Pharmacotherapeutic issues for women of childbearing age with epilepsy

Rates and determinants of breastfeeding initiation in women with and without epilepsy: A 25-year study

PURPOSE

To examine the rates and determinants of breastfeeding initiation (BFI) amongst women with epilepsy (WWE) and women without epilepsy (WWoE) in Manitoba, Canada.

METHODS

We conducted a retrospective cohort study using province-wide health databases from 1995 to 2019. Annual BFI rates for WWE and WWoE were examined. Multivariable logistic regression models were used to quantify the association between maternal and infant characteristics and BFI in both groups.

RESULTS

During the study period, 1,331 pregnant WWE and 357,334 WWoE were examined. Among WWE, 70.9 % initiated breastfeeding compared to 81.8 % among WWoE. We observed a significant small increase in yearly trends of BFI in both WWE (β=0.45, p = 0.008) and WWoE (β=0.23, p < 0.001). In WWE, BFI was associated with caesarean delivery (aOR=0.72,95 % CI: 0.53-0.97), chronic pain (aOR=0.67,95 % Cl: 0.46-0.97), lower income (aOR=0.34,95 % Cl: 0.26-0.44), and gestational age (aOR= 1.09,95 % CI:1.01-1.18). In WWoE, BFI was associated with chronic pain (aOR=0.83,95 % Cl: 0.80-0.86), lower income (aOR=0.45, 95 %CI:0.44-0.46), mood and anxiety disorder (aOR=0.84,95 % CI:0.81-0.86), and gestational age (aOR=1.13,95 % Cl:1.12-1.14). The use of any ASM (aOR=0.66,95 % Cl:0.51-0.85), new generation (aOR=0.86,95 % Cl: 0.62-1.20), polytherapy (aOR=0.46,95 % Cl: 0.31-0.69) and gabapentin (aOR=0.49,95 % Cl: 0.17-1.24) reduced the likelihood of BFI among WWE.

CONCLUSION

BFI was approximately 10 % lower in WWE compared to WWoE. Determinants such as low income, ASM use, and comorbidities were significant contributors to a reduced BFI in both groups. Targeted counselling for WWE on breastfeeding benefits is essential. Further research is needed to investigate breastfeeding continuation in WWE.

The Use of Antiepileptic Drugs During Pregnancy and Fetal Outcomes

Epilepsy affects approximately 1 percent of the population and roughly 1 million women of childbearing age. Estimates suggest that 0.3-0.7 percent of pregnancies occur in women with epilepsy. Epilepsy itself increases the risk of congenital malformation and medications add to this risk. Also, approximately one-half of the use of medications for epilepsy are used for other indications, possibly increasing exposure in some women. As controlled trials with these medications are not performed during pregnancy, data has been accumulated primarily through databases and case studies. This review is intended to update the practitioner about the use and concerns of antiepileptic medications in the presnant woman and the potential effects on the fetus and neonate.

Pharmacology and pharmacogenomics of neurological medications used in pregnancy

Pregnancy increases the pharmacological management challenge of numerous neurological diseases as a result of complex physiological changes. Understanding pregnancy-induced changes in pharmacokinetic and pharmacodynamic parameters can lead to better outcomes for both the mother and baby. Although the application of pharmacogenomics in maternal-fetal medicine is in its infancy, further research and developments will provide important new developments for managing the efficacy of drug treatments during pregnancy and improving maternal-fetal safety. Although a wide variety of neurological medications are used during pregnancy, this article will focus on the drugs with currently known pharmacogenomic implications.

Effect of zonisamide on the pharmacokinetics and pharmacodynamics of a combination ethinyl estradiol-norethindrone oral contraceptive in healthy women

BACKGROUND

Several antiepileptic drugs have clinically significant pharmacokinetic interactions with oral contraceptives (OCs) that may result in contraceptive failure.

