A double-blind, placebo-controlled, crossover trial to investigate the PPR of approximately 5 subjects with a known stable PPR on EEG, using 2 doses of NPT 2042 compared to placebo.

This study will compare the effect of 2 doses of NPT 2042 on the photoparoxysmal- electroencephalogram (EEG) response (PPR), compared to placebo. Subjects will be screened to ensure they have a stable PPR. Subjects will then return for 3 treatment visits, each lasting 1 day, with minimum 14-day washout period between visits. Subjects will be randomized to a treatment sequence in order to receive NPT 2042 (160 mg or 240 mg) or matching placebo on each treatment day. The PPR will be measured at predose (-0.5 hours) and 0.5, 1, 2, 3, 4, and 6 hours postdose. The PPR of the active treatments will be compared to the placebo response.

Inclusion Criteria:

1. Subject or legal authorized representative/guardian must be able to provide written informed consent signed prior to any study-specific procedures being conducted.

2. Individuals aged 18-75 years at the time of consent.

3. Subject has a diagnosis and history of a PPR with or without a diagnosis of epilepsy.

4. Subjects receiving zero to three concomitant antiseizure medications (ASMs).

   • Benzodiazepines: the chronic use of a benzodiazepine for any indication will be allowed and will be counted as an ASM.

   • Vagus nerve stimulator (VNS)/responsive neurostimulation (RNS): VNS/RNS will not be counted toward the number of concomitant ASMs. Subjects with surgically implanted VNS/RNS will be allowed to enter the study if all the following conditions are met:

     • The device has been in place for 1 year or more prior to the screening visit.
     • The settings have remained constant for 3 months or more prior to the screening visit and remain constant throughout the study.
     • The battery is expected to last for the duration of the study.

5. At least 3 of the EEGs performed during the screening visit must have an intermittent photic stimulation (IPS)-induced SPR of ≥3 points on a frequency assessment scale in the same eye condition, with documented confirmation by the Epilepsy Study Consortium, Inc. (ESCI).

6. Subject is in otherwise good health (with the exception of epilepsy), as determined by the investigator and documented in the medical history.

7. Subject has a body mass index (BMI) between 18 and 40 kg/m2.

8. Subject agrees to refrain from strenuous exercise which is not within the subject's normal daily routine the day before screening, as determined by the investigator.

9. Female subjects of childbearing potential and all men: agree to use of highly effective methods of contraception during the study and for 28 days after last dose of study drug.

10. Subject is able to communicate with the investigator and to understand and comply with all study requirements.

Exclusion Criteria:

1. Subject has a history of non-epileptic seizures (e.g., metabolic, structural, or pseudoseizures).
2. Females who are pregnant or lactating.
3. Subject has a clinically significant laboratory abnormality that, in the opinion of the investigator, will exclude the subject from the study.
4. Subject has an active central nervous system (CNS) infection, demyelinating disease, degenerative neurological disease, or any CNS disease deemed to be progressive during the course of the study that may confound the interpretation of the study results.
5. Subject has any clinically significant psychiatric illness, psychological, or behavioral problems which, in the opinion of the investigator, would interfere with the subject's ability to participate in the study.
6. Subject has clinically significant active liver disease (i.e., liver function tests greater than 3 times the upper limit of normal aspartate aminotransferase (AST), or alanine aminotransferase (ALT), porphyria, or has a family history of severe hepatic dysfunction.
7. Subject has a history of alcoholism, drug abuse, or drug addiction within the past 12 months.
8. Subjects who have participated in any other trials involving an investigational product or device within 30 days or five half-lives (whichever is longer) of Screening.
9. Subject is currently using of any prohibited medication, food or supplement
10. Inability of the investigator to reliably distinguish between spontaneous and provoked spike-wave burst discharges.
11. Subject uses a benzodiazepine as rescue medication within 24 hours of screening. If, in the judgment of the investigator, the subject meets all of the inclusion and none of the other exclusion criteria, rescreening may be done after appropriate wash-out period. If no other rescue medications have been used within the past month, the subject may be eligible for rescreening.
12. Subject has more than one use of rescue medications in the past 30 days.
13. Subject has a history of suicidal thoughts or behaviors in the past 6 months or more than one lifetime suicide attempt.
14. Subject is unable to complete ingestion of 12 placebo SGCs with a minimum of 8 ounces of water at screening.
15. Subject has a clinically significant medical condition that would interfere with the subject's ability to participate in the study (e.g. active cancer, cardiac disease, renal insufficiency, or active infectious processes).

The subject, investigator, staff, and EEG adjudicator will be blinded to the treatment assignment. All sponsor personnel will be unblinded except the sponsor's study monitor who will remain blinded.