Study of the mechanisms of action of sodium meclofenamic acid (Meclomen) a "double inhibitor" of the arachidonic acid cascade.

Meclofenamic acid sodium (Meclomen) was found to inhibit both the cyclooxygenase and the lipoxygenase pathways of arachidonic acid metabolism. It inhibited both 5-lipoxygenase and 15-lipoxygenase activities. Meclomen was also shown to interfere with leukotriene receptors or possibly post-receptor mechanisms. In isolated lung parenchyma strip preparations Meclomen inhibited leukotriene C4 and D4 induced contractions, but had no effect on histamine induced contractions. Ibuprofen, naproxen and indomethacin had no effect on lipoxygenases or on leukotriene receptors but were powerful inhibitors of cyclooxygenases.