A 15-year-old with asthma has symptoms after taking a drug. Which enzyme does this drug likely inhibit?

• A. Phospholipase A
• B. Cyclooxygenase
• C. 5-Lipoxygenase
• D. Thromboxane synthetase

Answer: (B)

In the context of asthma and the use of certain drugs, non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen, play a significant role. These medications primarily exert their effects by inhibiting cyclooxygenase (COX) enzymes, which are responsible for the conversion of arachidonic acid into prostaglandins and thromboxanes.

In some patients, particularly those with asthma, the use of NSAIDs can lead to adverse reactions that include bronchoconstriction, likely due to the body's compensatory increase in the production of leukotrienes when COX is inhibited. This is where the inhibition of cyclooxygenase becomes particularly relevant.

When cyclooxygenase is inhibited, the production of prostaglandins is reduced, leading to a shift in the arachidonic acid pathway toward the production of leukotrienes via the action of lipoxygenase. In susceptible individuals, this can exacerbate asthma symptoms. Therefore, the drug that the patient is reacting to most likely inhibits cyclooxygenase, which aligns with the known mechanisms behind asthma exacerbations following NSAID use.

This understanding emphasizes the importance of recognizing the pathways involved in asthma and the implications of drug interactions in managing patients with this