OBJECTIVE

The aim of this study was to assess the effect of zonisamide on the pharmacokinetics of the individual components of a combination OC (ethinyl estradiol [EE] 0.035 mg and norethindrone [NOR] 1 mg) and on pharmacodynamic variables that may be increased in the event of reduced contraceptive efficacy (concentrations of serum luteinizing hormone [LH], follicle-stimulating hormone [FSH], and progesterone).

METHODS

This was a single-center, open-label, 1-sequence, crossover study. Healthy, premenopausal women received the combination OC for three 28-day cycles (combination OC for 21 days, followed by placebo for 7 days). Following stabilization on the OC during the first cycle, blood was collected during cycle 2 for the determination of serum EE and NOR profiles (day 14) and serum LH, FSH, and progesterone concentrations (days 13-15). Starting on day 15 of cycle 2, zonisamide was administered orally at 100 mg/d and titrated to a target dose of 400 mg/d. EE and NOR profiles and serum LH, FSH, and progesterone concentrations were obtained again in cycle 3 (in the presence of zonisamide) and compared with those from cycle 2 (in the absence of zonisamide).

RESULTS

Thirty-seven healthy premenopausal women (mean age, 26.1 years [range, 18-51 years]; mean body weight, 65.5 kg [range, 50.4-93.1 kg]; mean height, 165.8 cm [range, 152.4-182.9 cm]) received > or =1 dose of zonisamide. Of the 33 subjects (89.2%) who completed the study, 26 (78.8%) underwent titration to a stable zonisamide dose of 400 mg/d. For EE, the mean (SD) AUC over a 24-hour dosing interval (AUC(tau)) was 1139 (317) pg.h/mL in cycle 2 and 1143 (312) pg.h/mL in cycle 3; the mean C(max) in the respective cycles was 133 (39) and 141 (46) pg/mL. For NOR, the corresponding values were 140 (48) and 159 (46) ng.h/mL for AUC(tau) and 21 (5.4) and 23 (6.7) ng/mL for C(max). The 90% Cls for the geometric mean ratios (cycle 3:cycle 2) for AUC(tau) and C(max) fell within the accepted range for lack of interaction (0.80-1.25). There were no increases in LH, FSH, or progesterone concentrations between cycle 2 and cycle 3.

CONCLUSIONS

In these healthy volunteers, steady-state zonisamide dosing had no clinically significant effect on the pharmacokinetics of EE or NOR. There was no pharmacodynamic evidence that zonisamide is likely to reduce the contraceptive effectiveness of OCs containing EE and NOR.

The Use of Antiepileptic Drugs-Principles and Practice

Up to 70% of people developing epilepsy may expect to become seizure free with optimum antiepileptic drug (AED) therapy. The remaining 30% are the most difficult to treat. Most patients are controlled on a single AED, but a small proportion requires a combination of two agents. Add-on therapy with a second drug, rather than substitution, may be a viable and rational approach in some patients, particularly if the first drug is relatively well tolerated. Precise classification of the type of seizures, as well as the epilepsy syndrome, together with careful recording of both seizures and adverse effects, are essential if rational management decisions are to be made. The goal of therapy should be complete seizure freedom with a single drug taken once or twice a day and without adverse effects. If control is difficult to achieve, the maximum tolerated dose of each drug should be explored, but a balance needs to be struck between adverse effects and control of seizures. In patients in whom treatment appears to be ineffective, the diagnosis of epilepsy and adherence to therapy should be reviewed. Drugs used in combination must be carefully selected, as poor adherence, drug interactions, and toxicity are more likely if more than one drug is prescribed. Agents are usually chosen according to seizure type, patient characteristics, and often by clinician preference. Those that are better tolerated have a low potential for pharmacokinetic and pharmacodynamic interactions, and those that can be easily introduced without any complicated titration schedule have an advantage.

Treatment of pain in pregnancy

BACKGROUND

The treatment of pain during pregnancy other than that of labor is a clinical issue that has not been addressed in a systematic manner.

MATERIALS AND METHODS

To assess current knowledge, a review of the human and animal literatures was undertaken using MEDLINE. In addition, the dynamics of three pharmacological compartments, the mother, the placenta, and the fetus, and fate of drugs given in pregnancy, was reviewed.

