Adaptation to irregularity of rest and activity

The adaptation to a 9-d schedule of irregular rest and activity was studied. Sleep was recorded; patterns of oral temperature, urinary excretion, and performance at a series of tasks were measured. The relationships between circadian rhythmicity, length of time on task, and cumulative sleep loss were examined.

Flurazepam hydrochloride and its principal metabolites: behavioural studies in the monkey (Macaca mulatta)

Effects of flurazepam and its two principal metabolites, hydroxyethylflurazepam and desalkylflurazepam (0.5, 1.0, 3.0 and 10.0 mg/kg), were studied on a delayed differentiation task in the monkey. Flurazepam (10.0 mg/kg) and hydroxyethylflurazepam (3.0 and 10.0 mg/kg) decreased the number of correct responses and increased response latency; effects persisted to 4 h with the highest dose. Marked impairment of performance was observed with all doses of desalkylflurazepam and effects of 3.0 and 10.0 mg/kg persisted to 24 h. Evidence of a disinhibitory effect of desalkylflurazepam was demonstrated. The study would point to a consideration of both metabolites in the hypnotic effect and in the impairment of performance observed after acute ingestion of flurazepam in man.

Visual motor co-ordination and dynamic visual acuity

Data on the effect of an antihistamine (triprolidine 10 mg) on visuo-motor coordination and dynamic visual acuity were used to establish interactions between these skills. Analysis of covariance and principal component analysis were used. The analyses suggested two main effects--an effect on the activity of the neuromuscular system and one which impaired ability to anticipate target movement. Detection of impaired performance by any task may have wider implications to the effectiveness of the individual than that obviously suggested by the skill itself.

The H2-antagonists, cimetidine and ranitidine: studies on performance

The effects of single oral doses of cimetidine (200 and 400 mg) and ranitidine (150 and 300 mg) were evaluated on visuo-motor coordination, dynamic visual acuity, digit symbol substitution, symbol copying, and critical flicker fusion, and on subjective assessments of mood and well-being in seven healthy female volunteers. The study was double blind and placebo controlled, and triprolidine (10 mg) was used as an active control. With cimetidine and ranitidine there were no adverse changes in performance, central nervous function or subjective assessment of mood. Triprolidine impaired visuo-motor coordination, reduced the number of substitutions on the digit symbol substitution test and the number of symbols copied, lowered the critical flicker fusion threshold and reduced dynamic visual acuity. Cimetidine (200-400 mg) and ranitidine (150-300 mg) are highly unlikely to impair performance, and may be used in individuals involved in skilled activity.

Studies on the possible central effects in man of a neuropeptide (ACTH 4-9 analogue)

The central effects of a neuropeptide, ACTH 4-9 analogue (Organon 2766), were studied in man using digit symbol substitution (DSS), symbol copying, digit span, electroencephalography and auditory evoked potentials, critical flicker fusion (CFF) and pupillary response to light. Performance was measured overnight, and each of 6 subjects ingested 300 mg caffeine, 40 mg ACTH 4-9 analogue and matching placebo. With placebo there was a marked deterioration in performance overnight. The number of substitutions on DSS and the numbers of symbols copied fell, and the threshold for CFF and number of errors on the vigilance task increased. These effects were not seen after ingestion of caffeine (300 mg), though caffeine may have led to some deterioration in the ability to remember digits. The neuropeptide did not attenuate the decrements in performance overnight.

Antihistamines and sedation

With careful use of antihistamines central effects may be minimised or even largely avoided while adequate peripheral antihistaminic activity is preserved. Tolerance to central effects may develop quickly with some drugs, so that sedation is no longer troublesome after a few days. With sustained-release antihistamines, early-evening dosage may provide sufficient activity, without sedation, the next day. For patients in whom daytime sedation is troublesome three drugs, astemizole, mequitazine, and terfenadine, are likely to prove useful. However, the response of the individual patient cannot be predicted, and the possibility of sedation can never be completely excluded.

Imidazobenzodiazepines: sleep and performance studies in humans

For hypnotics in which a fast elimination phase dominates the plasma decay, the initial fall in concentration from the peak value may nevertheless be slower than that of compounds with a sustained and rapid distribution. Drugs with fast elimination may therefore improve sleep throughout the rest period, even though residual sequelae, if any, around awakening will disappear rapidly. In the context of the balance between efficacy and residual effects, the activity of two imidazobenzodiazepines, loprazolam (0.5, 1.0, and 1.5 mg) and midazolam (10, 20, and 30 mg), each with fast elimination (about 6 and 2 hours, respectively) has been studied in healthy men with sleep electroencephalography, measures of performance, and assessments of mood. Loprazolam may be appropriate when a sustained hypnotic effect is required and when some residual activity is acceptable, while midazolam is likely to be suitable for those involved in skilled activity and may be useful in the management of sleep disturbance associated with shift work.

