How Do 5-Lipoxygenase Inhibitors Work?

Inhibitors of 5-lipoxygenase (5-LO) are medications prescribed for the treatment of asthma, an inflammatory bronchial condition that causes difficulty in breathing. Inhibitors of 5-LO relieve the symptoms of asthma by preventing the formation of leukotrienes, a group of fatty substances released during an asthma attack.

Asthma attacks are often triggered by allergens and the body’s immune system responds by releasing inflammatory substances to attack what it perceives as foreign to the body. Leukotrienes are one of the types of inflammatory molecules released by mast cells, which is part of the body’s frontline immune defense.

Inhibitors of 5-LO work by blocking the activity of 5-LO, an enzyme essential for the biosynthesis of leukotrienes. Inhibiting 5-LO prevents the formation of four types of leukotrienes, LTB4, LTC4, LTD4 and LTE4 which play a major role in promoting inflammation.

Leukotrienes promote inflammation in the following ways:

• Increase the migration of immune cells such as eosinophils and neutrophils to the airways which further promote inflammation.
• Induce the aggregation of neutrophils and monocytes, another type of immune cells.
• Increase the permeability of small blood vessels (capillaries) so that inflammatory proteins and immune cells are able to leak out into the bronchial tissue.
• Induce the contraction of airway smooth muscles.

Preventing the biosynthesis of leukotriene helps reduce inflammation, swelling of airways, excess mucus secretion and airway constriction, and eases breathing.

Side effects of 5-lipoxygenase inhibitors may include the following:

• Headache
• Generalized pain
• Myalgia (muscle pain)
• Dyspepsia (indigestion)
• Abdominal pain
• Diarrhea
• Nausea
• Sinusitis (inflammation of the sinuses)
• Asthenia (weakness)
• Pharyngolaryngeal pain (throat pain)
• Leukopenia (low count of leukocytes, a type of immune cells)
• Elevation of liver enzyme alanine transaminase (ALT)
• Hepatitis
• Jaundice
• Liver failure
• Behavioral changes
• Suicidality
• Suicide

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

The generic and brand names of the FDA-approved 5-lipoxygenase inhibitor drug is:

• zileuton
• Zyflo
• Zyflo CR