Use of valproate and carbamazepine in the therapy of epilepsy (guidelines for the practitioner)

The paper gives comparative data on the efficacy and tolerability of valproic acid (VA, valproate) and carbamazepine (CBZ) for different types of epilepsy and seizures in different age and clinical groups. The results of studies suggest that despite a more than 50-year history of their effective use, the extended-release formulations of VA and CBZ remain the drugs of first choice for many types of epilepsy.

CBZ is effective for focal epilepsy and isolated generalized tonic-clonic seizures. However, its use is substantially limited by properties, such as cytochrome P450 induction and autoinduction, high drug-drug interactions, the aggravation of absences, negative myoclonus, myoclonic and atonic seizures, an effect on the profile of steroid sex hormones, elevated concentrations of atherogenic lipids and cholesterol, myocardial conduction disorders, and hyponatremia.

Due to the multiple mechanism of action, VA is prescribed for almost all types of epilepsy and seizures in patients of different ages. VA should not be used (if the clinical situation allows) in women of childbearing age, in some infantile epileptic encephalopathy, inherited metabolic diseases, and chromosomal abnormalities. Effectiveness against different types of seizures and epilepsy, good tolerability, minimal aggravation risk, high retention rate of monotherapy, the presence of a variety of dosage forms, and favorable pharmacokinetic and pharmacodynamic profiles still make VA essential in many clinical situations.

Dibenzazepine Agents in Epilepsy: How Does Eslicarbazepine Acetate Differ?

Carbamazepine (CBZ), oxcarbazepine (OXC), and eslicarbazepine acetate (ESL) belong to the dibenzazepine family of antiepileptic drugs and are all thought to primarily act as sodium channel blockers (SCBs). However, ESL is structurally distinct from CBZ and OXC, resulting in differences in metabolism, pharmacokinetics, and pharmacodynamics. Despite a lack of direct comparative data, evidence for potential differences in effectiveness and tolerability within the dibenzazepine family has emerged from studies in which patients being treated with one dibenzazepine agent have received adjunctive treatment with another (having achieved insufficient seizure control with the first) or have transitioned from one dibenzazepine agent to another because of lack of effectiveness or poor tolerability. Most of these studies have been conducted in the real-world clinical practice setting. ESL has been shown to be effective as adjunctive therapy in patients who have previously achieved inadequate seizure control with CBZ, indicating that the use of different dibenzazepine agents in combination can provide additive effectiveness benefits, which may reflect underlying differences in their mechanisms of action. Similarly, ESL monotherapy can be effective in patients who have switched from another dibenzazepine, such as CBZ or OXC, because of inadequate efficacy. There is also considerable evidence to demonstrate that patients transitioning from OXC or CBZ to ESL as a result of adverse events experience improvements in tolerability, which may also be associated with improvements in quality of life, alertness, and/or lipid profiles. Current evidence therefore demonstrates that ESL differs from other dibenzazepine agents in terms of effectiveness and tolerability.

Funding: Eisai Ltd.

From clinical trials of antiepileptic drugs to treatment

Rational prescribing should be based on the assessment of high-quality evidence about the benefits and risks of available treatment options. Because clinical trials, particularly randomized controlled trials (RCTs), provide the best source of evidence, their design and results need to be carefully scrutinized. The majority of RCTs of antiepileptic drugs (AEDs) have been designed to address regulatory requirements, and generally they involve restrictive eligibility criteria, rigid dosing schemes, short duration of follow-up, and comparison with placebo rather than standard treatments. Although these studies have high internal validity, they are conducted in a setting that is distant from routine clinical practice and therefore their usefulness in guiding treatment decisions is limited. Information more directly applicable to clinical practice can be derived from a relatively small number of comparative effectiveness monotherapy RCTs, although the design of some of these studies was probably biased in favor of the sponsor's product. Alarmingly, there is a paucity of well-designed trials in epilepsy syndromes other than focal epilepsies, and no RCTs at all in most of the less common epileptic syndromes of infancy and childhood. In the light of these shortcomings, there is scope for re-assessing regulatory requirements to facilitate generation of data more directly applicable to the routine clinical setting. Likewise, research-funding organizations should be sensitized about the lack of adequate evidence to guide therapeutic practice in epilepsy, and the need to promote high-quality comparative effectiveness trials. Future prospective pragmatic trials may benefit from the increasingly widespread availability of electronic health records.