Effect of cetirizine, a new histamine H1 antagonist, on airway dynamics and responsiveness to inhaled histamine in mild asthma

Cetirizine, a major human metabolite of hydroxyzine, preserves the histamine H1-antagonist activity of the parent compound but poorly penetrates the blood-brain barrier, thus minimizing sedative and anticholinergic effects. In 10 young (mean age 27.7 years) subjects with mild asthma (FEV1 greater than 70% predicted), we evaluated the bronchodilator and protective efficacy of 5, 10, and 20 mg of cetirizine against bronchospasm induced by histamine inhalation (0.03 to 20 mg/ml) in comparison with placebo and hydroxyzine, 25 mg, using a random, double-blind crossover design. The provocative concentration of histamine causing a 20% decline in FEV1 for all 10 subjects from the postdiluent control value was more than fourfold greater after each active drug than after placebo. Cetirizine, 5 to 20 mg, provided significantly greater protection against histamine-induced bronchospasm than hydroxyzine (p less than 0.001); moreover, a dose-dependent protective effect was noted with cetirizine. Significant bronchodilation was also found: at 60 minutes, FEV1 increased significantly after all active antihistamines compared to placebo and after 20 mg of cetirizine compared to hydroxyzine (p less than 0.05). FEV1 increased significantly at 120 minutes after hydroxyzine and after cetirizine in both the 20 and 10 mg doses compared to placebo (p less than 0.05). We conclude that in subjects with mild asthma, orally administered cetirizine provides significant dose-dependent protection against histamine-induced bronchoconstriction, which in the doses studied is superior to that produced by the parent compound, hydroxyzine. In addition, cetirizine in 5 to 20 mg doses causes acute bronchodilation. These results suggest a possible role of cetirizine in asthma therapy.     

Pharmacologic prophylaxis of allergic rhinitis: Relative efficacy of hydroxyzine and chlorpheniramine

The efficacy of hydroxyzine and chlorpheniramine in preventing exacerbations of ragweed allergic rhinitis was compared in a double-blind, randomized manner. Ninety-five subjects with positive skin tests, a history of two previous symptomatic seasons, and discontinuation of immunotherapy for at least 1 yr received either hydroxyzine 150 mg/day, chlorpheniramine 24 mg/day, or placebo during the 1978 ragweed season. Subjects in the placebo group experienced annoying or disabling sneezing 50% of days during the period of highest pollen counts whereas those in the chlorpheniramine and hydroxyzine groups experienced this symptom with equal severity only 22% and 12% of days, respectively. Suppression of rhinorrhea and itchy nose was similar although less dramatic. Both antihistamines were more effective than placebo in altering conjunctivitis, but neither decreased the frequency or severity of nasal stuffiness. Skin tests to ragweed decreased in diameter during the season by 38%, 13%, and 3% among patients receiving hydroxyzine, chlorpheniramine, and placebo, respectively. Frequent drowsiness occurred initially in subjects taking both antihistamines but did not persist. Thus, prophylactic antihistamine therapy effectively prevents most symptoms of seasonal allergic rhinitis without persistent drowsiness. These data further suggest a therapeutic advantage for hydroxyzine over chlorpheniramine in the doses used.     

Suppression of seasonal allergic rhinitis symptoms with daily hydroxyzine.

The effectiveness of hydroxyzine in the suppression of allergic rhinitis symptoms was evaluated using a double-blind, parallel study design during the 1977 ragweed season. Forty-three subjects with positive ragweed skin tests and a history of an exacerbation of symptoms during August and September of the previous two years were randomly assigned to receive either hydroxyzine or placebo. Subjects scored the severity and duration of symptoms in a daily diary and adverse effects were evaluated from a structured interview at two-week intervals. Although drowsiness and dry mouth were frequent initially among the hydroxyzine-treated patients, these minor side effects rapidly disappeared as the dose was slowly increased, and all but one subject tolerated 150 mg/day. Subsequently, during the period of the highest ragweek pollen counts, the hydroxyzine-treated group spent significantly more days free of symptoms or with only mild sneezing, rhinorrhea, and eye symptoms than subjects who took placebo (p less than 0.05). Thus, hydroxyzine appeared to be well tolerated on a continuous daily basis and was effective in suppressing most of the symptoms of seasonal allergic rhinitis. Comparison of hydroxyzine with antihistamines more traditionally used for allergic rhinitis appears warranted.     

