Comparison of the central and peripheral effects of cetirizine and terfenadine

Layer 4 pyramidal neuron dendritic bursting underlies a post-stimulus visual cortical alpha rhythm

Alpha rhythms (9–11 Hz) are a dominant feature of EEG recordings, particularly over occipital cortex on cessation of a visual stimulation. Little is known about underlying neocortical mechanisms so here we constructed alpha rhythm models that follow cessation of cortical stimulation. The rhythm manifests following a period of gamma frequency activity in local V1 networks in layer 4. It associates with network level bias of excitatory synaptic activity in favour of NMDA- rather than AMPA-mediated signalling and reorganisation of synaptic inhibition in favour of fast GABA_A receptor-mediated events. At the cellular level the alpha rhythm depended upon the generation of layer 4 pyramidal neuron dendritic bursting mediated primarily by PPDA-sensitive NR2C/D-containing NMDA receptors, which lack the magnesium-dependent open channel block. Subthreshold potassium conductances are also critical. The rhythm dynamically filters outputs from sensory relay neurons (stellate neurons in layer 4) such that they become temporally uncoupled from downstream population activity.

The authors combine computational and electrophysiological approaches to study the neocortical mechanisms underlying alpha rhythms generated after visual stimuli cessation. They show that layer 4 pyramidal neuron bursting, as well as a shift towards NMDA- and GABA_A- receptor transmission is critical for the generation of these alpha oscillations.

Rupatadine does not potentiate the CNS depressant effects of lorazepam: randomized, double-blind, crossover, repeated dose, placebo-controlled study

AIM

The main objective was to assess whether benzodiazepine intake when rupatadine plasma concentrations were at steady-state would increase the CNS depressant effects. Rupatadine is a new H(1)-antihistamine which also inhibits platelet activating factor (PAF) release and has been shown to be clinically effective at doses of 10 mg.

METHODS

Sixteen healthy young volunteers took part in a crossover, randomized, double-blind, placebo controlled trial comprising two experimental periods (repeated administration for 7 days of rupatadine 10 mg or placebo as single oral daily doses, separated by a washout of 14 days). On days 5 and 7, according to a fully balanced design, a single oral dose of lorazepam 2 mg or placebo was added. CNS effects were evaluated on these days by seven objective tests of psychomotor performance and eight subjective visual analogue scales (VAS) at pre-dose and several times after drug intake. Four treatment conditions were evaluated: placebo, rupatadine 10 mg, lorazepam 2 mg and rupatadine 10 mg + lorazepam 2 mg.

RESULTS

Significant CNS effects, either impairment of psychomotor performance or subjective sedation, were observed when lorazepam was administered, either alone or in combination with steady state concentrations of rupatadine. No significant differences were found between these two conditions. In addition, rupatadine was not different from placebo. All treatments were well tolerated.

CONCLUSION

Repeated doses of rupatadine (10 mg orally) did not enhance the CNS depressant effects of lorazepam (2 mg orally, single dose) either in objective psychomotor tasks or in subjective evaluations.

Inhibition of the histamine-induced weal and flare response: a valid surrogate measure for antihistamine clinical efficacy?

Histamine plays a central role in allergic responses. Inhibition of the weal and flare response to histamine is a traditional pharmacodynamic tool to measure the activity of H(1)-receptor antagonists. The time course and duration of cutaneous weal and flare inhibition are often used as surrogate measures of clinical efficacy. Pharmacodynamic differences among antihistamines are often interpreted to indicate differences in clinical efficacy. A systematic review of literature from 1980 to 2006 regarding the histamine induced weal and flare was undertaken. Search terms included 'histamine', 'skin test', 'weal', 'flare', and 'antihistamine'; retrieved articles were searched for relevant studies not identified initially. Data from human studies on the inhibition of the weal and flare by second-generation antihistamines were extracted and assessed. A literature search from 1980 to 2006 was undertaken for comparative studies of second-generation antihistamines in the clinical settings of allergic rhinitis (AR) and chronic idiopathic urticaria; data extracted from these studies underwent systematic review. Differences were noted among second-generation antihistamines in terms of their ability to inhibit the histamine-induced weal and flare. Corresponding differences in terms of clinical efficacy in AR and chronic urticaria were not identified following a systematic review. The reasons for the disconnect between pharmacodynamic effects and clinical efficacy may include differences between the route and concentration of histamine, the involvement of mediators other than histamine in the allergic response, and the short time course of pharmacodynamic studies. The histamine-induced weal and flare response is a pharmacodynamic test that should not be used to compare the clinical efficacy of different antihistamines, and is not an adequate alternative to clinical end-point assessments in AR or chronic idiopathic urticaria.

