PURPOSE: Bronchospasm is a cardinal feature of bronchial asthma and other diseases characterized by bronchial hyperreactivity. In this pilot study, we tested the possibility of using a commercially available neurotoxin Botulinum Toxin A to reduce bronchial hyperreactivity in dogs.
METHODS: We subjected six healthy mongrel dogs to two bronchoscopy sessions two weeks apart. In the first session, we injected BTX-A in the concentration 10 U/ml in small aliquots submucosally in one caudal lobe and its subsegments, leaving the other side as control. Two weeks later, we performed the second bronchoscopy during which we measured the airway caliber, we induced bronchial hyperreactivity by instillation of methacholine in the concentration of 25mg/ml, and then we re-measured the airways and compared the two sets of measurements in the treated and untreated sides in each animal.
RESULTS: In the treated group of bronchi, the mean pre-treatment diameter was 3.356 mm ( 1.294), and after provocation, the diameter was 1.985 mm ( 0.888). In the untreated group, the mean pre-treatment diameter of the airways was 2.765 mm ( 0.603) and after provocation, the mean diameter was 0.873 mm ( 0.833). This showed that BTX-A resulted in reduction of bronchial hyperreactivity of 58.6% in the treated group of bronchi. There were no complications from the submucosal injection of BTX-A in the airways.
CONCLUSION: BTX-A reduced bronchial hyperreactivity induced by metacholine in the treated bronchi, although this did not abolish all the features of bronchial hyperreactivity e.g., bronchial wall edema.
CLINICAL IMPLICATIONS: Botulinum Toxin may be used for the management of disease entities characterized by bronchial hyperreactivity like Bronchial Asthma and COPD.
DISCLOSURE: Ahmed Al-Halfawy, No Financial Disclosure Information; Product/procedure/technique that is considered research and is NOT yet approved for any purpose. The use of Botulinum toxin is well documented for use in neurologic and plastic procedures, but this is the first time it is applied in the airways to treat conditions such as bronchial asthma. We have tested its application in dogs and there were no complications related to its endobronchial administration. the results were satisfactory regarding its potential ability to reduce bronchial hyperreactivity when the dogs were then exposed to methacholine provocation.