Studies on sleep and performance with a triazolo-1, 4-thienodiazepine (brotizolam)

Variables influencing patient satisfaction for hypnotics: difference between zolpidem and brotizolam

WHAT IS KNOWN AND OBJECTIVE

The pharmacokinetics of zolpidem and brotizolam is affected by gender and age, that is, increased clearance in males taking zolpidem and younger subjects taking brotizolam. The purpose of this study was to determine the variables including gender and age influencing patient satisfaction for hypnotics, zolpidem and brotizolam.

METHODS

The study included 329 patients who were treated with zolpidem (n = 172) and brotizolam (n = 157) for insomnia. Patients were interviewed to evaluate individual satisfaction and drug efficacy. The factors associated with dissatisfaction of zolpidem and brotizolam were identified using multiple logistic analysis.

RESULTS AND DISCUSSION

Of the participating patients, 40 (23%) and 41 (26%) complained of dissatisfaction with zolpidem and brotizolam, respectively. An insufficient amount of sleep (<6 h) and the number of awakenings were common factors cited for dissatisfaction for both drugs. Males were found to report a higher rate of dissatisfaction for zolpidem, whereas patients younger than 65 years and those receiving corticosteroid therapy reported a higher rate of dissatisfaction with brotizolam.

WHAT IS NEW AND CONCLUSION

These results suggested that patient satisfaction was different between zolpidem and brotizolam in terms of gender for zolpidem and age and corticosteroid co-administration for brotizolam, which could be used to help choose a better drug among the two in patients with insomnia.

Effects of quazepam as a preoperative night hypnotic: comparison with brotizolam

PURPOSE

The purpose of this study was to evaluate the effects of quazepam, a long-acting hypnotic, as a preoperative night medication in comparison with brotizolam, a shortacting hypnotic.

METHODS

Two hundred patients (aged 30 to 70 years) admitted for elective general anesthesia at various hospitals were enrolled. Quazepam 15 mg, 30 mg, or 45 mg, or brotizolam 0.25 mg (40 patients each), was administered orally at 9 p.m. in the evening of the day before surgery. The control group (40 patients) did not receive any drugs. The quality of night sleep between the night during hospitalization and the night before surgery was compared by using a questionnaire. In the first 8 patients who received quazepam 15 mg, 30 mg, and 45 mg, the plasma concentrations of quazepam and its metabolites were measured 12 h after the drug administration, when the patients were brought into the operating room.

RESULTS

In all the drug-administered groups, the speed of falling asleep, sleeping state, and feeling of freshness in the morning improved compared to the previous night and compared to the control group; the frequency of nocturnal awakening and dreaming decreased, and the total duration of sleep the night before surgery increased. Total duration of sleep was significantly longer in the groups with quazepam 30 mg and 45 mg than in the control and brotizolam 0.25 mg groups. No patients were drowsy with plasma concentrations of quazepam of 30 to 65 ngxml(-1).

CONCLUSION

The preoperative night hypnotics, quazepam and brotizolam improved sleep before surgery. As a preoperative night hypnotic, quazepam 30 mg and 45 mg increased the total duration of sleep compared to brotizolam 0.25 mg.

Sleepiness, alertness and performance during a laboratory simulation of an acute shift of the wake-sleep cycle

Monitoring the presence of sleepiness on the job and its effects on performance is of primary importance for improving schedule systems of shiftworkers. Shiftworkers, often involved in night-time operations and irregular work schedules, frequently complain of nocturnal sleepiness especially in conditions of abrupt shift of the wake-sleep cycle. In this study, the authors evaluated the effects of a laboratory simulation of acute night-shift changes on sleepiness, vigilance and performance, using Maintenance of Wakefulness Test, Multiple Sleep Latency Test and three pencil and paper tests: Digit Symbol Substitution Test, 'Deux Barrages' Test and a 3-Letter Cancellation Task. All of the tests were administered four times at 2-hourly intervals during the night after daytime sleep. Results showed that the ability to maintain wakefulness and to perform simple visuo-attentive tasks is substantially spared during the night. On the other hand, sleep tendency and performance on a more complex and monotonous task (Letter Cancellation Task) reveal, respectively, increasing sleepiness and degrading performance.

