Interactions between antiepileptic drugs and hormonal contraception

Sexual hormones and epilepsy: threat and opportunities

PURPOSE OF REVIEW

This article reviews recent developments in our knowledge of the reciprocal interactions between epilepsy and sex hormones and how these interactions may play a role in the pathophysiology and treatment of both.

RECENT FINDINGS

Community studies confirm that menstrual disorders are overrepresented among women with epilepsy, especially among women with high seizure frequency and in those on valproate or polytherapy. Reproductive function is not affected in women with epilepsy who discontinued antiepileptic drug therapy during pubertal maturation. While valproate has been implicated as having particularly notable disruptive effects on reproductive function in women with epilepsy (polycystic ovaries and hyperandrogenemia), this was not evident in non-epileptic primates. The role of epilepsy itself is evident from a study that showed that the laterality of unilateral temporolimbic discharges is associated with predictable directional changes in hormonal secretion at all levels of the reproductive neuroendocrine axis. Epilepsy in men is associated with reduced levels of sexual function, bioactive testosterone and sperm. Various antiepileptic drugs may differ in this regard.

SUMMARY

Epilepsy and antiepileptic drugs can alter sex hormone levels to promote the development of reproductive endocrine disorders in both women and men. Reproductive endocrine disorders may adversely affect both reproductive function and seizure control. Treatment of epilepsy and selection of antiepileptic drugs may be important to reproductive health in women and men with epilepsy. Sex steroids and their metabolites may also provide treatment for seizures.

New drugs for the treatment of epilepsy: a practical approach

The availability of new antiepileptic drugs has broadened the spectrum of medical treatment options in epilepsy. The new agents, together with established drugs, offer substantial choice for doctors treating patients with focal or generalised epilepsy. The newer antiepileptic drugs are not necessarily more effective but usually better tolerated than the traditional agents, mainly because of favourable pharmacokinetic profiles and fewer interactions. Because treatment options have increased, drug therapy can now be tailored to the requirements of individual patients. Nevertheless, significant safety and efficacy issues continue to exist and there is a need for the development of even better agents. This review describes the clinical use of the new antiepileptic drugs, but focuses in particular on monotherapy, the treatment of generalised seizures, teratogenicity, and the cognitive side effect profile of the newer compounds.

A treatment algorithm for neuropathic pain

BACKGROUND

Neuropathic pain is a chronic pain syndrome caused by drug-, disease-, or injury-induced damage or destruction of sensory neurons within the dorsal root ganglia of the peripheral nervous system. Characteristic clinical symptoms include the feeling of pins and needles; burning, shooting, and/or stabbing pain with or without throbbing; and numbness. Neuronal hyperexcitability represents the hallmark cellular mechanism involved in the underlying pathophysiology of neuropathic pain. Although the primary goal is to alleviate pain, clinicians recognize that even the most appropriate treatment strategy may be, at best, only able to reduce pain to a more tolerable level.

OBJECTIVE

The purpose of this review is to propose a treatment algorithm for neuropathic pain that health care professionals can logically follow and adapt to the specific needs of each patient. The algorithm is intended to serve as a general guide to assist clinicians in optimizing available therapeutic options.

METHODS

A comprehensive review of the literature using the PubMed, MEDLINE, Cochrane, and Toxnet databases was conducted to design and develop a novel treatment algorithm for neuropathic pain that encompasses agents from several drug classes, including antidepressants, antiepileptic drugs, topical antineuralgic agents, narcotics, and analgesics, as well as various treatment options for refractory cases.

RESULTS

Any of the agents in the first-line drug classes (tricyclic antidepressants, antiepileptic drugs, topical antineuralgics, analgesics) may be used as a starting point in the treatment of neuropathic pain. If a patient does not respond to treatment with at least 3 different agents within a drug class, agents from a second drug class may be tried. When all first-line options have been exhausted, narcotic analgesics or refractory treatment options may provide some benefit. Patients who do not respond to monotherapy with any of the first- or second-line agents may respond to combination therapy or may be candidates for referral to a pain clinic. Because the techniques used at pain clinics tend to be invasive, referrals to these clinics should be reserved for patients who are truly refractory to all forms of pharmacotherapy.

