Montelukast and bronchial inflammation in asthma: a randomised, double-blind placebo-controlled trial.

BACKGROUND: Examination of bronchoalveolar lavage, induced sputum, and peripheral blood indicate that cysteinyl leukotriene receptor blockers decrease inflammatory cells in asthma but these do not examine airway tissue per se. OBJECTIVES: Our objective was to determine the effect of montelukast, a leukotriene receptor antagonist, on airway tissue inflammatory cells by direct bronchoscopic examination of the bronchial mucosa. METHODS: Adult subjects with mild asthma (pre-bronchodilator FEV(1)> or =70% predicted; PC(20) of < or =4 mg/mL) were given 10mg/day oral montelukast (N=38) or placebo (N=37) for 6 weeks. Bronchial mucosal eosinophils and mast cells were identified and counted. RESULTS: Change from baseline in numbers of biopsy EG2+ ("activated") eosinophils was the primary endpoint; numbers of total (chromotrope 2R+) eosinophils and (tryptase+) mast cells were secondary. Unexpectedly, there were many patients with zero EG2+ eosinophils at baseline. There was a within-group decrease in EG2+ cells, from 13.54 cells/mm (at baseline) to 0.79 cells/mm at 6 weeks in the montelukast group (LS mean change; 95% confidence interval=-13.59 [-25.45, -1.74]cells/mm; P<0.05), a change not observed in the placebo group (-1.17 [-13.26, 10.91]cells/mm; NS). The zero-inflated Poisson statistical model demonstrated that montelukast significantly reduced post-treatment EG2+ cells by 80% compared with placebo (95% CI [70.6-86.8%]; P<0.0001). The data for total eosinophils showed similar changes. The reduction in mast cell numbers was 12% (95% CI [7.9, 16.0]; P<0.0001). CONCLUSION: Direct examination of airway tissue confirms that montelukast decreases the number of eosinophils and mast cells in asthma.

Montelukast improves symptoms of seasonal allergic rhinitis over a 4-week treatment period.

BACKGROUND: Proinflammatory mediators such as the cysteinyl leukotrienes are important in the pathophysiology of allergic rhinitis. This study evaluated the efficacy and tolerability of montelukast, a cysteinyl leukotriene receptor antagonist, given once daily in the morning for treatment of seasonal (fall) allergic rhinitis for 4 weeks. METHODS: This was a randomized, double-blind trial with a placebo run-in and a 4-week treatment period. Patients (n = 1079) with a history of allergic rhinitis and a positive skin test to seasonal pollen allergens were assigned to placebo, montelukast 10 mg, or loratadine 10 mg. Symptoms were assessed with a daily diary. RESULTS: Montelukast was more effective than placebo in improving scores for the primary endpoint of daytime nasal symptoms (P = 0.003) and the secondary endpoints of night-time, composite, and daytime eye symptoms, patient's and physician's global evaluations of allergic rhinitis, and rhinoconjunctivitis quality-of-life (P

Montelukast for treating seasonal allergic rhinitis: a randomized, double-blind, placebo-controlled trial performed in the spring.

