Oral Contraceptives Induce Lamotrigine Metabolism: Evidence from a Double-blind, Placebo-controlled Trial

Treatment of hypopituitarism in patients receiving antiepileptic drugs

Evidence suggests that there may be drug interactions between antiepileptic drugs and hormonal therapies, which can present a challenge to endocrinologists dealing with patients who have both hypopituitarism and neurological diseases. Data are scarce for this subgroup of patients; however, data for the interaction of antiepileptic drugs with the pituitary axis have shown that chronic use of many antiepileptic drugs, such as carbamazepine, oxcarbazepine, and topiramate, enhances hepatic cytochrome P450 3A4 (CYP3A4) activity, and can decrease serum concentrations of sex hormones. Other antiepileptic drugs increase sex hormone-binding globulin, which reduces the bioactivity of testosterone and estradiol. Additionally, the combined oestrogen-progestagen contraceptive pill might decrease lamotrigine concentrations, which could worsen seizure control. Moreover, sex hormones and their metabolites can directly act on neuronal excitability, acting as neurosteroids. Because carbamazepine and oxcarbazepine can enhance the sensitivity of renal tubules, a reduction in desmopressin dose might be necessary in patients with central diabetes insipidus. Although the effects of antiepileptic drugs in central hypothyroidism have not yet been studied, substantial evidence indicates that several antiepileptic drugs can increase thyroid hormone metabolism. However, although it is reasonable to expect a need for a thyroxine dose increase with some antiepileptic drugs, the effect of excessive thyroxine in lowering seizure threshold should also be considered. There are no reports of significant interactions between antiepileptic drugs and the efficacy of human growth hormone therapy, and few data are available for the effects of second-generation antiepileptic drugs on hypopituitarism treatment.

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.

Effect of oral contraceptives on lamotrigine levels depends on comedication

OBJECTIVES

To evaluate prospectively the influence of cyclic oral contraceptive (OC) use on lamotrigine (LTG) serum levels when used in combination therapy.

METHODS

Women with epilepsy using LTG in combination with valproate (VPA; n=7), carbamazepine (CBZ; n=3) or oxcarbazepine (OXC; n=1) were evaluated during two periods of 28 days cyclic OC use, monitoring antiepileptic drug (AED) levels every other day with the dried blood spot sampling method. Results were compared with women on LTG monotherapy and OCs (n=12). Pharmacokinetic analysis was performed using NONMEM software.

RESULTS

Mean study population value of LTG clearance estimated by the final model was 3.17 l/h. Introduction of covariates for comedication (VPA, CBZ, OXC and OC) significantly reduced the between-subject variability. A significant influence of OC comedication on LTG clearance was seen in both LTG monotherapy (clearance with OC 4.02±0.38 l/h, OC-free week 3.03±0.39 l/h) and in LTG-CBZ combination (clearance with OC 4.95±0.15 l/h, OC-free week 4.15±0.26 l/h). No influence of OC was found in LTG-VPA combination (clearance with OC 0.99±0.16 l/h, OC-free week 0.90±0.15 l/h).

CONCLUSIONS

Adding OCs to LTG monotherapy or the combination LTG-CBZ significantly increased the LTG clearance and thus reduced LTG serum levels. In the combination LTG-CBZ, OCs had a non-significant effect on CBZ clearance. No significant influence of cyclic OC use on LTG or VPA clearance was found when these AEDs were used in combination.

A mixed-methods exploration of the contraceptive experiences of female teens with epilepsy

PURPOSE

We explored the contraceptive experiences of female teens with epilepsy, including their knowledge and perceptions of interactions between antiepileptic drugs and hormonal contraception and contraceptive decision-making processes.

METHOD

From November 2012 to May 2013, we conducted one online survey (n=114) and 12 online focus group discussions (n=26) with female teens with epilepsy about their contraceptive experiences and unmet needs. Survey data were analyzed using descriptive statistics and focus group transcripts were analyzed thematically using modified grounded theory methods.