Blood level, metabolism and excretion of [14C]-brotizolam in mice

Blood level, metabolite pattern and excretion of [14C]-brotizolam, a hypnotic drug, were studied in mice following oral administration. [14C]-Brotizolam was rapidly absorbed which was indicated by a Tmax of the blood level of 0.5 h. Radioactive compounds were eliminated from the blood with a half-life of 5.6 h. Total excretion of radioactivity, the renal portion of which was 22.4%, was complete after 4 days. [14C]-Brotizolam was almost completely metabolized. Using TLC, HPLC and radioactivity measurement, the main metabolite in bile, urine and plasma was found to be brotizolam hydroxylated at the methyl group. Other major metabolites were brotizolam hydroxylated at the diazepine ring and a combination of both hydroxylations. In the bile, all metabolites were conjugated. The metabolism of brotizolam in mice is similar to that in dogs, monkeys and man but not in rats.

Acute and carry-over effects of brotizolam compared to nitrazepam and placebo in monotonous simulated driving

Eighteen healthy volunteers of both sexes, aged 20-35 years, were tested in the morning after three nights of medication with brotizolam 0.25 mg, nitrazepam 5 mg or placebo on a monotonous simulated driving task. The effect measures were subsidiary auditory reaction time and time outside road. Measurements of self-rated alertness were carried out as well. No effects were demonstrated from treatments on either measure. Nitrazepam however tended to score worst on all measures, except time outside road which could not be analysed with respect to statistical significance because of an insufficient number of subjects leaving the road. Twelve of the subjects were also tested immediately after drug intake on the first night of each medication period. Reaction time decrement was observed in both active drugs conditions with no difference between the two. The other measures, however non-significant, pointed in the same direction with the greatest decrement for nitrazepam.

Central effects of beta-adrenoceptor antagonists. II--Electroencephalogram and body sway

1. Effects of the beta-adrenoceptor antagonists, propranolol (40, 80 and 160 mg) and atenolol (50 and 100 mg) on the electroencephalogram and on body sway, were studied in 12 healthy male subjects. The study was double-blind, and included two placebos and an active control, oxazepam (15 mg). Medication was ingested at 11.00 h, and assessments were made before, and at 2 h and 4 h after ingestion. 2. All doses of both beta-adrenoceptor antagonists modified the electroencephalogram, and the changes reported were statistically significant at probability levels of less than 5%. The circadian rise in alpha activity was reduced by both beta-adrenoceptor antagonists as well as by oxazepam. Atenolol also decreased beta activity. 3. Body sway was modified by atenolol and oxazepam (P less than 0.05). The increase with oxazepam was most marked in the low frequency component (0.05-2.25 Hz) of the spectrum, while atenolol modified only the component of higher frequency (2.25-4.0 Hz). 4. These observations suggest that propranolol and atenolol have a sedative effect, and that hydrophilic antagonists are unlikely to be free of central activity. The changes in body sway could imply that peripheral mechanisms may be modified at least with atenolol.