Quantitative effects of cetirizine and diphenhydramine on mental performance measured using an automobile driving simulator

The purpose of this study was to assess the effects of cetirizine on objective measures of mental performance. Fifteen subjects were given single doses of cetirizine (20 mg, 10 mg, and 5 mg) diphenhydramine, 50 mg (positive control), and placebo (negative control) in this randomized, double-blinded, crossover study. An automobile driving simulator, digit symbol substitution, Trails B maze tracking and subjective feelings of drowsiness were measured at 0, 2, 4, 6, 8, and 24 hours after the dose. No differences between placebo and any of the three doses of cetirizine could be detected, however, diphenhydramine produced impaired mental performance and drowsiness. These data indicate that these doses of cetirizine produce little or no effect on cognitive function or mental performance.     

Effects of oral cetirizine, a selective H1 antagonist, on allergen- and exercise-induced bronchoconstriction in subjects with asthma

The protective efficacy of oral cetirizine, a selective and potent H1-receptor antagonist, against the immediate bronchoconstrictive response to allergen inhalation and exercise challenge was evaluated in 16 subjects with stable, predominantly mild asthma. The subjects underwent double-blind, crossover pretreatments in randomized order in two separate protocols with (1) three daily oral doses of 20 mg of cetirizine and placebo, followed by allergen inhalation, and (2) single oral doses of cetirizine (5, 10, and 20 mg), albuterol (4 mg), and placebo, followed by exercise with cold-air inhalation. Cetirizine failed to decrease bronchial sensitivity to inhaled allergen in eight of 10 subjects. Neither cetirizine nor albuterol uniformly inhibited exercise-induced bronchoconstriction. Serum concentrations of cetirizine were consistent with systemic H1-blocking activity. Modest bronchodilation occurred after administration of cetirizine and albuterol before exercise but not after the third dose of cetirizine in the allergen protocol. One subject developed moderate drowsiness during multiple dosing with cetirizine. Thus, cetirizine, in the doses studied, is not uniformly effective in preventing allergen- or exercise-induced bronchoconstriction. Histamine is one of many mediators participating in immediate asthmatic responses, and selective H1 antagonists do not completely block these airway events. However, cetirizine may still clinically benefit some patients with asthma, such as patients with allergic rhinitis or urticaria.     

A double-blind, placebo-controlled study of the effects of lithium on cognition in healthy subjects: mild and selective effects on learning

Background: Several studies have shown cognitive impairment in short-term memory, long-term memory and psychomotor speed in bipolar patients taking lithium. The aim of the study was to look at the effect of lithium in normal subjects (N=30) taking lithium for 3 weeks. A comprehensive battery was used to assess attention and memory. Methods: Subjects were randomized to double-blind treatment with either lithium (N=15) or placebo (N=15) for a 3-week period. Thirteen participants in the lithium group and 15 in the placebo group completed the study. The lithium and placebo were administered twice daily in doses varying from 1050 to 1950 mg (mean=1569 mg). The initial daily dose was calculated according to the Pepin formula to achieve a blood serum lithium level of about 0.8 mmol/l. Cognitive performance (attention, memory) was assessed in each subjects during three periods, i.e. at baseline, after 3 weeks of lithium or placebo, and 2 weeks after discontinuation of study medication. Results: In short-term memory tasks, the performance of subjects in the lithium group was worst 3 weeks after lithium treatment compared to 2 weeks after discontinuation. In long-term memory, a significantly higher number of words was recalled by the placebo group but not the lithium group. Conclusions. Lithium may have an effect on learning when long-term explicit memory test are administered repeatedly. It means that the practice effect when a subject performs the same task several times is less in the lithium-treated group than in the placebo group. This practice effect is related to the learning of a task.     

