In individuals with severe asthma, smoking asthma, and COPD where corticosteroids are less effective, they may operate in concert with corticosteroids due to their anti-inflammatory properties by restoring HDAC activity.156 Furthermore, leukotriene modifiers and long-acting inhaled β2-agonists are more expensive than slow-release theophylline, and oral medication may improve compliance. Here, HDAC9 is linked to chronic obstructive pulmonary disease.