Theophylline
THEO-24
What it isNon-selective phosphodiesterase inhibitor and adenosine antagonist; asthma and COPD.
Why this oneOral bronchodilation with a mild anti-inflammatory effect, and it is very cheap where inhalers are not available.
What limits itA narrow therapeutic index needing levels, and CYP1A2 makes it interaction-prone — ciprofloxacin and smoking cessation both push it into toxicity.
FDA-approved for
- asthma/COPD (~1940)
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Chronic asthma / reversible bronchospasm (maintenance) | Adults & children >45 kg (16–60 yr, no risk factors) | 300 mg/day divided Q12h | After 3 days →400 mg/day; after 3 more days →600 mg/day, guided by serum level | 600 mg/day (400 mg/day if elderly/risk factors for impaired clearance) |
| Chronic asthma / reversible bronchospasm | Children <45 kg (6–15 yr) | 12–14 mg/kg/day (max 300 mg) divided Q12h | After 3 days →16 mg/kg/day (max 400 mg); after 3 more →20 mg/kg/day (max 600 mg) | 20 mg/kg/day up to 600 mg/day (16 mg/kg/day up to 400 mg/day if risk factors) |
Titration Increase dose only if previous dose tolerated, at intervals of no less than 3 days
Renal Undefined
Hepatic Undefined
Titrate to peak serum theophylline 10–20 mcg/mL; cap at 400 mg/day with risk factors for impaired clearance or in the elderly
Instructions
- May be taken without regard to meals (high-fat meal may raise Cmax)
- Extended-release — do not use for acute symptoms
- Individualize and monitor serum theophylline (target peak 10–20 mcg/mL)
- Discontinue any dose causing adverse effects, then resume at a lower previously tolerated dose
- Once-daily dosing only after stabilized on Q12h dosing; do not give the once-daily dose at night
- Base mg/kg dosing on ideal body weight
Cautions
- Narrow therapeutic index — serum >20 mcg/mL causes arrhythmias, seizures, and death
- Transient caffeine-like effects at initiation
- Reduced clearance with sustained fever, elderly, and interacting drugs — dose adjustment needed
- Seizures reported even at <20 mcg/mL in underlying neurologic disease or the elderly
Adverse reactions
- Nausea
- Vomiting
- Headache
- Insomnia
- Restlessness / irritability
- Fine tremor
- Cardiac arrhythmias and seizures at toxic levels
Pregnancy Teratogenic in animals; use during pregnancy only if potential benefit justifies potential fetal risk
Lactation Undefined
NO BOXED WARNINGS
Principal riskNarrow index; CYP1A2 interactions push it into toxicity
Cost, est. cash$30–$500/month
Generic entry1982
Classes and tags
Clinical profile
Legacy pregnancy categoryC
Defining liabilityNarrow therapeutic index; overdose can cause refractory seizures and life-threatening tachyarrhythmias.
Mechanism of action: Theophylline ballicule
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