QUIBRON-T
Clinical safety rating
cautionComprehensive clinical and safety monograph for QUIBRON-T (QUIBRON-T).
Quibron-T (theophylline) inhibits phosphodiesterase, increasing intracellular cAMP in airway smooth muscle and inflammatory cells, leading to bronchodilation and anti-inflammatory effects. It also antagonizes adenosine receptors and enhances respiratory drive.
| Metabolism | Primarily hepatic metabolism via cytochrome P450 enzymes, mainly CYP1A2, with minor contributions from CYP2E1 and CYP3A4. |
| Excretion | Renal: 70% as metabolites (1,3-dimethyluric acid, 3-methylxanthine, and 1-methyluric acid) and 10% as unchanged drug in adults; biliary/fecal: minimal, <5%. |
| Half-life | Terminal elimination half-life: 7-9 hours in nonsmoking adults; prolonged in hepatic cirrhosis (up to 30 hours) or heart failure; shorter in smokers (4-5 hours) due to enzyme induction. |
| Protein binding | Approximately 40% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | 0.5 L/kg (0.3-0.7 L/kg); approximates total body water, indicating distribution into body tissues including the central nervous system. |
| Bioavailability | Oral immediate-release: 96-100%; food may alter absorption rate of sustained-release (not extent). |
| Onset of Action | Oral immediate-release: 30-60 minutes to peak serum concentration (theophylline). |
| Duration of Action | Duration: approximately 6-8 hours for immediate-release formulations; sustained-release preparations provide 8-12 hours of therapeutic effect (serum theophylline 10-20 mcg/mL). |
| Molecular Weight | 180.16 |
Oral: 200-400 mg every 6-8 hours; sustained-release: 200-600 mg every 12 hours.
| Dosage form | TABLET |
| Renal impairment | GFR <10 mL/min: decrease dose by 50% and extend dosing interval to every 12-24 hours; monitor serum concentrations. |
| Liver impairment | Child-Pugh Class A: no adjustment; Child-Pugh Class B: decrease dose by 50%; Child-Pugh Class C: decrease dose by 75% or consider alternative therapy. |
| Pediatric use | Oral: 5 mg/kg every 6 hours for immediate-release; sustained-release not recommended for children <6 years; for ages 6-12: 10-20 mg/kg/day divided every 12 hours. |
| Geriatric use | Start at lowest effective dose (e.g., 200 mg every 12 hours) due to reduced clearance; monitor serum concentrations to avoid toxicity. |
| 1st trimester | Avoid use during first trimester unless essential; animal studies show fetal anomalies. |
| 2nd trimester | Use only if potential benefit justifies risk; monitor fetal growth. |
| 3rd trimester | May cause fetal tachycardia or irritability; use near term with caution. |
Clinical note
Comprehensive clinical and safety monograph for QUIBRON-T (QUIBRON-T).
| Placental transfer | Crosses placenta readily; fetal serum levels approximate maternal levels. |
| Breastfeeding | Theophylline is excreted in breast milk; infant serum levels may reach therapeutic levels. Monitor infant for irritability or insomnia. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Theophylline (active ingredient of QUIBRON-T) is not considered a major teratogen. First trimester exposure is not associated with an increased risk of major congenital malformations based on population data. Second and third trimester use may be associated with transient neonatal effects such as irritability, jitteriness, tachycardia, and feeding intolerance due to transplacental passage. No specific structural teratogenicity has been established. |
| Fetal Monitoring | Monitor maternal serum theophylline levels (target 5-15 mcg/mL) to avoid toxicity. Assess maternal heart rate, respiratory rate, and signs of toxicity (nausea, vomiting, palpitations, seizures). Fetal monitoring: non-stress test and biophysical profile if maternal asthma is poorly controlled or if signs of fetal distress; fetal heart rate may increase with maternal toxicity. |
| Fertility Effects | No known adverse effects on human fertility. Animal studies have not shown impaired fertility at clinically relevant doses. |
■ FDA Black Box Warning
None for Quibron-T specifically. However, theophylline products carry warnings about the potential for serious adverse effects including seizures and arrhythmias, especially at serum levels above 20 mcg/mL.
| Serious Effects |
Hypersensitivity to theophylline or any componentSeizure disorder (uncontrolled)
| Precautions | Serum theophylline levels must be monitored to avoid toxicity; therapeutic range is 10-20 mcg/mL., Risk of seizures and cardiac arrhythmias, especially at supratherapeutic levels., Use with caution in patients with peptic ulcer disease, seizure disorders, cardiac arrhythmias, and hepatic impairment., Numerous drug interactions due to CYP1A2 inhibition or induction (e.g., cimetidine, fluoroquinolones, smoking). |
| Food/Dietary | High-fat meals may increase absorption, but consistent timing with food is key. Avoid excessive caffeine intake. Charcoal-broiled foods may increase metabolism, reducing effectiveness. |
| Clinical Pearls | Quibron-T (theophylline) has a narrow therapeutic index (5-15 mcg/mL). Monitor serum levels due to variable metabolism. Cimetidine, ciprofloxacin, and fluvoxamine inhibit metabolism, increasing toxicity risk. Smoking and carbamazepine induce metabolism, reducing efficacy. |
| Patient Advice | Take exactly as prescribed; do not change dose without consulting your doctor. · Avoid caffeine-containing products (coffee, tea, cola) as they may increase side effects. · Report symptoms of toxicity: nausea, vomiting, insomnia, tachycardia, or seizures. · Do not smoke or stop smoking suddenly; notify your doctor if you do. · Keep regular appointments for blood level monitoring. |
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