BACKGROUND: Cysteinyl leukotrienes are important proinflammatory mediators believed to have a role in allergic rhinitis. OBJECTIVE: This multicentre, randomized, double-blind, placebo- and active-controlled trial evaluated the effectiveness and tolerability of montelukast, a cysteinyl leukotriene receptor antagonist, for treating patients with seasonal allergic rhinitis. METHODS: After a 3- to 5-day, single-blind placebo run-in period, 1302 male and female patients (aged 15-81 years) with active allergic rhinitis symptoms were randomly assigned to receive montelukast 10 mg (n = 348), loratadine 10 mg (n = 602), or placebo (n = 352) administered once daily at bedtime for 2 weeks during the spring allergy season. RESULTS: Mean patient characteristics and symptom scores at baseline were similar for the three treatment groups. The primary end-point, daytime nasal symptoms score (mean of nasal congestion, rhinorrhea, nasal pruritus, and sneezing scores; 0-3 scale), improved from baseline during treatment by (least squares mean, 95% confidence interval) - 0.37 (- 0.43, - 0.31), - 0.47 (- 0.52, - 0.43), and - 0.24 (- 0.29, - 0.18) in the montelukast, loratadine, and placebo groups, respectively (P < or = 0.001 comparing each active treatment with placebo). Mean changes from baseline in all other diary-based scores, including night-time and eye symptom scores, were significantly greater for each active treatment than for placebo. The rhinoconjunctivitis quality of life overall score improved significantly with montelukast and with loratadine as compared with placebo. Montelukast and loratadine showed a safety profile comparable to that of placebo. CONCLUSION: Montelukast is well tolerated and provides improvements in daytime and night-time symptoms, as well as quality of life parameters, for patients with seasonal allergic rhinitis.

Analysis of montelukast in mild persistent asthmatic patients with near-normal lung function.

Few studies have specifically evaluated controller therapy in patients with mild persistent asthma. We used a subgroup analysis to investigate the effects of montelukast, a potent cysteinyl leukotriene receptor antagonist, on adult patients on the milder end of the asthma severity spectrum. We have identified seven double-blind, randomized, placebo-controlled studies of adult patients with mild-to-moderate chronic asthma in which montelukast was investigated. Subsets of patients with baseline forced expiratory volume in 1 sec (FEV1) > 80% and > 75% predicted or further restricted by less than daily rescue beta-agonist use were included as four cohorts (A, B, C, D), and efficacy measures, including change in FEV1 rescue-free days, beta-agonist use, nocturnal awakenings and blood eosinophil counts were evaluated. Cohorts A to D comprised 21%, 8%, 11%, and 4%, respectively, of patients from these studies. Mean pretreatment FEV1 ranged from 81% to 84% predicted and daily beta-agonist use from 2.4 to 4.5 puffs day(-1) in the four cohorts. Pooled results demonstrated a treatment effect for montelukast over placebo in all cohorts, for all endpoints. There was a significant improvement in FEV1 in montelukast-treated patients (7-8% over baseline) compared with placebo (1-4% over baseline, between-group difference P < or = 0.02) for all cohorts. Similarly, the percentage of rescue-free days increased substantially more with montelukast (22-30%) than with placebo (8-13%). This subgroup analysis indicates that montelukast produced improvements in parameters of asthma control in patients with milder persistent asthma that should be confirmed in additional prospective trials.

Long-term asthma control with oral montelukast and inhaled beclomethasone for adults and children 6 years and older.

BACKGROUND: Leukotriene receptor antagonists have demonstrated clinical benefits in chronic asthma studies of up to 3 months in duration. The effects of these agents over extended periods of time have not been reported. OBJECTIVE: To describe the long-term effect of oral montelukast, a potent and specific cysteinyl leukotriene receptor antagonist, compared with inhaled corticosteroids in both adult and paediatric patients with chronic asthma. METHODS: Male and female patients with chronic, stable asthma (adults aged 15-85 years, children aged 6-14 years), who had completed double-blind, placebo-controlled clinical studies, participated in three extension studies with oral montelukast taken once daily (10 mg tablet for adults, 5 mg chewable tablet for paediatric patients) or inhaled corticosteroids (beclomethasone 200 microg twice daily for adults, beclomethasone 100 microg or equivalent three times daily for children). A double-blind adult extension study was 37 weeks in duration; open-label adult extension studies were 156 (adults) and 112 (paediatric) weeks in duration. A total of 436, 374, and 245 patients entered these extension studies, respectively. RESULTS: Treatment with both montelukast and inhaled corticosteroids resulted in improvement in multiple parameters of asthma control. Improvements in daytime symptom scores were generally comparable among treatment groups. No tachyphylaxis to the effects of montelukast was evident. In the adult open-label study, however, the effect of beclomethasone on mean forced expiratory volume in 1 second (FEV1) gradually decreased from start of the study to the end of the follow-up treatment period. CONCLUSION: Both montelukast and inhaled corticosteroids were effective in controlling mild to moderate chronic asthma; the relative effectiveness of montelukast and beclomethasone were similar in open-label conditions. The hypothesis, that clinical practice conditions (e.g., adherence) may have a significant impact on the effectiveness of these therapies, should be tested in future clinical trials.

