A dose-ranging study of the effects of mequitazine on actual driving, memory and psychomotor performance as compared to dexchlorpheniramine, cetirizine and placebo

Usefulness of driver's eye movement measurement to detect potential risks under combined conditions of taking second-generation antihistamines and calling tasks

BACKGROUND

Concerns persist regarding the potential reduction in driving performance due to taking second-generation antihistamines or performing hands-free calling. Previous studies have indicated a potential risk to driving performance under an emergency event when these two factors are combined, whereas a non-emergency event was operated effectively. Currently, there is a lack of a discriminative index capable of detecting the potential risks of driving performance impairment. This study aims to investigate the relationship between driving performance and eye movements under combined conditions of taking second-generation antihistamines and a calling task, and to assess the usefulness of eye movement measurements as a discriminative index for detecting potential risks of driving performance impairment.

METHODS

Participants engaged in a simulated driving task, which included a calling task, both under taking or not taking second-generation antihistamines. Driving performance and eye movements were monitored during both emergency and non-emergency events, assessing their correlation between driving performance and eye movements. The study further evaluated the usefulness of eye movement as a discriminative index for potential driving impairment risk through receiver operating characteristic (ROC) analysis.

RESULTS

In the case of a non-emergency event, no correlation was observed between driving performance and eye movement under the combined conditions. Conversely, a correlation was observed during an emergency event. The ROC analysis, conducted to assess the discriminative index capability of eye movements in detecting the potential risk of driving performance impairment, demonstrated a high discriminative power, with an area under the curve of 0.833.

CONCLUSIONS

The findings of this study show the correlation between driving performance and eye movements under the concurrent influence of second-generation antihistamines and a calling task, suggesting the usefulness of eye movement measurement as a discriminant index for detecting potential risks of driving performance impairment.

Potential risk of driving performance under combined conditions of taking second-generation antihistamines and attending calls using a hands-free function

OBJECTIVE

Although second-generation antihistamines have reduced sedation-related side effects compared to first-generation antihistamines, sedation may still impair motor vehicle driving performance. Moreover, receiving/making phone calls using a hands-free function can negatively affect driving performance. Therefore, herein, driving performance was evaluated using a driving simulator to gain insights into the hazards of driving by combining second-generation antihistamines and a calling task, i.e., simulated calls using a hands-free function.

METHODS

In this study, 20 subjects drove in a driving simulator in the absence or presence of a calling task while taking or not taking second-generation antihistamines. Driving performances for nonemergency and emergency events were determined, and a comparative analysis of intra-individual variability when taking and not taking second-generation antihistamines was conducted.

RESULTS

First, when nonemergency and emergency were examined in the absence of a calling task, no significant difference in driving performance was observed between taking and not taking second-generation antihistamines. Next, when the nonemergency event was examined in the presence of a calling task, no significant difference in driving performance was observed between taking and not taking second-generation antihistamines. However, when the emergency event was examined in the presence of a calling task, a significant difference in driving performance was observed between taking and not taking second-generation antihistamines, thus resulting in reduced driving performance.

CONCLUSIONS

The new system with added calling tasks allowed the extraction of the potential risks of driving performance of second-generation antihistamines that may have been previously overlooked. This study suggests that pharmacists and other healthcare professionals may need to instruct people taking any second-generation antihistamine to focus on driving and not on subtasks that require cognitive load such as talking while driving.

The Usage of Histamine Type 1 Receptor Antagonist and Risk of Dementia in the Elderly: A Nationwide Cohort Study

Background

The histamine type 1 receptor antagonist (H1RA) has been commonly used. This study aimed to examine the association between the usage of H1RA and the risk of dementia.

Methods

A total of 8,986 H1RA users aged ≥50 and 26,958 controls matched a ratio of 1:3 for age, sex, and comorbidity, were selected between January 1, and December 31, 2000, from Taiwan’s National Health Insurance Research Database. Fine and Gray’s survival analysis (competing with mortality) was used to compare the risk of developing dementia during a 15-year follow-up period (2000–2015).

Results

In general, the H1RA usage was not significantly associated with dementia (adjusted subdistribution hazard ratio [SHR] = 1.025, 95% confidence interval [CI] = 0.883–1.297, p = 0.274) for the H1RA cohort. However, a differential risk was found among the groups at risk. The patients with the usage of H1RA aged ≥65 years (adjusted SHR: 1.782, 95% CI = 1.368–2.168, p < 0.001) were associated with a higher risk of dementia, in comparison to the control groups. Furthermore, the patients with the usage of H1RA that were male, or had more comorbidities, were also associated with an increased risk of dementia.

Conclusion

The usage of H1RA was associated with the risk of developing dementia in the patients aged ≥ 65 years.

Trends in the use of antihistamines with reference to drivers between 2015 and 2019: A population-based registry analysis

BACKGROUND

First-generation antihistamines are considered driving-impairing medicines (DIM), while second- and third-generation antihistamines are relatively safe for driving.

OBJECTIVES

The aim of this study was to know the trend of consumption of antihistamines and other DIMs in Spain between 2015 and 2019.

METHODS

This is a population-based registry study. The population distribution by age and gender has been taken into account, as well the treatment duration with these medicines and the concomitant use of other DIMs. Adjusted consumption for licensed drivers is also presented.

RESULTS

Between 2015 and 2019, antihistamines were dispensed to 12.1% of the population and 9.25% of drivers. Oral antihistamines are the most consumed with 85.83%, and generally more used by women than men. Regardless of systemic antihistamines, the second-generation were the most consumed (8.9%) followed by the third-generation (2.07%) and the first-generation (0.61%). Subacute use was predominant in second -generation antihistamines (4.96%) and third-generation (1.26%), while acute use was predominant in third-generation antihistamines. On the other hand, only 0.36% of the population consumed antihistamines daily. The concomitant use of antihistamines with other DIMS was considerable, especially anxiolytics, opioids, other analgesics and antipyretics and antidepressants. The results in drivers were similar than in the general population.

