RCT-proven efficacy of antitussives by three different cough measurement methods in acute bronchitis
| RCT-evidence for drug efficacy | Subjective clinical symptoms | Objective cough recording | Cough challenge | Remarks |
|---|---|---|---|---|
| Codeine | − | − | − | No convincing evidence of efficacy |
| Dextromethorphan | + | + | ++ | Well characterised in objective studies |
| Pentoxyverine | − | − | − | Only animal studies via 3 clinical studies >50 years old |
| Butamirate | − | − | − | No placebo-controlled study published |
| Levodropropizine | + | − | + | 6 short-term placebo or active comparator controlled studies n=174 |
| Ambroxol | + | − | − | Many additional non-interventional studies |
| N-acetylcysteine | Children + Adults − | − | − | Many studies for COPD, chronic cough, antioxidant properties |
| Oxomemazine | − | − | − | Only observational studies |
| Menthol | − | − | + | Widely used. Vapour antitussive via TRPM8 |
| Helicidine | − | − | − | No clinical evidence of efficacy in acute cough |
| Diphenhydramine | − | − | − | Broad clinical use |
COPD, chronic obstructive pulmonary disease; RCT, randomised controlled trial.