Antiseizure Medications in Development: Novel Mechanisms, Precision Therapy, and the Move Towards Disease Modification

Background: Despite more than 30 licenced antiseizure medications (ASMs), approximately one third of people with epilepsy remain drug-resistant, and developmental and epileptic encephalopathies represent one of the greatest unmet needs in epilepsy therapeutics. The past decade has produced a substantial reorientation of ASM discovery, driven by epilepsy genetics, new disease models, advances in drug screening, and innovative therapeutic modalities. Objective: The objective of this study was to review the contemporary clinical-stage pipeline of ASMs with novel or differentiated mechanisms of action, organized by molecular target, while placing recent regulatory successes and instructive failures within the broader transition toward mechanism-based, precision, and potentially disease-modifying therapies. Findings: A 2024 pipeline analysis identified more than 200 epilepsy therapies in preclinical or clinical development; at the cutoff of the present literature search (30 June 2026), over 40 compounds had reached phase II or III, with the majority directed at DEEs. Functional-state-selective sodium channel modulation has emerged as a leading conceptual advance supported by converging mechanistic and early clinical evidence, exemplified by relutrigine (PRAX-562), a preferential persistent-current inhibitor for which a regulatory decision is pending in SCN2A/SCN8A-DEEs, and vormatrigine (PRAX-628), whose large open-label effect was not reproduced in a controlled (blinded) trial. Several of the efficacy figures summarized here derive from congress presentations, interim analyses, or open-label extensions and await full peer-reviewed publication. Parallel advances include the selective Kv7 opener azetukalner; the dual-mechanism benchmark cenobamate; cholesterol-24-hydroxylase inhibition (soticlestat); selective serotonergic agonism (bexicaserin); glutamatergic precision agents (radiprodil); subtype-selective GABAA modulators (darigabat, ganaxolone); and gene-directed therapies (zorevunersen, elsunersen). Pre-symptomatic intervention in tuberous sclerosis complex provides an early, single-trial clinical proof of principle for delaying and reducing the incidence of epilepsy in a genetically defined population; this should not yet be equated with established disease prevention. Conclusions: The pipeline reflects an ongoing shift from broad symptomatic agents toward mechanism-led, genotype-matched, and potentially disease-modifying treatments. This shift is tempered by a persistent translational gap between early signals and randomized-trial confirmation, and by the preliminary status of much of the supporting evidence.