Study on 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.