Conditions: Sleep Initiation and Maintenance Disorders
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 48
Healthy volunteers: no

Brief summary:
The primary purpose of the study is to evaluate the long term efficacy of sodium oxybate (Xyrem®) and zolpidem tartrate (Ambien®) in treating chronic insomnia. We will compare the efficacy of sodium oxybate with zolpidem tartrate (Ambien®), and compare the efficacy of each of these two medications with placebos.

Detailed description:
Primary aim:

1\. To assess the long term efficacy of sodium oxybate and zolpidem tartrate in reducing insomnia and improving sleep quality as assessed by a range of self-reported measures.

Questionnaires and Rating Scales: Subjects completed the following questionnaires and scales: Insomnia Severity Index, Epworth Sleepiness Scale (ESS), Beck Depression Inventory, Pittsburgh Sleep Quality Index (PSQI), Profile of Mood States-Fatigue (POMS). These questionnaires were administered at study baseline, treatment week 4, 8 and 12.

Clinical Global Impression (CGI). The CGI is a clinician-rated scale composed of two subscales that measure disease severity and degree of change, respectively. CGI-Severity (CGI-S) is a single-item, global scale of disease severity that requires the investigator to compare the patient's symptoms with those of all other patients who have the disorder. It is scored from 1 (normal) to 6 (among the most extremely ill of patients). CGI-Change (CGI-C) is a single-item scale of symptomatic improvement or worsening that requires the investigator to compare the patient's status at the time of assessment with baseline severity (baseline CGI-S). One study investigator performed all CGI-S and CGI-C ratings for all subjects.

Randomization. After completing all baseline procedures, eligible subjects were randomized to receive either a combination of active SXB and placebo ZOL (pZOL), active ZOL and placebo SXB (pSXB), or pSXB and pZOL, in a 1:1:1 parallel double-dummy design. A member of the study team who had no contact with subjects and no other role in this study was responsible for preparing study medications according to a randomization schedule. ZOL was encapsulated in lactose powder filled gelatin capsules to be indistinguishable from placebo capsules. Liquid pSXB was designed to match active SXB in appearance, taste and consistency. Subjects were given both liquid and capsule study medications, to maintain the double dummy design. Due to the flexible dose design of this study, subjects and investigators were not blinded to the dosages of study medication/placebo. All subjects were instructed to start study medication at 2.25 grams of SXB/pSXB and 5mg of ZOL/pZOL at bedtime. One study investigator reviewed all potential known side effects of SXB and ZOL prior to dosing, and subjects were instructed to take study medications at the bedside immediately before attempting to sleep, as is the standard administration for SXB.

Arms:
arm 1: Eligible subjects randomized to this arm received placebo as gelatin capsule and a liquid capsule to fully maintain the blind. arm 2: Eligible subjects randomized to this arm received zolpidem as gelatin capsule and a placebo liquid capsule to fully maintain the blind. arm 3: Eligible subjects randomized to this arm received placebo as gelatin capsule and a sodium oxybate capsule to fully maintain the blind.

Interventions: intervention 1: zolpidem tartrate intervention 2: sodium oxybate intervention 3: Matching Placebos
Intervention descriptions: intervention 1: None intervention 2: None intervention 3: None

Protocol document: