Respiratory therapeutics
Practice questions with explanations

C. It is an add-on to optimised inhaled therapy for a defined phenotype, given by injection at intervals, and preventer treatment continues

Monoclonal antibodies against IgE, interleukin-5 or the IL-4 receptor reduce exacerbations and oral steroid requirements in selected patients with severe disease, identified by phenotype markers such as eosinophil count and IgE. They act over weeks and are never rescue therapy, and inhaled maintenance treatment continues alongside them.

D. Long-term low-dose macrolide therapy reduces exacerbations through anti-inflammatory and immunomodulatory effects rather than by treating infection

The benefit is real but comes with costs: macrolide resistance in the individual and the community, QT prolongation, and hearing loss, so it is used selectively in patients with frequent exacerbations after other measures. Baseline sputum culture to exclude non-tuberculous mycobacteria, hearing and ECG assessment precede it.

B. It has a narrow therapeutic index with concentration-dependent toxicity, and many interactions through CYP1A2

Theophylline sits close to its toxic range, where nausea, vomiting, tremor, tachyarrhythmia and seizures occur, sometimes without warning symptoms. Clearance falls in heart failure, liver disease and with ciprofloxacin, erythromycin or cimetidine, and rises with smoking and enzyme inducers, so stopping smoking can precipitate toxicity. These properties are why it has moved well down the treatment order.