CONCLUSIONS

The use of antihistamines has increased in recent years, however, in Spain, the use of less sedatives predominates, which is safe for driving. Finally, it is important to consider that concomitant use with other DIMs was frequent, which may affect the fitness to drive.

A novel and sensitive UPLC-MS/MS method to determine mequitazine in rat plasma and urine: Validation and its application to pharmacokinetic studies

The aim of this study was to develop an analytical method to determine mequitazine in rat plasma and urine. Mequitazine was separated by UPLC-MS/MS equipped with a Kinetex core-shell C₁₈ column (50 × 2.1 mm, 1.7 μm) using 0.1% (v/v) aqueous formic acid and acetonitrile containing 0.1% (v/v) formic acid as a mobile phase by gradient elution at a flow rate of 0.3 mL/min. Quantitation of this analysis was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique operating in multiple reaction monitoring positive ion mode. Mass transitions were m/z 323.3 → 83.1 for mequitazine and 281.3 → 86.3 for imipramine as internal standard. Liquid-liquid extraction with ethyl acetate and protein precipitation with methanol were used for sample extraction. Chromatograms showed that the method had high resolution, sensitivity and selectivity without interference from plasma constituents. Calibration curves for mequitazine in rat plasma and urine were 0.02-200 ng/mL, showing excellent linearity with correlation coefficients (r² ) >0.99. Both intra- and inter-day precisions (CV%) were within 4.08% for rat plasma and urine. The accuracies were 99.58-102.03%. The developed analytical method satisfied the criteria of international guidance. It could be successfully applied to pharmacokinetic studies of mequitazine after oral and intravenous administration to rats.

Brain histamine modulates recognition memory: possible implications in major cognitive disorders

Several behavioural tests have been developed to study and measure emotionally charged or emotionally neutral memories and how these may be affected by pharmacological, dietary or environmental manipulations. In this review, we describe the experimental paradigms used in preclinical studies to unravel the brain circuits involved in the recognition and memorization of environmentally salient stimuli devoid of strong emotional value. In particular, we focus on the modulatory role of the brain histaminergic system in the elaboration of recognition memory that is based on the judgement of the prior occurrence of an event, and it is believed to be a critical component of human declarative memory. The review also addresses questions that may help improve the treatment of impaired declarative memory described in several affective and neuropsychiatric disorders such as ADHD, Alzheimer's disease and major neurocognitive disorder. LINKED ARTICLES: This article is part of a themed section on New Uses for 21st Century. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.3/issuetoc.

Effects of levocetirizine and diphenhydramine on regional glucose metabolic changes and hemodynamic responses in the human prefrontal cortex during cognitive tasks

OBJECTIVE

Antihistamines often have sedative side effects. This was the first study to measure regional cerebral glucose (energy) consumption and hemodynamic responses in young adults during cognitive tests after antihistamine administration.

METHODS

In this double-blind, placebo-controlled, three-way crossover study, 18 healthy young Japanese men received single doses of levocetirizine 5 mg and diphenhydramine 50 mg at intervals of at least six days. Subjective feeling, task performances, and brain activity were evaluated during three cognitive tests (word fluency, two-back, and Stroop). Regional cerebral glucose consumption changes were measured using positron emission tomography with [¹⁸ F]fluorodeoxyglucose. Regional hemodynamic responses were measured using near-infrared spectroscopy.

RESULTS

Energy consumption in prefrontal regions was significantly increased after antihistamine administration, especially diphenhydramine, whereas prefrontal hemodynamic responses, evaluated with oxygenated hemoglobin levels, were significantly lower with diphenhydramine treatment. Stroop test accuracy was significantly impaired by diphenhydramine, but not by levocetirizine. There was no significant difference in subjective sleepiness.

CONCLUSIONS

Physiological "coupling" between metabolism and perfusion in the healthy human brain may not be maintained under pharmacological influence due to antihistamines. This uncoupling may be caused by a combination of increased energy demands in the prefrontal regions and suppression of vascular permeability in brain capillaries after antihistamine treatment. Further research is needed to validate this hypothesis.

On-the-road driving performance after use of the antihistamines mequitazine and l-mequitazine, alone and with alcohol

OBJECTIVE

Previous studies demonstrated that mequitazine produces mild sedation after single doses. Its enantiomer, l-mequitazine, has a stronger potency for the H1 receptor. The aim of the current study was to assess the effects of l-mequitazine and mequitazine, alone and with alcohol, on driving.

METHODS

Twenty-five healthy volunteers were treated with l-mequitazine 2.5, 5.0 and 10 mg, mequitazine 10 mg and placebo, alone and in combination with alcohol in a double-blind crossover design. Driving performance was assessed using the standardized highway driving test in normal traffic. Its primary measure is the Standard Deviation of the Lateral Position (SDLP). Secondary measures consisted of an auditory word learning test during driving, and subjective measures of driving performance.

RESULTS

L-mequitazine 2.5 and 5.0 mg showed no effect on SDLP in the highway driving test, while SDLP significantly increased after l-mequitazine 10 mg (alone +1.59 cm; with alcohol +1.41 cm) and mequitazine 10 mg (with alcohol +1.17 cm). Alcohol significantly impaired all performance measures (SDLP +2.63 cm) but did not interact with the effects of treatment. Subjective measures indicated that participants were aware of the impairing effects of alcohol, but not of l-mequitazine and mequitazine.

CONCLUSION

L-mequitazine can be considered safe to drive in dosages of 2.5 and 5.0 mg. L-mequitazine 10 mg led to mild driving impairment. Alcohol impaired all performance measures and added to the effects of l-mequitazine and mequitazine.

A simulated car-driving study on the effects of acute administration of levocetirizine, fexofenadine, and diphenhydramine in healthy Japanese volunteers

OBJECTIVE

Antihistamines are often used for treating allergic rhinitis. However, many older antihistamines cause sedative side effects. The sedative effects of antihistamines on car-driving have been investigated. This has not been investigated for levocetirizine, a new-generation antihistamine, in Asian populations, and so we evaluated its sedative effects in healthy Japanese subjects.

METHODS

In this double-blind, placebo-controlled, four-way crossover study, healthy volunteers received single doses of levocetirizine 5 mg, fexofenadine 60 mg, diphenhydramine 50 mg, and placebo at intervals of at least 6 days. Simple brake reaction time and choice brake reaction time task (CBRT), a lateral tracking (LT) task, and a multiple task, a mixture of CBRT and LT task, were used to compare driving performance between the four drugs. Subjective sedation was also assessed.

RESULTS

The simple brake reaction time and CBRT, and the CBRT component of the multiple task, did not show any significant differences between the drugs. In contrast, the LT, both as a single parameter and as a component of the multiple task, showed significant differences between diphenhydramine and the newer-generation antihistamines in a manner that corresponds with subjective sedation.

CONCLUSIONS

Levocetirizine and fexofenadine did not impair psychomotor performance in subjects performing simulated car-driving tasks, while diphenhydramine did impair psychomotor performance in the subjects. Copyright © 2016 John Wiley & Sons, Ltd.

Central nervous system effects of the second-generation antihistamines marketed in Japan--review of inter-drug differences using the proportional impairment ratio (PIR)-

Background

Second-generation antihistamines (AHs) have, in general, fewer sedative effects than the first-generation. However, important inter-drug differences remain in the degree of cognitive and/or psychomotor impairment. The extent to which a particular compound causes disruption can be conveniently compared, to all other AHs, using the Proportional Impairment Ratio (PIR). Although the PIR can differentiate the relative impairment caused by individual drugs, there is no indication of the reliability of the ratios obtained.

Objective

To calculate the PIRs –together with 95% confidence intervals (CIs), as an index of reliability– and compare AHs currently, or soon to be, available in Japan, with respect to their intrinsic capacity to cause impairment.

Methods

Results from studies of cetirizine, desloratadine, ebastine, fexofenadine, levocetirizine, loratadine, mequitazine, and olopatadine were included in the PIR calculations. All data utilised came from crossover studies in healthy volunteers which were randomised and placebo and positive-internal controlled. Existing databases from studies reporting the sedative effects of AHs on objective (speed, accuracy, memory) and subjective (feeling) psychometrics were augmented, via results from suitable studies published after the previous reviews. The null value for a PIR was one.

Results

A total of 45 studies were finally included for this review. Of the AHs assessed, fexofenadine, ebastine, and levocetirizine showed a PIR for objective tests of 0. However, only fexofenadine (PIR = 0.49) had an upper limit of the 95% CI of less than 1. Fexofenadine, levocetirizine, desloratadine, olopatadine, loratadine, and mequitazine all had a PIR for subjective ratings of 0, but the upper limits of the 95% CIs were all in excess of 1, although fexofenadine (PIR = 2.57) was the lowest.

Conclusions

The results show that there are differences between second-generation AHs in the extent of sedation produced. However, subjective ratings indicate that patients may not necessarily be aware of this.

Effects of central nervous system drugs on driving: speed variability versus standard deviation of lateral position as outcome measure of the on-the-road driving test

BACKGROUND

The on-the-road driving test in normal traffic is used to examine the impact of drugs on driving performance. This paper compares the sensitivity of standard deviation of lateral position (SDLP) and SD speed in detecting driving impairment.

METHODS

A literature search was conducted to identify studies applying the on-the-road driving test, examining the effects of anxiolytics, antidepressants, antihistamines, and hypnotics. The proportion of comparisons (treatment versus placebo) where a significant impairment was detected with SDLP and SD speed was compared.

RESULTS

About 40% of 53 relevant papers did not report data on SD speed and/or SDLP. After placebo administration, the correlation between SDLP and SD speed was significant but did not explain much variance (r = 0.253, p = 0.0001). A significant correlation was found between ΔSDLP and ΔSD speed (treatment-placebo), explaining 48% of variance. When using SDLP as outcome measure, 67 significant treatment-placebo comparisons were found. Only 17 (25.4%) were significant when SD speed was used as outcome measure. Alternatively, for five treatment-placebo comparisons, a significant difference was found for SD speed but not for SDLP.

CONCLUSIONS

Standard deviation of lateral position is a more sensitive outcome measure to detect driving impairment than speed variability.

Effects of low-dose mirtazapine on driving performance in healthy volunteers

OBJECTIVE

This study aimed to assess whether a lower initial dose of mirtazapine can lessen the harmful effect on driving performance or not in a double-blinded, placebo-controlled crossover trial.

METHODS

Thirteen healthy men received 8 days of continuous nocturnal doses of mirtazapine at 7.5 mg or 15 mg, or placebo. At baseline and on days 2 and 9, subjects performed three driving tasks (road-tracking, car-following, and harsh-braking tasks) using a driving simulator and a Continuous Performance Test. Stanford Sleepiness Scale (SSS) scores were also assessed. In the mirtazapine 7.5 mg series, 15 mg of mirtazapine was additionally administered on day 9, followed by all the same assessments on day 10.

RESULTS

Mirtazapine 7.5 mg had no significant effects on any tasks except for SSS compared with placebo. Mirtazapine 15 mg impaired road-tracking task and SSS. The increase in mirtazapine dose also had no significant effects on any tasks compared with those before dose increase.

CONCLUSIONS

Mirtazapine 7.5 mg did not cause driving impairment compared with mirtazapine 15 mg, while both doses of mirtazapine produced subjective somnolence. The increase in mirtazapine had no detrimental effects on psychomotor performance. Initial low-dose mirtazapine may be safer for automobile driving than the normal starting dose.

