title: Is opiate action in cough due to sedation?
abstract: OBJECTIVE
  Opiates have been used for cough suppression for centuries. It is unclear whether this antitussive action is due to their known sedative effects. We aimed to assess correlation between cough suppression and opiate usage.
  
  
  METHODS
  We performed a post hoc analysis of two published trials with three opioids. In study one, patients with chronic cough were treated with 4 weeks of modified release morphine sulphate (5 mg twice daily) or placebo in a double-blinded placebo-controlled fashion. Cough suppression was assessed subjectively by the Leicester Cough Questionnaire and objectively by citric acid aerosol (CAA) induced cough challenge. In study 2, normal volunteers were given single doses of placebo, codeine 30 mg or dextromethorphan 50 mg and cough suppression assessed using the CAA-induced cough challenge. Sedation was contemporaneously assessed by direct questioning.
  
  
  RESULTS
  There were 14 episodes of patient-reported sedation; 2 with modified release morphine sulphate, 9 with codeine and 3 with dextromethorphan. There was no correlation between change in the Leicester Cough Questionnaire or the CAA-induced cough challenge and reported sedation.
  
  
  CONCLUSIONS
  This observational study suggests that sedation is unlikely to underlie the antitussive properties of these opioids. Eliciting the mechanism of these medications in cough may be a target for future tailored drug development.
authors.affiliation: Academic Department of Respiratory Medicine, Hull York Medical School, University of Hull, Castle Hill Hospital, Cottingham, UK.
authors.forename: Rebecca S
authors.initials: RS
authors.lastname: Dickinson
authors.affiliation: Academic Department of Respiratory Medicine, Hull York Medical School, University of Hull, Castle Hill Hospital, Cottingham, UK.
authors.forename: Jaymin B
authors.initials: JB
authors.lastname: Morjaria
authors.affiliation: Academic Department of Respiratory Medicine, Hull York Medical School, University of Hull, Castle Hill Hospital, Cottingham, UK.
authors.forename: Caroline E
authors.initials: CE
authors.lastname: Wright
authors.affiliation: Main Administration Building, Castle Hill Hospital, Castle Road, Cottingham HU16 5JQ, UK.
authors.forename: Alyn H
authors.initials: AH
authors.lastname: Morice
keywords: antitussive; codeine phosphate; cough therapies dextromethorphan; morphine sulphate (MST); sedation