Objective antihistamine side effects are mitigated by evening dosing of hydroxyzine.

First-generation antihistamines have potency, pharmacokinetic, and cost advantages compared with nonsedating second-generation antihistamines. Bedtime dosing of hydroxyzine was investigated as a dosing strategy to minimize reaction time degradation and adverse subjective symptoms previously documented for hydroxyzine in divided doses. Hydroxyzine, 50 mg qhs, was compared with terfenadine, 60 mg bid, in this double-blind, placebo-controlled crossover study of 15 healthy, asymptomatic adults. Computer-based eye-hand reaction time tests of simple reaction time (SRT) and choice reaction time (CRT) were not statistically different among the three drugs. Drowsiness, dry mouth, and irritability were significant for hydroxyzine (P = .0001, .001 and .02, respectively) compared with terfenadine or placebo, but less than seen in a previous study of hydroxyzine, 25 mg bid. Symptom scores with terfenadine were comparable to placebo. Histamine skin test wheal and flare were both significantly and comparably suppressed by hydroxyzine and terfenadine (P = .0001). While wheal suppression by hydroxyzine was universal, four of the 15 subjects showed little or no suppression with terfenadine (P = .03). Although bedtime dosing of hydroxyzine did not eliminate subjective symptoms, it maintained skin H1-receptor antagonism the following morning and alleviated the prolongation of reaction times previously reported with hydroxyzine in divided doses. The significant adverse subjective symptoms and psychomotor performance degradations caused by first-generation antihistamines can be mitigated by creative dosing schedules.     

Effects of H1-antihistamine drug regimen on histamine release by nonlesional skin mast cells of patients with chronic urticaria.

Profiles of compound 48/80-induced histamine release (HR) from mast cells of uninvolved skin from patients with chronic urticaria (CU) and from a normal control (NC) group were compared, and the effects of anti-H1 medications were assessed versus placebo. Then, patients with CU (15) and NC subjects (10) were randomly assigned to take either hydroxyzine (100 mg/day), terfenadine (120 mg/day), or placebo for 28 days. The effects of such treatment on the clinical response and on the profile of compound 48/80-induced HR during a 4-hour period were analyzed. Treatment with hydroxyzine in patients with CU improved the clinical symptoms and modified the profile of HR; more histamine was recovered at 1 hour (p less than 0.05) and 2 hours (p less than 0.05), as compared with baseline. Terfenadine and placebo had no effect on the clinical response or on the profiles of HR. In the NC group, the amounts of histamine recovered at 1 hour after challenge with compound 48/80 were lower than amounts of the pretherapy values (p less than 0.01). It could be concluded that (1) the profile of HR in patients with CU is reproducible during a period of 28 days, (2) only hydroxyzine modifies both the clinical response and the profile of HR, and (3) anti-H1 compounds decrease the HR in the NC group.     

Withdrawal syndrome after the double-blind cessation of caffeine consumption.

BACKGROUND. People who stop consuming caffeine may have symptoms, but the incidence and severity of caffeine withdrawal are not known. This study was performed to determine the effects in the general population of ending one's dietary intake of caffeine. METHODS. We studied 62 normal adults whose intake of caffeine was low to moderate (mean amount, 235 mg--the equivalent of 2.5 cups of coffee--per day). They completed questionnaires about symptoms and tests of their mood and performance when consuming their normal diets (base-line period) and at the end of each of two two-day periods during which they consumed caffeine-free diets and under double-blind conditions received capsules containing placebo (placebo period) or caffeine (caffeine period) in amounts equal to their daily caffeine consumption. RESULTS. More subjects had abnormally high Beck Depression Inventory scores (11 percent), high scores on the trait scale of the State-Trait Anxiety Inventory (8 percent), low vigor scores (11 percent) and high fatigue scores (8 percent) on the Profile of Mood States, and moderate or severe headache (52 percent) during the placebo period than during either the base-line period (2, 0, 0, 0, and 2 percent, respectively; P less than 0.05) or the caffeine period (3, 2, 2, 0, and 6 percent; P less than 0.05). More subjects reported unauthorized use of medications during the placebo period (13 percent) than during the caffeine period (2 percent, P = 0.017). Performance of a tapping task was slower during the placebo period than during the base-line and caffeine periods (P less than 0.01). CONCLUSIONS. Persons who consume low or moderate amounts of caffeine may have a withdrawal syndrome after their daily consumption of caffeine ceases.     

