentol, tiagabine, topiramate, vigabatrin and zonisamide) and drugs used to treat non-epilepsy disorders. Interaction study details are described, as necessary, so as to allow the reader to take a view as to the possible clinical significance of particular interactions. Pharmacokinetic interactions relate to hepatic enzyme induction or inhibition and involved a variety of drugs including psychoactive drugs, cardioactive drugs, oral contraceptives, antituberculous agents, analgesics and antineoplastic drugs. A total of 68 pharmacokinetic interactions have been described, with lamotrigine (n = 22), topiramate (n = 18) and oxcarbazepine (n = 7) being associated with most, whilst lacosamide, pregabalin, stiripentol and vigabatrin are associated with none. Overall, only three pharmacodynamic interactions have been described and occur with oxcarbazepine, perampanel and pregabalin.

[Antiepileptics in women of childbearing age and during pregnancy: comparison of specialized information with the current state of knowledge in Germany and Switzerland]

BACKGROUND

Healthcare professionals regularly read the summary of product characteristics (SmPC) as one of the various sources of information on the risks of drug use in women of childbearing age and during pregnancy. The aim of this article is to present an overview of the teratogenic potential of various antiepileptic drugs and to compare these data with the information provided by the SmPCs.

METHODS

A literature search on the teratogenic risks of 19 antiepileptic agents was conducted and the results were compared with the information on the use in women of childbearing age and during pregnancy provided by the SmPCs of 38 commercial products available in Switzerland and Germany.

RESULTS

The teratogenic risk is discussed in all available SmPCs. Quantification of the risk for birth defects and the numbers of documented pregnancies are mostly missing. Reproductive safety information in SmPCs showed poor concordance with risk levels reported in the literature. Recommendations concerning the need to monitor plasma levels and possibly perform dose adjustments during pregnancy to prevent treatment failure were missing in five Swiss and two German SmPCs.

DISCUSSION

The information regarding use in women of childbearing age and during pregnancy provided by the SmPCs is heterogeneous and poorly reflects the current state of knowledge. Regular updates of SmPCs are warranted in order for these documents to be of reliable use for health care professionals.

Clinical pharmacokinetic interactions between antiepileptic drugs and hormonal contraceptives

Contraceptive management in women with epilepsy is critical owing to the potential maternal and fetal risks if contraception or seizure management fails. This article briefly describes the pharmacokinetic interactions between antiepileptic drugs (AEDs) and hormonal contraceptives and the rational strategies that may overcome these risks. Hormonal contraception, including the use of oral contraceptives (OCs), is widely used in many women with epilepsy - there is no strong evidence of seizures worsening with their use. AEDs are the mainstay for seizure control in women with epilepsy. However, there are many factors to consider in the choice of AED therapy and hormonal contraception, since some AEDs can reduce the efficacy of OCs owing to pharmacokinetic interactions. Estrogens and progestogens are metabolized by cytochrome P450 3A4. AEDs, such as phenytoin, phenobarbital, carbamazepine, felbamate, topiramate, oxcarbazepine and primidone, induce cytochrome P450 3A4, leading to enhanced metabolism of either or both the estrogenic and progestogenic component of OCs, thereby reducing their efficacy in preventing pregnancy. OCs can also decrease the concentrations of AEDs such as lamotrigine and, thereby, increase the risk of seizures. Increased awareness of AED interactions may help optimize seizure therapy in women with epilepsy.

Women and epilepsy: review and practical recommendations

Individuals with epilepsy experience a number of sex-specific problems. In women, pregnancy and delivery are obvious issues, fertility problems are more often encountered and they also seem to have a higher frequency of sexual problems. A large number of women with epilepsy experience seizure exacerbation in relation to the menstrual cycle and have higher frequencies of menstrual disturbances and polycystic ovaries. Cosmetic problems affecting skin, hair or weight may also be drug induced. The use of antiepileptic drugs may influence the effect of contraceptives leading to unplanned pregnancies and contraceptives may affect the serum levels of antiepileptic drugs. The care of pregnant women with epilepsy requires attention to a number of guidelines and close cooperation between neurologist and gynecologist is recommended. Although the majority of the women with epilepsy experience normal pregnancies and deliveries, their children have a higher risk of birth defects. At menopause, their seizure pattern may change and some antiepileptic drugs may increase the risk of osteoporosis. The optimal treatment of women with epilepsy should take into account these gender-specific issues in the different stages of life.

