Phase IV - A Trial of Xyrem in the Treatment of Chronic Fatigue Syndrome.

Medically unexplained fatigue occurs in about 5% of the population with 10% of that number fulfilling formal case definitions for chronic fatigue syndrome1. Medically unexplained fatigue is a major problem for both patient and practitioner - for both because there is no effective FDA-approved treatment for the symptom. One major problem for these patients is unrefreshing sleep. Formal sleep studies show reduced total sleep time and reduced sleep efficiency compared to controls.2;3 We are currently in the early stages of an NIH-funded grant designed to study cytokines during sleep. Preliminary results support awake time for patients relative to controls, producing a decreased sleep efficiency. These data lead to our working hypothesis that the problem of severe daytime fatigue is due to a previously unappreciated form of sleep pathology related to sleep fragmentation.

Patients with medically unexplained pain also complain of disturbed sleep. Sodium oxybate has been tested on patients with this complaint who fulfill a formal case definition for fibromyalgia and has found to reduce symptoms and improve sleep quality.4 Specifically, six of 7 pain/fatigue scores (overall pain, pain at rest, pain during movement, end of day fatigue, overall fatigue, and morning fatigue) were relieved by 29% to 33% with sodium oxybate, compared with 6% to 10% relief with placebo (p < 0.005). Alpha intrusion indicative of disturbed sleep, sleep latency, and rapid-eye-movement sleep were significantly decreased, while slow-wave (stage 3/4) sleep was significantly increased, compared with placebo (p < 0.005). Two of the 5 subjective sleep related variables were significantly different from placebo: morning alertness (improved by 18% with sodium oxybate, compared with 2% for placebo; p = 0.0033) and quality of sleep (improved by 33% and 10%, respectively; p = 0.0003).

Importantly, approximately 40% of patients in my study group fulfill case definitions simultaneously for CFS and FM. Since we do not know if patients in either sodium oxybate treatment trial had CFS, we cannot be sure whether efficacy was specific for FM or instead may have occurred due to the fact that a large representation of CFS had occurred.

An unpublished Phase II randomized double-blind placebo controlled trial in FM, done by Jon Russell and colleagues in Dallas and presented at the 2005 meeting of the American College of Rheumatology, reported substantial symptom improvement with statistically significant benefits in self reported pain scales and patient global impression of improvement at both doses of sodium oxybate tested compared with placebo [4.5g [9ml] total dose per night; p=0.005 and 6g [12 ml], p=0.048]. Improvement in outcome variables was 34.5% at the 4.5g and 27.3% at the 6g compared to 12.5% in the placebo group.

I have prescribed sodium oxybate in my own practice for patients who have both CFS and FM with good results. Anecdotally, patients reporting less pain also reported better quality sleep and less fatigue upon awakening. This has led me to hypothesize that sodium oxybate will reduce fatigue in patients with CFS alone (i.e., without also having FM).