The addition of zafirlukast to cetirizine improves the treatment of chronic urticaria in patients with positive autologous serum skin test results

BACKGROUND: Because leukotrienes have potent local effects on cutaneous vasculature, leukotriene antagonists might be effective in the treatment of chronic urticaria. OBJECTIVE: A double-blinded, placebo-controlled trial comparing cetirizine 10 mg daily in combination with zafirlukast 20 mg twice a day versus cetirizine 10 mg daily and placebo was conducted to determine whether subjects with chronic urticaria benefit from add-on therapy with a leukotriene-modifying agent. METHODS: Patients 12 years or older with a history of chronic urticaria (more than 6 weeks in duration) required diary documentation of 6 or more hives on at least 2 days/week and a suboptimal response to H(1)-antagonist therapy for enrollment. At baseline, all subjects were skin tested to autologous serum to assess for the potential presence of FcepsilonRI or IgE autoantibodies. Subjects meeting the initial entry criteria were treated with cetirizine 10 mg a day and placebo twice daily for 1 week. Those patients with persistent hives were randomized to receive cetirizine 10 mg daily and zafirlukast 20 mg twice a day or cetirizine 10 mg daily and placebo. At each successive weekly visit, physician and patient treatment effectiveness score (TES) and visual analog scale (VAS) ratings were recorded. Statistical analysis used generalizing estimating equations to compare the effect of combination therapy versus monotherapy on TES and VAS ratings. Results were adjusted for baseline rating, recruiting center, and autologous serum skin test (ASST). A separate analysis evaluated patients with positive ASST results receiving combination therapy versus monotherapy. RESULTS: Combination therapy with zafirlukast demonstrated a modest but significantly greater improvement compared with cetirizine monotherapy in physician and patient recorded VAS ratings at visit 4 and across treatment visits 4 through 6 (P <.05 unless stated otherwise). Subjects with ASST positive results receiving combination therapy as compared with subjects with negative ASST results exhibited a significant improvement in patient recorded VAS ratings across visits 4 through 6. Subgroup analysis of subjects with ASST positive results receiving combination therapy versus monotherapy showed improvement in physician recorded TES at visit 5, physician recorded VAS at visits 4 and 5 and across visits 4 through 6, as well as for patient recorded VAS at visit 5. There were no significant results for patients with ASST negative results. CONCLUSION: The results of this study indicate that only patients with autoimmune (ASST positive) chronic urticaria refractory to H(1)-antagonist monotherapy might benefit from the addition of the leukotriene D(4)-receptor antagonist zafirlukast to their treatment regimen. These results also suggest that routine screening of patients with chronic urticaria with the ASST might be useful in formulating therapeutic algorithms in the management of chronic urticaria.     

Central nervous system effects of H1-receptor antagonists in the elderly.