RESULTS

Both survey and focus group participants reported believing that interactions between epilepsy medications and hormonal contraceptives could lead to reductions in contraceptive efficacy and seizure control. However, their knowledge about these types of medication interactions was often incomplete. Many study participants viewed contraceptive decision making as a difficult process, and some participants reported avoiding hormonal contraceptives because of potential interactions with antiepileptic drugs. Study participants reported relying on health care providers and parents for contraceptive decision-making support. Focus group participants also reported they wanted health care providers to provide more in-depth and comprehensive counseling about contraception, and that they desired peer support with contraceptive decisions.

CONCLUSION

The ability to make informed contraceptive decisions is important for teens with epilepsy as interactions between anti-epileptic drugs and hormonal contraceptives can impact seizure occurrence and lead to an increased risk of unplanned pregnancy. Guidance for providers offering contraceptive care to this population is needed, as well as a contraceptive support tool that empowers teens with epilepsy to advocate for desired health care.

17β-Estradiol induces sulfotransferase 2A1 expression through estrogen receptor α

Sulfotransferase (SULT) 2A1 catalyzes sulfonation of drugs and endogenous compounds and plays an important role in xenobiotic metabolism as well as in the maintenance of steroid and lipid homeostasis. A recent study showed that 17β-estradiol (E2) increases the mRNA levels of SULT2A1 in human hepatocytes. Here we report the underlying molecular mechanisms. E2 enhanced SULT2A1 expression in human hepatocytes and HepG2-ER cells (HepG2 stably expressing ERα). SULT2A1 induction by E2 was abrogated by antiestrogen ICI 182,780, indicating a key role of ERα in the induction. Results from deletion and mutation assays of SULT2A1 promoter revealed three cis-elements located within -257/+140 region of SULT2A1 that are potentially responsible for the induction. Chromatin immunoprecipitation assay verified the recruitment of ERα to the promoter region. Electrophoretic mobility shift assays revealed that AP-1 proteins bind to one of the cis-elements. Interestingly, SULT2A1 promoter assays using ERα mutants revealed that the DNA-binding domain of ERα is indispensable for SULT2A1 induction by E2, suggesting that direct ERα binding to the SULT2A1 promoter is also necessary for the induction. Taken together, our results indicate that E2 enhances SULT2A1 expression by both the classical and nonclassical mechanisms of ERα action.

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.

The impact of age on lamotrigine and oxcarbazepine kinetics: a historical cohort study

Age as well as estrogen levels may have an impact on the pharmacokinetics of lamotrigine (LTG) and monohydroxycarbazepine (MHD), the active metabolite of oxcarbazepine (OXC). To assess the effects of age and menopause, we evaluated retrospectively a therapeutic drug-monitoring database. Samples from 507 women and 302 men taking LTG and 464 women and 319 men taking OXC were used to develop a population pharmacokinetic model. Data were analyzed using NONMEM software and were compared with a population pharmacokinetic model based on samples of 1705 women and 1771 men taking carbamazepine (CBZ). Age was a significant factor contributing to pharmacokinetic variability in individuals using LTG, OXC, and CBZ with increasing clearance as a function of bioavailability (Cl/F) over age 18, a maximum Cl/F at 33years (CBZ) and 36 years (LTG and OXC), and a gradual decrease of Cl/F towards older age. We found no effect of perimenopausal age range on LTG and MHD clearance.

Gynecologic and reproductive health concerns of adolescents using selected psychotropic medications

Psychiatric disorders are common in adolescent girls and may require chronic therapies with psychotropic medications. Antipsychotic medications and mood stabilizers have been increasingly prescribed to and widely used by adolescents for a variety of both "on" an "off" label indications. Studies on the safety and monitoring of these medications in adolescent girls have shown important potential for gynecologic and reproductive adverse effects. The objective of this article is to review the mechanisms for and management of menstrual disorders mediated by hyperprolactinemia associated with antipsychotic medications, hypothyroidism associated with lithium and quetiapine, and the independent association of polycystic ovary syndrome (PCOS) in girls using valproic acid. Beyond their susceptibility to these disruptions in the menstrual cycle, adolescent girls with psychiatric illness also have increased sexual risk behaviors. These behaviors makes it all the more important to review teratogenicity and clinically relevant contraceptive drug interactions in adolescent girls using these psychotropic medications.

Influence of the UGT2B7 -161C>T polymorphism on the population pharmacokinetics of lamotrigine in Thai patients

BACKGROUND AND OBJECTIVES

A high inter-individual variability in the pharmacokinetics of lamotrigine has been observed. Lamotrigine is primarily metabolized by UGT1A4 and UGT2B7, both of which show genetic polymorphisms. Both genetic and non-genetic factors may influence the pharmacokinetics of lamotrigine. The aim of this study was to determine the pharmacokinetic parameters of lamotrigine and to investigate the effect of genetic variants of UGT1A4 and UGT2B7 and various non-genetic factors on its pharmacokinetics.

METHODS

Four single nucleotide polymorphisms (SNPs; UGT1A4 142 T>G, UGT1A4 70C>T, UGT2B7 372A>G, UGT2B7 -161C>T) were identified using the TaqMan Allelic Discrimination Assay. Data were analyzed using NONMEM. Model evaluation was performed using the bootstrap approach and predictive check.

RESULTS

A total of 116 samples were obtained from 75 patients and included in the population analysis. The use of enzyme inducers, valproic acid, and the UGT2B7-161 C>T SNP were found to significantly influence lamotrigine apparent clearance (CL/F). Lamotrigine CL/F in patients carrying the UGT2B7 -161 CT or TT SNP was 18% lower than that in patients carrying the UGT2B7 -161 CC SNP.

CONCLUSION

Both genetic and non-genetic factors were found to influence lamotrigine pharmacokinetics. These factors should be considered when determining lamotrigine dosing. The model presented here could be useful for lamotrigine dose adjustment in clinical practice.

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.

Potent inhibition of human sulfotransferase 1A1 by 17α-ethinylestradiol: role of 3'-phosphoadenosine 5'-phosphosulfate binding and structural rearrangements in regulating inhibition and activity

Sulfotransferase (SULT) 1A1 is the major drug/xenobiotic-conjugating SULT isoform in human liver because of its broad substrate reactivity and high expression level. SULT1A1 sulfates estrogens with low micromolar K(m) values consistent with its affinity for sulfation of many small phenolic compounds. Binding studies showed the unexpected ability of 17α-ethinylestradiol (EE2) to bind and inhibit SULT1A1 activity toward p-nitrophenol and β-naphthol at low nanomolar concentrations, whereas EE2 was not sulfated until significantly higher concentrations were reached. EE2 had a K(i) of 10 nM for inhibiting p-nitrophenol and β-naphthol sulfation and inhibited 17β-estradiol (E2) sulfation in intact human MCF-7 breast cancer cells with a K(i) of 19 nM. In contrast, the K(m) for EE2 sulfation by SULT1A1 was 700 nM. The K(d) for EE2 binding of pure SULT1A1 was 0.5 ± 0.15 μM; however, the K(d) for EE2 binding to the SULT1A1-PAP complex was >100-fold lower (4.3 ± 1.7 nM). The K(d) for E2 binding to SULT1A1 changed from 2.3 ± 0.9 to 1.2 ± 0.56 μM in the presence of PAP. Docking studies with E2 indicate that E2 binds in a competent orientation in the resolved structure of SULT1A1 in the both presence and absence of 3'-phosphoadenosine 5'-phosphosulfate (PAPS). However, EE2 binds in a catalytically competent orientation in the absence of PAPS but in a noncompetent orientation via formation of a charge interaction with Tyr108 if PAPS is bound first. In conclusion, EE2 is a potent inhibitor, but not a substrate, of SULT1A1 at low nanomolar concentrations, indicating the possibility of drug-drug interactions during contraceptive therapy.

