Comparison of the antitussive effects of codeine and the GABA-agonist baclofen

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γ-Aminobutyric acid (GABA) is an inhibitory transmitter of the central nervous system that also exists in peripheral tissues, including the lung. The GABA-agonist baclofen has been shown, in animal studies, to inhibit cough via a central mechanism. We have recently demonstrated the antitussive activity of a 14-day course oflow-dose oral baclofen in normal subjects. In the present study, we evaluated a standard cough suppressant, codeine, and compared its antitussive effect with that of a single dose of baclofen. 10 healthy, adult volunteers who had previously participated in a study evaluating the antitussive effect of a 14-day course of baclofen, underwent capsaicin cough challenge on three occasions, 2 hours after the ingestion of codeine (30 mg), baclofen (40 mg) or placebo, which were dispensed in a randomised, double-blind manner. During each study, the concentration of capsaicin inducing 5 or more coughs (C5) was determined. Significant suppression of cough was achieved by codeine (p = 0.021). Although a single dose of baclofen demonstrated cough suppression in some individuals, its effect was not significant for the study group as a whole (p = 0.066). The change in cough threshold from baseline (ΔlogC5) produced by single doses of codeine and baclofen were not significantly different p = 0.434). In light of our previous study that demonstrated the significant antitussive effect of a 14-day course of low-dose baclofen, the inability of a single, large dose of baclofen to suppress cough in the current study suggests the need for multiple administrations to achieve the optimal inhibitory effect of this agent.

Original languageEnglish (US)
Pages (from-to)326-329
Number of pages4
JournalClinical Drug Investigation
Issue number4
StatePublished - Jan 1 1997

ASJC Scopus subject areas

  • Pharmacology (medical)


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