Brotizolam. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy as an hypnotic

Brotizolam is a new thienotriazolodiazepine derivative with a pharmacological profile similar to that of benzodiazepines. It is indicated for use as an hypnotic in the management of insomnia, although it also has anticonvulsant, antianxiety and muscle relaxant properties in animals. In clinical trials brotizolam 0.125 to 0.5mg improved sleep in insomniacs similarly to nitrazepam 2.5 and 5mg, flunitrazepam 2mg and triazolam 0.25mg, whilst brotizolam 0.5mg was shown to be superior to flurazepam 30mg in some studies. Brotizolam is an effective hypnotic for hospital patients awaiting surgery, in whom it also reduces anxiety. Brotizolam has an elimination half-life of about 5 hours, which is 'intermediate' compared with the shorter-acting hypnotic, triazolam, and longer-acting benzodiazepines. Consequently, it is able to induce sleep without producing early morning rebound insomnia, and can also maintain sleep throughout the night. Brotizolam at dosages below 0.5mg at night usually produced minimal morning drowsiness; no residual impairment of psychomotor performance occurs following dosages within the recommended range of 0.125 to 0.25 mg/kg. No serious side effects have been reported to date and the most frequently observed adverse experiences are drowsiness, headache and dizziness. Mild rebound insomnia may occur in some patients when treatment is stopped. Thus, brotizolam is a useful hypnotic which can be used in patients who have difficulty in falling asleep and also in patients who are troubled by night-time awakenings. Used in the recommended dosage it may be particularly useful for patients in whom daytime impairment of performance is unacceptable.

Pharmacokinetics of temazepam compared with other benzodiazepine hypnotics--some clinical consequences

When the various benzodiazepine hypnotics are studied, large differences are seen with regard to their pharmacokinetic properties and metabolism in man. Some are eliminated from the body at a relatively slow rate (e.g. nitrazepam), others are metabolized rather rapidly (temazepam, triazolam). Some benzodiazepine hypnotics have major active metabolites that are slowly eliminated (flurazepam, quazepam), while others have non-active metabolites (temazepam, lormetazepam). In hypnotic treatment, the duration of drug action should be restricted to the duration of the night, hence a compound with a relatively short elimination half-life may represent a more rational choice. An overview is given of the pharmacokinetics of the currently available benzodiazepine hypnotics with emphasis on temazepam and other hydroxylated benzodiazepines.

Kinetic and dynamic interaction of brotizolam and ethanol

Thirteen healthy male volunteers ingested a single 0.25 mg dose of the thienodiazepine hypnotic, brotizolam, on two occasions: once with a typical social cocktail (containing 60 ml of vodka), and in a second trial with an 'ethanol-placebo' cocktail. Brotizolam kinetics were determined from multiple plasma concentrations measured during the 24 h after dosage. Coadministration of brotizolam with ethanol, as opposed to the placebo cocktail, slightly imparied brotizolam clearance (1.85 vs 2.19 ml min-1 kg-1 P less than 0.005), increased peak plasma concentrations (5.3 vs 4.3 ng ml-1, P less than 0.05), and prolonged elimination half-life (5.2 vs 4.4 h, P less than 0.05). There was evidence of impairment of performance, although not statistically significant, for the first 4-6 h after brotizolam dosage in the reaction time test, the digit-symbol substitution test, and a tracking task. None of these was enhanced by ethanol. In both trials, brotizolam produced significant increases in self-rated perceptions of sedation, fatigue, feeling 'spaced-out', and thinking slowed down. These effects were more intense during the brotizolam-ethanol as compared to brotizolam-placebo. In both trials, recovery was essentially complete by 6-8 h after dosage. Coadministration of brotizolam with ethanol produces a small but significant impairment of brotizolam clearance. Brotizolam produced self-rated perceptions of sedation and fatigue during 4-6 h after dosage, but objective impairment of psychomotor performance was minimal. Subjective perceptions of sedation were enhanced by ethanol coadministration, but the effects on psychomotor performance were not.

Comparative pharmacokinetics of midazolam and loprazolam in healthy subjects after oral administration

The pharmacokinetics of oral midazolam (Dormicum, 15 mg) and loprazolam (Dormonoct, 1 mg) were studied in eight healthy young volunteers in a cross-over design. Plasma concentrations of midazolam were measured with a gas chromatographic method and loprazolam concentrations were determined by a radio-receptor technique. Absorption of midazolam proceeded very rapidly (median tmax = 0.4 h) and a rapid onset of sedative action was observed. Loprazolam absorption was relatively slow (median tmax = 3 h) and its absorption profile was often irregular. Most subjects fell asleep before peak concentrations were reached. Median peak concentrations were 94 ng ml-1 and 3.1 ng ml-1 for midazolam and loprozolam, respectively. The median elimination half-life of midazolam was 1.8 h and that of loprazolam 15 h. It is possible that the elimination half-life of loprazolam as determined by radioreceptor assay is determined by active metabolites rather than by loprazolam itself. Midazolam elimination half-life was the same when determined by radioreceptor assay or by GLC. There was no significant correlation between the half-lives of the two drugs.

