INTRODUCTION

TOP ABSTRACT INTRODUCTION METHODS RESULTS DISCUSSION REFERENCES

Asthma and allergic rhinitis are common conditions, occurring with increasing prevalence, and frequently coexisting (1). Both conditions occur in patients with underlying atopy and have a common etiology and pathophysiology. Untreated rhinitis can result in increased lower respiratory tract inflammation (2) due to a variety of possible mechanisms (3). There is good evidence to show that treating the upper airway inflammation in seasonal allergic rhinitis with intranasal corticosteroids alone has beneficial effect on lower airway inflammation in terms of an improvement in bronchial hyperreactivity (4).

Topically delivered inhaled and intranasal corticosteroids are widely recognized as effective anti-inflammatory treatment for both conditions (5, 6). They work by altering gene transcription to increase or decrease a plethora of cytokines, inflammatory mediators and enzymes, and adhesion molecules (7). Histamine and cysteinyl leukotrienes are important inflammatory mediators in the pathogenesis of asthma and allergic rhinitis. With the introduction of leukotriene receptor antagonists it is now possible to selectively block the effects of both of these mediators. This may have a theoretical advantage over corticosteroid therapy as a result of a better adverse effect profile as well as the preference for taking tablets rather than inhalers and nasal sprays.

The anti-inflammatory properties of leukotriene receptor antagonists have been shown to exhibit beneficial effects on asthma disease control (8). Antihistamines have been considered to be effective in the management of asthma associated with seasonal allergic rhinitis (SAR) (9). There is some evidence, however, that combined mediator blockade, with both histamine and leukotriene receptor antagonist, affords greater symptom control than a leukotriene receptor alone in patients with persistent asthma (10). The late-phase allergic response is considered to be due to influx of inflammatory cells and is associated with an increase in nonspecific bronchial hyperreactivity. Leukotriene receptor antagonists have been shown to attenuate this response (11). Roquet and coworkers (12) have shown that although zafirlukast exhibited greater bronchoprotection after allergen challenge than loratadine, in terms of early asthmatic response, the combination of both treatments was significantly more effective than either alone in terms of the late asthmatic response. There have, however, been no studies comparing combined mediator blockade with topical corticosteroids in patients with asthma and allergic rhinitis. The aim of our study was to compare the antiasthmatic efficacy of combined histamine and leukotriene receptor antagonism with combined inhaled and intranasal corticosteroids in patients with SAR and asthma with bronchial hyperreactivity.

The study was performed during the pollen season in Tayside. Because of the short window when pollen counts are high, it was only possible to assess the effects of 2 wk of each active therapy. However, this has been shown to be an adequate length of time to achieve the majority of response in patients with antileukotrienes, antihistamines, inhaled and intranasal corticosteroids (13).

	METHODS

TOP ABSTRACT INTRODUCTION METHODS RESULTS DISCUSSION REFERENCES

Twenty-one patients with a history of SAR and asthma initially attended for screening, of which 14 patients were found to have hyperresponsiveness to adenosine monophosphate (AMP) bronchial challenge (defined as a provocative concentration causing a 20% reduction in FEV₁ [PC₂₀] < 200 mg/ml). AMP was used as it is an indirect challenge (like allergen challenge) and acts via release of inflammatory mediators from primed mast cells. The data pertaining to upper airway inflammation and symptoms of SAR for all 21 patients will be reported elsewhere. This study reports the effect of therapy on lower airway parameters in the 14 patients with bronchial hyperresponsiveness. All patients had stable mild to moderate asthma and symptomatic SAR according to current criteria (17, 18), with mean (± SE) age 32 ± 2.3 yr, FEV₁ 81 ± 3.8% predicted.

Prior to study entry, six patients were taking inhaled corticosteroids (budesonide 800 µg/d n = 1; beclomethasone 800 µg/d n = 1, 400 µg/d n = 2, 200 µg/d n = 2), four were taking intranasal corticosteroids (beclomethasone 400 µg/d n = 3; fluticasone propionate 200 µg/d n = 1), and four were taking oral antihistamines (loratadine 10 mg/d n = 3; fexofenadine 120 mg/d n = 1). All patients had a positive skin-prick test to grass pollens. Five patients also had positive skin-prick test to tree pollens, six patients had a positive reaction to week pollen, and five patients had a positive reaction to house dust mite. No patient had received oral corticosteroids or antibiotics for 6 mo before the study. All patients were nonsmokers and had normal full blood count, biochemical profile, and urinalysis. Approval for the study was obtained from the Tayside Medical Ethics Committee and all patients gave their written informed consent.

