Look promising across the board of asthma severity

Leukotriene modifiers are an entirely new class of asthma treatment, which have entered clinical practice in 1996-7 in several countries including Britain, Japan, and the United States. Their development is an example of rational drug design following the elucidation of leukotriene structures in 1979-80 and the subsequent confirmation of their pathophysiological role as inflammatory mediators in asthma.1

There are two types of leukotriene modifier: leukotriene synthesis inhibitors and cysteinyl leukotriene receptor antagonists.2 Both are used to block the bronchoconstrictor and pro-inflammatory activity of cysteinyl leukotrienes within the asthmatic airway. Cysteinyl leukotrienes (LTC₄, LTD₄, and LTE₄) were originally identified as long lasting smooth muscle spasmogens and collectively termed “slow reacting substance of anaphylaxis” (SRS-A). They are now known to be metabolites of arachidonic acid formed by the 5-lipoxygenase pathway1 and are produced almost exclusively by inflammatory leucocytes, especially mast cells, basophils, and eosinophils. The leukotriene receptor antagonists block the activity of cysteinyl leukotrienes at their receptors (CysLT₁) on bronchial smooth muscle and elsewhere, while the leukotriene synthesis inhibitors block the synthesis of all leukotrienes by interrupting the 5-lipoxygenase pathway.2

Cysteinyl leukotrienes are among …