Contraception and prenatal vitamin supplementation for women on antiepileptic medications

This article identifies interactions among AEDs with hormonal contraceptives and summarizes management strategies from the literature. Recommendations for addressing folate, vitamin K, and vitamin D deficiency caused by AEDs are also reviewed.

Effect of eslicarbazepine acetate on the pharmacokinetics of a combined ethinylestradiol/levonorgestrel oral contraceptive in healthy women

OBJECTIVE

To investigate the effect of once-daily (QD) eslicarbazepine acetate (ESL) 800 mg and 1,200 mg administration on pharmacokinetics of a combined ethinylestradiol/levonorgestrel oral contraceptive (OC) in women of childbearing potential.

METHODS

Two two-way, crossover, two-period, randomized, open-label studies were performed in 20 healthy female subjects, each. In one period (ESL+OC period), subjects received ESL 800 mg QD in one study and ESL 1200 mg QD in the other study, for 15 days; concomitantly with the Day 14 ESL dose, an oral single dose of 30 μg ethinylestradiol and 150 μg levonorgestrel was administered. In the other period (OC alone), a single dose of 30 μg ethinylestradiol and 150 μg levonorgestrel was administered. Three weeks or more separated the periods. An analysis of variance (ANOVA) was used to test for differences between pharmacokinetic parameters of 30 μg ethinylestradiol and 150 μg levonorgestrel following ESL+OC and OC alone, and 90% confidence intervals (90%CI) for the ESL+OC/OC alone geometric mean ratio (GMR) were calculated.

RESULTS

ESL significantly decreased the systemic exposure to both ethinylestradiol and levonorgestrel. GMR (90%CI) for AUC0-24 of ethinylestradiol were 68% (64%; 71%) following 1,200 mg ESL and 75% (71%; 79%) following 800 mg ESL. GMR (90%CI) for AUC0-24 of levonorgestrel were 76% (68%; 86%) following 1,200 mg ESL and 89% (82%; 97%) following 800 mg ESL.

CONCLUSIONS

A clinically relevant dose-dependent effect of ESL administration on the pharmacokinetics of ethinylestradiol and levonorgestrel was observed. Therefore, to avoid inadvertent pregnancy, women of childbearing potential should use other adequate methods of contraception during treatment with ESL, and, in case ESL treatment is discontinued, until CYP3A4 activity returns to normal.

Reproductive and contraceptive issues in chronically ill adolescents

OBJECTIVES

To address reproductive and contraceptive issues in adolescent girls with chronic medical conditions in order to assist health-care providers when they counsel teenagers about contraceptive methods.

METHODS

The review is based on a literature search in Medline (1973-2010) about specific contraceptive use by adolescents with obesity, endocrine, cardiovascular, haematologic, oncologic, neurological, psychiatric, gastrointestinal, hepatobiliary, autoimmune, renal, pulmonary conditions and disabilities. The latest recommendations from the World Health Organisation for adolescents are also added. Contraceptive methods studied were combined hormonal contraceptives, progestogen-only contraceptives, and intrauterine contraceptives.

RESULTS

Adolescents are eligible to use any method of contraception. Contraceptive choices of chronically ill adolescents have changed over time. Given new developments in the field of adolescent sexual and reproductive health care, safe and effective forms of contraception are available for almost every adolescent with a chronic condition. When selecting a method, the nature of the medical illness and the expressed desires of the teenager must be taken into account.

CONCLUSIONS

Adolescents, including those with chronic conditions, are sexual beings; they are entitled to sexual and reproductive health care. Decisions on appropriate contraception must be based upon informed choice, after adequate sexual health education.

