An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. An SAE was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly. Treatment emergent were events between first dose of study drug and up to the follow up visit (up to 36 days in Part A, 49 days in Part B and C), that were absent before treatment or that worsened relative to pretreatment state.

Full physical examination included head, ears, eyes, nose, mouth, skin, heart, lung, lymph nodes, gastrointestinal, musculoskeletal, and neurological systems. Abnormality in physical examinations was based on investigator's discretion.

The neurological examination included the assessment of higher cortical function, the cranial nerves, motor function, deep tendon reflexes, sensory exam, and coordination and gait. Abnormality in neurological examinations was based on investigator's discretion.

C-SSRS is a questionnaire to assess suicidal ideation and suicidal behavior. C-SSRS assessed whether participant experienced following: completed suicide; suicide attempt (response of "Yes" on "actual attempt"); preparatory acts toward imminent suicidal behavior ("Yes" on "preparatory acts or behavior", "aborted attempt" or "interrupted attempt"), suicidal ideation ("Yes" on "wish to be dead", "non-specific active suicidal thoughts", "active suicidal ideation with methods without intent to act or some intent to act, without specific plan or with specific plan and intent, any self-injurious behavior with no suicidal intent). In this outcome measure, number of participants with positive response (response of "yes") to suicidal behavior, ideation or any non-suicidal self-injurious behavior, at baseline were reported.

C-SSRS is a questionnaire to assess suicidal ideation and suicidal behavior. C-SSRS assessed whether participant experienced following: completed suicide; suicide attempt (response of "Yes" on "actual attempt"); preparatory acts toward imminent suicidal behavior ("Yes" on "preparatory acts or behavior", "aborted attempt" or "interrupted attempt"), suicidal ideation ("Yes" on "wish to be dead", "non-specific active suicidal thoughts", "active suicidal ideation with methods without intent to act or some intent to act, without specific plan or with specific plan and intent, any self-injurious behavior with no suicidal intent). In this outcome measure, number of participants with positive response (response of "yes") to suicidal behavior, ideation or any non-suicidal self-injurious behavior, at Day 7 were reported.

C-SSRS is a questionnaire to assess suicidal ideation and suicidal behavior. C-SSRS assessed whether participant experienced following: completed suicide; suicide attempt (response of "Yes" on "actual attempt"); preparatory acts toward imminent suicidal behavior ("Yes" on "preparatory acts or behavior", "aborted attempt" or "interrupted attempt"), suicidal ideation ("Yes" on "wish to be dead", "non-specific active suicidal thoughts", "active suicidal ideation with methods without intent to act or some intent to act, without specific plan or with specific plan and intent, any self-injurious behavior with no suicidal intent). In this outcome measure, number of participants with positive response (response of "yes") to suicidal behavior, ideation or any non-suicidal self-injurious behavior, at Day 14 were reported.

C-SSRS is a questionnaire to assess suicidal ideation and suicidal behavior. C-SSRS assessed whether participant experienced following: completed suicide; suicide attempt (response of "Yes" on "actual attempt"); preparatory acts toward imminent suicidal behavior ("Yes" on "preparatory acts or behavior", "aborted attempt" or "interrupted attempt"), suicidal ideation ("Yes" on "wish to be dead", "non-specific active suicidal thoughts", "active suicidal ideation with methods without intent to act or some intent to act, without specific plan or with specific plan and intent, any self-injurious behavior with no suicidal intent). In this outcome measure, number of participants with positive response (response of "yes") to suicidal behavior, ideation or any non-suicidal self-injurious behavior, at Day 19 were reported.

Criteria for abnormal values of ECG parameters: maximum pulse rate (PR) interval greater than or equal to (\>=)300 milliseconds (msec); maximum PR interval increase from baseline (IFB): \>=25 percent (%) when baseline was greater than (\>)200 msec; or \>=50 % when baseline was greater than (\>)200 msec, maximum QRS interval \>=140 msec and QRS interval IFB: \>=50%. QT interval using Fridericia's correction (QTcF) ranges from 450 msec to maximum less than (\<)480 msec, less than or equal to (\<=) 480 msec to maximum \<500 msec and maximum \>=500 msec, maximum QTcF interval IFB range from \<=30 to \<60 msec and maximum \>=60 msec. Only categories which included at least 1 participant with abnormality are reported in this outcome measure.

In all Periods of Part A, continuous cardiac monitoring was maintained for 8 hours (or longer if considered clinically necessary by the investigator) following dose administration on Day 1. All abnormal cardiac rhythms were recorded and reviewed by the study physician for the presence of rhythms of potential clinical concern.

Criteria for vital signs abnormalities: systolic blood pressure (SBP) \<90 millimeter of mercury (mmHg), diastolic blood pressure (DBP) \<50 mmHg, supine pulse rate \<40 beats per minute (bpm). Maximum IFB in Supine SBP \>=30 mmHg, Maximum decrease from baseline (DFB) in Supine SBP \>=30 mmHg, maximum DFB in Supine DBP \>=20 mmHg.

Abnormalities criteria:hematology(hemoglobin; hematocrit; RBC\<0.8\*lower limit of normal \[LLN\]; platelets\<0.5\*LLN,\>1.75\*upper limit of normal \[ULN\]; WBC\<0.6\*LLN,\>1.5\*ULN; lymphocytes; neutrophils; basophils; eosinophils; monocytes\<0.8\*LLN,\>1.2\*ULN; coagulation(prothrombin ratio\>1.1\*ULN), liver(bilirubin\>1.5\*ULN; aspartate aminotransferase; alanine aminotransferase; alkaline phosphatase; gamma GT\>0.3\*ULN; protein; albumin\<0.8\*LLN,\>1.2\*ULN); renal(blood urea nitrogen, creatinine\>1.3\*ULN; uric acid\>1.2\*ULN); electrolytes(sodium\<0.95\*LLN,\>1.05\*ULN; potassium; chloride; calcium; bicarbonate\<0.9\*LLN,\>1.1\*ULN), chemistry(glucose\<0.6\*LLN,\>1.5\* ULN); urinalysis(pH \<4.5,\>8; glucose, ketones, protein, blood, urobilinogen, nitrite, bilirubin, leukocyte, esterase\>1; WBC; bacteria\>=20, epithelial cells\>=6; granular casts, hyaline casts, red cell casts, white cell casts\>1; lipids(cholesterol\[C\], LDL-C\>1.3\*ULN; HDL-C\<0.8\*LLN, triglycerides\>1.3\*ULN); hormones(T4, T3, T4, TSH\<0.8\*LLN,\>1.2\*ULN).