CONCLUSIONS

Neuropathic pain continues to be one of the most difficult pain conditions to treat. With the proposed algorithm, clinicians will have a framework from which to design a pain treatment protocol appropriate for each patient. The algorithm will also help streamline referrals to specialized pain clinics, thereby reducing waiting list times for patients who are truly refractory to traditional pharmacotherapy.

Unanswered questions in contraceptive management: What do the experts do?

CONTEXT

Several areas exist in the practice of contraception where evidence for practice is deficient, yet clinical decisions need to be made.

OBJECTIVES

The aim of the study was to find the practice habits of lead practitioners in the area of contraception in specific clinical scenarios where the published evidence is inadequate to provide clear guidance to clinicians. Results can provide 'Level V' evidence for practice for the 'nonexpert' practitioner.

DESIGN

Descriptive study.

PARTICIPANTS

The study was conducted as a postal questionnaire mailed to the 205 lead practitioners whose contact details were known through the Society of Consultants in Reproductive Health (hereafter referred to as 'consultants') working in reproductive health in the National Health Service.

RESULTS

A total of 138 consultants returned completed questionnaires (67% response rate). Important results included 100% of respondents being prepared to prescribe progestogen-only emergency contraception more than once in a cycle (contrary to product labelling) and 71% recommending two tablets daily of the progestogen-only pill for women of high body mass.

CONCLUSIONS

Some questions had responses that showed clear majorities, providing a clear guide to practice, while other areas remain doubtful. Comments from respondents indicated great interest in all areas covered and a desire for consensus on many of the issues. Certainly the licensing and the advice from pharmaceutical companies is conservative, and in many scenarios a majority of consultants indicated that in order to serve the best interests of their clients they feel constrained to practise outside the Summary of Product Characteristics.

Side Effects of Antiepileptics- A Review

Older generation antiepileptic drugs like Phenobarbital (Luminal), carbamazepine (Tegretol), phenytoin (Dilantin), and valproic acid (Depakote) have several shortcomings such as suboptimal response rates, significant adverse effects, several drug interactions, and a narrow therapeutic index. New antiepileptic drugs have been developed in the last decade to overcome some of these problems. These newer generation antiepileptics like felbamate (Felbatol), gabapentin (Neurontin), lamotrigine (Lamictal), levetiracetam (Keppra), oxcarbazepine (Trileptal), tiagabine (Gabitril), topiramate (Topamax), and zonisamide (Zonegran) have better tolerability profiles, low interaction potential, and significantly less enzyme inducing or inhibiting properties. As the use of antiepileptic drugs has expanded to include treatment of neuropathic pain, newer side effects have been reported. In addition to the common side effects of antiepileptic drugs, like dizziness, drowsiness, and mental slowing; other side effects like weight gain, metabolic acidosis, nephrolithiasis, angle closure glaucoma, skin rash, hepatotoxicity, colitis, and movement and behavioral disorders, to name a few, have been brought to our attention. This review is an attempt to highlight the features and incidences of some of these side effects.

Special considerations in treating bipolar disorder in women

There are obvious gaps in research surrounding issues specific to women who suffer from bipolar disorder, including gender differences and their implications for management, the impact of the reproductive cycle, and evidence based treatment guidelines for pregnancy and the postpartum period. Gender differences have not been reported for the prevalence of bipolar disorder; however, women are more likely to experience rapid cycling, mixed mania, and antidepressant-induced manias. This may affect response to treatment, which has been found, in some cases, to differ in men and women. In addition, side effects in response to treatments may well differ in men and women, especially with regard to lithium and valproate prescription. The course of bipolar disorder in women may be influenced by the menstrual cycle, pregnancy, the postpartum period, and menopause, although many issues require further clarification. Treatment of bipolar disorder during pregnancy and the postmenopausal period requires careful consideration, as does treatment during the childbearing years, as some mood stabilizers influence the metabolism of oral contraceptives. This review article has attempted to evaluate existing literature regarding women with bipolar disorder in a comprehensive and critical way, and to consolidate into a single source the gender-specific aspects of the disorder that may have treatment implications for women.

