Abstract Mkid 92

Narcoleptic patients have been treated with stimulants for sleep attacks as well as daytime somnolence, without effects on cataplexy, while this symptoms has been treated with antidepressants, that do not improve daytime somnolence or sleep attacks. Venlafaxine inhibits the reuptake of norepinephrine, serotonin, and to lesser extent dopamine, and also suppressed REM sleep. Because some of the symptoms of narcolepsy may be related to REM sleep deregulation, venlafaxine was studied in this sleep disorder. Six narcoleptic patients were studied, they were drug-free and all of them had daytime somnolence and cataplexy attacks. They underwent the following sleep procedure: one acclimatization night, one baseline night, followed by multiple sleep latency test. After two days of the sleep protocol, patients received 150 mg of venlafaxine XR at 08:00 h. Two venlafaxine sleep nights recordings were performed. Patients were followed for two months with weekly visits for clinical evaluation. Sleep log and analogvisual scale for alertness and somnolence were performed on each visit. Venlafaxine XR was increase by the end of the first month to 300 mg/day. Sleep recordings showed that during venlafaxine XR two days acute administration the following findings: increase in wake time and sleep stage 1, while REM sleep time was reduced. No changes were observed in the rest of sleep architecture variables. Cataplexy attacks were reduced since the first week of venlafaxine administration. Daytime somnolence was reduced also, but until the 7th week and with 300 mg/day of venlafaxine XR administration. Side effects were mild and they were nausea, hiporexia and anxiety. Venlafaxine XR administration improved cataplexy with mild effect on somnolence, that could be explained because at low doses venlafaxine XR acts like selective serotonin reuptake inhibitor and only at high doses the effects on the norepinephrine reuptake is observed. Double blind protocols with venlafaxine are needed in order to determine the utility of venlafaxine XR in narcolepsy.