Inhibition of airway hyperreactivity by oxybutynin chloride in subjects with cervical spinal cord injury.
OBJECTIVE
To further investigate mechanisms of airway hyperreactivity among subjects with chronic cervical spinal cord injury (SCI), we assessed airway responsiveness to aerosolized methacholine and histamine in subjects receiving chronic oxybutynin chloride therapy, and compared the findings with those not receiving the agent.


METHODS
Twenty-five male subjects with cervical SCI participated in this study; 12 were maintained on oral oxybutynin chloride and 13 served as age-matched controls. Six of the 12 subjects receiving oxybutynin were challenged with aerosolized methacholine, and six with histamine; seven of the 13 control subjects were challenged with aerosolized methacholine and the remaining six with histamine.


RESULTS
All 13 control subjects and all six oxybutynin/histamine subjects exhibited a significant bronchoconstrictor response (PC20 < 8 mg/ml), whereas mean PC20 values for the oxybutynin/methacholine group were > or =25 mg/ml.


CONCLUSIONS
Our finding that the bronchoconstrictor effects of methacholine were blocked by oxybutynin chloride while those of histamine were not suggests that oxybutynin acts primarily through anticholinergic pathways rather than by causing generalized airway smooth muscle relaxation.
Singas
E
E
Mount Sinai School of Medicine, Mount Sinai Medical Center, New York, NY, USA.
Grimm
D R
DR
Almenoff
P L
PL
Lesser
M
M
D000328:Adult; D000336:Aerosols; D016535:Bronchial Hyperreactivity / Q000188:drug therapy* / Q000209:etiology / Q000517:prevention & control; D001993:Bronchodilator Agents / Q000008:administration & dosage; D018680:Cholinergic Antagonists / Q000627:therapeutic use*; D006632:Histamine / Q000008:administration & dosage; D006801:Humans; D008297:Male; D008333:Mandelic Acids / Q000627:therapeutic use*; D016210:Methacholine Chloride / Q000008:administration & dosage; D008875:Middle Aged; D013119:Spinal Cord Injuries / Q000150:complications*; D013147:Spirometry
D000336:Aerosols; D001993:Bronchodilator Agents; D018680:Cholinergic Antagonists; D008333:Mandelic Acids; D016210:Methacholine Chloride; D006632:Histamine; C005419:oxybutynin