THEOVENT
Clinical safety rating: caution
Comprehensive 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. |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for THEOVENT (THEOVENT).
| Breastfeeding | Excreted in breast milk; M/P ratio approximately 0.6; use with caution, monitor infant for irritability and tachycardia. |
| 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. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Hypersensitivity to theophylline or any component","Seizure disorder not adequately controlled","Active peptic ulcer disease"]
| 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"] |
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| Fertility Effects | No known adverse effects on fertility in animal studies; human data lacking. |