Pharmacoresistance Mechanisms in Epilepsy

Epilepsy affects millions worldwide and, despite a growing arsenal of antiseizure medications, nearly one-third of patients remain refractory to pharmacotherapy. Resistance arises from multiple, often interlinked mechanisms. Alterations in drug targets—such as mutations or post-translational modifications of ion channels and neurotransmitter receptors—can reduce drug binding or efficacy. Concurrently, overexpression of multidrug efflux transporters at the blood–brain barrier and within epileptogenic regions lowers central drug concentrations. Persistent seizure activity fuels neuroinflammatory cascades that compromise endothelial integrity, promote aberrant angiogenesis and further induce transporter expression. Genetic and epigenetic factors, including gene variants and non-coding RNAs, influence individual susceptibility to resistance, while intrinsic network severity can create hyperexcitable circuits impervious to conventional drugs. Together, these processes form a self-reinforcing barrier to treatment, underscoring the need for biomarkers that predict resistance and for strategies that bypass or modulate these mechanisms.

Research from Nature Portfolio

Recent investigations have revealed how valproate’s downregulation of cyclooxygenase-2 in peripheral blood correlates with reduced prostaglandin E2 levels and suppression of seizure-mediated P-glycoprotein upregulation at the blood–brain barrier. This dual action enhances cerebral drug delivery in responders and positions peripheral COX-2 expression as a promising biomarker and therapeutic target for overcoming pharmacoresistance.

Pharmacoresistance Mechanisms in Epilepsy publication trend

The graph below shows the total number of articles in pharmacoresistance mechanisms in epilepsy across all publications each year (not limited to Nature Index journals).

Technical terms

P-glycoprotein (P-gp): A multidrug efflux transporter of the ATP-binding cassette family that limits antiseizure drug penetration across the blood–brain barrier and from neural tissue.

ATP-binding cassette transporters (ABC transporters): A superfamily of membrane proteins that use ATP hydrolysis to export diverse substrates, including drugs, out of cells.

Blood–brain barrier (BBB): A selective vascular interface composed of endothelial cells and tight junctions that regulates substance exchange between the bloodstream and the central nervous system.

Cyclooxygenase-2 (COX-2): An inducible enzyme involved in prostaglandin synthesis during inflammation, capable of modulating transporter expression at the blood–brain barrier.

Nanocarriers: Engineered nanoscale vehicles designed to deliver therapeutic compounds across biological barriers, improving target specificity and reducing systemic side effects.

References

1. Nanocarriers-based therapeutic strategy for drug-resistant epilepsy: A systematic review. International Journal of Pharmaceutics (2024).
2. Drug-Resistant Epilepsy: Multiple Hypotheses, Few Answers. Frontiers in Neurology (2017).
3. Mechanisms of Drug Resistance in the Pathogenesis of Epilepsy: Role of Neuroinflammation. A Literature Review. Brain Sciences (2021).
4. Downregulation of peripheral PTGS2/COX-2 in response to valproate treatment in patients with epilepsy. Scientific Reports (2020).
5. Transporter hypothesis in pharmacoresistant epilepsies. Is it at the central or peripheral level?. Epilepsia Open (2021).