Host factors affecting antiepileptic drug delivery-pharmacokinetic variability

Antiepileptic drugs (AEDs) are the mainstay in the treatment of epilepsy, one of the most common serious chronic neurological disorders. AEDs display extensive pharmacological variability between and within patients, and a major determinant of differences in response to treatment is pharmacokinetic variability. Host factors affecting AED delivery may be defined as the pharmacokinetic characteristics that determine the AED delivery to the site of action, the epileptic focus. Individual differences may occur in absorption, distribution, metabolism and excretion. These differences can be determined by genetic factors including gender and ethnicity, but the pharmacokinetics of AEDs can also be affected by age, specific physiological states in life, such as pregnancy, or pathological conditions including hepatic and renal insufficiency. Pharmacokinetic interactions with other drugs are another important source of variability in response to AEDs. Pharmacokinetic characteristics of the presently available AEDs are discussed in this review as well as their clinical implications.

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.

[Family planning in women with epilepsy]

Epilepsy is a common neurological condition with gender-related management implications. Epilepsy and antiepileptic drug treatment affect aspects of contraception, fertility and pregnancy which are discussed in the article.

The steroid metabolome in lamotrigine-treated women with epilepsy

BACKGROUND

Epilepsy in women may be associated with reproductive disorders and alterations in serum steroid levels. Some steroids can be induced by epilepsy and/or treatment with antiepileptic drugs; however, there are still limited data available concerning this effect on the levels of other neuroactive steroid metabolites such as 3a-hydroxy-5a/b-reduced androstanes.

AIM

To evaluate steroid alterations in women with epilepsy (WWE) on lamotrigine monotherapy.

SUBJECTS AND METHODS

Eleven WWE and 11 age-matched healthy women underwent blood sampling in both phases of their menstrual cycles (MCs). The steroid metabolome, which included 30 unconjugated steroids, 17 steroid polar conjugates, gonadotropins, and sex hormone-binding globulin (SHBG), was measured using gas chromatography-mass spectrometry (GC-MS) and radioimmunoassay (RIA).

RESULTS

WWE had lower cortisol levels (status p<0.001), but elevated levels of unconjugated 17-hydroxypregnenolone (status p<0.001). Progesterone was higher in the follicular menstrual phase (FP) in WWE than in the controls (status×menstrual phase p<0.05, Bonferroni multiple comparisons p<0.05), whereas 17-hydroxyprogesterone was higher in WWE in both menstrual phases (status p<0.001). The steroid conjugates were mostly elevated in WWE. The levels of 5α/β-reduced androstanes in WWE that were significantly higher than the controls were etiocholanolone (status p<0.001), 5α-androstane-3α,17β-diol (status p<0.001), and the 5α/β-reduced androstane polar conjugates (status p<0.001).

CONCLUSIONS

WWE showed a trend toward higher circulating 3α-hydroxy-5α/β-reduced androstanes, increased activity of 17α-hydroxylase/17,20 lyase in the Δ(5)-steroid metabolic pathway, and increased levels of the steroid polar conjugates.

Pharmacotherapeutics of epilepsy: use of lamotrigine and expectations for lamotrigine extended release

