BACLOFEN-INDUCED BRONCHOCONSTRICTION

OBJECTIVE: To report the occurrence of acute bronchospasm in one asthm atic patient and increased bronchial reactivity in another following t he administration of a single dose of oral baclofen. CASE SUMMARY: On two separate occasions, a 46-year-old asymptomatic asthmatic man devel oped dyspnea and chest tightness one hour after the ingestion of baclo fen 40 mg. Pulmonary function studies revealed a significant decrease in airflow relative to baseline. A 33-year-old asymptomatic woman with a history of exercise-induced dyspnea and wheezing displayed bronchia l hyperresponsiveness to inhaled methacholine 2 hours after ingesting 40 mg of baclofen. The patient had had a negative methacholine challen ge test 72 hours earlier. DISCUSSION: The gamma-aminobutyric acid-agon ist baclofen has been shown to reduce airway responsiveness to various bronchoconstricting agents in animal studies. The etiology of this se emingly paradoxical response in two patients is unclear, but may offer insight into the neurally mediated airway constriction that occurs in asthma. CONCLUSIONS: Clinicians should be aware of the possibility of baclofen-induced bronchospasm, especially in asthmatic patients.