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1 Clinica Pediatrica, University of Verona, Verona, 2 Istituto Pio XII, Misurina and 3 Dept of Statistics, University of Trento, Trento, Italy
CORRESPONDENCE: P. Diego, Clinica Pediatrica Universita' di Verona, Policlinico GB Rossi, Via Menegone, 37134, Verona, Italy. Fax: 39 0458200993. E-mail: peroni.diego@tiscalinet.it
Keywords: asthma, childhood, exercise-induced bronchoconstriction, loratadine, montelukast
Received: April 17, 2001
Accepted March 1, 2002
| Abstract |
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Nineteen children were enrolled in a double-blind randomised, single-dose, crossover study. For each treatment patients undertook two treadmill exercise tests, 2 and 12 h respectively after single-dose administration.
No significant differences were seen in the maximum fall in forced expiratory volume in one second (FEV1) 2 h after treatment and placebo. Whereas significant differences in maximum fall in FEV1 were observed between treatment groups 12 h after administration. Loratadine alone did not show any significant protection or any additional effect in comparison with montelukast alone. Single doses of montelukast and montelukast plus loratadine were significantly more effective than loratadine at 12 h.
The present study, performed using single-dose treatments, demonstrated that maximal protective effect by montelukast was obtained 12 h after dosing and that montelukast plus loratadine did not result in significant additive bronchoprotective effects on exercise-induced bronchoconstriction.
The role of leukotrienes in asthma is demonstrated by several studies showing positive prechallenge effects by leukotriene-receptor antagonists (LTRAs) in exercise- 1, 2 and allergen-induced bronchoconstriction 3. The LTRAs, such as montelukast, provide protection against exercise-induced bronchoconstriction (EIB) attenuating the fall in pulmonary function following exercise with no induced tachiphylaxis. ß2-agonists are highly effective in reducing the symptoms. However, recent studies highlighted that the extent of protection diminishes with their exclusive regular use after 68 weeks both for short-acting and long-acting agonists (reviewed in 4). Histamine has been implicated in EIB but antihistamines have been shown to offer modest protection against EIB 5. However, there is some evidence that combined mediator blockade with both leukotriene and histamine-receptor antagonists results in greater symptom control than LTRAs alone in patients with persistent asthma 6. In fact, it has been demonstrated that cysteinyl-leukotrienes and histamine synergise in vitro as immunoglobulin (Ig) E-dependent bronchoconstriction mediators 7. Furthermore, the combination of zafirlukast, a leukotriene antagonist, and loratadine was significantly more effective than either drug alone during allergen-induced early and late obstruction 3. The aim of this study was to investigate if single doses of the combination of a LTRA, montelukast, and a histamine-receptor antagonist, loratadine, may determine an addictive protective effect on EIB in children in comparison to either drug alone.
| Methods |
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15% of the pre-exercise value was considered diagnostic of EIB.
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Treadmill exercise tests
Children performed a baseline spirometry and then ran for 6 min on a treadmill, at speed, to obtain an increase of 80% in their maximum cardiac frequency in a specially designated room with constant temperature (21°C) and humidity (4050%). Following the exercise challenge, FEV1 was obtained at 1, 5, 10, 15, 20 and 30 min. To assess bronchoconstriction after the exercise challenge, the maximal percentage fall in FEV1 (
FEV1) from the baseline value and the area under the curve (AUC030min) with percentage change in FEV1 data over time were considered. Percentage of protection was calculated as:
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Statistical analysis
The effects of treatment on the response to exercise challenge were compared using
FEV1 expressed as the percentage of the prechallenge baseline. An analysis of variance model for repeated measures (ANOVA) in a crossover design was used to compare treatment groups. The hospitals' ethical committee approved the study and the parents gave informed consent.
| Results |
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Efficacy
There was no significant difference between patients' baseline FEV1 after each drug administration (table 2
). The
FEV1 during the screening test, expressed as mean±sem, were: 22.84±3.01 at 10:00 h and 21.31±2.60 at 20.00 h.