Correlation of airway obstruction and patient-reported endpoints in clinical studies.

To establish the correlation among asthma efficacy parameters over a long period, data from over 1,500 patients in two one-year asthma clinical trials with montelukast, a Cys-LT1 antagonist, were analysed. Airway obstruction measurements, forced expiratory volume in one second (FEV1) and peak expiratory flow (PEF), were measured at clinic visits. Patients recorded daytime symptom score, "as-needed" beta-agonist use, and PEF on a daily basis. Relationships among these parameters at baseline and during the one-year treatment period were established by correlation analyses. Multiple correlations between the airway obstruction (FEV1 and PEF) and patient-reported measurements were evaluated by canonical correlation analysis. Pairwise correlations of the efficacy parameters over a one-year time period were stable. Canonical correlation between the airway obstruction and patient-reported asthma efficacy endpoints was low, indicating that each category of endpoints measures a distinctively different aspect of the disease. It appears that at least one endpoint from each category should be used in asthma clinical studies.

Concomitant montelukast and loratadine as treatment for seasonal allergic rhinitis: a randomized, placebo-controlled clinical trial.

BACKGROUND: Nasal challenge studies have suggested histamine and cysteinyl leukotrienes are important proinflammatory mediators in allergic rhinitis. This study was designed to determine the efficacy of montelukast, a cysteinyl leukotriene receptor antagonist, administered alone or concomitantly with loratadine, an H(1)-receptor antagonist, in seasonal allergic rhinitis. OBJECTIVE: The purpose of this study was to determine the effect of concomitant use of montelukast and loratadine in the treatment of seasonal allergic rhinitis. METHODS: In this multicenter (N = 12) double-blind, randomized, parallel-group, placebo-controlled 2-week trial, 460 men and women, aged 15 to 75 years, with spring seasonal allergic rhinitis were randomly allocated to receive 1 of the following 5 treatments: montelukast 10 or 20 mg, loratadine 10 mg, montelukast 10 mg with loratadine 10 mg, or placebo, once daily in the evening. The primary end point was daytime nasal symptoms score (average of congestion, rhinorrhea, itching, and sneezing). Other end points were eye symptoms, nighttime symptoms, individual daytime nasal symptoms, global evaluations (patient's and physician's), and rhinoconjunctivitis quality-of-life scores. RESULTS: Concomitant montelukast with loratadine improved the primary end point significantly (P <.001) compared with placebo and each agent alone. Compared with placebo, montelukast with loratadine also significantly improved eye symptoms, nighttime symptoms, individual daytime nasal symptoms, global evaluations, and quality of life. Montelukast alone and loratadine alone caused modest improvements in rhinitis end points. All treatments were similarly well tolerated. CONCLUSIONS: Concomitant montelukast with loratadine provided effective treatment for seasonal allergic rhinitis and associated eye symptoms with a safety profile comparable with placebo.

Montelukast reduces airway eosinophilic inflammation in asthma: a randomized, controlled trial.