Concepts of contraception for adolescent and young adult women with chronic illness and disability

Sexual behavior is common in adolescents and young adults with or without chronic illness or disability, resulting in high levels of unplanned pregnancy and STDs. Individuals with chronic illness or disability should not receive suboptimal preventive health care. These individuals have a need for counseling regarding issues of sexuality and contraception. Sexually active adolescent and young adult women can be offered safe and effective contraception if they wish to avoid pregnancy. Women with chronic illnesses and disabilities who are sexually active should also be offered contraception based on their specific medical issues. Condoms are also recommended to reduce STD risks. Table 36 summarizes basic principles of contraception application for specific illnesses, which have been identified since the release of the combined OC in 1960. Clinicians should also consider the noncontraceptive benefits of this remarkable and life-changing technology that allows all reproductive age women to improve their lives, including those with chronic illnesses and disabilities.

Effect of ticagrelor on the pharmacokinetics of ethinyl oestradiol and levonorgestrel in healthy volunteers

BACKGROUND

Cytochrome P450 3 A is involved in ticagrelor and ethinyl oestradiol/levonorgestrel metabolism; so a potential drug-drug interaction may occur.

OBJECTIVES

To assess: ticagrelor effects on ethinyl oestradiol/levonorgestrel pharmacokinetics, endogenous sex hormone levels; ethinyl oestradiol/levonorgestrel effects on ticagrelor pharmacokinetics; tolerability of ticagrelor + ethinyl oestradiol/levonorgestrel.

METHODS

This trial was a randomized, double-blind, two-way crossover, single-center study. Twenty-two healthy female volunteers (on stable ethinyl oestradiol/levonorgestrel) received 90 mg ticagrelor or placebo twice daily with ethinyl oestradiol/levonorgestrel (0.03 mg/0.15 mg; Nordette) on cycle days 1-21. Volunteers crossed over treatment on day 1/cycle 2. Pharmacokinetic parameters were evaluated on cycle day 21, and endogenous hormones assayed on cycle days 1, 7, 14 and 21.

CLINICAL TRIAL REGISTRATION NUMBER

NCT006895906.

RESULTS

Ethinyl oestradiol absorption was rapid (median t(max) approximately 1 hour), and was not affected by ticagrelor. Ticagrelor co-administration (90% confidence interval [CI]) increased AUC(0-τ), C(min), and C(max) of ethinyl oestradiol by 20% (1.03-1.40), 20% (0.96-1.50) and 31% (1.18-1.44), respectively. Ticagrelor had no effect on levonorgestrel pharmacokinetic parameters versus placebo (90% CI: AUC(0-τ) 0.97-1.10; C(min) 0.94-1.10; C(max) 1.02-1.16). Steady-state ticagrelor, and AR-C124910XX (major and equally pharmacologically active metabolite), AUC(0-τ), C(max), and t(max) were comparable with published findings. Pre-dose ticagrelor and AR-C124910XX plasma concentrations were higher on cycle day 21 versus days 7 and 14. Endogenous sex hormone plasma levels were unaffected by ticagrelor. Co-administration of ticagrelor with ethinyl oestradiol/levonorgestrel was well tolerated. Study limitations included: no ticagrelor-only arm; only one type of oral contraceptive; short study duration; using oestradiol/levonorgestrel pharmacokinetic parameters as surrogate marker for contraceptive efficacy.

CONCLUSIONS

Ticagrelor co-administration with ethinyl oestradiol/levonorgestrel increased ethinyl oestradiol exposure by approximately 20%, with no effect on levonorgestrel pharmacokinetics. No clinically relevant effect on contraceptive efficacy is expected with ethinyl oestradiol/levonorgestrel and ticagrelor co-administration.

