Translational Considerations in the Development of Intranasal Treatments for Epilepsy

Intranasal administration of antiseizure medications in chronic and emergency treatment: Hopes and challenges

Despite the availability of many antiseizure medications (ASMs), 30 % of patients experience pharmacoresistant seizures. High-throughput screening methods undoubtedly remain one of the most important approaches for discovering new molecules to treat seizures. However, the costly and time-consuming nature of drug development prompts us to explore alternative strategies to counteract drug-resistant seizures. One such approach is to consider intranasal administration of known molecules for seizure treatment. In the case of treating epileptic seizures, administering ASMs intranasally may enhance treatment effectiveness and minimize adverse effects. A good example of changes in drug administration is the intranasal administration of fentanyl, which has become a clinical standard in the emergency setting to treat moderate to severe pain in adults and children. This review discusses the utilization of intranasally administered ASMs for both acute and chronic seizures. It addresses various targeted pharmacokinetic approaches, challenges and prospects associated with these regimens. Brief neuroanatomical and molecular rationale for nose-to-brain drug transport is also presented. Furthermore, recent preclinical studies validating the efficacy and brain distribution following intranasal administration of the most commonly used drugs in chronic treatment are also discussed.

Epilepsy: Mitochondrial connections to the 'Sacred' disease

Over 65 million people suffer from recurrent, unprovoked seizures. The lack of validated biomarkers specific for myriad forms of epilepsy makes diagnosis challenging. Diagnosis and monitoring of childhood epilepsy add to the need for non-invasive biomarkers, especially when evaluating antiseizure medications. Although underlying mechanisms of epileptogenesis are not fully understood, evidence for mitochondrial involvement is substantial. Seizures affect 35%-60% of patients diagnosed with mitochondrial diseases. Mitochondrial dysfunction is pathophysiological in various epilepsies, including those of non-mitochondrial origin. Decreased ATP production caused by malfunctioning brain cell mitochondria leads to altered neuronal bioenergetics, metabolism and neurological complications, including seizures. Iron-dependent lipid peroxidation initiates ferroptosis, a cell death pathway that aligns with altered mitochondrial bioenergetics, metabolism and morphology found in neurodegenerative diseases (NDDs). Studies in mouse genetic models with seizure phenotypes where the function of an essential selenoprotein (GPX4) is targeted suggest roles for ferroptosis in epilepsy. GPX4 is pivotal in NDDs, where selenium protects interneurons from ferroptosis. Selenium is an essential central nervous system micronutrient and trace element. Low serum concentrations of selenium and other trace elements and minerals, including iron, are noted in diagnosing childhood epilepsy. Selenium supplements alleviate intractable seizures in children with reduced GPX activity. Copper and cuproptosis, like iron and ferroptosis, link to mitochondria and NDDs. Connecting these mechanistic pathways to selenoproteins provides new insights into treating seizures, pointing to using medicines including prodrugs of lipoic acid to treat epilepsy and to potential alternative therapeutic approaches including transcranial magnetic stimulation (transcranial), photobiomodulation and vagus nerve stimulation.