Mechanism of action of zileuton: September 2012, March 2013
**Core Concept**
Zileuton is a medication used in the management of asthma, specifically targeting the inflammatory pathway. It acts by inhibiting the enzyme responsible for the synthesis of leukotrienes, which are key mediators of allergic inflammation.
**Why the Correct Answer is Right**
Zileuton is a leukotriene synthesis inhibitor, specifically targeting 5-lipoxygenase (5-LO), an enzyme crucial for the conversion of arachidonic acid to leukotriene A4. This step is essential in the production of cysteinyl leukotrienes, such as LTC4, LTD4, and LTE4, which are potent bronchoconstrictors and pro-inflammatory mediators in asthma. By inhibiting 5-LO, zileuton reduces the production of these leukotrienes, thereby alleviating symptoms of asthma.
**Why Each Wrong Option is Incorrect**
**Option A:** This option does not accurately describe the mechanism of action of zileuton, as it does not specifically mention the inhibition of 5-lipoxygenase.
**Option B:** This option is incorrect as it refers to a different class of medications, such as beta-agonists or anticholinergics, which have a distinct mechanism of action in the management of asthma.
**Option C:** This option does not accurately describe the mechanism of action of zileuton, as it does not specifically mention the inhibition of leukotriene synthesis.
**Clinical Pearl / High-Yield Fact**
Zileuton is a unique medication that targets the leukotriene pathway, making it a valuable option for patients with asthma who are resistant to other treatments. It is essential to remember that zileuton is not a bronchodilator and should not be used as a rescue medication for acute asthma attacks.
**Correct Answer: D**