Effects of acrivastine, loratadine and cetirizine on histamine-induced wheal and flare responses

It is accepted that studies evaluating histamine-induced wheal and flare reactions in the skin represent a simple and reliable method for demonstrating pharmacodynamic activity and pharmacokinetics of the H1-receptor antagonists. In this study, the effects of single oral doses of acrivastine (8 mg), loratadine (10 mg) and cetirizine (10 mg) on the histamine-induced wheal and flare reactions were compared in 60 healthy volunteers. The wheal and flare responses were produced by prick test using 1% histamine solution. Measurements were performed before the ingestion of antihistamines (baseline values) and afterwards at 15, 30, 90, 240, 360 min and 24 h. The values obtained for each antihistamine were compared with each other and with baseline values. Cetirizine was found to be superior to acrivastine and loratadine for the suppression of wheal and flare responses at 240, 360 min and 24 h (P < 0.05) and acrivastine was superior to the other two antihistamines for the suppression of flare response at 30 min (P < 0.05). Our results indicate that a single dose of cetirizine provides a more effective and long acting suppression on wheal and flare reactions in urticaria when compared to acrivastine and loratadine.

Lack of behavioural toxicity of mizolastine: a review of the clinical pharmacology studies

First-generation H1 antihistamines were associated with major sedative side-effects which were heavily disruptive to young active and aged patients when performing everyday activities. Mizolastine is a potent and selective H1-receptor antagonist which slowly penetrates into the brain and thus lacks the sedative effects of earlier antihistamines. In this paper we present an overview of five clinical pharmacology studies which were carried out with a view to assessing mizolastine effects on psychomotor and skilled performances, and on cognitive functions in young and aged subjects. The studies were all randomized, double-blind, placebo and (with the exception of one) active-drug controlled, cross-over studies. A total of 76 young and 15 aged subjects were enrolled. Two studies evaluated mizolastine over a range of doses (5-45 mg), and three involved a single or multiple administrations of the therapeutic dose (10 mg/day). Comparators were first generation (clemastine, tripolidine) and second generation (terfenadine, cetirizine) antihistamines. Drug effects were evaluated through standardized psychometric and memory tests, and subjective self-ratings (visual analogue scales). In two studies, driving performance was assessed using an actual driving test. Two studies investigated drug interaction with depressants of the central nervous system such as alcohol and lorazepam. The results of the five reported studies were consistent in that mizolastine showed to be free from sedative effects when administered at the therapeutic dose. As with other newly developed antihistamines, some changes occurred at higher dose levels. At the therapeutic dose mizolastine did not alter driving performance and did not potentiate the depressant effects of alcohol and lorazepam. Mizolastine was shown to be free from sedative effects that could affect the safe performance of everyday life activities in young and aged patients when administered at the therapeutic dose.

Comparative study of cetirizine and terfenadine versus placebo in the symptomatic management of seasonal allergic rhinitis

BACKGROUND

Cetirizine is a new antihistamine with greater selectivity for the histamine H1 receptor and a low rate of hepatic metabolism. Cetirizine once daily is effective in the symptomatic treatment of seasonal and perennial allergic rhinitis and chronic idiopathic urticaria.

OBJECTIVE

The efficacy and safety of cetirizine 10 mg qd, terfenadine 60 mg bid, and placebo were compared in patients with seasonal allergic rhinitis.