The study was of a randomized placebo-controlled, single-blind, double-dummy, crossover design (Table 1). Patients were recruited during June and July 1999 when grass pollen levels are typically high in Tayside. Patients were randomized to receive the following treatments for 2 wk, all given once daily at 8:00 A.M.: (1) 400 µg inhaled budesonide dry powder (Pulmicort Turbuhaler; Astra Zeneca, Kings Langley, Herts, UK as 2 puffs of 200 µg per actuation) plus 200 µg intranasal aqueous budesonide (Rhinocort Aqua; Astra Pharmaceuticals Ltd, as 1 squirt of 100 µg in each nostril) (BUD) plus placebo tablets; or (2) 10 mg oral montelukast (Singulair; Merck Sharpe & Dohme Ltd, Herts, UK) and 10 mg oral cetirizine (Zirtek; UCB Pharma, Watford, Herts, UK) (ML + CZ) plus placebo nasal spray and placebo Turbuhaler. Before each treatment, and at crossover, patients had a 1-wk washout period with placebo Turbuhaler (2 inhalations), placebo nasal spray (1 squirt in each nostril), and placebo tablets all taken at 8:00 A.M.

The Turbuhalers and nasal sprays were masked and sealed in envelopes by a pharmacist along with instruction sheets at the beginning of the trial. Before the study and at each visit, patients were given detailed instruction by a third party in how to use their nasal sprays and Turbuhaler. Nasal sprays were primed according the manufacturers' instructions and patients had to demonstrate adequate technique using Turbuhaler usage trainer (Astra Draco, Lund, Sweden) before progressing through the study. Each patient received a written instruction sheet, based on manufacturers' recommendations, to follow while taking their medication at home, and a simple tick chart was used as an aid to compliance. Data from patients with more than 90% compliance were considered to be evaluable.

Measurements

All laboratory measurements were made at trough 24 h after the last morning dose to coincide with the usual dosing interval.

AMP challenge testing. AMP bronchial challenge testing was performed, as previously described (19), between 8:00 A.M. and 10:00 A.M. Patients withheld their reliever medication for 12 h before each testing. In brief, AMP was administered in doubling cumulative doses given at 5-min intervals until a decrease in FEV₁ greater than or equal to 20% was recorded. The PC₂₀ was calculated using a computer- assisted curve-fitting package (Biolab Assistant 1.1; University of Dundee, Dundee, UK) and interpolation of the steep part of the log dose-response curve. A value of 10 mg/ml was assigned if the FEV₁ did not fall below 20% of baseline value.

Exhaled nitric oxide (NO). Patients had a measurement of exhaled NO using an integrated, LR2000 clinical, real-time, NO gas analyzer with an accuracy of 2 parts per billion (ppb) NO and a response time of 2 s (Logan Research, Rochester, UK) according to the procedures described by Kharitonov and coworkers (20). The conditions of temperature (20° C), flow rate (250 ml/min), and mouth pressure (70 mm H₂O) were standardized throughout the study. Three measures of NO were taken and the results were analyzed as the mean of the three values. The analyzer was calibrated weekly using a cylinder of NO at concentration of 108 ppb.

Spirometry. Spirometry was performed according the American Thoracic Society criteria (21) using a Vitalograph compact spirometer (Vitalograph Ltd, Buckinghamshire, UK) with a pneumotachograph head and pressure transducer. This equipment was calibrated daily using a precision syringe (Vitalograph Ltd).

Diary card data. Patients filled in a daily diary card in the evening during the placebo and active treatment limbs. Patients measured their peak expiratory flow (PEF) using a Mini-Wright peak flow meter (Clement Clarke International Ltd, Essex, UK) at 10:00 P.M. and recorded the highest of three readings. Patients recorded their asthma symptoms, according to a four-point scale with zero indicating no symptoms and three indicating severe symptoms, and their requirement for rescue inhaler requirement with ₂-agonists in the evening. Patients were also asked to record how much their symptoms were interfering with their daily activity on an 11-point scale, with 0 representing no symptoms and 10 representing maximal symptoms.

Skin-prick testing. Patients withheld antihistamine medication for 4 d before skin-prick testing. This was performed following a standard protocol (Bencard testing solutions, Welwyn Garden City, UK) using extracts including grass, tree, and weed pollen in addition to a negative control. Results were read after 15 min, a positive reaction being defined as a wheal diameter at least 2 mm greater than negative control.

Pollen count measurement. Data were collected locally (Scottish Crop Research Institute, Dundee, UK) using a 7-day recording volumetric spore trap (Burkard Manufacturing Co. Ltd., Hertfordshire, UK).

