SESSION TITLE: Asthma Posters
SESSION TYPE: Original Investigation Poster
PRESENTED ON: Wednesday, October 30, 2013 at 01:30 PM - 02:30 PM
PURPOSE: Tiotropium bromide, a long-acting anticholinergic agent, has been proven to benefit some patients with nocturnal asthma, uncontrolled asthma, and chronic obstructive pulmonary diseases. The American Thoracic Society guidelines for the Methacholine Challenge Test (MCT;1999 recommend that tiotropium bromide be withheld at least 48 hours, perhaps as long as a week but a definite period has not been clarified. The authors aimed to investigate the effect of tiotropium bromide on methacholine-induced bronchoconstriction after 72 hours in patients with asthma.
METHODS: Patients with asthma-associated symptoms, but with normal spirometry results, were prospectively enrolled between January and November 2012 at Phramongkutklao Hospital. The MCT was administered with these patients. If the MCT result was positive, a single, inhaled 18 microgram tiotropium bromide was prescribed and a further MCT was scheduled after 72 hours to re-evaluate the MCT result.
RESULTS: Of 25 patients with positive MCT results 18 completed the 72 hour MCT re-evaluation test. All patients were male, with a mean age of 21.17 (SD=1.38). For 10 patients (55.56%) the MCT result changed from positive to negative, the remaining 8 patients (45.44%) maintained positive results (p<0.001). The median PC20 (IQR) in the negative group was 5.79 mg/ml (5.03-6.90), in the positive group it was 0.52 (0.27-3.06) mg/ml (p<0.001).
CONCLUSIONS: Tiotropium bromide should be withheld at least 72 hours before administering the MCT. This is especially the case with mild bronchial hypersensitive patients.
CLINICAL IMPLICATIONS: Tiotropium has been shown to improve FEV1 and to decrease the exacerbation rate with asthma patients. It is likely to be increasingly used for this purpose. The use of the Methacholine challenge test (MCT), after asthma symptoms have been controlled, has been recommended to evaluate bronchial hyper-responsiveness and to confirm that the inflammation is in remission. The results of the MCT are then used to determine the appropriate step down therapy. Our research has provided information that can be used to determine how long the tiotropium should be discontinued before administering the MCT.
DISCLOSURE: The following authors have nothing to disclose: Pattarin Pirompanich, Amornchai Lertamornpong
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