Which of the following correctly describes the role of 5-lipoxygenase activating protein (FLAP) in leukotriene synthesis and the drug targeting it?
- A FLAP transfers arachidonic acid to 5-lipoxygenase; montelukast inhibits FLAP
- B FLAP catalyses the conversion of LTA4 to LTB4; its inhibition prevents neutrophil chemotaxis
- C FLAP is required for efficient 5-LO enzyme activity by presenting arachidonic acid; zileuton inhibits 5-LO itself rather than FLAP ✓
- D FLAP is a membrane anchor for cysteinyl leukotriene receptors; montelukast blocks FLAP to prevent receptor activation
Correct answer: C. FLAP is required for efficient 5-LO enzyme activity by presenting arachidonic acid; zileuton inhibits 5-LO itself rather than FLAP
Explanation
FLAP (5-LO Activating Protein) is a nuclear membrane scaffold protein that presents arachidonic acid to 5-lipoxygenase (5-LO), facilitating leukotriene synthesis. Zileuton directly inhibits 5-LO, reducing LTA4, LTB4, and cysteinyl leukotriene production. Montelukast and zafirlukast block cysteinyl leukotriene CysLT1 receptors; they do not inhibit FLAP or 5-LO. LTA4 hydrolase (not FLAP) converts LTA4 to LTB4.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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