Sherman attends his annual COPD review. He has no other known diagnosis, is an ex-smoker and his inhaled medication has been optimised as per GOLD,1 and remains appropriate. His CAT assessment and comments indicates that thick sticky sputum is an issue. He tells us he is often exhausted trying to clear his chest despite regular physical activity and adequate hydration, which he has been advised on in the past. He has two or three exacerbations of COPD annually. Sherman agrees to your suggestion that a mucolytic may be helpful. What would you consider prescribing?