METHODS

A multicenter, prospective, double-blind, randomized, parallel study was conducted for 2 weeks during the ragweed pollen season in patients with documented allergic rhinitis. Total symptom complex and total symptom complex plus nasal congestion scores, global efficacy, overall satisfaction, and adverse events were assessed at baseline and after 1 and 2 weeks of treatment.

RESULTS

Of the 311 patients randomized to treatment, 283 completed the study. Cetirizine produced a marked improvement in symptoms scores compared with placebo after 1 week of therapy (P = .001). By the end of week 1, total symptom complex scores were improved by 37% with cetirizine compared with 29% for terfenadine, and 23% for placebo. An overall treatment effect was evident at week 1 (P = .0019), with marked differences between cetirizine and both placebo (P = .0004) and terfenadine (P = .0464) but not between terfenadine and placebo (P = .1215). A more marked treatment effect was evident during the first week of the study; this appeared to be related to spontaneous resolution of symptoms, since mean pollen counts derived for each patient declined significantly each week of the study. Therapy was generally well tolerated. Headache was the most common side effect in each group. Four patients on cetirizine, one on terfenadine, and two on placebo withdrew because of side effects. Somnolence was reported in 12 patients on cetirizine (P < .05), 2 on terfenadine, and 3 on placebo.

CONCLUSION

Cetirizine produced a greater improvement in symptoms of seasonal allergic rhinitis than terfenadine or placebo.

Cutaneous antihistaminic action of cetirizine and dose-related EEG concomitants of sedation in man

The cutaneous antihistaminic action (prick test; 1:100, 1:200 and 1:1000) and neuropsychological and electroencephalographic (EEG) concomitants of sedation following the histamine H1 receptor antagonist cetirizine (10- and 20-mg acute oral doses) and chlorpheniramine, 4 mg, were investigated in a cross-over, placebo-controlled study in healthy male volunteers (age 23-29 years). With an average Cmax of cetirizine of 697.0 ng/ml (10 mg) and 1000.2 ng/ml (20 mg), the diameter of histamine-induced skin weals was reduced by 24.0-74.9% depending on histamine concentration and with no dose dependence for cetirizine. Placebo and chlorpheniramine were ineffective. Behavioral or neuropsychological signs of sedation were never observed. An increase of the 6.5-14.5 Hz EEG power, with anterior scalp preponderance, was observed after chlorpheniramine or cetirizine 20 mg. This effect of cetirizine was accounted for by a substantial increase of power in the 6.5-8.0 Hz frequency subsegment and is regarded, for these experimental conditions, as an established early EEG indication of mild sedation (vigilance 'state A'). No EEG effects were observed after placebo or cetirizine at the 10 mg dose. The existence of some histaminergic (H1) specificity of the mechanisms modulating vigilance and of a threshold dose of cetirizine for sedative action is suggested.

The effect of cetirizine on sulfidoleukotriene production by blood leukocytes in children with allergic rhinitis

Twelve children with allergic rhinitis due to monosensitivity to Dermatophagoides pteronyssinus (Dp) took part in a placebo-controlled, double-blind, crossover study to evaluate the effect of cetirizine, a second-generation, nonsedating H1-blocker-type antihistamine, on sulfidoleukotriene releasability by blood leukocytes and to determine its correlation with clinical findings and nasal challenge scores. Sulfidoleukotriene release by blood leukocytes was determined by the cellular allergen stimulation test (CAST), which measures leukotriene (LT)C4, LTD4, and LTE4, all in one assay. Compared to placebo, cetirizine significantly (P < 0.05) decreased daily symptom scores of nasal discharge, nasal itching, and sneezing, as well as the number of sneezings after nasal challenge with the antigen, without alleviating nasal obstruction (P > 0.05). It also suppressed both early (P < 0.05) and late skin reactions to intradermal tests. Although cetirizine did not influence in vitro sulfidoleukotriene production by blood leukocytes with buffer or anti-IgE (P > 0.05), it substantially reduced the release of these mediators upon challenge with Dp antigen. Furthermore, there was a high correlation between the number of sneezes after challenge and the amount of sulfidoleukotriene released in nine patients (r = 0.78; P < 0.01). It is concluded that the amount of sulfidoleukotrienes produced by blood leukocytes in vitro may reflect the nasal hyperreactivity of the patient, and that cetirizine, which is highly effective in the treatment of allergic rhinitis, owes part of its effect to inhibition of sulfidoleukotriene releasability by blood leukocytes in children.