Statistical Analysis

The study was powered at the 80% level to detect a 1.0 doubling dose difference (2.0-fold) in AMP PC₂₀ (the primary end-point) with the alpha error set at 0.05 (two-tailed). The data for AMP PC₂₀ were log-transformed in order to normalize their distribution before analysis. Daily tree, grass, and weed pollen count data were summed to provide a daily pollen score for each day of the study. For all domiciliary diary and pollen data, mean values for the last 5 d of the placebo periods and active treatment period were analyzed.

Overall comparisons between active treatments and placebos were made by multifactorial analysis of variance using subject, treatment, and period as factors. Analysis of covariance was used to account for any influence of pollen level. This was followed by multiple-range testing (set at 95% confidence interval [CI]) in order to obviate multiple pairwise comparisons. Consequently, comparisons are only denoted as being significant (p < 0.05, two-paired) or not significant in order to not confound the alpha error. The analysis was performed using Statgraphics statistical software package (STSC Software Publishing Group, Rockville, MD).

	RESULTS

TOP ABSTRACT INTRODUCTION METHODS RESULTS DISCUSSION REFERENCES

There were no significant carryover effects between the first and second placebo values in sequence with any of the measurements (Table 2).

Laboratory Data

For the primary end-point of AMP bronchial challenge, compared with pooled placebo (PL), there was significant (p < 0.05) bronchoprotection with combined mediator blockade, amounting to a geometric mean 3.9-fold difference (95% CI 1.5-fold to 10.1-fold), but not for inhaled budesonide (Figure 1). There was also significantly greater (p < 0.05) bronchoprotection with ML + CZ versus BUD: a 2.7-fold difference (95% CI 1.0 to 6.9). For exhaled NO, there was significant (p < 0.05) suppression with inhaled budesonide, amounting to a difference from pooled PL of 6.6 ppb (95% CI 2.3 to 10.9 ppb) but not with combined mediator blockade (Figure 1). For FEV₁ as percentage of predicted (mean ± SEM), there was a significant improvement with ML + CZ (101.9 ± 2.6), but not with BUD (96.6 ± 2.6), compared with pooled PL (93.1 ± 2.9). There was no significant suppression with either treatment in terms of overnight urinary cortisol/creatinine ratio (mean ± SEM): PL 6.4 ± 0.7; BUD: 6.2 ± 0.6; ML + CZ: 5.4 ± 0.7 nmol/mmol.

View larger version (19K): [in this window] [in a new window]   Figure 1.   (Top panel ) Geometric mean with SEM for AMP bronchial challenge PC20 for placebo, inhaled and intranasal budesonide (Budesonide), and oral montelukast plus cetirizine (Montelukast + Cetirizine). Asterisk denotes significant (p < 0.05) difference between active treatment and placebo. Cross denotes significant difference between active treatments. (Bottom panel ) Means with SEM for exhaled NO (ppb). Legend as in top panel.

Domiciliary Data

There was significant (p < 0.05) improvement in domiciliary measures with both treatments compared with pooled PL in terms of peak expiratory flow (PEF), rescue inhaler requirement, asthma symptom score, and daily activity score (Figure 2). There were no significant differences between the two active treatments.

View larger version (24K): [in this window] [in a new window]   Figure 2.   (Top left) Means with SEM for rescue inhaler requirement (units), (top right) PEFR (L/min), (bottom left) asthma symptom score (units), and (bottom right) daily activity score (units). Legend as in Figure 1, top panel.

	DISCUSSION

TOP ABSTRACT INTRODUCTION METHODS RESULTS DISCUSSION REFERENCES

We have shown that combined topical therapy with inhaled and intranasal budesonide exhibited significant suppression of exhaled NO but had no significant bronchoprotection against AMP bronchial challenge. In contrast, combined mediator blockade with histamine and leukotriene receptor antagonists resulted in the opposite finding in terms of significant bronchoprotection to AMP but no suppression of exhaled NO. Both treatments exhibited equal effects on domiciliary markers of asthma control. It is important to point out that all of our laboratory measurements were made at trough 24 h after the last morning dose. This timing would coincide with a period before the next dose when the airway would be most susceptible to bronchoconstrictor stimuli.

Exhaled NO has been shown to be particularly sensitive to the effects of inhaled corticosteroids with lower doses up to 400 µg/d resulting in near normalization of levels (22, 23). The activated glucocorticoid receptor avidly inhibits the induction of NO synthase (NOS) by inactivating nuclear factor kappa B (NF-B), an important inducing cytokine of NOS (24). There are few published data reporting the effects of leukotriene receptor antagonists on exhaled NO. Pranlukast has been shown to suppress exhaled NO in adults during step-down of high-dose inhaled corticosteroid (25), as has montelukast in asthmatic children (26).

