Zileuton
ZYFLO
Pronunciation: zye-LOO-ton (ZYE-floe)
What it is5-lipoxygenase inhibitor suppressing leukotriene synthesis; asthma maintenance.
Why this oneUpstream synthesis blockade inhibits more leukotriene effects than receptor antagonists do.
What limits itHepatotoxicity requires liver monitoring; frequent dosing and increased theophylline or warfarin exposure complicate use.
Zileuton prescription history
Animated chart of estimated U.S. prescriptions per year, Asthma/COPD meds (1924–2026). Zileuton enters in 1997 (estimated).
FDA-approved for
- asthma maintenance (1996)
Principal riskHepatotoxicity; four-times-daily dosing
Classes and tags
Clinical profile
Legacy pregnancy categoryC
Defining liabilityHepatotoxicity: check liver enzymes at baseline and during therapy. Interactions (theophylline, warfarin, propranolol) and sleep or behavior changes.
FDA label
Read the full label on DailyMed ↗
NO BOXED WARNINGS
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Asthma (prophylaxis and chronic treatment) | Adults & children ≥12 yr | Two 600 mg ER tabs BID | Two 600 mg ER tabs BID (2400 mg/day) | 2400 mg/day |
Renal No adjustment needed (incl. hemodialysis)
Hepatic Contraindicated in active liver disease or persistent ALT ≥3×ULN
Not for acute bronchospasm. ALT before start, monthly ×3 months, every 2-3 months for rest of year 1, then periodically; stop if ALT ≥5×ULN or liver dysfunction symptoms
Instructions
- Take within 1 hour after morning and evening meals
- Do not chew, cut or crush
- Missed dose: take next dose at scheduled time; do not double
Available strengths
- ER tab 600 mg
Contraindications
- Active liver disease or persistent hepatic enzyme elevations ≥3×ULN
Cautions
- Hepatotoxicity (monitor ALT)
- Neuropsychiatric events (sleep disorders, behavior changes)
Adverse reactions
- Sinusitis
- Nausea
- Pharyngolaryngeal pain
- Headache
- Upper respiratory tract infection
- Myalgia
- Diarrhea
Pregnancy No adequate human data; adverse developmental outcomes (incl. cleft palate in rabbits) in animal studies
Lactation Excreted in rat milk; human milk unknown; weigh breastfeeding benefits against tumorigenicity risk seen in animals
Cost
| Strength | #/mo | generic $/mo | CostPlus | |
|---|---|---|---|---|
| 600 mg | ER tab | 120 QID | $245.91 | offered |
Generic entry2017
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Self-check
- Which enzyme does zileuton inhibit?
5-lipoxygenase. - Why are liver tests needed with zileuton?
Hepatotoxicity.