The role of P-glycoprotein in CNS antihistamine effects

RATIONALE

P-glycoprotein (P-gp) is a drug efflux pump expressed, amongst others, on the luminal surface of the cerebral endothelial cells forming the blood-brain barrier. Studies in rodents have demonstrated that antihistamines that are substrates of the P-gp transporter display no or minor central nervous system (CNS) effects as compared to antihistamines that are not P-gp transporter substrates.

OBJECTIVES

The present study explored whether P-gp contributes in similar ways to the occurrence of sedative effects of antihistamines in humans.

METHODS

An fMRI study was conducted according to a double-blind, randomized, placebo-controlled, cross-over design in 13 healthy volunteers. Participants received cetirizine 15 mg (an antihistamine), verapamil 120 mg (a P-gp blocker), a combination of cetirizine + verapamil, and a placebo. Brain activity was assessed while conducting the attention network test (ANT) in a 3T magnetic resonance scanner. The ANT measures three independent attention domains: i.e., alerting, orienting, and executive attention. It was expected that the combined treatment of cetirizine with verapamil would prevent efflux of cetirizine from the CNS, thus increasing attentional impairment, as compared to cetirizine administered alone.

RESULTS

The present study provides evidence that the P-gp transporter is involved in central antihistamine effects in humans. Participants were less alert during the combined treatment of cetirizine and verapamil as indicated by longer reaction times and decreased blood oxygen level-dependent response in the right superior temporal gyrus.

CONCLUSION

It is concluded that the affinity for the P-gp transporter may contribute to the lower incidence of CNS side effects of certain antihistamines.

Effects of repeated dosing with mirtazapine, trazodone, or placebo on driving performance and cognitive function in healthy volunteers

OBJECTIVE

This study aimed to evaluate the effects of repeated treatments with the sedative antidepressants mirtazapine and trazodone on driving performance and cognitive function.

METHODS

Nineteen healthy men received continuous nocturnal doses of 15-mg mirtazapine , 25-mg trazodone, or placebo for 8 days in a double-blinded, three-way crossover trial. Subjects were asked to perform three driving tasks (road tracking, car following, and harsh braking) using a driving simulator and cognitive tasks (the Wisconsin Card Sorting Test, Continuous Performance Test, and N-back Test) at baseline and on Days 2 and 9. Stanford Sleepiness Scale scores were also assessed.

RESULTS

Mirtazapine significantly increased the standard deviation of lateral position in the road-tracking task as compared with trazodone on Day 2. Mirtazapine significantly increased Stanford Sleepiness Scale scores as compared with trazodone and placebo. For the remaining tasks, no significant effects of treatment were observed.

CONCLUSIONS

Acute treatment of mirtazapine impaired road-tracking performance and increased sleepiness, but sedative effects disappeared under repeated administrations. Trazodone did not affect driving performance or cognitive function under acute or repeated administrations. Both initial sedative effects and pharmacological profiles should be taken into consideration when using sedative antidepressants.

The prevalence and nature of stopped on-the-road driving tests and the relationship with objective performance impairment

INTRODUCTION AND OBJECTIVES

The on-the-road driving test in normal traffic is applied to examine the impact of drugs on driving performance. Although participants are accompanied by a licensed driving instructor, under Dutch law, the driver is primarily responsible for safe driving and is not permitted to continue driving when it is judged that the drug compromises safety. This review examined the prevalence and nature of stopped driving tests, and the relationship with Standard Deviation of Lateral Position (SDLP), i.e. the "weaving of the car".

MATERIALS AND METHODS

A literature search was conducted to gather all publications on clinical trials that applied the on-the-road driving test, examining the effects of Central Nervous System (CNS)-drugs such as anxiolytics, antidepressants, antihistamines, analgesics, and hypnotics.

RESULTS

47 papers reported on 50 Dutch clinical trials in which 1059 subjects participated (903 healthy volunteers and 156 patients). A total of 7232 driving tests were performed; 5050 after drug treatment and 2042 after placebo. 3.1% of all driving tests were terminated before completion: 4.1% after drug treatment, and 0.7% after placebo. The decision to stop a driving test was 3-4 times more often made by the driving instructor than the subject. The most common reasons for stopping were the driver feeling tired or sleepy, or the driving instructor noticing signs of drowsiness and performance impairment. Although SDLP values of stopped driving tests are sometimes high, there is no clear relationship between SDLP (changes from placebo) and the decision to stop a driving test. Based on 8 studies that reported exact data, 39.6% of stopped drivers had a lower and 60.4% had a higher SDLP than 35 cm, i.e. the cut-off point of safe driving. This confirms that perception of the driver as well as judgment by the instructor of driving to be 'unsafe' differs between individuals.

CONCLUSION

Driving tests are sometimes stopped after drug treatment or placebo. The decision to stop driving is not a good correlate of objective performance.

Acute and subchronic effects of bilastine (20 and 40 mg) and hydroxyzine (50 mg) on actual driving performance in healthy volunteers

Bilastine is a new second-generation H1 antagonist. Although bilastine has been demonstrated to produce little or no performance impairment in laboratory tests, it cannot be excluded that it produces impairments in real-life performance such as driving. This study aims to assess the effects of two doses of bilastine (20 and 40 mg) on actual driving after single and repeated administration. Hydroxyzine 50 mg was included as an active control. Twenty-two participants (11 females, 11 males) were tested in a placebo-controlled, randomized, double-blind, four-way cross-over design. Participants were treated with once-daily doses for eight consecutive days. On day 1 and 8 of each treatment period participants performed an actual highway driving test. The primary variable was standard deviation of lateral position (SDLP), a measure of weaving. Results demonstrated that hydroxyzine significantly increased SDLP on days 1 and 8 of treatment. Bilastine did not affect SDLP. It is concluded that hydroxyzine produces severe driving impairment after single doses and that this impairment only partly mitigates over time due to a lack of complete tolerance. Bilastine did not produce any driving impairment after single and repeated doses and can be safely used in traffic in doses up to 40 mg.