Antiepileptic drug interactions - principles and clinical implications

Antiepileptic drugs (AEDs) are widely used as long-term adjunctive therapy or as monotherapy in epilepsy and other indications and consist of a group of drugs that are highly susceptible to drug interactions. The purpose of the present review is to focus upon clinically relevant interactions where AEDs are involved and especially on pharmacokinetic interactions. The older AEDs are susceptible to cause induction (carbamazepine, phenobarbital, phenytoin, primidone) or inhibition (valproic acid), resulting in a decrease or increase, respectively, in the serum concentration of other AEDs, as well as other drug classes (anticoagulants, oral contraceptives, antidepressants, antipsychotics, antimicrobal drugs, antineoplastic drugs, and immunosupressants). Conversely, the serum concentrations of AEDs may be increased by enzyme inhibitors among antidepressants and antipsychotics, antimicrobal drugs (as macrolides or isoniazid) and decreased by other mechanisms as induction, reduced absorption or excretion (as oral contraceptives, cimetidine, probenicid and antacides). Pharmacokinetic interactions involving newer AEDs include the enzyme inhibitors felbamate, rufinamide, and stiripentol and the inducers oxcarbazepine and topiramate. Lamotrigine is affected by these drugs, older AEDs and other drug classes as oral contraceptives. Individual AED interactions may be divided into three levels depending on the clinical consequences of alterations in serum concentrations. This approach may point to interactions of specific importance, although it should be implemented with caution, as it is not meant to oversimplify fact matters. Level 1 involves serious clinical consequences, and the combination should be avoided. Level 2 usually implies cautiousness and possible dosage adjustments, as the combination may not be possible to avoid. Level 3 refers to interactions where dosage adjustments are usually not necessary. Updated knowledge regarding drug interactions is important to predict the potential for harmful or lacking effects involving AEDs.

Carbamazepine but not valproate induces CYP2A6 activity in smokers with mental illness

BACKGROUND

Antiepileptic drugs (AED) are being increasingly used in the management of serious mental illness, but their effects on nicotine metabolism have not been studied.

METHODS

This study investigated the effects of three AEDs (carbamazepine, oxcarbazepine, and valproic acid) on nicotine and nicotine metabolite levels in 149 smokers with schizophrenia and bipolar disorder who participated in an afternoon blood draw for nicotine, cotinine, and 3'-hydroxycotinine (3HC). The ratio of 3HC to cotinine was calculated as a marker of CYP2A6 metabolic activity. Among the participants, 8 smokers were taking carbamazepine, 6 were taking oxcarbazepine, and 40 were taking valproic acid.

RESULTS

The 3HC/cotinine ratio was significantly higher in individuals taking carbamazepine or oxcarbazepine (combined, n = 14) versus those not taking either (mean 0.993 versus 0.503; P < 0.001). The cotinine/cigarette per day ratio was significantly lower in individuals taking carbamazepine or oxcarbazepine. The 3HC/cotinine ratios were also significantly higher in the subgroup of individuals taking carbamazepine (n = 8) versus those not taking it. There were no significant differences in nicotine or cotinine levels or 3HC/cotinine ratios in individuals taking valproic acid versus those not taking it. We conducted backward stepwise linear regression models to identify predictors of the log transformed 3HC/cotinine ratios. Taking carbamazepine and number of cigarettes smoked per day were significant determinants of log 3HC/cotinine.

CONCLUSIONS

Carbamazepine likely induces hepatic metabolism via CYP2A6 and is associated with increased 3HC/cotinine ratios.

IMPACT

Increased nicotine metabolism in individuals using AED has implications for increased smoking behavior and exposure to more tobacco toxins, which warrants further study.

Selection of antiepileptic drugs in adults

Epilepsy affects approximately 50 million people worldwide, with an annual incidence of 50 to 70 cases per 100,000 population. The condition can strike at any time of life, with an immediate impact on everyday activities and routine. Key to optimal management is swift referral to an epilepsy specialist, appropriate investigation, and timely institution of antiepileptic drug therapy. In the past 20 years, the explosion of 13 new agents into the marketplace has greatly increased the potential for therapeutic intervention. This article explores the rationale for treatment selection in adults with epilepsy.

