Results of European post-marketing surveillance of bosentan in pulmonary hypertension.

After the approval of bosentan for the treatment of pulmonary arterial hypertension (PAH), European authorities required the introduction of a post-marketing surveillance system (PMS) to obtain further data on its safety profile. A novel, prospective, internet-based PMS was designed, which solicited reports on elevated aminotransferases, medical reasons for bosentan discontinuation and other serious adverse events requiring hospitalisation. Data captured included demographics, PAH aetiology, baseline functional status and concomitant PAH-specific medications. Safety signals captured included death, hospitalisation, serious adverse events, unexpected adverse events and elevated aminotransferases. Within 30 months, 4,994 patients were included, representing 79% of patients receiving bosentan in Europe. In total, 4,623 patients were naïve to treatment; of these, 352 had elevated aminotransferases, corresponding to a crude incidence of 7.6% and an annual rate of 10.1%. Bosentan was discontinued due to elevated aminotransferases in 150 (3.2%) bosentan-naïve patients. Safety results were consistent across subgroups and aetiologies. The novel post-marketing surveillance captured targeted safety data ("potential safety signals") from the majority of patients and confirmed that the incidence and severity of elevated aminotransferase levels in clinical practice was similar to that reported in clinical trials. These data complement those from randomised controlled clinical trials and provide important additional information on the safety profile of bosentan.

Regional differences in the dynamics of the cortical EEG in the rat after sleep deprivation.

OBJECTIVE: To investigate regional changes of the cortical sleep EEG in the rat, recordings were obtained from a frontal and an occipital derivation, on a baseline day (n = 14 male rats, Sprague-Dawley strain) and after 24 h sleep deprivation (SD, n = 7). METHODS: Spectral analysis of the vigilance states revealed state and frequency specific differences in EEG power by two-way ANOVA and post-hoc t tests. RESULTS: In the theta band (6.25-9.0 Hz) occipital power was larger than frontal power in waking and REM sleep, whereas frontal power was larger in the frequency range between 10.25-16.0 Hz in non-REM sleep and REM sleep. After SD frontal power in the 2-4 Hz band in non-REM sleep was increased more than occipital power and frontal power in the 10.25-16.0 Hz range was more attenuated. In REM sleep frontal power in the theta band and in the 10.25-16.0 Hz range was more increased than occipital power. Power in the waking EEG did not differ between the two derivations after SD. CONCLUSIONS: The differential responses to SD may reflect regional use-dependent aspects of sleep regulation. These observations support the notion that sleep is not only a global phenomenon but has also local, use-dependent features.

Prolonged effects of 24-h total sleep deprivation on sleep and sleep EEG in the rat.

Long-term effects of 24-h sleep deprivation (SD) on sleep and sleep EEG were analyzed in male rats during 4 recovery days (Rec). An increase of total sleep time and non-rapid eye-movement (NREM) sleep was present during Rec 1-4, and of REM sleep in Rec 1 and in the dark periods of Rec 2 and 3. After the initial increase of slow-wave activity (SWA, mean EEG power density in the 0.75-4.0 Hz range) in NREM sleep, SWA declined below baseline until Rec 3. Sleep continuity was increased in Rec 1. The persistent effects of SD which are probably due to homeostatic and circadian facets of sleep regulation, must be taken into account in the design of SD studies.

Effect of melatonin on sleep and brain temperature in the Djungarian hamster and the rat.

The effect of a single dose of melatonin (3-5 mg/kg intraperitoneally) on sleep, electroencephalographic power density, and cortical temperature (TCRT) was investigated. Melatonin was administered to Djungarian hamsters 4 h or 12 h after lights on in a 16-h light:8-h dark cycle (LD 16:8) and to rats at dark onset in a LD 12:12. The effects in both species were short lasting and depended on the time of day. Sleep latency was prolonged in the late light period, sleep fragmentation was enhanced in the early light period, and TCRT was elevated in all three conditions. Rapid eye-movement sleep was reduced in the first postdrug hour after the late light period treatment in the hamsters and in postdrug hours 2 and 3 after dark onset treatment in the rat. Therefore, we have no evidence for a sleep inducing effect of 3-5 mg/kg of melatonin in the hamster or rat. In view of some data that indicate that melatonin may exert a sleep inducing effect in humans, it is suggested that melatonin induces changes that are typical for the dark period of each species, i.e., waking in the nocturnal Djungarian hamster and rat, and sleepiness in the diurnal human.

Sleep homeostasis in the female rat during the estrous cycle.