Short-term effects of morning versus evening dose of hydroxyzine 50 mg on cognition in healthy volunteers

It is well known that the sedative properties of antihistamines can differ considerably between individual drugs. Several factors have been suggested to determine the presence, absence, and/or magnitude of sedation by antihistamines. Research has suggested that the sedative effects caused by central H1 blockade partly depend on the availability of histamine competing for the same receptor and that this competition is affected by a mechanism related to sleep. Consequently, the present study was designed to compare the effects of evening and morning doses of the first-generation antihistamine hydroxyzine on cognition. It was expected that the sedative effect of hydroxyzine would be apparent in the evening after an evening dose but would be smaller in the morning after a morning dose owing to the greater release of histamine shortly after awakening. Eighteen participants (9 females) participated in a placebo-controlled, randomized, double-blind 3-way crossover design. Performance was assessed using several psychomotor tests: that is, divided attention task, critical tracking task, stop signal task, the attention network test, and the experimental attention switch task. Results demonstrated that evening doses of hydroxyzine impaired performance on the divided attention and the attention network test. Impairment after morning doses was generally larger in magnitude and affected performance measures in all tasks. It is concluded that hydroxyzine-induced impairment at tmax is more prominent after morning doses compared with evening doses and that the present study could not present direct evidence to substantiate the hypothesis that histamine availability inversely affects the magnitude of antihistamine impairment.

Sleep disorders, medical conditions, and road accident risk

Sleep disorders and various common acute and chronic medical conditions directly or indirectly affect the quality and quantity of one's sleep or otherwise cause excessive daytime fatigue. This article reviews the potential contribution of several prevalent medical conditions - allergic rhinitis, asthma, chronic obstructive pulmonary disease, rheumatoid arthritis/osteoarthritis - and chronic fatigue syndrome and clinical sleep disorders - insomnia, obstructive sleep apnea, narcolepsy, periodic limb movement of sleep, and restless legs syndrome - to the risk for drowsy-driving road crashes. It also explores the literature on the cost-benefit of preventive interventions, using obstructive sleep apnea as an example. Although numerous investigations have addressed the impact of sleep and medical disorders on quality of life, few have specifically addressed their potential deleterious effect on driving performance and road incidents. Moreover, since past studies have focused on the survivors of driver crashes, they may be biased. Representative population-based prospective multidisciplinary studies are urgently required to clarify the role of the fatigue associated with common ailments and medications on traffic crash risk of both commercial and non-commercial drivers and to comprehensively assess the cost-effectiveness of intervention strategies.

Histamine H1 receptor antagonist cetirizine impairs working memory processing speed, but not episodic memory

BACKGROUND AND PURPOSE

The histaminergic neurotransmitter system is currently under investigation as a target for drug treatment of cognitive deficits in clinical disorders. The therapeutic potential of new drugs may initially be screened using a model of histaminergic dysfunction, for example, as associated with the use of centrally active antihistamines. Of the selective second generation antihistamines, cetirizine has been found to have central nervous system effects. The aim of the present study was to determine whether cetirizine can be used as a tool to model cognitive deficits associated with histaminergic hypofunction.

EXPERIMENTAL APPROACH

The study was conducted according to a three-way, double-blind, cross-over design. Treatments were single oral doses of cetirizine 10 and 20 mg and placebo. Effects on cognition were assessed using tests of word learning, memory scanning, vigilance, divided attention, tracking and visual information processing speed.

KEY RESULTS

Cetirizine 10 mg impaired tracking performance and both doses impaired memory scanning speed. None of the other measures indicated impaired performance.

CONCLUSION AND IMPLICATIONS

Cetirizine affects information processing speed, but these effects were not sufficient to serve as a model for cognitive deficits in clinical disorders.

Cognitive domains affected by histamine H(1)-antagonism in humans: a literature review

The neurotransmitter histamine has been suggested to be involved in cognitive functioning. Generally, studies in animals have shown a decrease in performance after decreasing histamine neurotransmission and improved performance after increasing histamine neurotransmission. It is unclear, however, what role histamine plays in cognition in humans. Up until now, most data are derived from studies and reviews that aimed to assess the sedative potential of H(1)-antagonists and not the effects on cognition in particular. The objective of this paper is specifically to review which cognitive domains are affected by H(1)-antagonists. Taken together, 90 experimental studies on the performance effects of sedative H(1)-antagonists published between 1973 and 2009 were reviewed. Results showed that psychomotor skills and attention are most frequently impaired and memory the least. Tasks assessing memory that were affected usually required rapid responses. It was concluded that both the complexity of the task as well as the demand for information processing speed determines the sensitivity to the effects of central H(1)-antagonism. The importance of the sensitive cognitive domains to histaminergic dysfunction, as well as the relation between histamine related decrease in arousal and task performance deserve further research.

Memory in humans is unaffected by central H1-antagonism, while objectively and subjectively measured sedation is increased

Animal literature suggests an important role for histamine in memory. In humans, this hypothesis has been scarcely tested and results from studies that have addressed this are conflicting. Second, impaired memory performance may be secondary to sedation. This study aimed to determine whether a centrally active antihistamine impairs memory performance and to dissociate such effects from sedation. Eighteen healthy volunteers received single oral doses of dexchlorpheniramine 4 mg, lorazepam 1mg and placebo in a 3-way, double blind, crossover designed study. The active control lorazepam impaired episodic- and working memory performance and increased sedation, while dexchlorpheniramine only increased sedation.

Dose dependency of brain histamine H(1) receptor occupancy following oral administration of cetirizine hydrochloride measured using PET with [11C]doxepin

AIMS

The strength of sedation due to antihistamines can be evaluated using positron emission tomography (PET). The purpose of the present study is to measure histamine H(1) receptor (H(1)R) occupancy following oral administration of cetirizine (10 and 20 mg) in order to examine dose dependency.

