OTC Drugs Don't Target Chronic Cough Mechanisms, Dr Jacky Smith Explains

Although they may have some benefit, OTC cough medicines don't penetrate the nerves in the airways, which are believed to be the mechanism behind refractory chronic cough, says Jacky Smith, MB, ChB, FRCP, PhD, professor of respiratory medicine at the University of Manchester and an honorary consultant at Manchester University NHS Foundation Trust.

Transcript

How do novel therapies being evaluated in clinical trials better address cough compared with over-the-counter therapies—for instance, are they getting at the underlying mechanisms?

I suspect they are. It's a little tricky to say because many of the over-the-counter cough medicines have been around for a long time. And that means they were evaluated many years ago, when the trials that we did and the evidence base for licensing therapies was quite different. Also, most of the over-the-counter cough medicines are very much aimed at treating acute cough, so coughing associated with viral upper respiratory tract infections, coughs and colds, which do get better by themselves anyway. Whereas the newer therapies are much more aimed at treating patients with refractory chronic coughing, so cough that's been there for more than 8 weeks, which is much longer than you'd expect just from a postviral cough. And I do think that whilst many of the over-the-counter medicines may well help soothe the throat, improve the cough tickling, perhaps suppress the cough to some degree if it contains things like codeine or dextromethorphan, it's probably not tapping into precise mechanisms in the same way that some of the new treatments are, which, certainly with the P2X3 antagonists, we believe most of the drugs been tested don't penetrate the central nervous system much and are actually addressing things that are activating the nerves in the airways like ATP, which is quite a specific mechanism.