RESULTS

The literature review yielded little information except for a few case studies in which opiates, nonsteroidal anti-inflammatory drugs, antidepressants, mu agonists, and anticonvulsants were used in the treatment of pain in pregnancy. In contrast, there is extensive information in the addiction medicine literature concerning the use of opioids in recovering pregnant addicts. Methadone, buprenorphine, and morphine have been used to treat women seeking recovery from opioids, and neonatal outcomes have been closely monitored with no evidence of harm to the newborn.

CONCLUSIONS

Experience in women seeking recovery from opioids and their newborns illustrates that opioids are an effective and safe pharmacological option for the treatment of pain during pregnancy. Controlled studies are needed to expand knowledge in this clinical area.

Teratogenic potential of the newer antiepileptic drugs: what is known and how should this influence prescribing?

The treatment of women of childbearing age who have epilepsy raises many questions because of the interactions between epilepsy, antiepileptic therapy and different aspects of reproductive life. Menstrual cycle disorders and reduced fertility have been partially ascribed to antiepileptic drugs (AEDs). Furthermore, most AEDs induce the cytochrome P450 (CYP) enzymatic system, altering the metabolism of sex hormones and contributing to the failure of oral contraceptives. Pregnancy represents, in this context, the most critical period because of the well known teratogenic potential of all established AEDs. For most of these drugs no specific patterns of malformations have been identified, although during the past few decades basic knowledge has been acquired, particularly concerning the mechanisms of AED-induced teratogenesis and related risk factors. These issues form the basis of the current guidelines for the management of epilepsy in pregnant women. In the past decade, several new AEDs have been introduced into clinical practice. For a number of reasons, these drugs appear to be more favourable than the older ones as treatments for epilepsy in women of childbearing age. They possess a good pharmacokinetic profile that makes them more stable during pregnancy, and they have a low potential for interaction with other drugs. They are also less likely than the older AEDs to be metabolised to compounds that are teratogenic. Furthermore, most of them do not possess antifolate properties. With the exception of topiramate and vigabatrin, the newer AEDs do not appear to be teratogenic in animals when administered in subtoxic doses. However, animal teratology may not be a reliable predictor of human teratogenicity, and there is a significant lack of information regarding the teratogenic profile of these newer agents in humans. Because clinical experience with these agents is limited, it is advisable to avoid exposure of the embryo to these drugs when pregnancy is planned. The establishment of pregnancy registries could allow for the rapid collection of data related to the administration of new AEDs in pregnancy and the outcomes of such exposure.

Effect of topiramate or carbamazepine on the pharmacokinetics of an oral contraceptive containing norethindrone and ethinyl estradiol in healthy obese and nonobese female subjects

PURPOSE

To study the pharmacokinetics of a combination oral contraceptive (OC) containing norethindrone and ethinyl estradiol during OC monotherapy, concomitant OC and topiramate (TPM) therapy, and concomitant OC and carbamazepine (CBZ) therapy in order to comparatively evaluate the pharmacokinetic interaction, which may cause contraceptive failure.

METHODS

This randomized, open-label, five-group study included two 28-day cycles. Five groups of female subjects received oral doses of ORTHO-NOVUM 1/35 alone (cycle 1) and then concomitant with TPM or CBZ (cycle 2). The treatment groups were group 1, TPM, 50 mg/day; group 2, TPM, 100 mg/day; group 3, TPM, 200 mg/day; group 4, TPM, 200 mg/day (obese women); and group 5, CBZ, 600 mg/day. Group 4 comprised obese women whose body mass index (BMI) was between 30 and 35 kg/m(2). The BMI of the remaining four groups was < or =27 kg/m2.

