QUIBRON-T
Clinical safety rating: caution
Comprehensive 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). |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for QUIBRON-T (QUIBRON-T).
| Breastfeeding | Theophylline is excreted into breast milk in small amounts (M/P ratio ~0.6-0.7). Milk levels are about 60-70% of maternal serum levels. Breastfeeding is generally considered acceptable, but monitor the infant for signs of theophylline toxicity (irritability, jitteriness, poor feeding). Caution is advised in preterm or medically fragile infants. |
| 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. |
■ 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 component of the formulation.","Pre-existing cardiac arrhythmias (excluding bradyarrhythmias).","Active seizure disorder unless controlled with anticonvulsants.","Concurrent use with ephedrine or other sympathomimetics (relative)."]
| 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)."] |
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| 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. |