Variability of response to hypnotics: sleep studies in man

Effect of diazepam on sleep in man was investigated in a series of placebo controlled studies and the data on various measures from two groups (young adults and middle age) were retrospectively analysed. Variability of the measures between the two groups with placebo was not different, but the variability of their response to the drug was different, and that of the middle aged group was high. In the young adults there were drug effects, but in the middle aged group no drug effects could be established. The studies suggest that variability of data must be taken into consideration when it is used to indicate the most appropriate dose range. If the variability of response is low the data may indicate the likely effect of the drug on each individual. On the other hand if the variability is high then data obtained from analysis of the group may have limited relevance, and suggest doses which are too high for the majority of the individuals within that group.

Zopiclone: sleep and performance studies in healthy man

Effects of 2.5, 5.0, 7.5, and 10.0 mg zopiclone on sleep and on performance the next day were studied in 6 healthy adult males aged between 21 and 33 years. The experiment was double-blind and placebo controlled. 5.0 and 10.0 mg zopiclone decreased the amount of awake activity and drowsy (stage 1) sleep over the first 6 h of sleep, but this effect was only present for the whole sleep period with the 10.0-mg dose. The duration and percentage of stage 3 sleep were increased with 7.5 mg. The 7.5- and 10.0-mg doses increased the combined duration of stages 2, 3, and 4 sleep over the first 6 h and over the whole night. The first period of rapid eye movement sleep was delayed with 7.5 mg, and with 10.0 mg the time spent in rapid eye movement sleep was reduced during the first 6 h of sleep, but not over the whole night. The number of substitutions in the digit symbol substitution test was decreased 9 h after ingestion of 7.5 and 10.0 mg, and the number of symbols copied reduced after 10.0 mg. The clinical dose range of zopiclone is likely to be up to 7.5 mg. The latter dose provides a useful hypnotic effect with minimal residual effects the next day, whilst 5.0 mg is appropriate for those involved in skilled tasks where even the most minor changes in performance during the early part of the next day must be avoided.

Midazolam: sleep and performance studies in middle age

Effects of 10, 20 and 30 mg midazolam on sleep and on performance the next day were studied in six healthy adult males aged between 47 and 53 years. The study was double-blind, placebo-controlled and included another rapidly eliminated benzodiazepine (brotizolam, 0.25 mg) as an active control. With 10 mg midazolam, sleep-onset latency was quicker, and the duration and percentage of stage 2 sleep was increased over the first 6 h. Effects of 20 and 30 mg midazolam were similar to each other. Sleep onsets were earlier, total sleep times and stage 2 sleep were increased, and the sleep efficiency indices improved. During the first 6 h there was reduced duration and percentage of drowsy (stage 1) sleep. There was no consistent evidence of delay to the first period of rapid eye movement sleep, but over the dose range the duration was reduced during the first 2 h. Digit symbol substitution did not show any residual decrement 9 h after ingestion of 10, 20 or 30 mg midazolam. Midazolam may prove to be a particularly useful hypnotic for shiftworkers whose rest periods tend to be shorter than in those who have a regular nocturnal sleep pattern.

Brotizolam: studies of effects on sleep and on performance in young adulthood and in middle age

Effects of brotizolam (0.2, 0.4 and 0.6 mg), on sleep and performance, were studied in young adults. All doses increased total sleep time, improved the sleep efficiency index, and reduced drowsy sleep and number of awakenings. Brotizolam (0.4 and 0.6 mg) also reduced awake activity. There was some evidence of a delay to the first REM period, but only 0.6 mg reduced the total duration of REM sleep. There were no changes in slow wave sleep. Visuomotor coordination was impaired up to 15.0 h after overnight ingestion of 0.6 mg, but there were no residual effects after the overnight ingestion of 0.2 mg, and with 0.4 mg residual effects did not persist beyond 9.5 h. In middle-aged subjects 0.25 and 0.5 mg were studied. The lower dose (0.25 mg) increased total sleep time, and improved the sleep efficiency index, shortened sleep onset latency, and reduced drowsy sleep. The effect of the higher dose (0.5 mg) was more marked. In a performance study using digit symbol substitution, no residual effect was observed after 0.25 mg brotizolam. Brotizolam is a short-acting hypnotic. Doses up to 0.25 mg are likely to prove adequate over the main span of life and be free of adverse effects on sleep and residual effects on performance.

The H1-antagonist mequitazine: studies on performance and visual function

The effects of single oral doses of mequitazine (5 and 10 mg), terfenadine (60 mg) and triprolidine (10 mg) as active controls, and placebo were evaluated on visuo-motor coordination, digit symbol substitution, critical flicker fusion and dynamic visual acuity, and on subjective assessments of mood and well-being in six normal female volunteers. The study was double-blind. Mequitazine (5 mg) impaired visuo-motor coordination 7.5 h after ingestion (considered to be a chance result), but there was no effect on digit symbol substitution, critical flicker fusion threshold or dynamic visual acuity. Mequitazine (10 mg) impaired visuo-motor coordination and reduced the number of substitutions on the digit symbol substitution test. Terfenadine (60 mg) had no effect on performance or on subjective feelings. Triprolidine (10 mg) impaired visuo-motor coordination, reduced the number of substitutions on the digit symbol test, lowered the critical flicker fusion threshold and reduced dynamic visual acuity. Mequitazine (5 mg) and terfenadine (60 mg) are likely to prove acceptable H1 antagonists when sedation must be avoided.

