Background and purpose: This study was conducted to demonstrate the long-term efficacy of sodium oxybate for the long-term treatment of cataplexy in patients with narcolepsy.
Patients and methods: Fifty-five (55) narcoleptic patients with cataplexy who had received continuous treatment with sodium oxybate for 7-44 months (mean 21 months) were enrolled in a double-blind treatment withdrawal paradigm. A 2-week single-blind sodium oxybate treatment phase established a baseline for the weekly occurrence of cataplexy. This was followed by a 2-week double-blind phase in which patients were randomized to receive unchanged drug therapy or placebo. Patients recorded the incidence of cataplexy attacks and adverse events in daily diaries.
Results: During the 2-week double-blind phase, the abrupt cessation of sodium oxybate therapy in the placebo patients resulted in a significant increase in the number of cataplexy attacks (median=21; P<0.001 ) compared to patients who remained on sodium oxybate (median=0). Cataplexy attacks returned gradually with placebo patients reporting a median of 4.2 and 11.7 cataplexy attacks during the first and second weeks, respectively. There were no symptoms of frank withdrawal.
Conclusions: This controlled trial provides evidence supporting the long-term efficacy of sodium oxybate for the treatment of cataplexy. In contrast with antidepressant drug therapy, there is no evidence of rebound cataplexy upon abrupt discontinuation of treatment.