BACKGROUND: The potential adverse central nervous system effects of H1-receptor antagonists have not been optimally studied in the elderly. OBJECTIVE: We hypothesized that newer H1-receptor antagonists such as cetirizine and loratadine would cause less central nervous system dysfunction than the older H1-receptor antagonists diphenhydramine and chlorpheniramine in this population, as they do in younger subjects. METHODS: We performed a randomized, double-blind, single-dose, placebo-controlled, 5-way crossover study in 15 healthy elderly subjects (mean age 71 +/- SD 5 years). On study days at least 1 week apart, they received cetirizine 10 mg, loratadine 10 mg, diphenhydramine 50 mg, chlorpheniramine 8 mg, or placebo. Outcome measures, recorded before and 2 to 2.5 hours after dosing were latency of the P300 event-related potential in which increased latency reflects a decreased rate of cognitive processing, visual analogue scale for subjective somnolence, and histamine skin tests for measurement of peripheral H1-blockade. RESULTS: The changes in P300 following each treatment yielded variances that were not equal (P > .05), precluding usual statistical analysis of the means. These variances were ranked: chlorpheniramine > diphenhydramine > loratadine > placebo > cetirizine. The rank of mean differences in the visual analogue scale increase from pre-dose baseline was: diphenhydramine > chlorpheniramine > cetirizine > loratadine > placebo. All H1-receptor antagonists suppressed the histamine-induced wheal and flare significantly compared to baseline. CONCLUSION: In the elderly, the new H1-receptor antagonists cetirizine and loratadine are less likely to cause adverse central nervous system effects than the old H1-antagonists chlorpheniramine or diphenhydramine, but this requires confirmation using additional objective tests of central nervous system function.     

Autonomic nervous system effects of acute doses of caffeine in caffeine users and abstainers

The effects of caffeine on autonomic nervous system (ANS) activity were tested in 20 adult males who were either high or low consumers of caffeine. Subjects received placebo, 3 mg/kg, and 10 mg/kg of caffeine in a counterbalanced order (double-blind) before 3 test sessions 48 h apart. Skin conductance (SC), heart rate, and skin temperature (ST) were recorded during a rest period, a series of non-signal tones, and a simple reaction time task. Caffeine increased resting electrodermal activity (EDA) and increased the SC orienting response to the first non-signal tone, but reduced the increase in tonic EDA due to task performance. ST was reduced by caffeine in both rest and task periods. Increases in nervous/jittery ratings occurred after caffeine ingestion, but task performance was not affected. Low consumers of caffeine showed significantly more ANS responsivity than high consumers under all conditions and did not differ in ANS, behavioral, or subjective effects of caffeine. The acute physiological changes are partly similar to those reported for patients with anxiety disorders, suggesting a possible role of ANS activity in mediating the anxiogenic effects of caffeine. Effects of user status may reflect a predisposing trait, but an effect of chronic caffeine use on ANS sensitivity cannot be ruled out.     

The effects of caffeine on caffeine users and non-users

This work examined the effects of consuming relatively small amounts of caffeine, from 20 to 160 mg, on performance and self-reports of mood in a group of caffeine users. A group of non-caffeine users were studied after ingesting 160 mg of caffeine. At regular intervals after consumption subjects were tested on several behavioral measures and blood samples were taken for caffeine analysis. Results showed caffeine users had higher blood caffeine levels and lower blood pressure at some doses than did non-users. Regular caffeine users showed a tendency toward better performance on a rotary pursuit task than non-caffeine users given a placebo treatment. They also experienced a performance decrement, relative to users given placebo, when blood caffeine levels were relatively high. Caffeine users showed no sign of caffeine withdrawal when compared to non-users before caffeine treatment. Performance of non-users given caffeine was poorer than control performance, and they tended not to report altering effects of caffeine. However, in caffeine users, the ratio of alertness:tension self-ratings tended to roughly track plasma caffeine with the lowest ratios occurring when plasma caffeine peaked after 160 mg dose. Low ratios were also found after 0, 20, and 40 mg caffeine treatments. The ratio was highest after 80 mg caffeine, suggesting that an optimum caffeine dose might exist for peak alertness:tension, with higher or lower doses resulting in a decrease of that ratio. These data suggest that real or expected mood and perhaps performance benefits experienced by caffeine users contribute to the motivation for consumption.     

Choline chloride effects on memory in the elderly

Choline chloride (2 g QID) and placebo were administered to 10 subjects over age 60 in a placebo-drug-placebo design. Subjects first took placebo for 7 days, followed by choline for 21 days and finally took placebo for another 21 days. Memory tests were given at the end of both placebo periods and twice during choline administration. Choline did not significantly affect performance on a test of memory storage, a test of retrieval from memory or on the digit span test. In addition, a correlational analysis showed that the difference between memory performance during choline administration and during placebo administration was not significantly related to baseline memory performance. These results, together with results of previous studies indicate that choline is not an effective agent for improving memory in nondemented elderly patients.     