Leukotrienes are pro-inflammatory mediators which may contribute to tissue, sputum, and blood eosinophilia seen in allergic and inflammatory diseases, including asthma. Montelukast is a cysteinyl leukotriene1 (CysLT1) receptor antagonist which improves asthma control; the aim of this study was to investigate its effect on induced sputum eosinophils. Montelukast 10 mg (n=19) or placebo (n=21) were administered orally once in the evening for 4 weeks to 40 chronic adult asthmatic patients, aged 19-64 yrs, in a double-blind, randomized, parallel group study. Patients were included if, at prestudy, they had >5% sputum eosinophils, symptomatic asthma with a forced expiratory volume in one second > or =65% of the predicted value and were being treated only with "as needed" inhaled beta2-agonists. In addition to sputum eosinophils, blood eosinophils and clinical endpoints were also assessed. Four weeks of montelukast treatment decreased sputum eosinophils from 7.5% to 3.9% (3.6% decrease, 95% confidence interval (CI) -16.6-0.4). In contrast, placebo treatment was associated with an increase in sputum eosinophils from 14.5% to 17.9% (3.4% increase, 95% CI -3.5-9.8). The least squares mean difference between groups (-11.3%, 95% CI -21.1-(-1.4)) was significant (p=0.026). Compared with placebo, montelukast significantly reduced blood eosinophils (p=0.009), asthma symptoms (p=0.001) and beta2-agonist use (p<0.001) while significantly increasing morning peak expiratory flow (p=0.001). Montelukast was generally well tolerated in this study, with a safety profile similar to the placebo. These results demonstrate that montelukast decreases airway eosinophilic inflammation in addition to improving clinical parameters. Its efficacy in the treatment of chronic asthma may be due, in part, to the effect on airway inflammation.

A placebo-controlled, dose-ranging study of montelukast, a cysteinyl leukotriene-receptor antagonist. Montelukast Asthma Study Group.

BACKGROUND: The cysteinyl leukotrienes are important mediators of bronchial asthma. The clinical effect of montelukast, a potent cysteinyl leukotriene-receptor antagonist, was investigated in a randomized, placebo-controlled, multicenter, parallel-group, dose-ranging study. METHODS: After a 3-week, single-blind, placebo run-in period, 343 asthmatic patients (FEV1 40% to 80% of the predicted value with an improvement in FEV1 of at least 15% [absolute value] after receiving inhaled beta-agonists on at least two occasions) were randomly assigned to one of six treatment groups: placebo; 10, 100, or 200 mg once daily montelukast in the evening; or 10 or 50 mg twice daily montelukast for a 6-week, double-blind treatment period followed by a 1-week placebo washout period. All patients used inhaled, short-acting beta-agonists as needed. RESULTS: All montelukast doses caused similar and significant differences compared with placebo in asthma control endpoints. The least-square mean difference between pooled montelukast groups and placebo in the percentage change from baseline in morning FEV1 (10.30%; 95% CI: 5.56 to 15.04), as-needed beta-agonist use (-0.98 puffs; 95% CI: -1.53 to -0.44), morning peak expiratory flow rate (18.80 L/min; 95% CI: 8.62 to 28.98), physicians' and patients' global evaluations, and asthma-specific quality-of-life scores were all significant (p < or = 0.050). The incidence of adverse experiences was not dose related and was similar between placebo and montelukast treatment. CONCLUSION: Montelukast caused a significant improvement in chronic asthma at an oral, once daily evening dose as low as 10 mg.

Effect of montelukast on single-dose theophylline pharmacokinetics.

The effect of montelukast (MK-0476), a cysteinyl leukotriene receptor antagonist in development for treatment of asthma, on single-dose theophylline plasma concentrations was studied in three separate clinical trials. Montelukast was evaluated at 10 mg once daily (the clinical dosage), 200 mg once daily, and 600 mg (200 mg three times daily). At the clinical dosage, montelukast did not change single-dose theophylline plasma concentration in a clinically important manner. The geometric mean ratios for theophylline area under the plasma concentration versus time curve (AUC0-->infinity ) (0.92) and maximal plasma concentration (Cmax ) (1.04) were well within the predefined and generally accepted bioequivalence range of 0.80 and 1.25. Montelukast decreased theophylline Cmax by 12% and 10%, AUC0-->infinity by 43% and 44%, and elimination half-time by 44% and 39% at 200 mg/d (oral and intravenous, respectively), and at 600 mg/d, montelukast decreased theophylline Cmax by 25%, AUC0-->infinity by 66%, and elimination half-time by 63%. These results show that montelukast at the clinical dosage did not change theophylline pharmacokinetics in a clinically important manner, but at 20- to 60-fold higher dosages, montelukast significantly reduced the theophylline pharmacokinetics parameters; an apparent dosage dependence is suggested.

