AMINOPHYLLINE DYE FREE
Clinical safety rating
cautionComprehensive clinical and safety monograph for AMINOPHYLLINE DYE FREE (AMINOPHYLLINE DYE FREE).
Aminophylline is a salt form of theophylline that exerts bronchodilation by inhibiting phosphodiesterase, increasing intracellular cAMP. It also blocks adenosine receptors, stimulates central respiratory drive, and reduces diaphragmatic fatigue.
| Metabolism | Primarily hepatic via CYP1A2, with minor contributions from CYP3A4, CYP2E1, and CYP2D6. Metabolism may be saturated, leading to nonlinear kinetics at therapeutic doses. |
| Excretion | Primarily hepatic metabolism (approximately 90%) to 1,3-dimethyluric acid and other metabolites; renal excretion of unchanged drug accounts for about 10-13% of the dose. Less than 1% is excreted via bile or feces. |
| Half-life | Terminal elimination half-life is approximately 7-9 hours in healthy adults. In smokers, half-life decreases to 4-5 hours. In patients with hepatic cirrhosis, heart failure, or COPD, half-life may prolong to 20-30 hours. |
| Protein binding | Approximately 40% bound, primarily to albumin. In neonates, protein binding is lower (about 30%). |
| Volume of Distribution | Approximately 0.5 L/kg (range 0.3-0.7 L/kg). Higher in premature infants and neonates (0.6-0.9 L/kg). Vd corresponds to total body water; aminophylline distributes into extracellular and intracellular fluid. |
| Bioavailability | Oral immediate-release: nearly 100%. Oral sustained-release: 80-100% depending on formulation. Rectal: variable (80-100%). Intravenous: 100%. |
| Onset of Action | Intravenous: immediate (within minutes). Oral: 15-30 minutes for sustained-release formulations; 1-2 hours for immediate-release tablets. Rectal (enema): 30-60 minutes. |
| Duration of Action | Intravenous: 6-8 hours. Oral sustained-release: 12-24 hours depending on formulation. Oral immediate-release: 4-6 hours. Rectal: 6-8 hours. |
| Molecular Weight | 420.44 |
Loading dose: 6 mg/kg IV over 30 minutes (use ideal body weight). Maintenance: 0.5-0.7 mg/kg/hour IV infusion for non-smoking adults; 0.8-1.0 mg/kg/hour for smokers. Oral: 200-400 mg every 6-8 hours (extended-release formulations available).
| Dosage form | SOLUTION |
| Renal impairment | No specific dose adjustment required for GFR >10 mL/min. For GFR <10 mL/min: reduce dose by 50% and monitor serum theophylline levels closely. |
| Liver impairment | Child-Pugh Class A: reduce dose by 50%. Child-Pugh Class B: reduce dose by 75%. Child-Pugh Class C: use alternative therapy or reduce dose by 80-90% with close monitoring. |
| Pediatric use | Loading dose: 5-6 mg/kg IV over 30 minutes. Maintenance IV infusion: age 1-6 months: 0.5 mg/kg/hour; 6-12 months: 0.6-0.7 mg/kg/hour; 1-9 years: 0.8-1.0 mg/kg/hour; >9 years: 0.5-0.7 mg/kg/hour. Oral: 5-6 mg/kg every 6 hours (immediate-release) or every 12 hours (extended-release). |
| Geriatric use | Lower initial doses recommended (e.g., 300-400 mg/day oral) with slower titration, as clearance is decreased. Monitor serum theophylline levels and adjust to achieve 5-15 mcg/mL. |
| 1st trimester | Use only if clearly needed; aminophylline is a methylxanthine bronchodilator that crosses the placenta; associated with possible risk of respiratory depression and cardiovascular stimulation in fetus; limited human data; avoid in first trimester if possible. |
| 2nd trimester | Use with caution; monitor maternal serum levels and fetal heart rate; may cause fetal tachycardia; benefits must outweigh risks; consider alternative therapies. |
| 3rd trimester | Use with caution near term; may cause neonatal irritability, jitteriness, and heart rate elevation; discontinue prior to delivery if possible; monitor infant for withdrawal symptoms. |
Clinical note
Comprehensive clinical and safety monograph for AMINOPHYLLINE DYE FREE (AMINOPHYLLINE DYE FREE).
