The main aim of this study is to check how rifampin affects the way soticlestat is processed by the body.

Participants will be required to stay at the study clinic for 18 consecutive days. On the first full day and 15th day, participants will take a single dose of soticlestat. Rifampin will be taken each day starting on the 5th day for 13 consecutive days.

Clinic staff will follow up with each participant about 15 days after the last soticlestat dose to check for any side effects.

The drug being tested in this study is called soticlestat (TAK-935). The study will evaluate the safety and tolerability of soticlestat when co-administered with rifampin in healthy participants.

The study will enroll 14 participants. The participants will be assigned to treatment group to receive following therapies:

• Soticlestat 300 milligram (mg) + Rifampin 600 mg

The study will have two periods: Period 1 and Period 2. In Period 1, participants will receive soticlestat in fasted condition while in Period 2 participants will receive soticlestat along with rifampin. The data will be collected and stored in electronic case report form (eCRF).

This single-center trial will be conducted in the United Kingdom. The overall study duration of the study will be approximately 58 days including 28 days screening and follow up duration. There will be a follow up contact required for all participants approximately 15 days after the last dose of soticlestat.

Inclusion criteria:

1. Healthy, adult, male or female of non-childbearing potential, 18-55 years of age, inclusive, at screening.
2. Has body mass index (BMI) greater than or equal to (>=) 18.0 and less than or equal to (<=) 32.0 kilogram per square meter (kg/m^2) at screening.
3. Continuous non-smoker who has not used nicotine-containing products for at least 90 days prior to the first dosing.
4. Able to swallow multiple tablets/capsules.

Exclusion criteria:

1. Has history of any illness that, in the opinion of the Investigator or designee, might confound the results of the study or poses an additional risk to the participant by their participation in the study.

2. Any positive responses on the C-SSRS that in the clinical judgment of the Investigator has a risk of suicide or has made a suicide attempt in the previous 12 months prior to the first dosing.

3. Unable to refrain from or anticipates the use of:

   • Any drug, including prescription and non-prescription medications, herbal remedies, or vitamin supplements within 14 days prior to the first dosing. Thyroid hormone replacement medication may be permitted if the participant has been on the same stable dose for the immediate 3 months prior to first dosing.
   • Any drugs known to be significant inducers of cytochrome (CYP)3A, CYP2C19, UGT1A9 or UGT2B4 enzymes, and/or P-glycoprotein (P-gp), including St. John's Wort, within 28 days prior to the first dosing.

   Appropriate sources (example, Flockhart TableTM) will be consulted to confirm lack of pharmacokinetic (PK)/pharmacodynamics interaction with study drug.

4. History of alcohol consumption exceeding 2 standard drinks per day on average (1 glass is approximately equivalent to the following: beer 354 milliliter [mL]/12 ounce [oz], wine [118 mL/4 oz], or distilled spirits [29.5 mL/1 oz] per day).

5. Consumes excessive amounts, defined as greater than 4 servings (1 serving is approximately equivalent to 120 mg of caffeine), of coffee, tea, cola, energy drinks, or other caffeinated beverages per day.

6. Has been on a diet incompatible with the on-study diet, in the opinion of the Investigator or designee, within the 30 days prior to the first dosing and throughout the study.

7. Donation of blood or significant blood loss within 56 days prior to the first dosing.

8. Plasma donation within 7 days prior to the first dosing.

9. Participation in another clinical study within 30 days or 5 half-lives prior to the first dosing. The 30-days window or 5 half-lives will be derived from the date of the last blood collection or dosing, whichever is later, in the previous study to Day 1 of Period 1 of the current study.

Takeda provides access to the de-identified individual participant data (IPD) for eligible studies to aid qualified researchers in addressing legitimate scientific objectives (Takeda's data sharing commitment is available on https://clinicaltrials.takeda.com/takedas-commitment?commitment=5). These IPDs will be provided in a secure research environment following approval of a data sharing request, and under the terms of a data sharing agreement.

IPD from eligible studies will be shared with qualified researchers according to the criteria and process described on https://vivli.org/ourmember/takeda/ For approved requests, the researchers will be provided access to anonymized data (to respect patient privacy in line with applicable laws and regulations) and with information necessary to address the research objectives under the terms of a data sharing agreement.

The safety set included all participants who received at least one dose of the study drug(s).

TEAEs were adverse events (AE) that started from Day 1 of Period 1 up to 15 days after the last dose of Soticlestat in Period 2 (up to Day 31)

At each visit the investigator had to document any occurrence of adverse events and abnormal laboratory findings. Any event spontaneously reported by the participant or observed by the investigator was recorded, irrespective of the relation to study treatment.