Dose-related protection of exercise bronchoconstriction by montelukast, a cysteinyl leukotriene-receptor antagonist, at the end of a once-daily dosing interval.

The dose-related protective effects of montelukast, a potent and selective cysteinyl leukotriene-receptor antagonist, against exercise-induced bronchoconstriction were investigated in a five-period, randomized, incomplete-block, crossover study with montelukast (0.4, 2, 10, 50 mg) and placebo. The study subjects were 27 nonsmoking, healthy stable patients with asthma (mean forced expiratory volume in 1 second [FEV1], 82.0% predicted) who demonstrated a > or = 20% decrease in FEV1 while beta-agonist was withheld for 6 hours before treadmill exercise. The standard exercise challenge was performed 20 to 24 hours, and again 32 to 36 hours, after the second of two once-daily doses. The effect of oral montelukast on exercise was measured by the area above the postexercise percentage decrease in FEV1 versus time curve from 0 to 60 minutes [AUC(0-60)], the maximal percentage decrease in FEV1 after exercise, and time after maximal decrease to recovery of FEV1 to within 5% of the preexercise baseline. Twenty to 24 hours after administration, montelukast caused dose-related protection, while providing similar protection against exercise-induced bronchoconstriction at the two highest doses. The AUC(0-60) values (mean +/- SD) were 637 +/- 898, 715 +/- 870, 988 +/- 1147, and 927 +/- 968 min. % for 50, 10, 2, and 0.4 mg montelukast, respectively, and 1193 +/- 1097 min. % for placebo (p = 0.003). No important clinical effect was present 36 hours after dosing. Montelukast was generally well tolerated at all dose levels. In conclusion, montelukast caused dose-related protection against exercise-induced bronchoconstriction at the end of a once-daily dosing interval. Protection against exercise-induced bronchoconstriction can be used to determine appropriate dose selection.

Effects of montelukast (MK-0476); a potent cysteinyl leukotriene receptor antagonist, on bronchodilation in asthmatic subjects treated with and without inhaled corticosteroids.

BACKGROUND: Cysteinyl leukotriene release in association with airway inflammation is a feature of clinical asthma. The acute effects of montelukast (MK-0476), a potent, orally administered, specific cysteinyl leukotriene receptor antagonist, on airways obstruction was assessed in patients with mild to moderately severe asthma. METHODS: Twenty two asthmatic subjects were randomised to receive montelukast, 100 mg or 250 mg, or placebo in a double blind, three period, crossover trial. Ten of the patients were using concomitant inhaled corticosteroids. RESULTS: Montelukast increased the forced expiratory volume in one second (FEV1) from predose baseline values compared with placebo, the percentage point differences between montelukast and placebo being 8.6% (95% CI 3.6 to 13.6) and 8.5% (95% CI 3.5 to 13.5) for the 100 mg and 250 mg doses, respectively. CONCLUSION: Single oral doses of montelukast 100 mg and 250 mg produced significant increases in FEV1 irrespective of the concurrent use of inhaled corticosteroids in asthmatic subjects with airflow limitation.

Montelukast causes prolonged, potent leukotriene D4-receptor antagonism in the airways of patients with asthma.