Modafinil improves alertness, vigilance, and executive function during simulated night shifts

STUDY OBJECTIVES: To assess the effect of 200 mg of modafinil compared to placebo on alertness, neurobehavioral performance, and executive function during 4 consecutive simulated night shifts. DESIGN: Double-blind, randomized, parallel groups. SETTING: Sleep research facility. PARTICIPANTS: 32 male and female volunteers between the ages of 18 and 55 years. INTERVENTIONS: 200 mg of modafinil or placebo given nightly on the 4 consecutive simulated night shifts. MEASUREMENTS AND RESULTS: Subjects were randomly assigned to 1 of the 2 treatment conditions, following medical, psychiatric, and polysomnographic screening. On 4 consecutive nights, subjects took study drug at 2200, and then from about 2300 to 0730 participated in a simulated night shift that included the Maintenance of Wakefulness Test, Psychomotor Vigilance Test, Digit Symbol Substitution Test, measures of subjective alertness, and multiple executive-function measures. At 0800, daytime sleep periods were recorded polysomnographically for 6 to 8 hours. Alertness--as measured by the MWT, vigilance and reaction time as indexed by Psychomotor Vigilance Test lapses, and slowest 10% of reaction times--and 3 executive-function tasks showed significant enhancement with modafinil versus placebo. Subjective sleepiness at night and some performance measures did not show consistent treatment differences. Daytime sleep showed minimal differences between conditions. CONCLUSIONS: The physiologic sleepiness and neurobehavioral deficits that occurred during the hours of a typical night shift were clearly attenuated by modafinil. Modafinil also had beneficial effects on some measures of executive function.     

Influence of caffeine on selective attention in well-rested and fatigued subjects

Effects of caffeine were studied in a visual focused selective search task in well-rested and fatigued subjects. A dose of 200 + 50 mg caffeine or placebo, dissolved in decaffeinated coffee, was administered in a double-blind and deceptive fashion. The task was to detect a target letter on one diagonal of a visual display designated as relevant and ignore stimuli presented on the irrelevant diagonal. Behavioral measures were supplemented by event-related potential (ERP) measures. Subjects reacted faster in the caffeine condition. Caffeine enhanced the N1 and the N2b components. Selection of relevant information apparently was more adequate in this condition. Search negativity was not affected by caffeine. Caffeine effects on the P3 elicited by target letters were more pronounced in the fatigued than in the well-rested subjects, indicating that the effects of caffeine are dependent on the state of the subject. The results suggest that caffeine has specific rather than general effects on information processing.     

Efficacy and safety of cetirizine therapy in perennial allergic rhinitis.

A double-blind, placebo-controlled trial was undertaken to assess the safety and efficacy of once daily cetirizine in alleviating the symptoms of perennial allergic rhinitis. Subjects were adults with perennial allergic rhinitis, characterized by nasal congestion, postnasal discharge, sneezing, rhinorrhea, nasal itching, lacrimation, ocular itching, and itching of the roof of the mouth, and a total pretreatment symptom severity score of greater than or equal to 8. Patients were randomized to treatment with 10 mg cetirizine, 20 mg cetirizine, or placebo for 4 weeks. Efficacy was assessed in 215 patients and safety in 216. Cetirizine in once daily dosages of 10 or 20 mg proved to be effective in relieving the overall symptoms of perennial allergic rhinitis and particularly postnasal discharge and sneezing. The 10-mg dose afforded optimal symptomatic relief, and the 20-mg dose provided little or no additional benefit. Cetirizine was well tolerated, and the frequency of somnolence was not significantly greater in patients receiving this drug than in those given placebo.     

