The long-term safety and therapeutic response of sodium oxybate ( SXB ) in fibromyalgia syndrome ( FM ) patients were assessed for a combined period of up to @ year in a prospective , multicenter , open-label , extension study in patients completing @ of @ phase @ randomized , double-blind , controlled , @-week trials that examined the efficacy and safety of SXB @ g , SXB @ g , and placebo for treatment of FM .