Preventing and treating symptoms and blockage of airway due to asthma or other lung diseases (eg, emphysema, bronchitis). It may also be used for other conditions as determined by your doctor.Quibron-T is a xanthine derivative. It works by relaxing the muscle around the airways in the lungs, which allows them to widen and makes breathing easier. It also improves contraction of the diaphragm (the major breathing muscle) and decreases the response of the airways to irritants.