Relief may be on the horizon for sufferers of unexplained chronic cough, a condition estimated to effect 4-10% of the adult population. Although often linked to underlying factors such as smoking, asthma or environmental irritants, many people develop a chronic cough for no obvious reason, and there is no safe, long-term treatment for these cases.
The latest study is a phase 2b clinical trial of the drug gefapixant, which blocks a neuronal receptor involved in the cough reflex. 253 patients with unexplained or untreatable cough participated in the 12 week randomised, double-blind and placebo-controlled trial across the US and UK. Each participant was assigned to either a placebo group or on of three doses of gefapixant: 7.5mg, 20mg or 50mg.
Results were recorded using a cough diary, a sound recording device and three treatment visits, during which clinicians also recorded any possible side effects.
The trial did record a significant placebo effect, with those in the placebo group coughing roughly 30% less at the end of 12 weeks compare to at the start. However, those given gefapixant did have better results, which reached statistical significance in the 50mg group with a 37% additional decrease in coughing.
The most common side effect recorded was changes to sense of taste, which rose in-line with higher dosages and resulted in 10 of the 63 patients receiving 50mg discontinuing. Most patients who continued said they would be happy to receive treatment for at least a year.
The full details are published in The Lancet Respiratory Medicine journal, and phase 3 trials of gefapixant are currently underway.
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Source: Eurekalert!
