Abstracts

Rationale: Sleep in patients with epilepsy is often fragmented and abnormal, frequently giving rise to secondary morbidities. Recently, evidence has accumulated suggesting that treatment with certain AEDs can impact endogenous timing mechanisms as well as key components of patient sleep-wake cycles. Pregabalin, a voltage-gated calcium channel modulator indicated for the adjunctive treatment of partial seizures in adults, has been shown to exert a potentially therapeutic modulatory effect on abnormal sleep patterns in epilepsy, particularly in the percentage of REM / Non-REM sleep. Methods: We conducted a review of 13 clinical and preclinical studies available in the PubMed database from 2001 through 2008 in which the effect of pregabalin on sleep architecture in epilepsy patients or models was assessed as either the primary or secondary focus of the study. Whenever appropriate, data from a given assessment parameter (e.g. polysomnography) were combined to best characterize pregabalin effect across different subject groups. Results: Pregabalin, which shows analgesic, antiepileptic, and anxiolytic activity in clinical studies, binds with high affinity to the alpha-2-delta subunit of voltage-gated Ca++ channels in CNS. With binding sites widely distributed in cortex, hippocampus and hypothalamus, it is likely to impact both endogenous rhythmic neural activity and sleep-associated EEG. Pregabalin’s action on voltage-gated Ca++ channels in hypothalamus may, as does nimodipine, potentiate circadian entrainment of circulating melatonin as well as ACTH/cortisol rhythms. Analyses of sleep mechanisms have shown that pregabalin can also enhance EEG low frequency (0.5-4 Hz) activity, increasing non-REM sleep by extending the duration of sequential episodes. The inhibition of REM sleep seen in several studies may thus be associated with pregabalin’s improved synchronization of EEG slow waves, rather than disruption of the REM sleep generating process. Potentiation of entrainment mechanisms and modulation of sleep architecture can enable pregabalin, in certain epilepsy patients, to yield improved sleep consolidation, increased continuity/cycle length, reduction in number of awakenings, and improvements in wake time after sleep onset. Comparative studies with other AEDs have shown that phenytoin and valproate increase Stage 1 sleep and decrease slow-wave sleep, while gabapentin, like pregabalin, appears in contrast to increase beneficial slow-wave sleep. These observations have been substantiated in several recent trials of pregabalin in terms of sleep disturbance and sleep adequacy assessed using the MOS sleep analysis scale. Conclusions: Effects on endogenous rhythms, sleep consolidation, and increased synchronized EEG slow wave activity suggest that pregabalin may induce more restorative sleep in patients with partial epilepsy, and potentially have some application in the treatment of circadian-based disorders.