Lack of interaction between a new antihistamine, mizolastine, and lorazepam on psychomotor performance and memory in healthy volunteers

1. The possible interaction between a new H1 antihistamine, mizolastine, and lorazepam was assessed in a randomised, double-blind, cross-over, placebo-controlled study involving 16 healthy young male volunteers who received mizolastine 10 mg or placebo once daily for 8 days with a 1 week wash-out interval. The interaction of mizolastine, at steady-state, with a single oral dose of lorazepam or placebo was assessed on days 6 or 8 of each treatment period. 2. Psychomotor performance and cognitive function were evaluated using objective tests (critical flicker fusion threshold, choice reaction time, tapping, arithmetic calculation, body sway) and self-ratings (visual analogue scale, ARCI) before and at 2, 4, 6 and 8 h after dosing. Short-term memory (Sternberg memory scanning immediate free recall of a word list) and long-term memory (delayed free recall and recognition of words and pictures) were assessed before and at 3 h after dosing. Pharmacodynamic interactions were evaluated by repeated measures ANOVA in a 2 x 2 factorial interaction model. 3. Mizolastine, 10 mg once daily, at steady-state, was devoid of sedation and detrimental effect on skilled performance and memory. 4. In contrast, a single 2 mg dose of lorazepam produced marked impairment of psychomotor performance, cognitive functions (significant reduction in flicker fusion threshold, tapping and arithmetic calculation and increase in reaction times and body sway) and subjective sedation from 2 to 8 h after dosing. In addition, lorazepam induced an anterograde amnesia, characterised by a decrease in delayed free recall and recognition, and a deficit in short term memory.(ABSTRACT TRUNCATED AT 250 WORDS)

Sleepiness and performance during three-day administration of cetirizine or diphenhydramine

OBJECTIVE

The sedative effects of cetirizine (10 mg once daily), diphenhydramine (50 mg three times daily), and placebo, each administered during a 3-day period, were compared with objective measures of sleepiness and performance.

METHODS

Twelve atopic subjects received each of the three treatments for 3 consecutive days in a double-blind Latin square design. Subjects received either cetirizine at 8:00 AM and placebo at 3:00 PM and 10:00 PM; diphenhydramine at 8:00 AM, 3:00 PM, and 10:00 PM; or placebo at all three times. Sleepiness was measured on days 1 and 3 with the multiple sleep latency test at 9:00 AM, 11:00 AM, 1:00 PM, 3:00 PM, and 5:00 PM. Performance was assessed with a 60-minute simulated assembly line task at 9:30 AM, 11:30 AM, 1:30 PM, and 3:30 PM. Nightly sleep duration was estimated with actigraphy.

RESULTS

Compared with placebo and cetirizine, diphenhydramine produced marked impairment only on the first day of drug administration. The multiple sleep latency test and the simulated assembly line task values remained stable across days with cetirizine and placebo but improved with diphenhydramine, resulting in no differences among the three conditions on the third day.

CONCLUSION

Unlike cetirizine, diphenhydramine produced acute impairment of alertness and performance. By the third day of administration, however, this impairment was no longer present, apparently because of development of tolerance to the sedative effects.