METHODS

Fifteen healthy male volunteers (age range, 20-35 years) were divided into 3 subgroups and were studied following single oral administration of cetirizine at 10 mg (n = 5) and 20 mg (n = 5) or hydroxyzine at 30 mg (n = 5) using PET with 11C-doxepin. Each subject was scanned also following the administration of placebo. Binding potential and H(1)RO values were calculated in the prefrontal and anterior cingulate cortices. Subjective sleepiness was also measured, and the correlation to H(1)RO was examined for each antihistamine.

RESULTS

The averaged H(1)ROs of cetirizine 10 mg, 20 mg, and hydroxyzine 30 mg in the prefrontal and cingulate cortices was 12.6%, 25.2%, and 67.6%, respectively. The H(1)RO of hydroxyzine 30 mg correlated well with subjective sleepiness (p < 0.001); however, those of cetirizine 10 and 20 mg showed no correlation with subjective sleepiness.

CONCLUSION

It was demonstrated that the brain penetration of orally administered cetirizine was dose-dependent. Cetirizine 10 mg, with its low H(1)RO and thus minimal sedation, could be more safely used than cetirizine 20 mg for the treatment of various allergic disorders.

Histamine H1 receptor blockade predominantly impairs sensory processes in human sensorimotor performance

BACKGROUND AND PURPOSE

Centrally active antihistamines impair cognitive performance, particularly sensorimotor performance. The aim of the present study was to further elucidate the scarcely studied subprocesses involved in sensorimotor performance, which may be affected by H1 receptor blockade. Better knowledge about the cognitive deficits associated with histamine dysfunction can contribute to better treatment of clinical disorders in which histamine hypofunction may be a contributing factor, such as in schizophrenia.

EXPERIMENTAL APPROACH

Interactions of dexchlorpheniramine with specific task manipulations in a choice reaction time task were studied. Task demands were increased at the level of sensory subprocesses by decreasing stimulus quality, and at the level of motor subprocesses by increasing response complexity. A total of 18 healthy volunteers (9 female) aged between 18 and 45 years participated in a three-way, double-blind, crossover design. Treatments were single oral doses of 4 mg dexchlorpheniramine, 1 mg lorazepam and placebo. Behavioural effects were assessed by measuring reaction times and effects on brain activity by event-related potentials.

KEY RESULTS

Dexchlorpheniramine significantly slowed reaction times, but did not significantly interact with task manipulations. However, it did significantly interact with stimulus quality, as measured by event-related potentials. Lorazepam slowed reaction times and interacted with perceptual manipulations, as shown by effects on reaction times.

CONCLUSIONS AND IMPLICATIONS

The results confirm that the histamine system is involved in sensory information processing and show that H1 blockade does not affect motoric information processing. Histamine hypofunction in clinical disorders may cause impaired sensory processing, which may be a drug target.

Sedation and antihistamines: an update. Review of inter-drug differences using proportional impairment ratios

BACKGROUND

The use of antihistamines (AHs) has been associated with cognitive and psychomotor impairments, largely caused by the sedative properties of many of these drugs. Due to the ambulant nature of the population using AHs, it is important to evaluate these effects using standardised methodology and psychometric tests. A previous extensive review of the literature collated the results of studies of H(1) receptor antagonists to determine the extent to which a particular AH produced impairments on a battery of psychometric tests by calculating a proportional impairment ratio for each AH.

OBJECTIVE

In light of a number of major studies published following the previous review, and the development of the second and new-generation AHs, the present review aims to add to the database and update the review, using the same methodology.

RESULTS AND CONCLUSION

The newer generation AHs appear to be the least impairing, and the first generation, as expected, appear to be the most impairing. There are also differences within the AH drug generations. The review highlights the necessity to consider the sedating potential of AHs, along with other factors such as efficacy, when prescribing AHs to ambulant patients.

The relationship between drug treatment and the clinical characteristics of febrile seizures

BACKGROUND

Drugs such as theophylline, antihistamines, and antiallergics with anti-histaminic actions have been shown to induce febrile seizures. The relationship between febrile seizures and medications has not been actively investigated. The present study aimed to investigate the relationship between the clinical characteristics of febrile seizures and the use of medications.

METHODS

Two hundred and sixty-five children treated at our emergency room due to febrile seizures were studied to investigate the relationship between the clinical characteristics of febrile seizures, such as the type and duration of convulsions, and the drug treatment.

RESULTS

The duration of convulsions was longer among children who took theophylline and antihistamines than among children who did not take these medications. Of the antihistamines, mequitazine did not prolong the duration of convulsion.

CONCLUSIONS

Theophylline should not be used in febrile children, particularly infants. Cautions should be taken in using histamine H1 antagonists in young infants because such drugs could potentially disturb the anticonvulsive central histaminergic system. However, mequitazine appears to be a suitable antihistamine for use in children with febrile seizures, since it does not prolong convulsions.

Histamine H1-receptor blockade in humans affects psychomotor performance but not memory

Results from recent animal studies suggest an important role for histamine in memory functioning. Histaminergic drugs might prove beneficial for people suffering from memory impairment. To determine if histamine is involved in memory functioning this study evaluates the effects of histaminergic dysfunction on memory performance by administrating a H1-antagonist to humans. The study was conducted according to a 4-way, double-blind, crossover design in 20 healthy female volunteers, aged 18-45 years. On each test day subjects completed three test sessions: before and around 2 and 4 h after administration of single oral doses of dexchlorpheniramine 2 mg or 4 mg, scopolamine 1 mg or placebo. Drug effects were assessed using tests of memory, psychomotor and attention performance, and subjective alertness. Results showed that dexchlorpheniramine impaired performance in tests of spatial learning, reaction time, tracking and divided attention but showed no effects on working memory, visual memory, word learning or memory scanning. Scopolamine induced a similar pattern of effects. In addition, both drugs decreased subjective alertness. In conclusion results show that dexchlorpheniramine and scopolamine clearly impaired performance on psychomotor and attention tasks but do not suggest a specific role of the histaminergic system in learning and memory in humans.