FFPRHC Guidance (October 2003): First Prescription of Combined Oral Contraception

The Guidance provides information for clinicians on the steps to be taken before providing a woman with her first prescription for combined oral contraception. It updates and replaces previous Faculty Guidance. A key to the grades of recommendations, based on levels of evidence, is given at the end of this document. Details of the methods used by the Clinical Effectiveness Unit (CEU) in developing this Guidance, and evidence tables summarising the research basis of the recommendations, are available on the Faculty website (www.ffprhc.org.uk). Abbreviations used include: blood pressure (BP), body mass (BMI), bone mineral density (BMD), breakthrough bleeding (BTB), British National Formulary (BNF), combined oral contraception (COC), Committee on Safety of Medicines (CSM), confidence interval (CI), deep vein thrombosis (DVT), emergency contraception (EC), ethinyl oestradiol (EE), Faculty Aid to Continuing Professional Development Topics (FACT), Family Planning Association (fpa), follicule-stimulating homone (FSH), general practitioner (GP), intermenstrual bleeding (IMB), luteinising hormone (LT), microgram, myocardial infarction (MI), odds ratio (OR), oral contraception (OC), pulmonary embolism (PE), relative risk (RR), Scottish Intercollegiate Guideline Network (SIGN), sexually transmitted infection (STI), Summary of Product Characteristics (SPCs), venous thomboembolism (VTE), World Health Organization (WHO), WHO Medical Eligibility Criteria (WHOMEC), WHO Selected Practice Recommendations (WHOSPR).

Clinically important drug interactions in epilepsy: interactions between antiepileptic drugs and other drugs

Antiepileptic drugs (AEDs) are commonly prescribed for long periods, up to a lifetime, and many patients will require treatment with other agents for the management of concomitant or intercurrent conditions. When two or more drugs are prescribed together, clinically important interactions can occur. Among old-generation AEDs, carbamazepine, phenytoin, phenobarbital, and primidone are potent inducers of hepatic enzymes, and decrease the plasma concentration of many psychotropic, immunosuppressant, antineoplastic, antimicrobial, and cardiovascular drugs, as well as oral contraceptive steroids. Most new generation AEDs do not have clinically important enzyme inducing effects. Other drugs can affect the pharmacokinetics of AEDs; examples include the stimulation of lamotrigine metabolism by oral contraceptive steroids and the inhibition of carbamazepine metabolism by certain macrolide antibiotics, antifungals, verapamil, diltiazem, and isoniazid. Careful monitoring of clinical response is recommended whenever a drug is added or removed from a patient's AED regimen.

Valproate: past, present, and future

Preclinical studies have been carried out during the past four decades to investigate the different mechanisms of action of valproate (VPA). The mechanisms of VPA which seem to be of clinical importance include increased GABAergic activity, reduction in excitatory neurotransmission, and modification of monoamines. These mechanisms are discussed in relation to the various clinical uses of the drug. VPA is widely used as an antiepileptic drug with a broad spectrum of activity. In patients, VPA possesses efficacy in the treatment of various epileptic seizures such as absence, myoclonic, and generalized tonic-clonic seizures. It is also effective in the treatment of partial seizures with or without secondary generalization and acutely in status epilepticus. The pharmacokinetic aspects of VPA and the frequent drug interactions between VPA and other drugs are discussed. The available methods for the determination of VPA in body fluids are briefly evaluated. At present, investigations and clinical trials are carried out and evaluated to explore the new indications for VPA in other conditions such as in psychiatric disorders, migraine and neuropathic pain. Furthermore, the toxicity of VPA, both regarding commonly occurring side effects and potential idiosyncratic reactions are described. Derivatives of VPA with improved efficacy and tolerability are in development.

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.

Epilepsy and women's health: family planning, bone health, menopause, and menstrual-related seizures

Epilepsy uniquely affects more than 1 million American women and girls. Health care providers must be aware of the specific concerns and issues regarding the different effects epilepsy has on male and female patients. Epilepsy and antiepileptic drugs substantially affect women's health in the areas of menstruation, contraception, sexual function, pregnancy, menopause, and bone health. Optimal care of women with epilepsy requires collaboration among neurologists, obstetrician-gynecologists, internists, family practitioners, genetic counselors, and nurse educators. This article reviews some areas of concern for women living with epilepsy.