Elimination of brotizolam in elderly patients after multiple doses

Plasma brotizolam levels were measured in 5 elderly patients given 0.25 mg daily. The half-life of brotizolam elimination was 6.0 h after a single dose and 6.9 h after continuous administration for 3 weeks. The brotizolam concentration in plasma 2 h after the dose was 3.5 and 3.4 ng/ml, respectively, on the first and last days of the study. Brotizolam levels measured several times during the study 10 h after dosing were between 1.2 and 1.8 ng/ml. Thus, administration of brotizolam 0.25 mg/d to elderly patients for 3 weeks led neither to its accumulation nor to faster elimination. The half-life of brotizolam elimination in elderly patients was in the upper range of that found in young volunteers.

Brotizolam radioimmunoassay: development, evaluation, and application to human plasma samples

A radioimmunoassay for the determination of the hypnotic agent brotizolam (11) was developed. With this procedure, an antiserum was used which was obtained from rabbits immunized with the hapten 10 (We 934) covalently bound to bovine serum albumin and tritium-labeled brotizolam as the radioligand. Compound 10 represents a structural analogue of brotizolam: the bromine was replaced by a carboxyethyl group. By such manipulation high assay specificity against the primary human metabolites was achieved. The sensitivity limit of the assay was about 100 pg of brotizolam per mL of plasma when 0.1-mL samples were used. The assay showed good accuracy and high precision. Repeated assays after keeping plasma samples frozen for various periods again indicated high precision as well as the stability of the brotizolam molecule under these conditions. Application of the assay to plasma samples of eight subjects who received single oral 0.25-mg doses of brotizolam showed a mean maximum plasma concentration of 4.6 ng of unchanged drug per mL at 0.9 h after administration. The brotizolam plasma concentration declined with a mean elimination half-life of 5.1 h. The pharmacokinetic parameters estimated by RIA agree well with those obtained with other specific brotizolam determination procedures.

Central effects during the continuous osmotic infusion of a benzodiazepine (triazolam)

The effects of relatively constant plasma levels of a rapidly eliminated benzodiazepine (triazolam) were studied in young healthy males to determine whether tolerance to certain effects may develop over a relatively short period of time. The drug was given over a period of 30 h (2 days and 1 night) at zero-order rate using a rectal osmotic pump. Performance was measured at 2 hourly intervals during the day and was continuously impaired during the infusion, though there was a rapid recovery when the infusion ceased. All tasks were affected, in particular mental arithmetic and letter cancellation, but there was some improvement in performance during the second day. The normal circadian improvement in performance may have contributed to this effect, but some degree of tolerance to the effect of the drug cannot be excluded. Overnight there was a marked reduction in wakefulness, suppression of slow wave sleep, and delay to the onset and reduction in the duration of rapid eye movement sleep. During the night after infusion there was less slow wave sleep and increased wakefulness. The experimental design may prove useful in the study of tolerance to drugs.