The goal in managing patients with epilepsy is complete seizure freedom. Pharmacotherapeutic management of epilepsy is complicated by multiple syndromes, inter-individual differences in drug sensitivities, inter-individual differences in drug disposition, and drug interactions. Most anti-epileptic drugs (AEDs) have a therapeutic window with only a 2- to 3-fold concentration range. Extended release formulations offer advantages over their immediate release counter parts with less fluctuation in the serum concentration vs time curve and improved compliance. However, missed doses are more likely to result in prolonged “sub-therapeutic serum concentrations”. Best clinical outcome may sometimes require twice daily dosing of extended release formulations even though approved for once daily dosing, as this optimally balances pharmacokinetics against compliance. Lamotrigine (LTG) is a broad spectrum AED with efficacy in partial and generalized epilepsy syndromes and good tolerability. Its metabolism is affected by co-medications which may be inducing, neutral or inhibiting of hepatic glucuronidation. Furthermore, though the average half-life in monotherapy is about 24 hours, there is a large inter-individual variation that may, including the extremes, approach a range of 10-fold. LTG-XR is expected to decrease fluctuation of serum concentration in the presence of hepatic inducing or neutral drugs. However, optimal clinical benefit in some patients may require twice daily dosing when metabolism is rapid.

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.

Hormonal contraception--what kind, when, and for whom?

BACKGROUND

In Germany today, one-third of the 20 million women of child-bearing age use combined oral contraceptives (COCs). In this article, we summarize the current knowledge of the mode of action, wanted and unwanted side effects, and long-term risks of COCs. The levonorgestrel intrauterine device (IUD) and long-acting injectable or implantable monophasic progestogen preparations offer comparable contraceptive efficacy to COCs. Nonetheless, they are less frequently used in Germany than COCs, because of their propensity to cause breakthrough bleeding.

METHOD

Selective review of the literature.

RESULTS

COCs suppress gonadotropin secretion and thereby inhibit follicular maturation and ovulation. Their correct use is associated with 0.3 pregnancies per 100 women per year, their typical use, with 1 pregnancy per 100 women per year (Pearl index). COCs have effects on the cardiovascular and hemostatic systems as well as on lipid and carbohydrate metabolism. When given in the presence of specific risk factors, they significantly increase the likelihood of cardiovascular disease and thromboembolism. Women with persistent human papilloma virus (HPV) infection who take COCs are at increased risk of developing invasive cervical cancer. On the other hand, COCs lower the cumulative incidence of endometrial and ovarian cancer by 30% to 50%, and that of colorectal cancer by 20% to 30%. Other malignancies seem to be unaffected by COC use.

CONCLUSION

As long as personal and familial risk factors are carefully considered, COCs constitute a safe, reversible, and well-tolerated method of contraception.

The treatment of women with epilepsy

BACKGROUND

Women with epilepsy and their doctors are often unsure of the implications of the disease and the limitations it causes. There is a major need for counseling.

METHODS

Selective review of the literature as of November 2009.

RESULTS

Recommendations on pregnancy and childbearing for women with epilepsy can be found in the guidelines issued by the German Societies of Neurology and Epileptology and by the American Epilepsy Society. Only low-level evidence is available on other relevant questions, including contraception, the influence of hormones on epilepsy, and the influence of antiepileptic drugs on endocrine and bone metabolism, because of a lack of controlled studies. Polycystic ovarian syndrome is more commonly seen in women with epilepsy who take valproate. Antiepileptic drugs that induce CYP3a can diminish the efficacy of oral contraceptives; conversely, oral contraceptives can markedly lower the blood levels of antiepileptic drugs. According to the most recent studies, the risk of congenital malformations and spontaneous abortions is 1% to 2% in the normal population and 3% to 9% in the offspring of women with epilepsy who are taking antiepileptic drugs. Women with epilepsy who want to have children are currently advised to take folic acid prophylactically starting before conception and until the end of the first trimester. New mothers with epilepsy are advised to breastfeed their children.

CONCLUSION

Proper treatment and counseling of women with epilepsy, with due attention to aspects that are specific to women patients, can reduce the limitations to which they are subject in everyday life.