A comparison of the electroencephalographic spectral modifications induced by diazepam and by hydroxyzine

A double-blind, randomized controlled trial using an electroencephalograph computerized analysis and cartography was carried out to investigate the spectral modifications induced by diazepam and hydroxyzine. Without monitoring response to stimulation, the spectra found for diazepam and for hydroxyzine were qualitatively very similar, showing increase of the slow waves, reduction of the alpha rhythm and accentuation of the beta 1 rhythms. These traces suggested strongly that both drugs had produced a sedative, anti-anxiety effect. The intensity of the effect produced by 50 mg of hydroxyzine appeared to be less than that produced by 10 mg diazepam. After monitoring response to stimulation, the spectra were modified and the reactivity of the two drugs differed with regard to the slow delta, theta and alpha 1 frequency bands. It was possible to distinguish between the sedative and anti-anxiety effects of both diazepam and hydroxyzine. Even if the two drugs had some similar effects, the mode of action in the central nervous system was certainly different, as can be seen from the characteristics of distribution of the slow waves, their reactivity and, with regard to frequency, the fluctuation of the dominant frequency of rapid rhythms.

A comparison of the efficacy of cetirizine and terfenadine. A double-blind, controlled study of chronic idiopathic urticaria

In a 20-d, double-blind, randomized, parallel study, the efficacy of cetirizine and terfenadine was compared in 30 patients with chronic idiopathic urticaria. Subjects were randomly divided into two 15-patient groups. The first group was given cetirizine (10 mg once daily); the second terfenadine (60 mg twice daily). Cetirizine proved to be more effective than terfenadine in controlling urticaria symptoms. In fact, the score of the investigators' overall assessment was significantly lower in the cetirizine-treated group than in the terfenadine-treated group. Moreover, patient evaluation by a visual analog scale and symptoms assessed on a 4-point scale showed a better improvement in the cetirizine group. The number and severity of side-effects were similar in both treatment groups.

The comparison of the effects of multi and single doses of buspirone, chlordiazepoxide and hydroxyzine on psychomotor function and EEG

This study compares the effects of buspirone (5 mg), chlordiazepoxide (5 mg), hydroxyzine (10 mg) and placebo on psychomotor function and EEG, when taken thrice daily for a period of two weeks, with those after a single dose administration. Nine healthy volunteers participated in the study. The battery of psychomotor tests included peak velocity of saccadic eye movements (SEM), a Sternberg memory scanning and choice reaction time test (SMS-CRT) and critical flicker fusion frequency (CFFF). The peak velocity of saccadic eye movements was significantly impaired by the single dose of hydroxyzine (P = 0.03) in comparison to the multidose results. A similar comparison regarding buspirone only approached significance (P = 0.07). The SMS-CRT and CFFF did not reveal any difference between the multi and single dose regimens. Spectral analysis of the EEG did not distinguish between the multi and single dosage schedules regarding the respective drugs in the low doses administered.

Cetirizine: a new H1 antagonist with antieosinophilic activity in chronic urticaria

Although the action of H1 antagonists in the early phase of IgE-mediated, allergic skin reactions is well established, the effect of these antihistamines on the ensuing late-phase reaction has only recently been investigated. The eosinophilic late-phase reaction, sometimes associated with the tissue damage that occurs in chronic idiopathic urticaria, is important in allergic responses. Cetirizine is a new H1 antagonist with potent inhibitory action against the infiltration of eosinophils into involved tissue, thereby affecting the late-phase reaction. No other antihistamine has yet been reported to possess this antieosinophilic property. The mechanisms by which cetirizine acts against eosinophils, although not thoroughly understood, seem to involve direct action against these cells.

The effect of cetirizine on the human isolated bronchus: interaction with salbutamol

