General Information

Zyflo (zileuton) is an orally active inhibitor of 5-lipoxygenase, the enzyme that catalyzes the formation of leukotrienes from arachidonic acid.

Zyflo is specifically indicated for the prophylaxis and chronic treatment of asthma in adults and children 12 years of age and older.

Zyflo is supplied as a tablet for oral administration. The recommended dosage for the symptomatic treatment of patients with asthma is one 600-mg tablet four times a day for a total daily dose of 2400 mg. For ease of administration, Zyflo may be taken with meals and at bedtime. Hepatic transaminases should be evaluated prior to initiation of Zyflo and periodically during treatment.

Mechanism of Action

Zyflo acts as a leukotriene pathway inhibitor (LPI) by inhibiting the enzyme 5-lipoxygenase (5-LO). Zyflo inhibits the formation of leukotrienes. Leukotrienes are molecules that contribute to the inflammation, swelling (edema), bronchoconstriction (tightening of muscles wrapped around the outside of the airways) and mucus secretion seen in the airways of patients with asthma.

Side Effects

Adverse effects associated with the use of Zyflo may include, but are not limited to, the folloiwng:

• headache
• unspecified pain
• abdominal pain
• asthenia
• dyspepsia
• nausea
• myalgia

Clinical Trial Results

In clinical trials involving patients with mild-to-moderate asthma who used daily inhaled beta-agonists, Zyflo decreased the percentage of patients requiring steroid rescues for worsening asthma compared to patients treated with placebo. Overall, the percentage of Zyflo patients requiring steroid rescue was 7 percent, compared with 18.7 percent of patients in the placebo group. This represents a reduction of 62 percent.

In addition, patients receiving Zyflo also were able to reduce their use of inhaled beta-agonists. At the end of the six-month study, the number of beta-agonist puffs needed per day was 1.77 puffs, or 31 percent lower than baseline in Zyflo-treated patients; there was a 0.22 puff decrease in the placebo group. The reduction in the use of these medications was accompanied by improvements in lung function.

Patients’ asthma symptoms improved by 36 percent, and night-time symptoms improved 31 percent in patients treated with Zyflo. For placebo-treated patients, improvements were 21 percent and 5 percent, respectively.