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FEV1 was 15.33±2.93 for placebo, 13.9±2.67 for loratadine, 13.33±2.03 for montelukast and 10.07±1.96 for the combination, with no significant differences. At 12 h the
FEV1 was 18.69±2.83 for placebo, 14.64±2.55 for loratadine, 9.78±1.85 for montelukast and 9.51±2.55 for montelukast plus loratadine. Significant differences were observed between placebo and montelukast (p<0.02), placebo and the combined treatment (p<0.02) and between respectively montelukast and the combination in comparison to loratadine (p<0.05). No significant difference was observed between placebo and loratadine. At 2 h AUC030min, (% x min) expressed as mean±sem, was 34.32±11.5% for placebo, 50.66±20.46% for loratadine, 23.74±10.06% for montelukast and 18.87±7.14% for the combination, with no significant differences. When the challenges were performed 12 h after the drug administration, AUC030min was 43.60±9.34% after placebo, 39.6±10.89% after loratadine, 15.03±5.38% after montelukast and 7.76±6.14% after the combination, with significant differences between montelukast and montelukast plus loratadine in comparison to placebo (p<0.01) and to loratadine alone (=0.02).
Protection
At 2 h after dose administration, no significant difference in the percentage of protection was observed between placebo (33%), loratadine (43%), montelukast (47%) and montelukast plus loratadine (59%). At 12 h there was a significant difference in the percentage of protection between placebo (20%) and montelukast (63%) (p<0.01), and between placebo and the combination (59%) (p<0.01), but not between placebo (20%) and loratadine (45%). Montelukast provided clinical protection in three subjects (15%) at 2 h and in 12 subjects (63%) at 12 h. The combination of the two drugs gave a similar trend with clinical protection in six subjects (31%) at 2 h, and in 12 subjects (63%) at 12 h.
| Discussion |
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75% 3. As the efficacy has appeared to begin acutely, different anti-inflammatory mechanisms might be involved including effects on the vascular system, the airway oedema, mucous production and neurogenic inflammation 9. These events may also contribute to the development of the hypertonicity of airway lining fluid which seems to be the major determinant of EIB, determining mediator release by inflammatory cells. In the present study, the authors analysed drug efficacy at 2 and 12 h, and the effects of the combination at the beginning and the end of a once-daily single dosage were investigated. In several studies two or more doses of montelukast were used in order to achieve steady-state blood levels 1, 2. In the present study the use of a single administration of drugs was adopted in an attempt to clarify, as much as possible, the contribution of both antileukotriene and antihistaminic drugs in the protection from EIB. To the best of the authors' knowledge this is the first study examining the effect of a single dose of montelukast and loratadine alone and in combination. No statistically significant additive effect using the combination of the two drugs in comparison to montelukast alone was obtained. However, results showed that even after 2 h there was a trend towards protection when the children were treated with the combination. Mean values of the
FEV1 and the percentage of protection obtained after both drug administration (2 and 12 h respectively) did not change significantly, but at 2 h there was a strong placebo effect. This effect in EIB has been described previously in children, and it has been characterised by dose and duration time effect 10. At 12 h montelukast and the combination were significantly more effective than placebo and loratadine alone. To conclude, the combination of montelukast and loratadine single-dose administration, demonstrated no additive effect in exercise-induced bronchoconstriction protection. However, since antileukotrienes in association with antihistamines have been demonstrated to provide a significant improvement in chronic asthma 6 and allergic rhinitis 11, 12 in adults, combined and prolonged oral therapy should also be evaluated in children. Further studies are necessary to evaluate long-term clinical effects of this and other therapeutic combinations on asthma and exercise-induced bronchoconstriction in childhood.
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W. Busse and M. Kraft Cysteinyl Leukotrienes in Allergic Inflammation: Strategic Target for Therapy Chest, April 1, 2005; 127(4): 1312 - 1326. [Abstract] [Full Text] [PDF] |
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