The effects of cetirizine (C), a new generation, nonsedative, H1-antihistamine drug, were studied on human isolated bronchi. C is a potent antagonist of the bronchial muscle contraction induced by histamine, irrespective of whether C is administered by cumulative addition or prophylactically. In the former case, this effect of C was significant at a concentration of 3 X 10(-8) mol/L and was maximal at a concentration of 10(-5) mol/L. The -log of concentration of C causing 50% of the maximal effect induced was 7.30 +/- 0.05 (n = 6), and the effect produced was not significantly modified by bronchial epithelium removal. When C was administered prophylactically, the concentration-response curves to histamine were displaced to the right, but the reduction of maximum histamine response suggests a noncompetitive type of antagonism. C is devoid of notable anticholinergic effects. At concentrations of 10(-8) to 10(-7) mol/L, C proved capable of enhancing the relaxant effect produced by salbutamol (10(-7) to 3 X 10(-7) mol/L) on human isolated bronchi that had been contracted by either histamine or acetylcholine (ACh). The synergy appeared to be additive or potentiating, depending on salbutamol (SAL) concentrations. Under similar conditions, mepyramine does not potentiate the effects of SAL against histamine. Finally, at concentrations of 10(-8) to 10(-6) mol/L, C reduced the functional antagonism observed between SAL and ACh, as can be observed by the increase, in the presence of C, of the maximal relaxant effect of SAL on contractions produced by 10(-3) mol/L of ACh. We may, therefore, conclude that C appears to be a specific antihistamine on human isolated bronchi and that it appears to potentiate the bronchodilator effect of SAL on this preparation.

A comparison of central and peripheral effects of cetirizine and loratadine

In a double-blind, crossover, randomized clinical pharmacological study performed on 10 healthy volunteers, peripheral and central effects of 10 mg cetirizine and 10 and 40 mg loratadine were compared. Cetirizine (10 mg) significantly (P less than 0.001) inhibited 10 or 100 mg/ml histamine-induced weals 2 and 6 h after drug intake. Cetirizine was more potent than 10 mg loratadine after 2 and 6 h, and was even more potent than 40 mg loratadine after 6 h. Neither drug affected subjective evaluation of central effects and cetirizine was completely devoid of electro-encephalographic (EEG) changes, whereas 10 and 40 mg loratadine induced only slight and limited EEG changes.

Cetirizine. A review of its pharmacological properties and clinical potential in allergic rhinitis, pollen-induced asthma, and chronic urticaria

Cetirizine, a piperazine derivative and carboxylated metabolite of hydroxyzine, is a potent histamine H1-receptor antagonist with antiallergic properties. It has marked affinity for peripheral histamine H1-receptors and, at the standard dose of 10mg daily, lacks the CNS depressant effects of standard antihistamines. In addition, it inhibits histamine release and eosinophil chemotaxis during the secondary phase of the allergic response. Results from controlled clinical trials indicate that cetirizine is an effective and well tolerated treatment of seasonal and perennial allergic rhinitis and chronic idiopathic urticaria. Cetirizine appears to be as effective as conventional dosages of terfenadine, chlorpheniramine and hydroxyzine in relieving symptoms associated with these disorders and produces a markedly lower incidence of sedation than chlorpheniramine, hydroxyzine and several other standard antihistamines. Thus, cetirizine appears to provide a useful alternative to other 'nonsedating' antihistamines; cetirizine may also have a future role in the treatment of allergic asthma and certain forms of physical urticaria.

Astemizole and cetirizine in the treatment of seasonal allergic rhinitis: a comparative double-blind, multicentre study

In a double-blind, multicentre trial, 105 patients with seasonal allergic rhinitis were treated with 10 mg astemizole or 10 mg cetirizine once daily for 4 days. Patients were thereafter allowed to change their treatment if not satisfied with the clinical efficacy. In the cetirizine-treated group, there were significantly fewer (P = 0.02) patients who asked to change their treatment compared to patients receiving astemizole for 4 days. At day 4, there was a significant improvement in the clinical scores for the patients who did not want to change treatment but scores were hardly altered in those patients that wished to change. After treatment for a further 10 days, there was a decrease in all the scored symptoms but this was less marked in the two groups of patients who wanted to change treatment.

The effects of terfenadine with and without alcohol on an aspect of car driving performance

Twelve healthy female volunteers received acute doses of terfenadine, 60 mg, 120 mg, 240 mg or placebo, followed by a 'social' dose of alcohol equivalent to 0.5 g absolute alcohol/kg body weight. Performance was assessed on laboratory analogues of car driving both before and after alcohol administration. Terfenadine (240 mg) was found to significantly impair performance alone and following alcohol. The results demonstrate the importance of establishing the behavioural effects of drugs over a range of doses.