"These effects are very promising and raise hope for many people with refractory chronic cough—a condition that can be both psychologically and physically disabling and for which no effective drugs are available—who now have a potential new treatment option"*, says Nicole Ryan from The University of Newcastle in Australia who led the research.
Chronic cough is an increasing clinical problem that currently affects 11% of the population. The precise cause of cough persistence is not known, but research suggests it might be related to central sensitisation** which is also implicated in neuropathic pain. Gabapentin has shown a robust effect on chronic neuropathic pain and as such could have a similar effect in people with chronic cough, but until now, no randomised studies have been done.
In this study, 62 patients with refractory chronic cough (a cough lasting 8 weeks or longer) who had not responded to standard treatment were recruited from an outpatient clinic in Australia and randomly assigned to either gabapentin (maximum tolerable daily dose 1800 mg) or placebo for 10 weeks.
Patients returned to the clinic five times to give a rating of their cough using the Leicester cough questionnaire (LCQ) that assigns a score based on physical, social, and psychological impact of the cough, and to assess cough frequency and severity.
Overall, gabapentin had a significant and sustained improvement on cough-specific quality of life, cough severity, and cough frequency compared with placebo.
After 8 weeks of treatment, significantly more coughers in the gabapentin group reported an improvement in LCQ score of greater than 1.3 (the smallest change in score considered as clinically meaningful) compared with the placebo group (74% vs 46%).
The authors point out that these beneficial effects were not sustained after treatment was stopped adding that, "the reduction in efficacy of gabapentin after withdrawal further supports its antitussive [cough suppressant] effect."
Gabapentin was generally well-tolerated, with less than a third of patients given gabapentin experiencing side-effects (the most common being nausea and fatigue), that were managed by reducing the dose.
According to Ryan, "Gabapentin is effective, well tolerated, and has few drug interactions and therefore its addition to chronic cough standard practice guidelines should be considered, although replication studies are necessary before this happens."*
In a linked Comment, Kian Fan Chung from Imperial College, London, UK says, "These results suggest that gabapentin is worth trying in patients with refractory chronic cough and should provide the impetus to pursue similar trials of other drugs developed to suppress cough sensitisation pathways or target primary afferent nerves associated with cough."
Dr Nicole Ryan, The University of Newcastle, Hunter Medical Research Institute, Newcastle, NSW, Australia. T) +61 2404 20123 or +61 2042 1746 202 (mobile) E) Nicole.ryan@newcastle.edu.au
Dr Kian Fan Chung, Imperial College, London, UK. T) +44 (0) 207 351 8714 E) f.chung@imperial.ac.uk
Notes to Editors:
*Quotes direct from author and cannot be found in text of Article.
**Central sensitisation occurs when people experience the need to cough, but there is no cough stimulus present. It is caused by neurones in the central nervous system firing off to cause cough unnecessarily. People with chronic cough recognise this as an extreme sensitivity to any range of triggers, such a talking, cold air, or smells.
Journal
The Lancet