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RESPIRATORY SYSTEM › DRUGS FOR OBSTRUCTIVE AIRWAY DISEASES › OTHER SYSTEMIC DRUGS FOR OBSTRUCTIVE AIRWAY DISEASES › Xanthines
theophylline, combinations with psycholeptics
R03DA74
Forms & Strengths
- Oral tablets (100 mg, 200 mg)
- Oral capsules (100 mg)
- Oral solution (10 mg/mL)
- IV injection (5 mg/mL)
- Fixed‑dose combination with psycholeptics (e.g., phenobarbital, chloral hydrate)
Adult Dosing
- Usual total theophylline 200–300 mg day⁻¹ in 2–3 divided doses (adjust to serum 10–20 µg/mL)
- IV loading 5 mg/kg over 20 min, then 0.5 mg/kg/h infusion (target 10–20 µg/mL)
- Dose reduction 25‑50 % when combined with CYP1A2 inhibitors (e.g., cimetidine, fluoroquinolones)
Pediatric Dosing
- 5–7 mg/kg/day divided q6‑8 h (adjust to serum 10–20 µg/mL)
- Neonates: 5 mg/kg/day divided q8 h (serum target 5–10 µg/mL)
- Reduce dose by 30 % with concurrent CYP1A2 inhibitors
Indications
- Bronchial asthma (especially nocturnal or exercise‑induced)
- Chronic obstructive pulmonary disease (COPD) as adjunct bronchodilator
- Prevention of asthma attacks in patients requiring psycholeptic sedation
Mechanism of Action
- Non‑selective phosphodiesterase inhibition → ↑cAMP → bronchial smooth‑muscle relaxation
- Adenosine‑receptor antagonism → reduced bronchoconstriction and CNS stimulation
- Synergistic CNS depressant effect when combined with psycholeptics
Contraindications
- Hypersensitivity to theophylline or any psycholeptic component
- Active peptic ulcer disease
- Severe uncontrolled cardiac arrhythmias
- Seizure disorders not controlled with medication
- Concurrent use of MAO inhibitors or other potent CNS depressants
Adverse Reactions
- Nausea, vomiting, abdominal discomfort
- Headache, dizziness, insomnia
- Tachycardia, palpitations, arrhythmias
- Seizures at toxic levels
- Central nervous‑system depression (enhanced by psycholeptics)
Drug Interactions
- CYP1A2 inhibitors (cimetidine, fluoroquinolones, macrolides, oral contraceptives) ↑theophylline levels
- CYP1A2 inducers (smoking, carbamazepine, rifampin, phenobarbital) ↓theophylline levels
- Concurrent CNS depressants (benzodiazepines, barbiturates) ↑sedation risk
- β‑blockers may potentiate tachyarrhythmias
- Allopurinol and interferon‑α may increase toxicity
Curated Content: Needs Vetting Before Put to Clinical Use