Study to evaluate the pharmacokinetics of oxybate formulations in healthy subjects.

JZP-258 is an investigational compound that is being evaluated for the
treatment of cataplexy in subjects with narcolepsy. Narcolepsy is a sleeping
disorder that involves excessive daytime sleepiness and, in some patients, a
sudden loss of muscle tone usually triggered by strong emotion (cataplexy).
JZP-258 is not an approved drug product, but it has been tested in humans in
other research studies. JZP-258 is a low-salt version of the approved product
Xyrem® (sodium oxybate) marketed worldwide for the treatment of cataplexy and
excessive daytime sleepiness in patients with narcolepsy. JZP-258 and Xyrem
contain the same active ingredient (oxybate) and are oral solutions. This study
will compare the results of the JZP-258 study compound to the results of Xyrem
study compound.

The purpose of the study is to investigate how much JZP-258 is absorbed into
the body, how fast JZP-258 is absorbed and eliminated from the body (this is
called pharmacokinetics) compared to Xyrem. This comparison is called the
relative bioavailability. In addition, it will be investigated if the
pharmacokinetics of JZP-258 are similar to Xyrem. This comparison is called the
bioequivalence. Subjects will receive both JZP-258 and Xyrem in this study so
that the results can be compared within each subject. Also, the effect of food
and different amounts of water taken with the study compound on the
pharmacokinetics of JZP-258 and Xyrem will be investigated. The safety and
tolerability of JZP-258 will also be carefully monitored throughout this study.

Day 1 is the first day of administration of study compound (JZP-258 or Xyrem).
The volunteers are expected at the clinical research center at 14:00 h in the
afternoon prior to the day of first administration of the study compound. They
will be required not to have consumed any food or drinks during the 4 hours
prior to arrival in the clinical research center (with the exception of water).

Each treatment with JZP-258 or Xyrem is separated by a period of 1 day. They
will receive JZP-258 or Xyrem on Days 1, 3, 5, 7, 9 and 11. During the study
they will stay for 13 days (12 nights: from Day -1 to Day 12) in the clinical
research center.

On the final study day (Day 12) they will undergo a post study evaluation,
during which they will get similar examinations as in the pre-study screening.
If the participation in the study is ended earlier than Day 12 for any reason,
they will be asked to undergo the post-study evaluations to check on their
safety and to complete any final tests.

The participation in the entire study, from the pre-study screening until the
post study evaluations, will be maximally 33 days.

Treatment A: 4.5 g JZP-258 taken with 60 mL water under fasting conditions, once
Treatment B: 4.5 g Xyrem taken with 60 mL water under fasting conditions, once
Treatment C: 4.5 g JZP-258 taken with 60 mL water under fed conditions, once
Treatment D: 4.5 g Xyrem taken with 60 mL water under fed conditions, once
Treatment E: 4.5 g Xyrem taken with 240 mL water under fasting conditions, once
Treatment F: 4.5 g JZP-258 taken with 240 mL water under fasting conditions,
once

During the study various examinations are carried out that can be experienced
more or less stressful.
Blood sampling, indwelling canula, heart tracing (ECG).