Leukotriene Modulators

Leukotriene Modulators

Types of Leukotriene Modulators

  1. Leukotriene Receptor Antagonists

  2. 5'-Lipoxygenase Inhibitors

Overview of Leukotrienes

  • Fatty acid-derived mediators with a conjugated triene structure.

  • Formed by the liberation of arachidonic acid from cell membranes after cell activation by allergens or noxious stimuli.

Key Enzyme

  • 5'-Lipoxygenase:

    • Essential for synthesizing LTA4, an unstable epoxide precursor of biologically important leukotrienes.

Biologically Important Leukotrienes

  1. LTB4:

    • A potent pro-inflammatory chemo-attractant (20-carbon dihydroxy fatty acid).

  2. Cysteinyl Leukotrienes (LTC4, LTD4, LTE4):

    • LTC4: A conjugate of LTA4 and glutathione.

    • Conversion: LTC4 to LTD4 (active metabolite) and then to LTE4 (less active).

    • Collectively known as 'sulphidopeptide leukotrienes' or 'cysteinyl leukotrienes'.

    • Previously referred to as 'slow-reacting substance of anaphylaxis' (SRS-A).

Mechanism of Action

  • Bind to Cys-LT1 receptor:

    • Effects include bronchoconstriction, eosinophil attraction, and oedema production.