Managing epilepsy in women of childbearing age

Epilepsy affects the menstrual cycle, aspects of contraception, fertility, pregnancy and bone health in women. It is common for seizure frequency to vary throughout the menstrual cycle. In ovulatory cycles, two peaks can be seen around the time of ovulation and in the few days before menstruation. In anovulatory cycles, there is an increase in seizures during the second half of the menstrual cycle. There is also an increase in polycystic ovaries and hyperandrogenism associated with valproate therapy. There are no contraindications to the use of non-hormonal methods of contraception in women with epilepsy. Non-enzyme-inducing antiepileptic drugs (AEDs) [valproate, benzodiazepines, ethosuximide, levetiracetam, tiagabine and zonisamide] do not show any interactions with the combined oral contraceptive (OC). There are interactions between the combined OC and hepatic microsomal-inducing AEDs (phenytoin, barbiturates, carbamazepine, topiramate [dosages>200 mg/day], oxcarbazepine) and lamotrigine. Pre-conception counselling should be available to all women with epilepsy who are considering pregnancy. Women with epilepsy should be informed about issues relating to the future pregnancy, including methods and consequences of prenatal screening, fertility, genetics of their seizure disorder, teratogenicity of AEDs, folic acid and vitamin K supplements, labour, breast feeding and care of a child. During pregnancy, the lowest effective dose of the most appropriate AED should be used, aiming for monotherapy where possible. Recent pregnancy databases have suggested that valproate is significantly more teratogenic than carbamazepine, and the combination of valproate and lamotrigine is particularly teratogenic. Most pregnancies in women with epilepsy are without complications, and the majority of infants are delivered healthy with no increased risk of obstetric complications in women. There is no medical reason why a woman with epilepsy cannot breastfeed her child. The AED concentration profiled in breast milk follows the plasma concentration curve. The total amount of drug transferred to infants via breast milk is usually much smaller than the amount transferred via the placenta during pregnancy. However, as drug elimination mechanisms are not fully developed in early infancy, repeated administration of a drug such as lamotrigine via breast milk may lead to accumulation in the infant. Studies have suggested that women with epilepsy are at increased risk of fractures, osteoporosis and osteomalacia. No studies have been undertaken looking at preventative therapies for these co-morbidities.

Transitional polytherapy: tricks of the trade for monotherapy to monotherapy AED conversions

The goal of epilepsy therapy is to help patients achieve seizure freedom without adverse effects. While monotherapy is preferable in epilepsy treatment, many patients fail a first drug due to lack of efficacy or failure to tolerate an initial medication, necessitating an alteration in therapy. Sudden changes between monotherapies are rarely feasible and sometimes deleterious given potential hazards of acute seizure exacerbation or intolerable adverse effects. The preferred method for converting between monotherapies is transitional polytherapy, a process involving initiation of a new antiepileptic drug (AED) and adjusting it toward a target dose while maintaining or reducing the dose of the baseline medication. A fixed-dose titration strategy of maintaining the baseline drug dose while titrating the new medication is preferable when breakthrough seizures are occurring and no adverse effects are present. However, a flexible titration strategy involving reduction of the baseline drug dose to ensure adequate tolerability of the new adjunctive medication is preferred when patients are already experiencing adverse effects. This article reviews pharmacokinetic considerations pertinent for ensuring successful transitional polytherapy with the standard and newer antiepileptic drugs. Practical consensus recommendations "from an expect panel (SPECTRA, Study by a Panel of Experts Considerations for Therapy Replacement and Antiepileptics) for a successful monotherapy" AED conversions are then summarized. Transitional polytherapy is most successful when clinicians appropriately manage the titration strategy and consider pharmacokinetic factors germane to the baseline and new adjunctive medication.

