A 32-year-old asthmatic is switched from montelukast to an oral agent that directly blocks leukotriene synthesis rather than leukotriene receptor action. Which laboratory parameter must be monitored periodically in every patient receiving this drug?

• A Serum creatinine
• B Hepatic transaminases ✓
• C Serum potassium
• D Platelet count

Explanation

Zileuton inhibits 5-lipoxygenase, preventing conversion of arachidonic acid to LTA4 and thereby reducing all leukotrienes including LTB4 and cysteinyl leukotrienes. Its recognised adverse effect is hepatotoxicity with elevation of ALT, so liver enzymes are checked at baseline and periodically during therapy. Montelukast blocks only the CysLT1 receptor and has no hepatotoxicity signal, which distinguishes the two classes.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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