RESULTS

Coadministration of TPM at daily doses of 50, 100, and 200 mg (nonobese) and 200 mg (obese) nonsignificantly (p > 0.05) changed the mean area under the curve (AUC) of ethinyl estradiol by -12%, +5%, -11%, and -9%, respectively, compared with OC monotherapy. A similar nonsignificant difference was observed with the plasma levels and AUC values of norethindrone (p > 0.05). CBZ (600 mg/day) significantly (p < 0.05) decreased the AUC values of norethindrone and ethinyl estradiol by 58% and 42%, respectively, and increased their respective oral clearance by 69% and 127% (p < 0.05). Because CBZ induces CYP 3A-mediated and glucuronide conjugation metabolic pathways, the significant increase in the oral clearance of ethinyl estradiol and norethindrone was anticipated.

CONCLUSIONS

TPM, at daily doses of 50-200 mg, does not interact with an OC containing norethindrone and ethinyl estradiol. The lack of the TPM-OC interaction is notable when it is compared with the CBZ-OC interaction.

Oral contraception and epilepsy: findings in a large cohort study

There is no good evidence that oral contraceptives (OCs) increase the risk of epilepsy in unaffected women or increase the frequency of seizures in those suffering from the disorder. Nonetheless, manufacturers' literature continues to include warnings about OCs and epilepsy. We have analyzed the available data about epilepsy in the Oxford-Family Planning Association contraceptive study that includes 17,032 women followed for periods of up to 26 years. In total, 82 women (with no record of having suffered epilepsy when recruited to the study) were referred to hospital for diagnosis or treatment of epilepsy during the follow-up period. No association was found between OC use and the occurrence of the condition. Referral to hospital was, however, more frequent in women of low social class and in those with a high body mass index.

Levetiracetam does not alter the pharmacokinetics of an oral contraceptive in healthy women

PURPOSE

This study was designed to evaluate whether levetiracetam, a novel antiepileptic drug (AED), influences the pharmacokinetics of steroid oral contraceptives.

METHODS

During a run-in phase, 18 healthy female patients received an oral contraceptive containing ethinyl estradiol, 0.03 mg, and levonorgestrel, 0.15 mg, for the first 21 days of two consecutive menstrual cycles. In a subsequent double-blind, randomized, two-way crossover treatment phase, subjects received either levetiracetam, 500 mg, or placebo twice daily concomitant with the oral contraceptive. Plasma concentrations of ethinyl estradiol and levonorgestrel were measured on days 14 and 15 of the two treatment periods for the evaluation of the 24-h kinetic parameters, and an additional sample was collected on day 21 to determine the trough plasma concentrations. Serum progesterone and luteinizing hormone (LH) levels were determined on days 13, 14, 15, and 21 of each cycle of the treatment phase.

RESULTS

The plasma concentration-time curves and pharmacokinetic parameters of ethinyl estradiol and levonorgestrel were not statistically different during concomitant treatment with either levetiracetam or placebo. The ratios of the log-transformed geometric mean areas under the plasma concentration-time curves (AUCs), maximal (Cmax) and minimal (Cmin) plasma concentrations, and trough concentrations on day 21 (C21) ranged from 99.12 to 99.96% for ethinyl estradiol and from 97.13 to 99.41% for levonorgestrel. The 90% confidence intervals of these ratios were well within the 80 to 125% acceptance range for lack of interaction. Serum progesterone and LH concentrations were fairly constant during the run-in and treatment phases and remained markedly below their respective physiologic levels. Safety and menstrual-bleeding patterns were comparable during levetiracetam and placebo administration.

CONCLUSIONS

Levetiracetam does not affect the pharmacokinetics of an oral contraceptive containing ethinyl estradiol and levonorgestrel, and on the basis of serum progesterone and LH levels, it does not affect the contraceptive efficacy.

