Study to Assess Drowsiness, Cognition, Fall Risk After Metaxalone 640 mg and Metaxalone 800 mg

A Prospective, Randomized, Single-blind, Pilot Study to Assess Drowsiness, Cognition, and Fall Risk Following Oral Metaxalone 640 mg (M640) Versus Metaxalone 800 mg in Healthy Subjects"

Every participant will receive Metaxalone in two (2) stages, one week after the other. A single dose of each Metaxalone dose will be taken one (1) time after a high fat meal which must be eaten within 30 minutes. Every participant will be given written tests to measure drowsiness, reaction time and thinking process and will also be asked to take walking tests to assess fall risk. Participation in this study will last approximately 2-4 weeks.

The Screening-Baseline Visit will include vital signs and urine testing, and a discussion of medications and current medical history. Participants will be given written tests to measure drowsiness, reaction time and thinking process and will also be asked to take walking tests to assess fall risk.

Visit 2 approximately one to two (1 to 2) week(s) later will be the first dosing day (Arm 1) after eating the high fat meal. The testing from Baseline will be repeated four (4) hours after the medication dose is taken.

Visit 3 approximately one (1) week later will be the second dosing day (Arm 2) after eating the high fat meal. The testing from Baseline will be repeated four (4) hours after the medication dose is taken.

The End of Study safety visit will take place one (1) week after Visit 3 by phone with a discussion of any side effects from the drug, recent medications, and any illness or injury experienced since the previous visit. Participants will be given end of study and discharge instructions.

Inclusion Criteria:

• Weigh at least 120 pounds at Screening
• Medically healthy with no clinically significant medical co-morbidities impact endpoints

Exclusion Criteria:

• Current use of any medications known to affect sleep-wake cycle.
• Known sleep disorder.
• Current use of cimetidine.
• Current use of a monoamine oxidase Inhibitor (MAOI), selective serotonin reuptake inhibitor (SSRI), selective norepinephrine reuptake inhibitor (SNRI), 5- hydroxytryptamine (5-HT) agonist or any drug that has the potential to affect the serotonergic neurotransmitter system (e.g. mirtazapine, trazodone, tramadol).
• Positive urine test for amphetamines, barbiturates, cocaine, opiates, benzodiazepines, or cannabinoids.
• Participants taking skeletal muscle relaxants or sedative hypnotics.
• Participants with gastrointestinal disease affecting absorption.
• Participants with severe hepatic or renal impairment.