Low-dose slow-release morphine sulfate cuts the severity and frequency of chronic intractable cough by 40%, British research has found.
The small study shows the drug to be a “credible therapeutic option” when the cough is refractory to antitussives, reported Dr Alyn Morice, of the University of Hull and Castle Hill Hospital, and colleagues. The results are published in the 15 February issue of the American Journal of Respiratory and Critical Care Medicine.
27 patients were recruited from a cough clinic and randomised to four weeks of 5 mg extended-release morphine sulfate twice daily and four weeks of matched placebo.
The patients all had chronic, persistent cough for greater than three months that had failed to respond to trials of specific antitussive therapies. None had significant lung disease or used any other cough remedies during the study. Eighteen of the patients were women and the average age was 55.
Using Leicester Cough Questionnaire scores, the team registered significant improvements in the morphine group in physical, psychological, social and overall scores, reflecting an impact on daily living tasks.
The average improvement in overall scores was higher than 2.56, which the researchers said was clinically significant. Patients also completed a daily cough diary detailing cough severity. These scores rapidly improved by 40% on morphine and remained significantly better than baseline throughout the four weeks of treatment whereas scores were no different on placebo than at baseline.
Following the initial study, 18 patients continued on into a three month open-label phase. Two-thirds chose to increase their morphine dose to 10 mg twice daily, though both these patients and those who stayed at 5 mg had similar improvements in cough.
At the end of this extension study, cough severity scores were similar between dose groups (2 for the 5-mg group versus 3 for the 10-mg group). However, Leicester Cough Questionnaire scores significantly improved in the group that doubled their dose compared to placebo in the earlier study, whereas the group that stayed at 5 mg has scores similar to placebo in the double-blind phase.
Commenting on the scores, the team said that the best dose may lie between 5 and 10 mg twice daily for suppression of chronic cough.
“Side effects and dependence are obvious concerns with opiate therapy for what is a disabling but non-life-threatening condition,” Dr. Morice and colleagues wrote but added: “We believe that the risk-benefit risk ratio makes low-dose morphine sulfate a credible therapeutic option in patients with chronic cough who fail with specific treatment.”
Follow us on