Female issues in epilepsy: a critical review

The focus on gender-related issues for women with epilepsy has heightened in recent years. The emphasis, however, has been on the childbearing years. Epilepsy and antiepileptic drug treatment affect sexual development, the menstrual cycle, and aspects of contraception, fertility, and reproduction. Female patients with epilepsy at a reproductive age face a unique set of reproductive issues, ranging from descriptions of disorders of reproduction in epilepsy and its causes, to contraception, pregnancy, sexuality, menopause, and osteoporosis. Conditions and diseases that specifically affect women are discussed. The role of hormones across the life cycle--endogenous and exogenous hormones and their effects on drug interactions, drug metabolism, and therapeutic outcomes--is described. Contraception and pregnancy issues for women with epilepsy have received the appropriate attention.

Antiepileptic drug interactions

INTRODUCTION

Antiepileptics are drugs used in the long-term treatment of epilepsy and other conditions such as pain or psychiatric diseases. They are often administered as polytherapy or in combination with other treatments. It is therefore important to know their potential interactions (with each other and with other substances) in order to avoid altering their efficacy or potentiating their side effects.

OBJECTIVE

The purpose of this article is to review these aspects and stress the most important interactions in day-to-day clinical practice.

RESULTS

Older antiepileptic drugs (AEDs) such as phenytoin, carbamazepine, phenobarbital and valproic acid can significantly interfere not only with each other and other AEDs, but also with other treatments. Although newer AEDs have a more favourable pharmacokinetic profile, they are not entirely exempt from interactions and they are also commonly administered in combination with older AEDs. Another aspect that should be considered is the existence of any clinically important pharmacokinetic and pharmacodynamic interactions in patients requiring the continuous administration of other treatments.

CONCLUSION

We must be aware of the pharmacokinetic and pharmacodynamic interactions of AEDs. Because of a lack of significant interactions, drugs such as levetiracetam, gabapentin or pregabalin can be recommended in particular groups such as patients with cancer, transplants, anticoagulant treatments or HIV infection. In all cases, it is important to ensure AED efficacy and prevent serious complications.

Pharmacokinetic interactions between contraceptives and antiepileptic drugs

The occurrence of bi-directional drug interactions between antiepileptic drugs (AEDs) and combined oral contraceptives (OCs) pose potential risks of un-intended pregnancy and as well as seizure deterioration. It is well established that several of the older AEDs (carbamazepine, phenytoin and phenobarbital), are strong inducers of the hepatic cytochrome P450 (CYP) 3A4 enzyme system, and are associated with increased the risk of contraceptive failure. In addition, it is demonstrated that also some of the newer AEDs, oxcarbazepine and topiramate influence on the pharmacokinetics of OCs, which is thought to be due to a more selective induction of subgroups of the hepatic enzyme system. Estrogens containing OCs induce the glucuronosyltransferase and may reduce the plasma levels and the effect of AEDs cleared by glucuronidation. This has been most intensively studied for lamotrigine but also other AEDs, which undergoes glucuronidation processes, such as valproate and oxcarbazepine, may be affected by OCs. The magnitude of the drug-drug interactions show in general wide inter-individual variability and the change in the elimination rate is often unpredictable and can be influenced by a number of co-variants such as co-medication of other drugs, as well as genetic and environmental factors. It is therefore recommended that change in OC use is assisted by AED monitoring whenever possible.

Pregnancy, epilepsy, and anticonvulsants

The majority of epileptic disorders are not self-limiting over time, and therefore require a long-lasting and often even lifelong antiepileptic drug (AED) treatment, in Wi/omen with epilepsy, the influence of their disease on the possibility and course of pregnancies, as well as the potential impact of the AED treatment on mother and child, are crucial questions.

This review addresses the clinically relevant knovledge concerning the impact of the disease itself and the AED treatment on fertility, pregnancy, delivery, the postpartum period, and teratogenicity. Some of the new AEDs appear to have a favorable profile due to a lack of clinically relevant interactions and promising teratogenic profiles. However, the finding of decreases in lamotrigine serum concentrations during hormonal contraception and pregnancy is an instructive example, shovt/ing that ongoing studies are urgently needed to further investigate stillunanswered questions. Several prospective multinational surveys are currently being performed, and should add essential information in this context.