Cetirizine in horses: Pharmacokinetics and pharmacodynamics following repeated oral administration

The pharmacokinetics of the histamine H(1)-antagonist cetirizine and its effect on histamine-induced cutaneous wheal formation were studied in six healthy horses following repeated oral administration. After three consecutive administrations of cetirizine (0.2 mg/kg body weight, bw) every 12h, the trough plasma concentration of cetirizine was 16+/-4 ng/mL (mean+/-SD) and the wheal formation was inhibited by 45+/-23%. After four additional administrations of cetirizine (0.4 mg/kg bw) every 12 h, the trough plasma concentration was 48+/-15 ng/mL and the wheal formation was inhibited by 68+/-11%. The terminal half-life was about 5.8 h. A pharmacokinetic/pharmacodynamic link model showed that the maximal inhibition of wheal formation was about 95% and the EC(50) about 18 ng/mL. It is concluded that cetirizine in doses of 0.2-0.4 mg/kg bw administered at 12 h intervals exhibits favourable pharmacokinetic and pharmacodynamic properties without causing visible side effects, and the drug may therefore be a useful antihistamine in equine medicine.

Effects of a sedative antihistamine, D-chlorpheniramine, on regional cerebral perfusion and performance during simulated car driving

OBJECTIVES

The sedative side effects of antihistamines have been recognized to be potentially dangerous in car driving, but the mechanism underlying these effects has not yet been elucidated to date. The aim of the present study is to examine regional cerebral blood flow (rCBF) responses during a simulated car-driving task following oral administration of D-chlorpheniramine using positron emission tomography (PET) and [15O]H2O, based on a single-blind cross-over study-design.

METHODS

Right-handed, healthy male volunteers (n = 14) drove a car in a simulated environment following oral administration of D-chlorpheniramine repetab 6 mg or placebo. Their rCBF was measured using PET with [15O]H2O in the following three conditions: (1) resting, (2) active driving, and (3) passive driving. All 'in-car' views during the simulated driving were videotaped and used for rating driving performance.

RESULTS

Performance evaluation revealed that the number of lane deviations significantly increased in the D-chlorpheniramine condition compared with the placebo condition (p < 0.01). Subjective sleepiness was not significantly different between the two drug conditions. The regions of diminished brain responses following D-chlorpheniramine treatment were detected in the parietal, temporal and visual cortices, and in the cerebellum. The regions of augmented rCBF responses were found in the orbitofrontal cortex and cerebellar vermis.

CONCLUSION

These results suggest that D-chlorpheniramine tends to suppress visuo-spatial cognition and visuo-motor coordinating functions rather than attention and motor functions during car driving.

Effects of sedative and non-sedative H1 antagonists on cognitive tasks: behavioral and near-infrared spectroscopy (NIRS) examinations

RATIONALE

It is well known that the newer H1-receptor antagonists elicit better performance of working memory and selective attention relative to the first generation drugs in this class. However, the neural correlates of the poorer performance associated with first-generation H1-receptor antagonists remain unknown.

OBJECTIVES

This study examined the effects of first- and second-generation H1-receptor antagonists on neural correlates of cognitive tasks using near-infrared spectroscopy (NIRS), a novel method of brain imaging suitable for psychological experiments.

MATERIALS AND METHODS

We measured the NIRS responses of 12 healthy volunteer subjects during the performance of working memory, selective attention, and visual perception tasks, 3 h after taking a first-generation antagonist (ketotifen), second-generation antagonist (epinastine), or placebo. We also measured subjective sleepiness by visual analogue scale (VAS) test.

RESULTS

Cortical activation at the lateral prefrontal region increased during the performance of working memory and selective attention tasks in subjects receiving epinastine and placebo but not in those who took ketotifen. No significant difference was observed at the occipital region in the visual perception task among the three drug groups. VAS score and the behavioral performance during working memory and visual perception tasks indicated sedative effects of ketotifen consistent with the findings of previous studies.

CONCLUSIONS

Our results suggest that the neural response for working memory and selective attention task was impaired by the administration of ketotifen in comparison with that of epinastine and placebo. The sedative effect in the neural response was not observed after epinastine administration.

Lack of effects between rupatadine 10 mg and placebo on actual driving performance of healthy volunteers

INTRODUCTION

Rupatadine fumarate is a potent, selective, histamine H(1)-receptor antagonist and PAF inhibitor with demonstrated efficacy for the relief of allergic rhinitis. Rupatadine does not easily cross the blood-brain barrier and is believed to be non-sedating at therapeutic doses. Consequently, rupatadine should show no impairment on car driving.

OBJECTIVE

This study compared the acute effects of rupatadine, relative to placebo and hydroxyzine (as an active control), on healthy subjects' driving performance.

METHODS

Twenty subjects received a single dose of rupatadine 10 mg, hydroxyzine 50 mg, or placebo in each period of this randomized, double-blind, three-way crossover study. Two hours postdosing, subjects operated a specially instrumented vehicle in tests designed to measure their driving ability. Before and after the driving tests ratings of sedation were recorded.

RESULTS

There was no significant difference between rupatadine and placebo in the primary outcome variable: standard deviation of lateral position (SDLP); however, hydroxyzine treatment significantly increased SDLP (p < 0.001 for both comparisons). Objective (Stanford sleepiness scale) and subjective sedation ratings (Visual Analogue Scales) showed similar results: subjects reported negative effects after hydroxyzine but not after rupatadine.

CONCLUSION

Rupatadine 10 mg is not sedating and does not impair driving performance.