Extended-release lamotrigine in the treatment of patients with epilepsy

IMPORTANCE TO THE FIELD

Epilepsy is a neurological disorder primarily characterized by recurrent, unprovoked seizures resulting from excessive or synchronous neuronal activity in the brain. Depending on the case definition and population studied, the lifetime prevalence of epilepsy in the USA is estimated to be 1.2 - 2.9%. In general, epilepsy is related to a significant increased risk of mortality and injury. A cornerstone of epilepsy management is use of antiepileptic drugs (AEDs). This review focuses on the AED lamotrigine, with particular emphasis on the extended-release formulation, in the management of patients with epilepsy, and the significant clinical issues that may be relevant with once-daily AED therapy.

AREAS COVERED IN THIS REVIEW

An introductory section overviews the prevalence of epilepsy, current treatment recommendations for patients with epilepsy, and unmet needs in epilepsy management. This is followed by an overview of the AED market with currently available and developing compounds, a summary of lamotrigine and extended-release lamotrigine, clinical efficacy and tolerability studies with extended-release lamotrigine, and regulatory issues. The review concludes with an expert opinion summary on the important issue of treatment adherence, the possible role of extended-release lamotrigine in adherence enhancement, and additional research and areas which need further focus for optimal epilepsy outcomes.

WHAT THE READER WILL GAIN

The reader will gain familiarity with extended-release (once-daily) lamotrigine and clinical issues that may be relevant to once-daily use. Once-daily AED use might be one way to simplify the epilepsy treatment regimen and can pave the way for other approaches that can maximize adherence, such as a frank discussion of risks, benefits, and attitudes towards treatment - all critical components of a strong and positive doctor-patient relationship.

TAKE HOME MESSAGE

The AED lamotrigine is widely used in clinical settings and has become available in a once-daily extended-release version, which may minimize serum concentration fluctuation and presumably would both reduce patient burden and maximize treatment adherence as opposed to the immediate-release version of the compound. Adverse effects and safety concerns between the immediate- and extended-release versions of lamotrigine seem similar based upon interpretation of the limited literature.

Update on anticonvulsant drugs

In 2009, the US Food and Drug Administration approved three medications for the treatment of epilepsy: rufinamide, lacosamide, and vigabatrin. In addition, extended-release formulations of lamotrigine and levetiracetam were approved recently. When added to the dozen medications for treating epilepsy, the choice is a luxury in terms of additional options, but also a challenge for practitioners to use them all with expertise. Recently, there has been much interest surrounding medications for epilepsy and their possible association with osteoporosis, safety during pregnancy, biological equivalence to generic versions, and possible association with higher rates of suicidality. This review discusses these issues and provides a current overview for the medical management of epilepsy.

Hormonal aspects of epilepsy

The relationships among hormones, epilepsy, and the medications used to treat epilepsy are complex, with tridirectional interactions that affect both men and women in various ways. Abnormalities of baseline endocrine status occur more commonly in people with epilepsy. Abnormalities are most often described for the sex steroid hormone axis, commonly presenting as sexual dysfunction in men and women with epilepsy and lower fertility. Other signs and symptoms in women with epilepsy include menstrual irregularities, premature menopause, and polycystic ovarian syndrome. The evaluation and care of adult patients with epilepsy should include considerations of the common hormonal aberrations that occur in this patient population. Questions about reproductive health disorders, sexual function, symptoms of thyroid disorders, and bone health should be part of the evaluation of all adult patients with epilepsy. Further laboratory or radiologic testing and referral to other specialists to participate in collaborative care may be warranted if underlying disorders are suspected, especially given that many of these hormone abnormalities can result in long-term health risks as well as negatively affect quality of life. AEDs and hormones have a bidirectional interaction that can impair the efficacy of contraceptive hormone treatments and of the AEDs. Endogenous hormones can influence seizure severity and frequency, resulting in catamenial patterns of epilepsy. However, this susceptibility to hormonal influences can be used to develop hormonal strategies to improve seizure control in women with epilepsy with use of cyclic PROG supplementation or alteration of the endogenous hormone release. Additionally, development of the neurosteroid analog ganaxolone provides a novel approach that can potentially be used across both genders and all age groups.