To investigate whether sleep homeostasis in the female rat is modulated by the estrous cycle, the vigilance states, EEG power spectra and cortical temperature (TCRT) were assessed on the basis of 4-day continuous recordings. A regulatory response was elicited by 6-h sleep deprivation (SD) during the proestrous (PRO) and the estrous (EST) day and compared to the baseline recordings. The vigilance states varied across the estrous cycle. In the PRO dark period the amount of sleep was reduced. The decrease in rapid-eye-movement (REM) sleep was already evident towards the end of the preceding light period, and an increased fragmentation of sleep was present throughout PRO. Compared to the other days of the estrous cycle, slow-wave activity (SWA; EEG power density 0.75-4.75 Hz) in nonREM (NREM) sleep was lower in PRO at the end of the light period and in the beginning of the dark period. High-frequency activity (HFA; EEG power density 10.25-25.0 Hz) was increased in the dark period of PRO. The SD performed during the first 6 h of the light period of PRO and EST enhanced SWA in NREM sleep and reduced sleep fragmentation during the subsequent 6 h. The extent and time course of the response to SD did not differ between the two phases of the estrous cycle. It is concluded that despite the marked baseline variations of the vigilance states and the EEG, homeostatic regulation is little affected by the estrous cycle.

Selective and total sleep deprivation: effect on the sleep EEG in the rat.

Although sleep deprivation is known to exert an antidepressant effect in depressed patients, the involvement of sleep regulation is still unknown. Selective sleep deprivation experiments were performed in the rat to investigate the interactions between non-REM sleep (NREMS) and REM sleep (REMS) in an animal model. A12-h total sleep deprivation (TD) period ending at lights on was followed by one of the following protocols: (1) recovery sleep (TD12); (2) 4-h total sleep deprivation (TD16); (3) 4-h slow-wave deprivation (SWD); (4) 4-h REMS deprivation (RD). In the SWD protocol, the reduction of EEG slow-wave activity (SWA; power density in the 0.75-4.0 Hz band) was obtained by curtailing NREMS episodes to 20 s. During RD the number of interventions required to prevent REMS increased during the first 2 h and then remained constant. While RD caused only a minor reduction of NREMS, it increasingly suppressed SWA in NREMS. The rebound of SWA occurred later and was less prominent after RD than after SWD. Whereas an REMS rebound occurred after all three 4-h sleep deprivation protocols, a persistent increase in the dark period was present only after TD16. It is concluded that (a) SWA in NREMS is inhibited by an increased level of REMS propensity; (b) the hypothesis that REMS propensity increases only during NREMS is not supported; and (c) the results are compatible with the hypothesis that the suppression of NREMS intensity is the common denominator of different antidepressive sleep manipulations in depressive patients.

Effects of N6-cyclopentyladenosine and caffeine on sleep regulation in the rat.

To study the role of adenosine in sleep regulation, the adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) and the antagonist caffeine were administered to rats. Intraperitoneal (i.p.) CPA 1 mg/kg but not 0.1 mg/kg, suppressed rapid-eye-movement (REM) sleep and enhanced electroencephalographic (EEG) slow-wave activity (power density 0.75-4.0 Hz) in non-REM sleep. The latter effect was remarkably similar to the response to 6-h sleep deprivation. The effects persisted when CPA-induced hypothermia was prevented. Caffeine (10 and 15 mg/kg i.p.) elicited a dose-dependent increase in waking followed by a prolonged increase of slow-wave activity in non-REM sleep. The combination of caffeine (15 mg/kg) and sleep deprivation caused less increase in slow-wave activity than sleep deprivation alone, indicating that caffeine may reduce the buildup of sleep pressure during waking. The results are consistent with the involvement of adenosine in the regulation of non-REM sleep.

Behavioural sleep in the giraffe (Giraffa camelopardalis) in a zoological garden.

Behavioural sleep was assessed for 152 nights in 5 adult, 2 immature and 1 juvenile giraffes at a zoological garden, using continuous time-lapse video recording. Sleep occurred while the giraffes were standing (SS) and in recumbency (RS). Paradoxical sleep (PS) was recognized by the peculiar positioning of the head on the croup and by phasic events. The 24-h sleep profile had a main bimodal nocturnal sleep period between 20.00 and 07.00 hours, with a trough between 02.00 and 04.00 hours, and several short naps between 12.00 and 16.00 hours. Total sleep time (TST), excluding the juvenile, was 4.6 h, whereby PS comprised only 4.7%. TST was not age dependent, but the lowest amount of RS and the highest amount of SS occurred in the oldest and the two oldest animals, respectively. Sleep was fragmented, as indicated by the predominance of RS episodes lasting less than 11 min. Sleep cycle duration was very variable with most values between 1 and 35 min (when no waking or RS was allowed within PS episodes), or 6-35 min (when the criteria for ending a PS episode allowed 1-2 min interruptions by RS). There were several indications for sleep regulation: (i) RS and SS complemented each other to yield a relatively stable daily value of TST; (ii) sleep was redistributed on nights following a day when the giraffes spent a few hours in an outside enclosure. The first peak of the bimodal sleep profile was absent and RS was more prominent in the second half of the night compared with nights following days spent in the barn; and (iii) napping was followed by a minor reduction of RS and an increase in SS in the subsequent night compared with nights following days without naps.