Codeine-induced Bronchoconstriction and Putative Bronchial Opiate Receptors in Asthmatic Subjects

✍ Scribed by V. Popa

• Publisher: Elsevier
• Year: 1994
• Tongue: English
• Weight: 512 KB
• Volume: 7
• Category: Article
• ISSN: 0952-0600
• DOI: 10.1006/pulp.1994.1039

✦ Synopsis

SUMMARY: To determine whether a mu opiate agonist can constrict the human airways, the dose of codeine (C) or histamine ((\mathrm{H})) producing a (40 %) decrease (\left(\mathrm{PD}{40}\right.) ) in specific airway conductance (SGAW) was measured in 17 asthmatic and 14 normal subjects. Then, the subjects were skin tested with (\mathrm{C}) and (\mathrm{H}), and the effect of naloxone (N) and chlorpheniramine (CP) on (\boldsymbol{P D}{40}-\mathrm{C}) was assessed. In five asthmatic subjects responding to less than (5 \mathrm{mg}) ( (16.6 \mathrm{~mol}) ) inhaled (\mathrm{C}, S G \mathrm{AW}) was also recorded after oral administration ((30 \mathrm{mg}) ) and pharyngeal spraying ((5 \mathrm{mg}) ) of C. (P D_{40}-) could be determined in 11 of the 17 asthmatics but in none of the normal subjects. This constrictor effect lasted less than (15 \mathrm{~min}), was unrelated to resting airway caliber, and required a relatively high bronchial sensitivity to (\mathrm{H}\left(\boldsymbol{P D _ { 4 0 }}-\mathrm{H}\right.) usually less than (\left.0.2 \mu \mathrm{mol}\right)) and high doses of (\mathrm{C}(11.93 \pm 12.0 \mu \mathrm{mol})). However, in (\mathrm{C}) responders, (P D_{40}-\mathrm{C}) and (P D_{40}-\mathrm{H}) were unrelated. C-induced bronchoconstriction was blunted by (\mathrm{N}) in a dose-dependent fashion and to a mild and inconsistent degree, by CP. Pharyngeal spraying or oral challenge with C failed to change SGAw. Skin sensitivity to (\mathrm{H}) and (\mathrm{C}) was similar in (\mathrm{C})-responders and non-responders. In conclusion, large doses of inhaled (\mathrm{C}) constrict the airways of asthmatic subjects highly sensitive to (\mathrm{H}). This effect seems mediated through (mu?) opiate receptors located bronchially rather than centrally, pharyngeally or in the skin. In C-induced bronchoconstriction (\mathrm{H}) liberation plays a contributory but minor role. Skin and bronchial sensitivity to (\mathrm{C}) are unrelated.