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Antitussive effect of the GABA-agonist baclofen
P V Dicpinigaitis1, J B Dobkin
1Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Background:
gamma-Aminobutyric acid (GABA) is a central inhibitory neurotransmitter 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, but has not been investigated in humans (to our knowledge).
Study Objective:
To evaluate the antitussive effect of baclofen in normal human subjects.
Design:
Randomized, double-blind, placebo-controlled study.
Setting:
Academic medical center.
Participants:
Twenty healthy, adult volunteers.
Interventions:
Subjects underwent cough challenge with inhaled capsaicin before and after a 14-day course of baclofen, 10 mg three times daily, or placebo. Capsaicin cough threshold (C5) was defined as the concentration of inhaled capsaicin inducing five or more coughs.
Results:
Subjects receiving baclofen (n=10) demonstrated a significant elevation of capsaicin cough threshold compared with placebo subjects (n=10). Mean delta log C5 after treatment was 0.48+/-0.19 (SEM) for the baclofen group, and -0.06+/-0.12 for the placebo group (p=0.024). Six of 10 subjects receiving baclofen, but none of the 10 subjects receiving placebo, demonstrated a fourfold or greater increase in capsaicin cough threshold (p=0.0054).
Conclusion:
The antitussive activity of low-dose, oral baclofen demonstrated in this study supports further investigation of this drug, or other GABA-agonists, for a potential therapeutic role in the treatment of pathologic cough.