Interaction between chloroquine and indomethacin in airways smooth muscle in vivo

The indomethacin-induced enhancement of airways smooth muscle contractility to histamine reported earlier in vitro has now been demonstrated in conscious guinea-pigs. Chloroquine, an anti-malarial drug with phospholipase A2 inhibitory activity, antagonized histamine and also reversed the indomethacin-induced enhancement. These observations indicate that histamine-induced bronchospasm in vivo is modulated by the arachidonate system and that chloroquine-type phospholipase A2 inhibitors may ameliorate such bronchospasm. These findings also explain the observed clinical benefits of chloroquine in chronic asthmatics.