A Phase 1, Randomized, Subject- And Investigator-blind, Sponsor Open, Placebo Controlled, Single Ascending Dose Escalation Study To Evaluate The Safety, Tolerability And Pharmacokinetics Of Pf-04958242 Following Oral Dose Capsules in Healthy Subjects

Number of Participants With Categorical Scores on the Columbia Suicide Severity Rating Scale (C-SSRS) Post-Baseline

Time Frame: Baseline up to Day 10

The C-SSRS (mapped to Columbia Classification Algorithm of Suicide Assessment \[C-CASA\]) is an interview-based rating scale to systematically assess suicidal ideation and suicidal behavior. C-SSRS assessed whether participant experienced the following: completed suicide (1), suicide attempt (2) (response of "Yes" on "actual attempt"), preparatory acts toward imminent suicidal behavior (3)("Yes" on "preparatory acts or behavior"), suicidal ideation (4) ("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 suicidal behavior or ideation, self-injurious behavior (7)("Yes" on "Has participant engaged in non-suicidal self-injurious behavior").

Number of Participants With Treatment-Emergent Adverse Events (AEs) and Serious Adverse Events (SAEs)

Time Frame: Baseline up to 28 days after last study drug administration.

An AE was any untoward medical occurrence in a participant who received study drug. 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 are events between first dose of study drug and up to 28 days after last dose that were absent before treatment or that worsened relative to pre-treatment state. AEs included both SAEs and non-SAEs.

Number of Participants With Laboratory Abnormalities Meeting the Criteria for Potential Clinical Concern

Time Frame: Baseline up to Day 10

The following laboratory parameters were analyzed: hematology (hemoglobin, hematocrit, red blood cell \[RBC\] count, mean corpuscular volume \[MCV\], mean corpuscular hemoglobin \[MCH\], mean corpuscular hemoglobin concentration \[MCHC\], platelet count, white blood cell \[WBC\] count, total neutrophils, eosinophils, monocytes, basophils, lymphocytes); blood chemistry (blood urea nitrogen \[BUN\], creatinine, glucose, calcium, sodium, potassium, chloride, total bicarbonate, aspartate aminotransferase \[AST\], alanine aminotransferase \[ALT\], total bilirubin, alkaline phosphatase, uric acid, albumin, and total protein; urinalysis (pH, glucose, protein, blood, ketones, nitrites, leukocyte esterase, urobilinogen, urine bilirubin and microscopy \[if urine dipstick was positive for blood, protein, nitrites or leukocyte esterase\]); others (follicle stimulating hormone \[FSH\], and urine drug screening).

Number of Participants With Potentially Clinically Significant Vital Signs Findings

Time Frame: Baseline up to Day 10

Vital signs assessment included pulse rate and blood pressure. Criteria for vital sign values meeting potential clinical concern included: supine/sitting pulse rate \<40 or \>120 beats per minute (bpm), standing pulse rate \<40 or \>140 bpm; systolic blood pressure (SBP) \>=30 millimeters of mercury (mm Hg) change from baseline in same posture or SBP \<90 mm Hg, diastolic blood pressure (DBP) \>=20 mm Hg change from baseline in same posture or DBP \<50 mm Hg. IFB = increase from baseline; DFB = decrease from baseline.

Number of Participants With Potentially Clinically Significant Electrocardiogram (ECG) Findings

Time Frame: Baseline up to Day 10

ECG parameters included pulse rate (PR) interval, QRS interval, corrected QT interval using Bazett's formula (QTcB)and corrected QT interval using Fridericia's formula (QTcF). Criteria for ECG changes meeting potential clinical concern included: PR interval greater than or equal to (\>=)300 milliseconds (msec) or \>=25% increase when baseline is greater than (\>)200 msec and \>=50% increase when baseline is less than or equal to (=\<)200 msec; QRS interval \>=140 msec or \>=50% increase from baseline (IFB); and QTcF \>=450 msec or \>=30 msec increase. The number of participants with potentially clinically significant ECG findings at any visit were reported.

Number of Participants With Abnormal Physical Examination Findings

Time Frame: Baseline up to Day 10

A full physical examination included head, ears, eyes, nose, mouth, skin, heart and lung examinations, lymph nodes, gastrointestinal, musculoskeletal, and neurological systems. The brief physical examination focused on general appearance, the respiratory and cardiovascular systems, as well as towards participant reported symptoms.

Number of Participants With Abnormal Neurological Examination Findings

Time Frame: Baseline up to Day 10

The extended neurological examination, performed by a board certified neurologist, included observation for cerebellar (intention) tremor and for non-cerebellar tremors (eg, resting or positional), finger nose, heel shin, Romberg, tandem walking, positional and gaze evoked nystagmus, reflexes, muscle strength, cranial nerves, sensory function of upper and lower extremities. The brief neurological examination included an assessment of motor and sensory function, cranial nerves, reflexes, non-cerebellar tremor (eg, resting or positional) and cerebellar function. The assessment of cerebellar function were complemented by the Scale for Assessment and Rating of Ataxia (SARA)