zileuton
Meaning of zileuton: An asthma tablet that shuts down the enzyme making leukotrienes, rather than blocking the receptors those chemicals act on.
Definition of zileuton
Zileuton is a prescription tablet used to prevent asthma symptoms. It blocks 5-lipoxygenase, the enzyme cells use to manufacture leukotrienes, inflammatory chemicals that tighten airway muscle, swell the lining and increase mucus. Stopping production means fewer leukotrienes are made at all. It is taken regularly as a preventive medicine and has no role in relieving an attack already under way.
How is it different from other leukotriene medicines?
Two approaches exist to the same pathway, and zileuton takes the earlier one.
| Approach | Where it acts | Effect |
|---|---|---|
| Enzyme blocker (zileuton) | Before the chemicals are made | Reduces all leukotrienes produced |
| Receptor blocker | At the target cell | Blocks one class from acting |
Because it works upstream, zileuton reduces leukotrienes that act on receptors the blockers do not cover, including one involved in drawing immune cells into the airway. Whether that translates into a larger clinical effect is not firmly settled.
What is the leukotriene pathway?
Cell membranes store arachidonic acid, a fatty acid. When an immune cell is triggered, that acid is released and can go down one of two routes. One route produces prostaglandins, the chemicals blocked by common anti-inflammatory painkillers. The other, controlled by 5-lipoxygenase, produces leukotrienes. In an allergic airway, leukotrienes contract the muscle around the tube, make the lining leak and swell, and drive mucus production. Zileuton blocks the enzyme at the head of that second route.
What are its practical limitations?
It is taken several times a day, more often than most preventive asthma treatments, which makes it harder to keep to. It can raise liver enzymes, so liver blood tests are checked at the start of treatment and periodically after. It also slows the breakdown of theophylline, warfarin and propranolol, raising their levels. Leukotriene pathway blockers have been examined in research on the prevention of lung cancer, on the reasoning that this inflammatory pathway is active in damaged airways, but no such use is established.
Also known as
Used in a sentence
Zileuton was selected as the controller after leukotriene receptor blockade proved insufficient.
Good to know
Zileuton acts on the enzyme that makes leukotrienes rather than on their receptors, and it can raise liver enzymes and slow the clearance of theophylline, warfarin and propranolol.