Effects of brotizolam, a new thieno-triazolo-diazepine derivative, on the central nervous system

The effects of brotizolam, a new thieno-triazolo-diazepine derivative, on the central nervous system were analyzed in mice, rats and rabbits. Diazepam, estazolam and triazolam were used as control drugs. Brotizolam inhibited spontaneous motor activities; performances in the rotarod test, staircase test, and maximal electroshock seizure test; and pentetrazol- or bemegride-induced convulsion. Moreover, catalepsy inducing action and potentiating effect on sleep elicited by pentobarbital or ethanol were observed. Following intraperitoneal or oral administration of brotizolam to rabbits with chronically implanted electrodes, the electroencephalographic profile in spontaneous EEG was characterized by slow waves with high amplitudes in the neocortex. The arousal responses by stimulation of the midbrain reticular formation and posterior hypothalamus were slightly inhibited, but the recruiting responses induced by stimulation of the diffuse thalamic projecting system were not inhibited, and seizure discharges induced by stimulation of the dorsal hippocampus were inhibited markedly. When motor activities and pentetrazol-induced convulsions were observed as indices of tolerance for brotizolam, tolerance was not developed by repeated administration of brotizolam up to 14 days. These results suggested that brotizolam, a new thieno-triazolo-diazepine derivative, is judged to be a safer and stronger sleep inducer than diazepam and estazolam.

Pharmacokinetics of benzodiazepines: metabolic pathways and plasma level profiles

Large differences exist among the various benzodiazepines with regard to their pharmacokinetic properties and metabolism in man. Some are eliminated from the body at a relatively slow rate, e.g. desmethyldiazepam, and others are metabolized rapidly, e.g. midazolam, triazolam. Several benzodiazepines have major active metabolites that are slowly eliminated, e.g. medazepam, halazepam , quazepam and, consequently, should be considered as potentially long-acting. Such differences may be very important clinically because pharmacokinetic data will help to optimize drug therapy with respect to the choice of the proper drug and drug preparation, as well as with the choice of a proper dose and dosage regimen. The therapeutic objectives of drug therapy differ quite considerably for the various clinical indications of benzodiazepines. In anti-anxiety and anti-epileptic therapy, prolonged or continuous treatment is pursued, so that compounds with relatively long or intermediate elimination half-lives of parent drug or active metabolites are of advantage. In hypnotic treatment, on the other hand, the duration of drug action should be restricted to the duration of the night, hence a compound with a short elimination half-life may be preferred. An overview is given of the pharmacokinetics of the major benzodiazepines currently available and of some interesting new ones that are still in the development stage.

Inhibitory effects of brotizolam, a new thienodiazepine, on limbic forebrain and neostriatal dopaminergic systems in vivo and in vitro

Studies were performed to elucidate the effects of brotizolam, a newly synthesized thienodiazepine, chemically related to the benzodiazepines, on dopamine turnover in the limbic forebrain and neostriatum. Intraperitoneally administered brotizolam retarded the rate of alpha-methyl-p-tyrosine-induced depletion of dopamine in the olfactory tubercle (OT), nucleus accumbens (NA) and caudate nucleus (CN). Significant retardation was observed with brotizolam in doses ranging from 0.1-10 mg/kg in the olfactory tubercle, and from 1-10 mg/kg in the nucleus accumbens and caudate nucleus. These inhibitory effects of brotizolam were antagonized by bicuculline, a GABA antagonist, in all of the regions examined. Using slices of the olfactory tubercle, nucleus accumbens and caudate nucleus, the effects of brotizolam on dopaminergic nerve terminals were examined in vitro. Basal release of dopamine was not affected by brotizolam in concentrations up to 10(-6) M; however, K+-stimulated release of dopamine was significantly reduced by brotizolam at 10(-7) M or above. The reduction of K+-stimulated release of dopamine was antagonized by bicuculline, added in the superfusion medium. These data suggest that brotizolam inhibits the release of dopamine in the limbic forebrain and neostriatal systems probably through mechanisms including a facilitation of GABAergic action on dopaminergic nerve terminals.

Brotizolam and chronic insomnia: a multi-centre study

A double-blind, crossover study was carried out on the acceptability of three doses of brotizolam (0.125, 0.25 and 0.5 mg) in chronic insomniacs aged between 21 and 75 years (33 men: 42 women). Patients reported a shorter time to fall asleep and less nocturnal awakenings. Improvement in sleep was evident during the first week of the study when each patient received 0.25 mg. There were no dose-related side-effects, and on withdrawal from the medication there was no evidence of disturbed sleep which would have suggested a rebound effect.

