Between 4% and 10% of adults around the world have an unexplainable chronic cough that has lasted for over 8 weeks. Although no treatments are currently available, a drug developed by Afferent Pharmaceuticals known as Gefapixant has shown promise as a potential treatment in a company-funded Phase 2b trial.
In the study, a total of 253 patients suffering from a chronic cough for an average of 14.5 years were randomly assigned to either receive Gefapixant or a placebo (63 patients) twice daily for 84 days. Under double-blind conditions across 44 sites between the UK and US, the drug was administered in one of three doses: 7.5 mg (64 patients), 20 mg (63 patients) or 50 mg (63 patients). The frequency of each patient’s coughing was then recorded both by patients in their diaries and by sound recording devices over four 24-hour periods.
Prior to the treatment, each of the patients coughed between 24 and 29 times per hour. After the 12-week trial however, the researchers found that while the placebo group coughed an average of 18 times per hour, those in the 50 mg Gefapixant dose group coughed just 11 times per hour. Meanwhile, results from the other two dosage groups of the drug were deemed insignificant.
Although a distorted sense of taste alongside other taste-related side effects saw 10 patients (16%) in the 50 mg group withdraw from the trial, the majority of the remaining participants said they were satisfied with the drug’s effects, and so would gladly continue to take it for at least another year.
Based on these results, the researchers have already organized a series of Phase 3 trials with a larger group of people to be monitored over a longer period of time. Principle researcher of the study, Professor Jacky Smith from the University of Manchester, UK said, “This drug has exciting prospects for patients who suffer from the often distressing condition of chronic cough...Effective treatments for cough are a significant unmet clinical need and no new therapies approved in over 50 years...Effective treatments for cough are a significant unmet clinical need and no new therapies approved in over 50 years.”