A Study of Different Forms of TAK-994 in Healthy Adults

It is hoped that TAK-994 will eventually help people with a sleep condition called narcolepsy. Narcolepsy is a condition that causes extreme sleepiness during the day, including falling asleep suddenly. Before then, the sponsor needs to understand how the body processes TAK-994.

The main aims of the study are to learn how the body processes 4 different new forms of TAK-994, when taken with food and without food, compared to a standard form of TAK-994.

At the first visit, the study doctor will check who can take part. Then the participants will be picked for 1 of 3 groups by chance. These groups of participants will take different new forms of TAK-994 and the standard form. They will take these with and without food. This will happen again 3 or 4 times but will take TAK-994 in a different order each time. After each treatment with TAK-994, the study doctors will check the amount of TAK-994 in the blood of the participants, over time. The study doctors will also check if the participants have any side effects from TAK-994.

Participants will wait 5 or more days between each dose to allow time for TAK-994 to completely leave their bodies. Participants will stay in the clinic during their treatment with TAK-994. They will stay in the clinic for 15 days or longer. Participants who have 4 treatments with TAK-994 will stay in the clinic for 20 days or longer.

Then, the clinic will telephone the participants 12 days after their final treatment of TAK-994 to check if they have any health problems.

The drug being tested in this study is called TAK-994. TAK-994 is being tested in healthy participants. This study will look at the relative BA of different TAK-994 test formulations relative to the currently used formulation (T1) and the effect of food on the test formulations in healthy participants.

The study will enroll approximately 54 participants. The study consists of three parallel groups (Group 1, Group 2, and Group 3). In each group, one test TAK-994 formulation (T2 formulations in Group 1; T3 formulations in Group 2; and T4 and T5 formulations in Group 3) will be evaluated under fed and fasting condition compared to reference T1 formulation under fasting conditions in a cross-over design. Participants will be randomly assigned into 6 sequences within each group.

This multi-center trial will be conducted in United States. The overall time to participate in this study is approximately 57 days. Participants will be followed up for up to 14 days after the last dose of study drug for a follow-up assessment.

Eligibility Criteria:
Inclusion Criteria:

1. 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 the screening.
2. Medically healthy with no clinically significant medical history, physical examination, laboratory profiles, vital signs or electrocardiograms (ECGs), as deemed by the Investigator or designee.

Exclusion Criteria:

1. Mentally or legally incapacitated or has significant emotional problems at the time of the screening visit or expected during the conduct of the study.
2. Current or past history of epilepsy, seizure, or convulsion, tremor, or related symptoms.
3. Positive urine drug or alcohol results at screening or check-in.
4. Positive results at screening for human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg) or hepatitis C virus (HCV).
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. Is lactose intolerant or unable/unwilling to eat the high-fat/high-calorie breakfast.
8. Donation of blood or significant blood loss within 56 days prior to the first dosing.
9. Plasma donation within 7 days prior to the first dosing.
10. Participation in another clinical study within 30 days or 5 half-lives (whichever is longer) prior to the first dosing. The 30-day 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.