Effects of acute administration of brotizolam in subjects with disturbed sleep

Effects of ingestion of brotizolam (0.25 and 0.50 mg) over 1-3 days on polysomnographic measures of sleep were assessed in patients complaining of insomnia. Brotizolam reduced latency to sleep, number of awakenings and wake during sleep, and increased total sleep time. It also increased stage 2 sleep and decreased slow wave and rapid eye movement sleep. Increasing the dose from 0.25 to 0.50 mg increased hypnotic efficacy, and there was a more consistent and reliable effect. Discontinuation of brotizolam had minimal effects on sleep compared with placebo over the 3 nights after acute administration. No side-effects or disruption of daytime function was found using questionnaires and objective tests of performance.

Quantitative pharmaco-EEG and performance after administration of brotizolam to healthy volunteers

The activity of brotizolam (0.1, 0.3 and 0.5 mg) was studied in normal subjects using quantitative pharmaco-EEG, psychometric and clinical evaluation. Power spectral density analysis showed no changes after placebo, while brotizolam increased beta-activity, decreased alpha-activity and increased the average frequency (anxiolytic pharmaco-EEG profile). In addition, 0.3 and 0.5 mg brotizolam augmented delta-activity indicating hypnotic activity. The highest dose (0.5 mg) of brotizolam decreased attention, concentration, psychomotor performance and affectivity, and increased reaction time. The lower doses of brotizolam also caused a decrease in attention and concentration, but tended to improve psychomotor performance, shorten reaction time, and did not influence mood or affectivity. Brotizolam (0.1 mg) is the minimal effective psychoactive dose with a tranquillizing effect, while 0.5 mg and to some extent 0.3 mg induce a sedative effect and may be regarded as hypnotic doses.

Effects of brotizolam, flurazepam and placebo upon nocturnal auditory arousal thresholds

Auditory awakening thresholds (AAT) and the back-to-sleep latency (BSL) after nocturnal awakenings from Stage 2 sleep were studied in normal male subjects after placebo, brotizolam (0.25, 0.375 and 0.50 mg) and flurazepam (30 mg). AAT (dB) was measured in five trials spaced across the night in a 'double awakening' procedure with the second awakening in each trial made from Stage 2 sleep. Each drug condition was associated with elevated mean AAT across the five trials in comparison with placebo. In a trial-by-trial analysis only 0.50 mg brotizolam and 30 mg flurazepam were consistently higher in the first three trials compared with placebo. All active drug conditions decreased the mean BSL across all trials in comparison with placebo, but only 30 mg flurazepam and 0.50 mg brotizolam consistently shortened BSL in the first three trials. Brotizolam (0.50 mg) and 30 mg flurazepam are similar in their effects. The subjective improvement reported in insomniac subjects following hypnotic administration may be related to elevation in arousal thresholds and a quick return to sleep after nocturnal sleep disruption.

Comparative studies on the efficacy of brotizolam and nitrazepam: a multi-centre study

Efficacy and tolerability of brotizolam (0.25 and 0.5 mg) were compared over a 6-day period with nitrazepam (5.0 mg) in middle-aged patients (less than 65 years) with sleep disturbances requiring medication. The study was double-blind and randomised with a cross-over design. Each preparation reduced sleep onset latency and frequency of awakenings, and improved quality and duration of sleep as well as subjective condition on awakening. Brotizolam 0.25 mg was found to be equally effective as 0.5 mg, and so the lower dose is recommended for the middle aged.

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.