| Placental transfer | Readily crosses the placenta; fetal serum concentrations similar to maternal; detectable in cord blood. |
| Breastfeeding | Aminophylline (theophylline ethylenediamine) is excreted into breast milk in low concentrations (approximately 1% of maternal dose). High maternal doses may lead to infant irritability, insomnia, and jitteriness. Monitor infant for signs of stimulation. Consider using if benefits outweigh risks; may be used with caution, especially in preterm infants. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Pregnancy Category C. First trimester: No adequate human studies; animal studies show no teratogenicity at clinically relevant doses. Second and third trimesters: Potential risk of fetal tachycardia, jitteriness, and hypoglycemia due to maternal theophylline levels; no clear teratogenic signal. Close monitoring recommended. |
| Fetal Monitoring | Monitor maternal serum theophylline levels (target 10-20 mcg/mL), heart rate, and respiratory status. Fetal monitoring for heart rate and growth via ultrasound if prolonged use. Assess for maternal signs of toxicity (nausea, palpitations, seizures). |
| Fertility Effects | No specific adverse effects on human fertility documented. Limited animal data show no impairment at therapeutic doses. Use only if clearly needed. |
■ FDA Black Box Warning
Theophylline has a narrow therapeutic index; serum levels must be monitored. Severe toxicity can occur at levels above 20 mcg/mL, including seizures, cardiac arrhythmias, and death. Use with caution as serious adverse effects may occur without warning.
| Serious Effects |
Hypersensitivity to aminophylline or theophyllineHypersensitivity to ethylenediamineActive seizure disorder (uncontrolled)Severe cardiac arrhythmias (e.g., ventricular tachycardia, atrial fibrillation with rapid ventricular response)Peptic ulcer disease (active)
| Precautions | Monitor serum theophylline levels; adjust dose accordingly, Risk of toxicity is increased in patients with hepatic impairment, congestive heart failure, cor pulmonale, and elderly patients, May exacerbate or induce peptic ulcer disease, seizures, and other cardiac arrhythmias, Concurrent use with other xanthines can increase toxicity, Smoking cessation decreases clearance and may require dose reduction |
| Food/Dietary | Avoid excessive intake of caffeine-containing foods and beverages (coffee, tea, cola, chocolate) as they may potentiate stimulant effects and increase risk of toxicity. High-fat meals may slow absorption of extended-release formulations. No other significant food interactions. |
| Clinical Pearls | Aminophylline is a bronchodilator that contains theophylline and ethylenediamine. Use with caution in patients with peptic ulcer, hyperthyroidism, or seizure disorders. Monitor serum theophylline levels (therapeutic range 10-20 mcg/mL). Avoid use in patients with active peptic ulcer disease. Ethylenediamine component may cause allergic reactions in sensitive patients. Dose adjustment required in hepatic impairment, heart failure, or elderly. Tachyphylaxis may occur with prolonged use. Cigarette smoking increases clearance; monitor levels closely. Consider drug interactions with cimetidine, fluoroquinolones, and macrolides which decrease clearance. |
| Patient Advice | Do not chew or crush extended-release tablets; swallow whole. · Avoid consuming large amounts of caffeine (coffee, tea, cola, chocolate) as it may increase side effects. · Report symptoms of toxicity such as nausea, vomiting, insomnia, rapid heartbeat, or seizures immediately. · Take this medication exactly as prescribed; do not change dose without consulting your doctor. · Inform your doctor if you have a history of seizures, ulcers, or liver disease. · Do not smoke or stop smoking without medical advice as it affects how this medication works. |
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