Pharmacokinetics and tolerability of voriconazole and a combination oral contraceptive co-administered in healthy female subjects

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

* Voriconazole, a broad-spectrum antifungal drug, is a substrate and inhibitor of CYP2C19 and CYP3A4 isozymes. * Ethinyl oestradiol and norethindrone, components of the combination oral contraceptive drug Ortho-Novum 1/35, also are substrates of cytochrome P450 CYP2C19 and CYP3A4 isozymes. * Because co-administration of voriconazole and Ortho-Novum 1/35 could potentially result in pharmacokinetic interactions that increase systemic exposure of one or both drugs to unsafe levels, clinical studies are needed to define better the two-way pharmacokinetic interaction between these drugs.

WHAT THIS STUDY ADDS

* Although co-administered voriconazole and oral contraceptive did result in increased systemic exposures of all three drugs relative to respective monotherapy, co-administered treatment was generally safe and well tolerated. * It is recommended, however, that patients receiving co-administered voriconazole and oral contraceptives be monitored for the development of adverse events commonly associated with these medications.

AIM

To assess the two-way pharmacokinetic interaction between voriconazole and Ortho-Novum 1/35, an oral contraceptive containing norethindrone 1 mg and ethinyl oestradiol 35 microg.

METHODS

In this open-label, three-period, fixed-sequence study, 16 healthy females received voriconazole (400 mg q12 h, day 1; 200 mg q12 h, days 2-4) (period 1), oral contraceptive (q24 h, days 12-32) (period 2), and combination voriconazole (400 mg q12 h, day 57; 200 mg q12 h, days 58-60) and oral contraceptive (q24 h, days 40-60) (period 3).

RESULTS

Voriconazole geometric mean AUC(tau) and C(max) increased 46% (12 682-18 495 ng h ml(-1); 90% confidence interval [CI] 32, 61) and 14% (2485-2840 ng ml(-1); 90% CI 3, 27), respectively, when co-administered with oral contraceptive vs. voriconazole alone. Ethinyl oestradiol geometric mean AUC(tau) and C(max) increased 61% (1031-1657 ng h ml(-1); 90% CI 50, 72) and 36% (119-161 ng ml(-1); 90% CI 28, 45), respectively, and norethindrone geometric mean AUC(tau) and C(max) increased 53% (116-177 ng h ml(-1); 90% CI 44, 64) and 15% (18-20 ng ml(-1); 90% CI 3, 28), respectively, during voriconazole co-administration vs. oral contraceptive alone. Neither ethinyl oestradiol nor norethindrone levels were reduced in subjects following voriconazole co-administration. Adverse events (AEs) were generally mild, occurring less in subjects receiving voriconazole alone (36 events) vs. oral contraceptive alone (88 events) or combination treatment (68 events); four subjects experienced a severe AE.

CONCLUSIONS

Co-administration of voriconazole and oral contraceptive increased systemic exposures of all analytes relative to respective monotherapy. Although generally safe and well tolerated, it is recommended that patients receiving co-administered voriconazole and oral contraceptive be monitored for development of AEs commonly associated with these medications.

Pharmacology of antiepileptic drugs during pregnancy and lactation

Most women with epilepsy require continuous treatment during pregnancy, making antiepileptic drugs (AEDs) one of the most frequent chronic teratogen exposures. Therapeutic decisions should balance the risks to the developing fetus of AED exposure and of not treating or undertreating the epilepsy. The International AED Pharmacology Work Group of the Health Outcomes in Pregnancy and Epilepsy (HOPE) Forum identified four pharmacology topics critical to enhancing maternal and fetal outcomes for pregnancies exposed to AEDs: (1) hormonal therapies and endogenous changes: bidirectional interactions with AEDs; (2) pharmacokinetic alterations during pregnancy, the role of therapeutic drug monitoring, and the influence on seizure control and maternal and fetal outcomes; (3) multidrug transporters and their various roles during pregnancy; (4) breastfeeding in mothers taking AEDs. The report provides an overview of these key topics, highlights gaps in the current knowledge, and provides future directions for needed research.