Residual effects of flurazepam and brotizolam on psychomotor performance

Residual effects of brotizolam (0.25 mg) and flurazepam (30 mg) were studied in healthy young adults. Performance and subjective assessments were observed from 7 to 8 h after overnight ingestion, and effects were compared with that of placebo. Visuo-motor coordination, visuo-mental processing time, visuo-motor reaction time and reading errors were not impaired with brotizolam. There were residual effects with 30 mg flurazepam. Visuo-motor coordination, visuo-mental processing time, visuo-motor reaction time, and reading errors were impaired compared with placebo and 0.25 mg brotizolam. Subjective assessments of performance correlated with measured performance. There was a decrease with flurazepam (visuo-motor coordination and visuo-mental processing time) compared with placebo.

Pharmacokinetics of brotizolam in healthy subjects following intravenous and oral administration

Pharmacokinetics and bioavailability of brotizolam after i.v. and oral administration were studied in healthy young volunteers. Kinetic parameters after i.v. administration were: volume of distribution 0.66 +/- 0.19 1/kg, total plasma clearance 113 +/- 28 ml/min, distribution half-life 11 +/- 6 min, and elimination half-life 4.8 +/- 1.4 h (mean values +/- s.d.). Kinetic parameters after oral administration were: absorption lag-time 8 +/- 12 min, absorption half-life 10 +/- 11 min, and elimination half-life 5.1 +/- 1.2 h (mean values +/- s.d.). Bioavailability of brotizolam was 70 +/- 22% when calculated by comparing oral and intravenous area-under-curve values, corrected for intra-individual half-life differences. An alternative calculation method, which is relatively independent of large clearance variations, provided a bioavailability of 70 +/- 24% (range: 47-117%).

Comparative pharmacokinetics of brotizolam and triazolam in healthy subjects

Pharmacokinetics of oral brotizolam (0.50 mg) and triazolam (0.50 mg) were studied in healthy young volunteers. The plasma concentration profile of brotizolam can be described as a one compartmental open model with first-order absorption. The absorption of triazolam was less regular and in half of the subjects was not consistent with first-order kinetics. Inter-individual variability in absorption rate (peak times) was larger for brotizolam. Mean peak times were 1.1 +/- 1.0 h for brotizolam and 1.2 +/- 0.5 h for triazolam. Mean peak concentrations were 7.3 +/- 3.1 ng/ml and 5.0 +/- 3.9 ng/ml respectively. The elimination half-life of brotizolam was twice that of triazolam with mean values of 5.0 +/- 1.1 h and 2.6 +/- 0.7 h respectively. There was no correlation between the half-lives of the two drugs. Protein unbound fraction was similar for triazolam and brotizolam with mean values of 9.9 +/- 1.5% and 8.4 +/- 0.7% respectively.

Pharmacokinetics of brotizolam in the elderly

Disposition of brotizolam in patients aged 71-93 years was compared with that of healthy young subjects aged 21-26 years. The mean elimination half-life of brotizolam was about twice as long in the elderly as in the young subjects: 9.3 (4.0-19.5) h and 4.8 (3.1-6.3) h respectively. Increase in elimination half-life was attributable to a decrease in hepatic clearance, i.e. 40 (20-58) ml/min in the elderly and 109 (77-156) ml/min in the young. Volume of distribution and protein binding were the same with mean values of 0.56 (0.45-0.72) l/kg and 9.0 (6.8-11.9) % in the elderly and 0.63 (0.40-0.77) l/kg and 8.4 (7.5-9.4) % in the young. Absorption rate of brotizolam was relatively slow in the elderly with a mean peak time of 1.7 h compared with 1.1 h in the young. Mean bioavailability was almost 70% for both groups. Normalized for body weight and dose (0.25 mg) mean peak concentrations were 247 (137-395) ng ml-1 kg in the young and 343 (251-446) ng ml-1 kg in the elderly. It is unlikely that substantial drug accumulation will occur if elderly patients ingest 0.25 mg brotizolam nightly.