Cetirizine in horses: pharmacokinetics and effect of ivermectin pretreatment

The pharmacokinetics of the histamine H(1)-antagonist cetirizine and the effects of pretreatment with the antiparasitic macrocyclic lactone ivermectin on the pharmacokinetics of cetirizine were studied in horses. After oral administration of cetirizine at 0.2 mg/kg bw, the mean terminal half-life was 3.4 h (range 2.9-3.7 h) and the maximal plasma concentration 132 ng/mL (101-196 ng/mL). The time to reach maximal plasma concentration was 0.7 h (0.5-0.8 h). Ivermectin (0.2 mg/kg bw) given orally 1.5 h before cetirizine did not affect its pharmacokinetics. However, ivermectin pretreatment 12 h before cetirizine increased the area under the plasma concentration-time curve by 60%. The maximal plasma concentration, terminal half-life and mean residence time also increased significantly following the 12 h pretreatment. Ivermectin is an inhibitor of P-glycoprotein, which is a major drug efflux transporter in cellular membranes at various sites. The elevated plasma levels of cetirizine following the pretreatment with ivermectin may mainly be due to decreased renal secretion, related to inhibition of the P-glycoprotein in the proximal tubular cells of the kidney. The pharmacokinetic properties of cetirizine have characteristics which are suitable for an antihistamine, and this substance may be a useful drug in horses.

A combined neurophysiological and behavioural study into the stimulating effects of fexofenadine on performance

Antihistamines are known for their sedative effects. However, some studies suggested mild stimulant effects in the case of fexofenadine. The goals of this study are to examine whether fexofenadine possesses stimulating properties and to determine whether such stimulating effects are related to workload. Sixteen healthy volunteers received a single dose of 180 and 360 mg fexofenadine and placebo on separate test days. Drug effects were assessed using a divided attention task (DAT), continuous performance task (CPT) and motor choice reaction time test (MCRT). Sensitivity of the tasks was increased by manipulating the workload during task performance. Event Related brain Potentials (ERPs) were measured in the DAT and CPT to study the underlying neurophysiological processes. An interaction effect of Treatment and Workload was found on tracking performance in the DAT and on movement time in the MCRT. Performance on the DAT was less affected by increments in workload after fexofenadine as compared to placebo. P1 and P3 latency were affected by Treatment x Workload and Treatment respectively and indicated faster attentional and information processing latencies following fexofenadine treatment. Treatment did not influence performance in the CPT task or in the ERPs measured during this task. The MCRT demonstrated faster movement times following fexofenadine treatment. These results suggest that although the neurophysiological data indicate central nervous system (CNS) activation after fexofenadine treatment, the magnitude of the centrally activating effects is too small to produce relevant performance improvement at the behavioural level.

Repeated-dose effects of mequitazine, cetirizine and dexchlorpheniramine on driving and psychomotor performance

AIMS

Previous studies have demonstrated that the antihistamines mequitazine, cetirizine and dexchlorpheniramine produce mild sedation after single doses. It is unknown, however, whether acute sedation persists after repeated dosing. Therefore, this study assessed the effects of repeated dosing of these antihistamines on driving and psychomotor performance.

METHODS

Sixteen healthy volunteers were treated with mequitazine 10 mg q.a.m., cetirizine 10 mg q.a.m., dexchlorpheniramine Repetab 6 mg b.i.d. and placebo for four separate 8-day periods. Drug effects were assessed on days 1 and 8 using on-the-road driving tests (highway driving and car following), psychomotor tests (tracking and divided attention) and subjective questionnaires.

RESULTS

Dexchlorpheniramine and mequitazine significantly impaired driving performance on the highway driving test on the first day; dexchlorpheniramine increased Standard Deviation of Lateral Position by 2 cm [95% confidence interval (CI) 0.5, 3.8] and mequitazine by 2.5 cm (CI 1.0, 4.3). These effects on driving performance disappeared after 8 days of treatment. No effect of treatment was found on car following, tracking and divided attention. Although subjective ratings confirmed that subjects knew their driving had been impaired in the mequitazine and dexchlorpheniramine condition after completion of the highway driving test on day 1, they did not expect their driving to be affected before the start of the test. Cetirizine did not impair performance on any of the tests.

CONCLUSIONS

Single doses of mequitazine 10 mg and dexchlorpheniramine Repetab 6 mg cause mild driving impairment. However, when taken over several days, the impairing effect wears off, possibly as a result of tolerance.

Effects of fexofenadine and hydroxyzine on brake reaction time during car-driving with cellular phone use

Antihistamines are a mainstay treatment for allergic rhinitis; however, many older agents cause adverse events, including sedation and central nervous system (CNS) impairment. Research has shown sedating effects of antihistamines on driving; currently, no known study has examined whether cellular phone usage while driving further compounds impairment in individuals administered antihistamines. The aim of this study was to examine this endpoint. In a randomized, double-blind, placebo-controlled, three-way crossover study, healthy volunteers received fexofenadine HCl 120 mg, hydroxyzine HCl 30 mg and placebo. Brake reaction time (BRT) was used to examine driving performance across four conditions: driving only; driving while completing simple calculations; complex calculations; and conversing on a cellular phone. Subjective sedation assessments were also conducted. Brake reaction time with and without cellular phone usage in fexofenadine-treated subjects did not differ significantly from placebo in any condition. In contrast, hydroxyzine-treated subjects were significantly more sedated and had slower BRTs, suggesting slower hazard recognition and brake application, compared with the fexofenadine and placebo groups in all conditions. Importantly, cellular phone operation was an additive factor, increasing BRTs in hydroxyzine-treated volunteers. Fexofenadine did not impair CNS function in subjects involved in a divided attention task of driving and cellular phone operation.

Cognitive Effects of Allergic Rhinitis and its Treatment

Allergic rhinitis (AR) can, by itself, introduce significant sedation and impairment of cognition and performance. AR can also impede restorative sleep, resulting in increased fatigue and decreased daytime performance. It is not clear whether improved alertness resulting from blocking histamine production offsets the sedating effects of antihistamines or whether the effects of disease and treatment combine to create even greater sedation. This article reviews and integrates this literature, offers conclusions based on the collective evidence, and suggests guidelines for future research.