Montelukast, a new specific oral cysteinyl LT3-receptor antagonist was evaluated for its activity in attenuating inhaled leukotriene D4 (LTD4) bronchoconstriction in patients with asthma. In two double-blind, placebo-controlled, randomized crossover studies, patients with mild asthma (forced expiratory volume in 1 second [FEV1] > or = 70%) were studied. In trial A, LTD4 challenge began 4 hours (peak plasma concentration) after a single dose of placebo or 5, 20, 100, and 250 mg montelukast. In trial B, and LTD4 challenge was started 20 hours after administration of placebo, 40 mg montelukast, or 200 mg montelukast. During each challenge, twofold increasing concentrations of LTD4 were inhaled until specific airways conductance (sGaw) decreased by at least 50% (PC50) or the highest concentration of LTD4 was inhaled. In trial A with all doses and in trial B with the 200 mg dose, bronchoconstriction was attenuated (50% fall in sGaw was not observed) up to the highest dose of LTD4 administered. In trial B, during the 40 mg period, only two of six patients exhibited a 50% fall in sGaw; PC50 ratios (montelukast 40 mg/placebo) were 18 and 45 in these two patients. These results indicate that montelukast is a highly potent and long-lasting antagonist of LTD4-induced bronchoconstriction in patients with asthma.

Increased urinary excretion of LTE4 after exercise and attenuation of exercise-induced bronchospasm by montelukast, a cysteinyl leukotriene receptor antagonist.

BACKGROUND: A study was undertaken to determine whether montelukast, a new potent cysteinyl leukotriene receptor antagonist, attenuates exercise-induced bronchoconstriction. The relationship between the urinary excretion of LTE4 and exercise-induced bronchoconstriction was also investigated. METHODS: Nineteen non-smoking asthmatic patients with a forced expiratory volume in one second (FEV1) of > or = 65% of the predicted value and a reproducible fall in FEV1 after exercise of at least 20% were enrolled. Subjects received placebo and montelukast 100 mg once daily in the evening or 50 mg twice daily, each for two days, in a three-period, randomised, double blind, crossover design. In the evening, approximately 20-24 hours after the once daily dose or 12 hours after the twice daily dose, a standardised exercise challenge was performed. Data from 14 patients were available for complete analysis. RESULTS: The mean (SD) maximal percentage decrease in FEV1 after exercise was 29.6 (16.0), 17.1 (8.2), and 14.0 (9.4) for placebo, once daily, and twice daily regimens, respectively. The mean (95% CI) percentage protection was 37 (15 to 59) for the group who received 50 mg twice daily and 50 (31 to 69) for those who received 100 mg once daily. Active treatments were not different from each other. The mean (SD) plasma concentrations of montelukast were higher after the twice daily regimen (1.27 (0.81) microgram/ml) than after the once daily regimen (0.12 (0.09) microgram/ml); there was no correlation between the percentage protection against exercise-induced bronchoconstriction and plasma concentrations. After exercise urinary excretion of LTE4 increased significantly during placebo treatment (from 34.3 to 73.7 pg/mg creatinine; p < 0.05) but did not correlate with the extent of exercise-induced bronchoconstriction. CONCLUSIONS: Montelukast protects similarly against exercise-induced bronchoconstriction between plasma concentrations of 0.12 and 1.27 micrograms/ml. The increase in the urinary excretion of LTE4 after exercise and the protection from exercise-induced bronchoconstriction with a cysteinyl leukotriene receptor antagonist provide further evidence of the role of leukotrienes in the pathogenesis of exercise-induced bronchoconstriction.

Effects of montelukast (MK-0476), a new potent cysteinyl leukotriene (LTD4) receptor antagonist, in patients with chronic asthma.

