THEOVENT
Clinical safety rating
cautionComprehensive clinical and safety monograph for THEOVENT (THEOVENT).
Theovent is a brand name for theophylline, a xanthine derivative that acts as a bronchodilator by inhibiting phosphodiesterase, leading to increased intracellular cAMP levels, and by antagonizing adenosine receptors.
| Metabolism | Primarily hepatic via CYP1A2, CYP2E1, and CYP3A4. Metabolites include 3-methylxanthine, 1-methyluric acid, and 1,3-dimethyluric acid. |
| Excretion | Renal (70% as unchanged drug), biliary/fecal (30% as metabolites). |
| Half-life | Terminal elimination half-life 7-9 hours, prolonged in patients with hepatic impairment (up to 12 hours) or heart failure. |
| Protein binding | 40% bound primarily to albumin. |
| Volume of Distribution | 0.3-0.5 L/kg, approximating total body water. |
| Bioavailability | Oral immediate-release: 96%; sustained-release: 80-90%. |
| Onset of Action | Oral: 30 minutes; Intravenous: 2-5 minutes. |
| Duration of Action | 4-6 hours for bronchodilation, sustained-release formulations up to 12 hours. |
| Molecular Weight | 180.17 |
Oral: 200-400 mg every 12 hours; maximum 800 mg/day. Intravenous: 200 mg loading dose over 30 minutes, then 200 mg every 12 hours.
| Dosage form | CAPSULE, EXTENDED RELEASE |
| Renal impairment | GFR 30-50 mL/min: reduce dose by 25%. GFR 10-29 mL/min: reduce dose by 50%. GFR <10 mL/min: reduce dose by 75% or extend interval to every 24 hours. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50%. Child-Pugh C: reduce dose by 75% or consider alternative therapy. |
| Pediatric use | Oral: 5-10 mg/kg every 12 hours; maximum 400 mg/day. Intravenous: 5 mg/kg loading dose, then 5 mg/kg every 12 hours. |
| Geriatric use | Initiate at 200 mg every 12 hours; increase cautiously to 400 mg every 12 hours; monitor renal function and adjust per renal guidelines. |
| 1st trimester | Avoid: theophylline crosses placenta; risk of fetal tachycardia and irritability; use only if benefit outweighs risk. |
| 2nd trimester | Caution: monitor maternal serum levels; adjust dose to maintain therapeutic range; risk of neonatal apnea and withdrawal reported. |
| 3rd trimester | Caution: neonatal accumulation may occur; monitor for toxicity (jitteriness, vomiting); use lowest effective dose. |
Clinical note
Comprehensive clinical and safety monograph for THEOVENT (THEOVENT).
| Placental transfer | Crosses placenta freely; fetal levels approximate maternal levels. Associated with neonatal tachycardia, jitteriness, and withdrawal. |
| Breastfeeding | Theophylline is excreted into breast milk (approximately 10% of maternal serum concentration). In full-term infants, levels are usually low, but caution in preterm or compromised infants due to immature clearance. Monitor infant for irritability, insomnia, or feeding difficulties. |
| Lactation Rating | L2 (Safer): limited data but appears compatible with breastfeeding; avoid in high maternal doses. |
| Teratogenic Risk | First trimester: No evidence of major malformations; second/third trimester: Risk of fetal tachycardia and intrauterine growth restriction with high maternal doses; overall pregnancy category C. |
| Fetal Monitoring | Monitor maternal heart rate, serum theophylline levels, and fetal heart rate and growth via ultrasound. |
| Fertility Effects | No known adverse effects on fertility in animal studies; human data lacking. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
Allergy to theophylline or xanthine derivativesActive peptic ulcer diseaseUncontrolled seizure disorder
| Precautions | High risk of toxicity with narrow therapeutic index; monitor serum levels, Use caution in patients with cardiac disorders (e.g., arrhythmias), liver disease, renal impairment, seizure disorders, or peptic ulcer disease, Drug interactions with fluoroquinolones, macrolides, cimetidine, allopurinol, and others can increase theophylline levels, Cigarette smoking and certain anticonvulsants can decrease theophylline levels |
| Food/Dietary | Avoid high-fat meals as they can alter absorption of sustained-release formulations. Caffeine-containing foods and beverages (coffee, tea, cola, chocolate) may increase the risk of toxicity and should be limited. Charcoal-grilled foods and a high-protein diet may reduce theophylline clearance, while a high-carbohydrate diet may increase clearance; maintain consistent diet. |
| Clinical Pearls | THEOVENT is a brand of theophylline, a methylxanthine bronchodilator. Narrow therapeutic index; monitor serum levels (target 5-15 mcg/mL). Avoid in patients with seizure disorders. Use with caution in heart failure, hepatic impairment, and elderly. Caffeine and other methylxanthines can increase toxicity. Smoking induces metabolism, requiring dose adjustments. Consider alternative in acute exacerbations due to slow onset. |
| Patient Advice | Take exactly as prescribed; do not change dose without consulting your doctor. · Avoid consuming large amounts of caffeine (coffee, tea, cola, chocolate) as it can increase side effects. · Do not smoke or stop smoking without medical advice, as smoking affects how the drug works. · Contact your doctor if you experience nausea, vomiting, insomnia, rapid heartbeat, or seizures. · Take with food if gastrointestinal upset occurs. · Do not crush or chew extended-release tablets; swallow whole. · Keep a regular dosing schedule to maintain consistent blood levels. |
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