Up-regulation of UDP-glucuronosyltransferase (UGT) 1A4 by 17beta-estradiol: a potential mechanism of increased lamotrigine elimination in pregnancy

Oral clearance of lamotrigine, an antiepileptic drug commonly used in pregnant women, is increased in pregnancy by unknown mechanisms. In this study, we show that 17beta-estradiol (E(2)) up-regulates expression of UDP glucuronosyltransferase (UGT) 1A4, the major enzyme responsible for elimination of lamotrigine. Endogenous mRNA expression levels of UGT1A4 in estrogen receptor (ER) alpha-negative HepG2 cells were induced 2.3-fold by E(2) treatment in the presence of ER alpha expression. E(2) enhanced transcriptional activity of UGT1A4 in a concentration-dependent manner in HepG2 cells when ER alpha was cotransfected. Induction of UGT1A4 transcriptional activity by E(2) was also observed in ER alpha-positive MCF7 cells, which was abrogated by pretreatment with the antiestrogen fulvestrant (ICI 182,780). Analysis of UGT1A4 upstream regions using luciferase reporter assays identified a putative specificity protein-1 (Sp1) binding site (-1906 to -1901 base pairs) that is critical for the induction of UGT1A4 transcriptional activity by E(2). Deletion of the Sp1 binding sequence abolished the UGT1A4 up-regulation by E(2), and Sp1 bound to the putative Sp1 binding site as determined by a electrophoretic mobility shift assay. Analysis of ER alpha domains using ER alpha mutants revealed that the activation function (AF) 1 and AF2 domains but not the DNA binding domain of ER alpha are required for UGT1A4 induction by E(2) in HepG2 cells. Finally, E(2) treatment increased lamotrigine glucuronidation in ER alpha-transfected HepG2 cells. Together, our data indicate that up-regulation of UGT1A4 expression by E(2) is mediated by both ER alpha and Sp1 and is a potential mechanism contributing to the enhanced elimination of lamotrigine in pregnancy.

The management of epilepsy in pregnancy

While most women with epilepsy can expect a normal pregnancy outcome, epilepsy remains a significant contributor to both maternal and perinatal morbidity. Pre-pregnancy planning must address reliable contraception and optimisation of antiepileptic drug (AED) regimens to minimise teratogenic risk while maintaining seizure control. The most recent data from the AED registries regarding malformations is presented in this review, as is the limited data on the newer AEDs and studies linking neurocognitive outcomes to AED exposure. During pregnancy, important considerations include; therapeutic drug monitoring, surveillance for obstetric complications and vigilance for seizures during the intrapartum and postpartum period.

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 drugs--best practice guidelines for therapeutic drug monitoring: a position paper by the subcommission on therapeutic drug monitoring, ILAE Commission on Therapeutic Strategies

Although no randomized studies have demonstrated a positive impact of therapeutic drug monitoring (TDM) on clinical outcome in epilepsy, evidence from nonrandomized studies and everyday clinical experience does indicate that measuring serum concentrations of old and new generation antiepileptic drugs (AEDs) can have a valuable role in guiding patient management provided that concentrations are measured with a clear indication and are interpreted critically, taking into account the whole clinical context. Situations in which AED measurements are most likely to be of benefit include (1) when a person has attained the desired clinical outcome, to establish an individual therapeutic concentration which can be used at subsequent times to assess potential causes for a change in drug response; (2) as an aid in the diagnosis of clinical toxicity; (3) to assess compliance, particularly in patients with uncontrolled seizures or breakthrough seizures; (4) to guide dosage adjustment in situations associated with increased pharmacokinetic variability (e.g., children, the elderly, patients with associated diseases, drug formulation changes); (5) when a potentially important pharmacokinetic change is anticipated (e.g., in pregnancy, or when an interacting drug is added or removed); (6) to guide dose adjustments for AEDs with dose-dependent pharmacokinetics, particularly phenytoin.

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.