The XEN901 Phase 1 clinical trial is a randomized, double-blind, placebo-controlled study that will evaluate the safety, tolerability and pharmacokinetics (PK) of both single ascending doses (SAD) and multiple ascending doses (MAD) of XEN901 in healthy subjects. It is estimated there will be approximately 64 subjects in the planned SAD and MAD cohorts.

Key Inclusion Criteria:

• Healthy male or females aged between 18 and 55 years inclusive with a body mass index (BMI) between 18.5 and 32.0 kg/m2
• Must agree to use effective methods of contraception, if applicable
• Able to swallow capsules
• Able to provide written, personally signed and dated Informed Consent Form

Key Exclusion Criteria:

• Any history of seizures
• Any current and relevant history of significant disease or disorder which, in the opinion of the investigator, may either put the subject at risk, affect clinical or laboratory results, or the subject's ability to participate in the study
• Answering "yes" to any of the questions within the Columbia Suicide Severity Rating Scale
• Mental incapacity or language barriers precluding adequate understanding, cooperation, and compliance with the study
• No prescription or over-the-counter (OTC) medications (except hormonal contraception), herbal or dietary supplements OTC medications 14 days prior to dosing to study end
• No smoking 60 days prior to dosing to study end
• Any clinically significant abnormalities in vital signs, ECG, physical exam, or laboratory evaluations