Our results showing no effect on bronchial hyperresponsiveness were in keeping with those of Jatakanon and coworkers (23), who showed no significant bronchoprotection against methacholine bronchial challenge with budesonide 400 µg/d for 4 wk; although there was a significant effect with budesonide 1,600 µg/d for 4 wk. There is a dose-response effect with inhaled glucocorticoid for bronchoprotection against both direct and indirect challenges (22) although the curve will be shifted to the left or right on an individual basis depending on asthma severity and corticosteroid receptor responsiveness. The lack of response in terms of bronchial challenge with budesonide in our study may also be due to the fact that our patients were taking their inhaler once daily and challenges were performed at trough 24 h after dosing.

The different stimuli for a bronchial challenge testing have different advantages and disadvantages. AMP bronchial challenge has been shown to be more sensitive than methacholine in terms of effects of inhaled corticosteroids. It also has a shorter time required to achieve a maximal response with inhaled corticosteroids than direct bronchial challenges, for example, with methacholine. Indeed, in a recent study with inhaled fluticasone propionate given twice daily there was suppression of bronchial hyperreactivity to AMP on the second day of treatment with a 3.4 and 3.75 doubling dose difference after 3 and 7 doses respectively (13). Bronchial challenge testing with AMP is also considered to be more representative than methacholine of real-life asthmatic responses (27), and is an indirect stimulus like allergen, cold air, or exercise.

AMP acts indirectly by binding to adenosine receptors on mast cells causing them to degranulate and release inflammatory mediators inducing bronchoconstriction. Of these mediators, the most important are histamine, prostaglandins, and leukotrienes (28). Roquet and coworkers (12) have shown that these mediators play a major part in both the early and late asthmatic response to allergen challenge as airway response was blocked by the combination of zafirlukast plus loratadine. Therefore, blocking two of these mediators specifically will result in protection of the bronchoconstrictive effects of AMP (29, 30). It may pose problems when interpreting the results of studies comparing different classes of anti-inflammatory therapy for asthma.

In terms of the patients' symptoms, rescue inhaler requirement, and PEF, there were significant improvements with both topical corticosteroids and combined mediator blockade when compared with placebo, although there were no significant differences between these forms of treatment. Our results with montelukast and cetirizine are in keeping with previous abstracted data showing improvements in asthmatic symptoms and daily ₂-agonist usage with combined therapy of montelukast and loratadine compared with placebo (10). Other larger multicenter studies have also demonstrated the antiasthmatic efficacy of 400 µg once-daily inhaled budesonide in terms of PEF, symptoms, -agonist use, and quality of life in mild to moderate asthmatic patients (31).

It is worth noting that we did not show any systemic adverse effects with inhaled budesonide at a dose of 400 µg per day in terms of overnight urinary cortisol/creatinine ratio. This parameter has been shown to be as sensitive as a full 24-h urinary collection and more sensitive than morning serum cortisol suppression (32). These data are in keeping with previous work where 400 µg or 800 µg of inhaled budesonide given via a pressurized metered-dose inhaler (pMDI) once daily had no effect on urinary cortisol excretion in asthmatic patients (33).

This study highlights the difficulty in determining the anti-inflammatory response of different classes of disease-modifying therapy for asthma. Unfortunately there is no single test that can be used to quantify airways inflammation. Assessment of peripheral blood markers is unlikely to be adequate as many cellular and mediator responses occur locally within airway inflammatory tissue only. Assessment of eosinophil concentration or eosinophilic cationic protein in induced sputum is also problematic as assessment is made of more proximal rather than smaller airways (34). Indeed, in a recent study with a new inhaled corticosteroid it was possible to show a dose-response effect on AMP challenge but not on induced sputum eosinophil count (35). Clearly, different markers of inflammation should be considered together when comparing treatment response in patients with allergic rhinitis and asthma.

In conclusion, we have shown that combined topical corticosteroid and combined mediator blockade were equally effective therapeutic options in patients with asthma and SAR. Both drugs exhibited anti-inflammatory activity with montelukast and cetirizine reducing airway hyperresponsiveness and budesonide suppressing exhaled NO. The choice of treatment will depend on various factors, including patient compliance, preference and ability to use inhalers and nasal sprays, as well as cost. Further studies are required to investigate the long-term effects in patients with more severe persistent asthma and perennial allergic rhinitis.