BACKGROUND: Cysteinyl leukotrienes mediate signs and symptoms of asthma. In a double-blind, placebo-controlled, crossover study, a new potent and specific cysteinyl leukotriene (LTD4) receptor antagonist, montelukast (MK-0476), was evaluated for tolerability and clinical efficacy in patients with chronic asthma (receiving and not receiving inhaled corticosteroids). METHODS: Twenty-nine nonsmoking patients with asthma (15 treated concomitantly with inhaled corticosteroids) with FEV1 percent predicted values between 50% to 80% received MK-0476, 200 mg, or placebo three times daily for 10 1/3 days (31 doses) in a random, crossover manner, after a 2-week, open, baseline period. Comparisons in FEV1 (mean percent change from baseline after the first and last dose), mean daily daytime asthma and nocturnal awakening scores, and mean daily beta-agonist use were made between treatment periods. RESULTS: Montelukast, compared with placebo, caused improvements in FEV1 (mean percentage point difference of the percentage change from baseline) 3 and 4 hours after dosing on day 1 (hour 3, 9.0%; 95% confidence interval [CI] 0.53, 18.72; hour four, 10.9%; 95% CI -0.25, 20.20) and day 11 (hour 3, 14.0%; 95% CI 0.76, 31.43; hour 4, 13.4%; 95% CI 1.24, 28.83). Reductions were observed in mean daily beta-agonist use (1.0 puff/day [95% CI -1.61, -0.26]), mean daytime symptom scores, and nocturnal awakenings over the 10 1/3 day treatment period. There were no important differences between the groups receiving and those not receiving inhaled corticosteroids. Montelukast was well tolerated with no serious clinical adverse events reported. CONCLUSIONS: In this study Montelukast, 200 mg, administered three times daily for 10 1/3 days, compared with placebo, was generally well tolerated and resulted in significant improvement in chronic asthma, irrespective of the presence of inhaled corticosteroids.

Acute bronchodilation with an intravenously administered leukotriene D4 antagonist, MK-679.

Descriptive studies suggest an association between the release of the cysteinyl leukotrienes and clinical asthma. To help clarify this association, we tested the hypothesis that an intravenous infusion of a potent and specific investigational LTD4 receptor antagonist, MK-679, would cause rapid bronchodilation. In a three-period, randomized, double-blind, crossover study, single doses of MK-679, 125 and 500 mg, and placebo were given intravenously by bolus infusion to nine patients with moderate, stable asthma (FEV1 40 to 80% predicted) on individual study days separated by a week. Spirometry was preformed predose and at intervals for as long as 8 h postdosing; blood samples for MK-679 concentrations were drawn over this time. Fifteen minutes after the end of infusion, the FEV1 percent change from baseline increased a mean of 15.8 +/- 15.7 and 7.8 +/- 11.6% with the 500- and 125-mg doses, respectively, compared with a mean decrease of 2.6 +/- 6.2% with placebo (p = 0.01, overall; p = 0.003, 500 mg versus placebo). The mean end-of-infusion MK-679 plasma concentrations were 86.2 +/- 13.9 and 19.9 +/- 2.7 micrograms/ml for the 500- and 125-mg doses, respectively. MK-679 was well-tolerated, with no significant adverse experiences observed. We conclude that a single, intravenously administered, bolus infusion of MK-679 causes bronchodilation in patients with moderate, stable asthma.

Effects of 0.60 PPM nitrogen dioxide on circulating and bronchoalveolar lavage lymphocyte phenotypes in healthy subjects.