Effects of triazolam (0.5 mg) on sleep, performance, memory, and arousal threshold

The effects of a short-acting benzodiazepine hypnotic, triazolam (0.5 mg), on sleep, performance, and arousal threshold were assessed in 20 male poor sleepers (age 21 +/- 2.37 years). Following in a laboratory screening night, all subjects received placebo for 3 nights (single-blind), ten received triazolam and ten placebo for 6 nights (double-blind), and all received placebo on 2 withdrawal nights (single-blind). All effects described below were statistically significant. Triazolam reduced sleep latency and increased total sleep time and sleep efficiency. Percent Stage 2 was increased and percent Stage 4 was reduced during treatment. Morning performance, measured 8.25 h post-drug, showed no decrements. Acute effects were assessed on treatment night 6 during arousals from sleep at 1.5, 3, and 5 h post-administration: performance was impaired in triazolam subjects on the Wilkinson 4-Choice Reaction Time Test, Digit Symbol Substitution Test, Williams Word Memory Test, and Card Sorting Task. In the morning following treatment night 6, long-term memory was tested using a recognition task requiring subjects to identify words presented during night-time test batteries: triazolam subjects correctly identified fewer target words. Triazolam administration produced anterograde amnesic effects. However, in a Paired Associates Test learned prior to drug ingestion on the previous evening, triazolam did not impair morning recall of word pairs. Threshold for arousal from slow wave sleep was elevated during treatment, and triazolam subjects did not show increased sensitivity to the arousing tone over nights as did placebo subjects.

The use of short- and long-acting hypnotics in clinical medicine

1 Activity of short- and long-acting benzodiazepines is reviewed with reference to pharmacokinetics and residual sequelae, and to efficacy and adverse effects. 2 Some benzodiazepines may not lead to obvious effects on performance, such as nordiazepam and clobazam, and the persistence of residual sequelae may not relate obviously to elimination half-lives (as with diazepam and possibly flunitrazepam). However, benzodiazepines with mean half-lives less than 8 h may have residual sequelae, whereas hypnotics with mean half-lives greater than 16 h are likely to lead to impared performance and/or anxiolytic effects the next day. 3 Potassium chlorazepate 15 mg, with its long-acting metabolite nordiazepam, would seem to be the drug of choice for insomnia secondary to anxiety. For the insomniac without significant psychopathology, temazepam 10-20 mg, triazolam 0.125-0.25 mg and for occasional use, diazepam 5-10 mg, provide the initial approach. Flurazepam hydrochloride 15-30 mg, nitrazepam 5-10 mg and flunitrazepam 1 mg and above, have persistent residual effects and should be reserved for refractory patients, and for those in whom some impairment of performance the next day would be acceptable. 4 There is little or no evidence to suggest that the proper use of the short-acting hypnotics, triazolam and temazepam, leads to a worsening of sleep on withdrawal. However, some benzodiazepines may lead to disturbances of sleep and/or rebound insomnia, and nitrazepam and flunitrazepam may be implicated.

Efficacy of some benzodiazepines for day-time sleep

1 Effects of flunitrazepam (0.25-0.50 mg) and the 1,4-triazolodiazepines, triazolam (0.25-0.50 mg) and brotizolam (0.3-0.6 mg), on day time sleep were studied by electroencephalography. 2 Flunitrazepam (0.25-0.50 mg) and triazolam (0.25-0.50 mg) reduced awake activity (P < 0.05) and improved the sleep efficiency index (P < 0.05). The higher dose of each drug increased total sleep time (P < 0.05 and < 0.01 respectively) and duration of stage 2 sleep (P < 0.01), and also delayed the first REM period (P < 0.05 and < 0.01 respectively). 3 Brotizolam (0.6 mg) markedly increased total sleep time (P < 0.001) and the sleep efficiency index (P < 0.01), and prolonged stages 2 (P < 0.01 and slow wave (P < 0.01) sleep. Over the dose range 0.3-0.6 mg, the latency to stage 3 sleep was shortened (P < 0.05), and that to the first REM period lengthened (P < 0.05). 4 All three drugs improved day time sleep. However the present observations and data from previous studies suggest that flunitrazepam (0.25-0.50 mg) may be particularly appropriate for sleep at unusual times.