Characterization and health risk assessment of postmenopausal women with epilepsy

Postmenopausal women with epilepsy represent an understudied patient population. The objectives of this cross-sectional study were to characterize the impact of menopause on seizure activity and to conduct a health risk assessment. We conducted telephone interviews of 40 postmenopausal women with epilepsy concerning the effect of menopause on seizure frequency. We surveyed use of hormone replacement therapy, postmenopausal bone fractures, use of vitamins, and frequency of exercise. The average age and mean seizure duration were 55.8 and 27.6 years, respectively. Twenty-six women had onset of seizure activity before menopause. Of these 26, 3 reported fewer seizures after menopause, 7 reported more seizures, 11 reported no change, and 5 were unsure whether menopause affected their seizures. Only 30% of the 40 women were currently taking hormone replacement therapy. The impact of menopause on seizure activity was variable. Osteoporotic and cardiovascular preventive measures are underutilized. Patient education on these protective measures should be part of the comprehensive treatment approach in this "at-risk" patient population.

The effects of epilepsy and its treatment on sexual and reproductive function

Male and female sexuality and reproductive functions are complex systems with cortical, limbic system, hypothalamic, pituitary, and end organ interactions. Sexual steroids are produced in the sexual glands, the adrenals, and the brain. They undergo interconversion in the brain, bind to different brain areas, and have multiple effects behaviorally and neurophysiologically. Progesterone, estrogen and testosterone have neuroendocrine effects that alter epileptogenicity. Seizure frequency may change throughout the life cycle as a result of hormonal status. Changes in central control, peripheral hormone levels, and/or medication effects may all contribute to decreased libido, potency, and fertility. Antiepileptic drugs (AEDs) interact with hormone-binding metabolism, resulting in altered human reproductive function. AEDs alter contraceptive hormone treatments. Information on the effects of new AEDs is being gathered by the National Pregnancy Registry. Catamenial epilepsy and some sexual dysfunction in men may be treatable.

Anticonvulsants and breast feeding: a critical review

Progress in the diagnosis and management of seizure disorders and the availability of effective anticonvulsive medications has enabled increasing numbers of epileptic women of child-bearing age to raise families. Breast feeding, which these women may wish to choose, provides health, nutritional, immunological, developmental, social, economic and environmental benefits. The traditional anticonvulsants, such as phenytoin, carbamazepine and valproic acid (valproate sodium), are generally considered safe for use during breast feeding; however, observation for adverse effects is recommended. The use of phenobarbital while breast feeding is controversial because of its slow elimination by the nursing infant. The newer anticonvulsants, such as clobazam, felbamate, gabapentin, lamotrigine, oxcarbazepine, tiagabine, topiramate, and vigabatrin, are used mainly as adjunctive therapy. Data on the use of these drugs in pregnancy and lactation, and regarding long term effects on cognition and behaviour, are sparse. Weighing the benefits of breast feeding against the potential risk to the nursing infant, breast feeding is considered to be safe when the mother is taking carbamazepine, valproic acid or phenytoin. Infant monitoring for potential adverse effects is advisable when the mother is taking phenobarbital, clobazam, gabapentin, lamotrigine, oxcarbazepine or vigabatrin. Monitoring of infant serum drug concentrations is advisable but not compulsory. The use of felbamate, tiagabine and topiramate during breast feeding should await further study.

Ganaxolone: a novel positive allosteric modulator of the GABA(A) receptor complex for the treatment of epilepsy

Ganaxolone is a member of a novel class of neuroactive steroids which modulates the GABA(A) receptor complex (GRC) via an unique recognition site, distinct from those of benzodiazepines and barbiturates. Preclinical data from an array of chemically- and electrically-induced seizure models demonstrate that ganaxolone possesses broad spectrum anticonvulsant activity with potential clinical utility in both generalised and partial seizures, as well as cocaine-induced seizures. Clinical data to date support a favourable safety profile with somnolence, an extension of GABAergic activity, being the most frequently reported adverse event at higher doses. Target indications include infantile spasms and complex partial seizures. Open-label data in paediatric patients with intractable epilepsy suggest that ganaxolone may be effective in treating infantile spasms. A controlled trial utilising an in-patient, monotherapy design demonstrated that ganaxolone effectively decreases complex partial seizure activity compared to placebo. An important area of further evaluation is ganaxolone's potential role in the treatment of women with catamenial epilepsy.