Nitrogen dioxide (NO2) is a common oxidant air pollutant. Animal studies have suggested that NO2 exposure causes a decrease in the numbers of some splenic lymphocyte subtypes and impairs lymphocyte-dependent immune responses. To investigate whether ambient levels of NO2 alter circulating and bronchoalveolar lavage fluid (BALF) human lymphocytes, we studied five healthy nonsmoking adult volunteers. In each subject, blood and bronchoalveolar lavage fluid was obtained and then, more than 2 weeks later, volunteers were exposured to 0.60 ppm NO2 for 2 hr with intermittent light to moderate exercise on 4 separate days within a 6-day period. We measured standard tests of pulmonary function (airway resistance, thoracic gas volume, maximal expiratory flow) and had the subjects rate the severity of respiratory symptoms before and after each NO2 exposure. Circulating and BALF lymphocytes were labeled with fluorochrome-conjugated monoclonal antibodies to human lymphocyte antigens and a flow cytometer was used to count lymphocyte subtypes. Neither any single day's exposure nor all four exposures caused a change in symptoms or in the results of tests of pulmonary function. The total number of circulating lymphocytes obtained after NO2 exposure was slightly greater than at baseline (1792 +/- 544 vs 1598 +/- 549 cells/mm3 at baseline; P = not significant) but the proportions of lymphocyte subtypes did not differ. In the BALF obtained after NO2 exposure and in the baseline state, the total number of lymphocytes and the percentages of T cells (CD 3), B cells (CD 20), T cytotoxic-suppressor cells (CD 8), T helper-inducer cells (CD 4), and large granular lymphocytes (CD 57) also did not differ after NO2 exposure. A slightly but significantly greater proportion of natural killer cells (CD 16) was found in the BALF obtained after NO2 exposure (7.2 +/- 3.1 vs 4.2 +/- 2.4% of total lymphocytes). We conclude that repeated exposures of healthy nonsmoking adults to 0.60 ppm NO2 are not associated with clinically significant symptoms, changes in airway caliber, or alterations in circulating and BALF lymphocyte subtypes. We suggest that brief, daily exposures to NO2 at levels higher than those achieved in urban atmosphere are unlikely to provoke acute respiratory impairment in healthy, nonsmoking adults.

Abnormal lung gallium-67 uptake preceding pulmonary physiologic impairment in an asymptomatic patient with Pneumocystis carinii pneumonia.

Pneumocystis carinii pneumonia was suggested by a diffuse, bilateral pulmonary uptake of gallium-67 in an asymptomatic, homosexual male with the antibody to the immunodeficiency virus (HIV) who was undergoing staging evaluation for lymphoma clinically localized to a left inguinal lymph node. Chest radiograph and pulmonary function evaluation, including lung volumes, diffusing capacity and arterial blood gases, were within normal limits. Bronchoalveolar lavage revealed Pneumocystis carinii organisms. In this asymptomatic, HIV-positive patient, active alveolar infection, evidenced by abnormal gallium-67 scanning, predated pulmonary physiologic abnormalities. This observation raises questions concerning the natural history of this disease process and the specificity of physiologic tests for excluding disease. It also has implications for the treatment of neoplasia in the HIV-positive patient population.

Local mediator release after antigen challenge of a bronchial segment in allergic dogs.

To investigate the local intraluminal bronchial response to an antigenic stimulus, we developed a bronchoscopic double-balloon system to challenge and lavage a segment of the left main-stem bronchus. We studied whether fluid from above or below the occlusion balloons leaked into the bronchial segment. Lavage was performed before and after placement of red and blue pigments proximal and distal to the inflated balloons, respectively, and the recovered lavage fluid was analyzed visually and spectrophotometrically in three experiments. There was no evidence for pigment leakage into the segment. In six anesthetized ragweed-allergic dogs, local ragweed antigen challenges were performed. After balloon inflation in the left main-stem bronchus, we performed two baseline lavages of the interballoon segment, introduced a ragweed antigen solution, and performed two postchallenge lavages. The recovered fluid was analyzed for the concentrations of prostaglandin D2 (PGD2; radioimmunoassay) and histamine (fluorometric technique) and for total and differential cell counts. Antigen challenge was associated with a significant increase in PGD2 concentration in the recovered fluid, rising from a median of 178 pg/ml (range, 157-647) before to 919 pg/ml (range, 149-2,452) after challenge. Median histamine concentrations were 3.1 ng/ml (range, 1-5.4 ng/ml) before and 5.6 ng/ml (range, 1-16.2) after challenge (P = not significant). In four dogs, a control challenge with the antigen vehicle alone showed no change in either mediator. Changes in cell counts after challenge were inconsistent.(ABSTRACT TRUNCATED AT 250 WORDS)