Performance on the continuous performance test in children with ADHD is associated with sleep efficiency

STUDY OBJECTIVE: To examine whether the level of sleep efficiency of children diagnosed with ADHD moderates their performance on the Continuous Performance Test (CPT) while receiving a placebo and while receiving methylphenidate (MPH). DESIGN: Nightly sleep actigraphic assessment during a double-blind, placebo-controlled, crossover clinical study (1 week of 0.5 mg/kg MPH; 1 week of placebo) were obtained on 37 children between 6 and 12 years of age with a DSM-IV diagnosis of ADHD. Subjects were divided into 2 groups based on the mean sleep efficiency score during the placebo condition, with subjects above and below the mean placed in the Poor Sleep Group (PSG) and Good Sleep Group (GSG), respectively. SETTING: Vigilance testing was conducted in the laboratory; sleep was assessed in the home. MEASUREMENTS: Sleep was monitored using actigraphy for 2 weeks. In addition, parents were asked to complete nightly sleep logs and a sleep questionnaire. The Conners' Continuous Performance Test (CPT) was used to assess vigilance. RESULTS: Significant interaction of Sleep Group with Medication was found on 1 CPT factor. CONCLUSIONS: The findings of the present study support the hypothesis that sleep moderates performance on CPT in children with ADHD while receiving placebo or MPH.     

Controlled comparison of the efficacy and safety of cetirizine 10 mg o.d. and fexofenadine 120 mg o.d. in reducing symptoms of seasonal allergic rhinitis

BACKGROUND: The efficacy, onset and duration of action and safety of cetirizine 10 mg o.d., fexofenadine 120 mg o.d., and placebo were compared in this investigator-blinded, crossover study involving the use of the Vienna Challenge Chamber. METHODS: 40 volunteers with seasonal allergic rhinitis were exposed to a controlled grass pollen concentration for 6 h on 2 consecutive days. Subjective symptoms and objective measurements were recorded during the allergen exposure periods. RESULTS: Both active medications were significantly more effective than placebo and had a comparable onset of action in alleviating the symptoms of seasonal allergic rhinitis. The efficacy of both active drugs was comparable for the first 4 h after administration of the drugs on day 1 and day 2. However from 22 to 24 h after the first dose cetirizine was significantly superior to fexofenadine for the major symptom complex score and for sneezing. Concerning the total symptom complex score at day 2 fexofenadine could not reach superiority to placebo. No serious adverse events were reported. CONCLUSIONS: Cetirizine and fexofenadine were significantly better than placebo, also in reducing the symptom of nasal congestion. However cetirizine appears to have a longer duration of action than fexofenadine.     

Effect of cetirizine on histamine- and leukotriene D4-induced bronchoconstriction in patients with atopic asthma.

Cetirizine, a derivative of hydroxyzine, is a new compound with potent antihistaminic property without antiserotonin and anticholinergic activities. The effect of both a single dose (15 mg) and 7 days of treatment (15 mg twice daily) with cetirizine, a potent H1 antagonist on bronchoconstriction induced by histamine and leukotriene D4 (LTD4) has been examined in 10 patients with mild atopic asthma in a placebo-controlled, double-blind, crossover study. Cetirizine, after a single dose and 7 days of treatment with placebo, the geometric mean values of the provocative concentration of histamine causing a 20% fall in FEV1 (millimolars) were 1.60 (95% confidence interval, 0.82 to 3.11) and 1.67 (0.77 to 3.65), compared with 118.07 (77.22 to 180.54) (p less than 0.0001) and 53.16 (20.50 to 137.84) after cetirizine administration (p less than 0.0002). The mean inhibition after a single dose was twofold higher than after 1 week of treatment (p less than 0.05). After a single dose and 7 days of treatment with placebo, the geometric mean values of the provocative concentration of LTD4 causing a 20% fall in FEV1 (micromolars) were 2.26 (1.74 to 2.94) and 2.37 (1.77 to 3.17), compared with 3.90 (2.60 to 5.86) (p less than 0.05) and 3.21 (2.28 to 4.52) after cetirizine administration. This result suggests that cetirizine is a potent H1 antagonist in the human airways. Diminished activity after 1 week of treatment suggests subsensitivity of H1 receptors developing in human airways. The small protective effect after a single dose against LTD4-induced bronchoconstriction indicates a nonspecific rather than a specific receptor antagonism.