Leukotriene

Allergies occur when the immune system treats a harmless foreign protein as an invader. The immune system mounts a full-scale response to the protein. This response involves releasing inflammatory chemicals. These chemicals recruit the involvement of other cells and promote more inflammation.

What Are Leukotrienes?

Leukotrienes are fatty immune system chemicals that come from dietary omega-3 and omega-6 fatty acids. They play a key role in some of the more severe symptoms of allergic rhinitis and allergy-induced asthma.

The symptoms of allergic rhinitis may include:

  • swelling of the nasal passages
  • increased mucus production
  • a stuffy or runny nose
  • itchy skin

In people with asthma, leukotrienes bind with receptors on muscle cells. This causes the smooth muscles of the windpipe to contract. When airways are constricted, people with asthma experience shortness of breath and wheezing. 

How Do Leukotriene Modifiers Work?

Drugs that modify the production or activity of leukotriene are known as leukotriene inhibitors, leukotriene receptor antagonists, or leukotriene modifiers. Some of these drugs work by limiting the production of leukotrienes. Others block leukotrienes from binding to their receptors on smooth muscle cells. If the fatty signaling molecules cannot bind with their cellular targets, they cannot trigger muscle contraction.

Drugs such as montelukast (Singulair) and zafirlukast (Accolate) are widely prescribed to treat exercise and allergy-induced asthma. A third drug called zileuton (Zyflo) indirectly inhibits leukotriene synthesis. Montelukast is also prescribed for the treatment of year-round and seasonal allergic rhinitis. These drugs are usually taken by mouth.

When Would Your Doctor Prescribe Leukotriene Modifiers?

Inhaled corticosteroids are the most effective treatment. These drugs offer comprehensive relief from the various symptoms of allergic rhinitis, so they’re considered first-line treatment. However, in cases where people experience both allergy-induced asthma and allergic rhinitis, leukotriene modifiers may be considered first-line treatment. 

Leukotriene modifiers are one of several types of drugs used to treat allergies or asthma. However, they’re still considered second-line treatment. They were introduced in the 1990s. They were the first new class of drugs for the treatment of asthma and allergies in 30 years. Some studies have shown that leukotriene modifiers provide an effective singular, first-line therapy for the control of mild asthma in children.

Side Effects of Leukotriene Modifiers

Although they’re widely prescribed and considered relatively safe, leukotriene modifiers cause side effects in some people. Possible side effects listed for the drug montelukast, for instance, include changes in mood and increased suicidal thoughts.

The U.S. Food and Drug Administration (FDA) initiated an inquiry into these and other neuropsychiatric effects in 2008. In 2009, they concluded that existing clinical trials reveal an increased risk of developing insomnia among users of this class of drugs, compared to a placebo.

According to the FDA, information gathered from people after the public release of these drugs indicates an increased risk of:

  • agitation
  • aggression
  • anxiety
  • dream abnormalities
  • hallucinations
  • depression
  • insomnia
  • irritability
  • restlessness
  • suicidal thinking and behavior
  • tremor

The FDA concluded its review by noting, “neuropsychiatric events were not commonly observed,” at least not in clinical trials, although the FDA also noted that these trials weren’t specifically designed to detect such reactions.

Leukotriene modifiers can help people manage severe asthma and the symptoms of allergies. You should make sure you understand all of the possible side effects before you start a new medication. You should always let your doctor know if you’re concerned about any symptoms you’ve developed after starting a new medication.