Antihistamines and visual function: studies on dynamic acuity and the pupillary response to light

1 Effects of three antihistamines, triprolidine (10 mg) in a sustained release form, astemizole (10 mg) and terfenadine (60 mg), have been studied on dynamic visual acuity and on the response of the pupil to light, together with critical flicker fusion, digit symbol substitution and cancellation, and subjective assessment of mood. The study was double-blind and effects were observed from 0.5-4.0 h after ingestion. 2 Triprolidine impaired dynamic acuity and reduced the threshold for subjective fusion of a flickering light, but there were no changes with astemizole or terfenadine. The diameter of the pupil and its response to light were not changed by the drugs. 3 Performance on digit symbol substitution and cancellation was not altered by the drugs. 4 Astemizole and terfenadine are promising antihistamines for those involved in skilled activity.

Hypnotic activity and effects on performance of lormetazepam and camazepam--analogues of temazepam

1 The effects of lormetazepam and camazepam on sleep electroencephalography, visuo-motor coordination, digit symbol substitution and subjective assessments of mood and sleep quality were compared with placebo in six young adult males (18-27 years). The study was double blind. 2 Over the dose range 0.5, 1.0 and 2.0 mg, lormetazepam increased total sleep time (P less than 0.05), reduced wakefulness (P less than 0.05) and drowsy sleep (linear effect P less than 0.05). With 2.0 mg there were increases in stage 3 (P less than 0.05) and reduction in rapid eye movement sleep (P less than 0.01). Overnight ingestion of 2.0 mg, was followed by impaired visuo-motor coordination and fewer substitutions with the digit symbol test. 3 The hypnotic effect of 10-20 mg camazepam was limited to reduced awake activity (P less than 0.05), and with 20 mg there were increased substitutions on the digit symbol test. After 40 mg overnight stage 4 sleep was reduced (P less than 0.001) and performance at the digit symbol test was impaired (P less than 0.05 at 9.75 h). Morning ingestion of 20 mg camazepam did not alter performance, and the subjects assessed themselves to be more relaxed. 4 Lormetazepam is not specially indicated for those involved in skilled activity, but may prove useful for patients with insomnia resistant to other drugs. Camazepam would appear to be a promising anxiolytic with minimal effects on performance.

Performance studies with the H1-histamine receptor antagonists, astemizole and terfenadine

1 Effects of the antihistamines, terfenadine (60 mg) and astemizole (10 and 20 mg), on performance (visuo-motor coordination, arithmetical ability and digit symbol substitution) and on mood were studied in six healthy adult females. The study was double-blind, placebo controlled and included an antihistamine with known central effects (triprolidine 10 mg in sustained release form). 2 There were no changes in performance after terfenadine (60 mg) and astemizole (10 and 20 mg). Triprolidine (10 mg) caused a decrement in visuo-motor coordination (P less than 0.01) 0.5 h after ingestion which lasted until 3.5 h (P less than 0.001). The subject assessed their performance as impaired from 1.5-3.5 h (P less than 0.05) with triprolidine (10 mg), and their mood assessments were also altered. 3 Terfenadine (60 mg) and astemizole (10 and 20 mg) are likely to prove useful antihistamines for those involved in skilled activity.

6-(3-chloro)-phenoxy-2-methyl-1-oxa-4-azospiro-[4,5]decane-3-one (CERM 3726) and sleep of healthy men

Immediate effects on sleep of 100, 200 and 300 mg 6-(3-chloro)-phenoxy-2-methyl-1-oxa-4-azospiro-[4,5]decane-3-one (CERM 3726) were studied in six healthy males. There was some sleep disturbance in two subjects with 100 and 200 mg, but only with 300 mg was there unequivocal evidence of reduced total sleep time and stage 2 sleep, together with a trend toward reduced rapid eye movement sleep. Arousal, at least as indicated by sleep studies, may be associated with the reported effect of the drug to oppose the deterioration in performance of tests of prolonged duration.

Response to transient haemorrhage after acute and chronic section of the carotid sinus nerves

Adaptation to denervation of the carotid sinus region was studied on cats during hypotension induced by a controlled haemorrhage. After denervation, the fall in arterial pressure in response to haemorrhage was increased, but rhe partial recovery of blood pressure was preserved. In chronic animals, this pattern of response was also seen, but a resting hypertension developed and ensured that the minimal blood pressure and the recovery reached during the haemorrhage were similar to those of intact animals. The studies suggest that the primary role of the carotid receptors is to minimize the effect of stresses which lead to hypotension, rather than to set the level of the resting blood pressure.