4-HYDROXYBUTYRIC ACID ANALOGS

1 . (canceled)

2 . A pharmaceutical composition comprising an effective amount of a compound of Formula IV

wherein:

A is hydrogen, deuterium, —CH 2 —C(O)OR 2 or —CH(R 1 )—C(O)OR 2 ;

R 1 is a C 1-6 alkyl, C 2-10 alkoxyalkyl, or C 3-6 cycloalkyl group that is optionally substituted by an R 3 group;

R 3 is C 1-3 alkyl, C 1-3 alkoxy, phenyl, —O—(CH 2 CH 2 O) n —CH 3 , or -(heterocyclyl)-C 1-3 alkyl where the heterocyclyl moiety is a four to six-membered ring having an oxygen ring atom;

n is 1, 2, or 3;

R 2 is hydrogen, deuterium, —C 1-4 alkyl, —C 1-4 alkyl-phenyl, —C 3-6 cycloalkyl, —C 3-6 cycloalkyl-phenyl, —CH 2 —(C 3-6 cycloalkyl), —CH 2 —(C 3-6 cycloalkyl)-phenyl, phenyl, or biphenyl;

X is hydrogen, deuterium, —C(O)-indanyl, —C(O)-indenyl, —C(O)-tetrahydronaphthyl, —C(O)—C 1-6 alkyl, —C(O)—C 1-6 alkenyl, —C(O)—C 1-6 alkynyl, —C(O)—C 1-3 alkyl-(C 3-6 cycloalkyl), or —C(O)—C 3-6 cycloalkyl optionally substituted by C 1-6 alkyl, phenyl or naphthyl; and

each Y is independently selected from hydrogen and deuterium,

or a pharmaceutically acceptable salt thereof; and a pharmaceutically acceptable carrier.

3 . The composition of claim 2 , wherein the compound is a compound of the formula IV-a:

or a pharmaceutically acceptable salt thereof.

4 . The composition of claim 2 , wherein the compound is a compound of the formula IV-b:

or a pharmaceutically acceptable salt thereof.

5 . The composition of claim 2 , wherein the compound is a compound of the formula IV-c:

or a pharmaceutically acceptable salt thereof.

6 . The composition of claim 2 , wherein the compound is a compound of the formula IV-d:

or a pharmaceutically acceptable salt thereof.

7 . The composition of claim 2 , additionally comprising a second therapeutic agent selected from a dual serotonin-norepinephrine reuptake inhibitor and an alpha2-delta subunit calcium channel modulator.

8 . The composition of claim 7 , wherein the second therapeutic agent is selected from duloxetine, milnacipran, venlafaxine, pregabalin, gabapentin, and prodrugs thereof.

9 . A method of treating a disease or disorder selected from abnormal nocturnal sleep, narcolepsy, fibromyalgia, excessive daytime sleepiness (EDS), cataplexy, hypnagogic hallucinations, sleep paralysis, fragmented sleep, alcohol withdrawal and dependence, Parkinson's disease, narcolepsy with cataplexy, obstructive sleep apnea syndrome, insomnia including insomnia associated to schizophrenia, sleep initiation and maintenance disorders, chronic fatigue syndrome, essential tremor, hemiplegia in patients with alternating hemiplegia of childhood, sedative abuse, binge eating disorder, or other diseases or disorders beneficially treated by improving nocturnal sleep or by administering sodium oxybate, comprising the step of administering to a patient in need thereof an effective amount of a composition of claim 2 .

10 . The method of claim 9 , wherein the disease or disorder is selected from abnormal nocturnal sleep, narcolepsy, fibromyalgia, and other diseases or disorders beneficially treated by improving nocturnal sleep or by administering sodium oxybate.

11 . The method of claim 9 comprising the additional step of administering to the patient in need thereof a second therapeutic agent selected from a dual serotonin-norepinephrine reuptake inhibitor and an alpha2-delta subunit calcium channel modulator.

12 . The method of claim 11 , wherein the second therapeutic agent is selected from duloxetine, milnacipran, venlafaxine, pregabalin, gabapentin, and prodrugs thereof.

13 . A method of selectively inhibiting polysynaptic reflexes without significantly affecting monosynaptic reflexes in a patient in need thereof comprising the step of administering to the patient an effective amount of a composition of claim 2 .

14 . The pharmaceutical composition of claim 2 , wherein the compound is a compound of formula IV′

or a pharmaceutically acceptable salt thereof.

15 - 29 . (canceled)