Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
PHYLLOCONTIN vs AMINOPHYLLIN
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Sustained-release theophylline; nonselective phosphodiesterase (PDE) inhibitor, adenosine receptor antagonist, and histone deacetylase activator. Bronchodilation via relaxation of bronchial smooth muscle; also reduces airway hyperresponsiveness and inflammation.
Non-selective phosphodiesterase inhibitor, increasing intracellular c AMP and c GMP; adenosine receptor antagonist, causing bronchodilation, CNS stimulation, and positive chronotropic/inotropic effects.
Treatment of asthma (maintenance therapy),Chronic obstructive pulmonary disease (COPD) maintenance therapy
Treatment of acute bronchial asthma, reversible bronchospasm associated with chronic bronchitis and emphysema,Neonatal apnea (off-label),Adjunctive therapy in COPD exacerbations
For chronic obstructive pulmonary disease and asthma: initial dose 225 mg orally twice daily; may increase to 450 mg twice daily. Based on theophylline, target serum concentration 5-15 mcg/m L.
Loading dose: 6 mg/kg IV over 30 minutes (if not on theophylline); maintenance: 0.5-0.7 mg/kg/hr IV continuous infusion for adults (non-smoking), higher for smokers (0.7-0.9 mg/kg/hr). Oral: immediate-release 200-400 mg every 6 hours; sustained-release 400-600 mg every 12 hours.
Terminal elimination half-life: 3-8 hours in non-smoking adults; reduced to 1.5-5 hours in smokers; prolonged to 10-30 hours in heart failure or hepatic cirrhosis.
Terminal elimination half-life: 3–12 hours in adults (mean ~6 hours); prolonged in hepatic impairment, heart failure, or COPD (up to 30 hours); shorter in smokers (4–5 hours due to CYP1A2 induction); neonates: 20–40 hours.
Primarily hepatic via CYP1A2, with minor contributions from CYP2E1 and CYP3A4. Metabolites: 1,3-dimethyluric acid, 3-methylxanthine, and 1-methyluric acid.
Hepatic demethylation and oxidation via cytochrome P450 isoenzymes (CYP1A2, CYP3A4, CYP2E1); approximately 10% excreted unchanged in urine.
Renal: approximately 10% unchanged; hepatic metabolism accounts for ~90% of clearance; metabolites eliminated renally.
Renal excretion of unchanged drug accounts for ~10%, with the remainder eliminated as metabolites (caffeine, 3-methylxanthine, 1-methyluric acid, 1,3-dimethyluric acid) via urine; minimal biliary/fecal elimination (<5%).
Approximately 40-60% bound, primarily to albumin.
~40% bound to plasma proteins (primarily albumin).
0.45 L/kg (range 0.3-0.7 L/kg), approximating total body water; increased in neonates and cirrhosis.
0.5 L/kg (range 0.3–0.7 L/kg); increased in neonates, cirrhosis, and malnutrition; reflects distribution into total body water.
Oral immediate-release: 96-100%; sustained-release: 90-100%; rectal: approximately 80-90%.
Oral (immediate-release): 100% (well absorbed); rectal: ~80% (variable); IV: 100%.
GFR < 30 m L/min: reduce dose by 50% and monitor serum levels; avoid use if possible due to accumulation risk.
GFR >50 m L/min: no adjustment; GFR 10-50 m L/min: reduce dose by 25% and monitor levels; GFR <10 m L/min: reduce dose by 50% and monitor levels closely.
Child-Pugh Class A: reduce dose by 50%; Child-Pugh Class B: reduce dose by 75%; Child-Pugh Class C: contraindicated. Monitor serum levels closely.
Child-Pugh A: reduce dose by 50%; Child-Pugh B: reduce dose by 75%; Child-Pugh C: use with extreme caution, reduce dose by 90% or consider alternative.
Weight-based dosing (theophylline): 10-16 mg/kg/day orally divided every 6-12 hours; individualize based on serum levels (target 5-10 mcg/m L). Use immediate-release formulations; sustained-release not recommended.
Loading dose: 5-6 mg/kg IV over 30 minutes (if not on theophylline); maintenance: infants <1 year: 0.4-0.7 mg/kg/hr IV; children 1-9 years: 0.8-1.0 mg/kg/hr IV; children >9 years: 0.6-0.8 mg/kg/hr IV. Oral: immediate-release 5 mg/kg every 6 hours; sustained-release not recommended under 6 years.
Lower initial doses (e.g., 112.5 mg twice daily) due to decreased clearance; monitor serum levels and adjust to target 5-10 mcg/m L. Avoid in elderly with cardiac arrhythmias or seizures.
Reduce maintenance dose by 50-75% compared to younger adults; monitor serum theophylline levels closely; typical starting maintenance: 0.3-0.5 mg/kg/hr IV; avoid doses >400 mg/day oral.
No FDA boxed warning.
No specific FDA boxed warning for aminophylline; however, theophylline (its active metabolite) has a narrow therapeutic index and requires serum concentration monitoring to avoid toxicity.
Narrow therapeutic index; monitor serum theophylline levels. Risk of toxicity (seizures, arrhythmias) at high doses. Caution in patients with peptic ulcer, seizure disorders, cardiac disease, hepatic impairment, or in elderly. Drug interactions (CYP1A2 inducers/inhibitors).
Narrow therapeutic index; monitor serum concentrations (target 10-20 mcg/m L); caution in patients with peptic ulcer, hyperthyroidism, seizure disorders, cardiac arrhythmias; use with drugs that affect CYP1A2 (e.g., cimetidine, fluoroquinolones, fluvoxamine) or induce metabolism (e.g., smoking, rifampin, phenytoin).
Hypersensitivity to theophylline; pre-existing cardiac arrhythmias (unless appropriate monitoring); active peptic ulcer disease.
Hypersensitivity to aminophylline, theophylline, or ethylenediamine; active peptic ulcer disease; uncontrolled seizure disorders; severe cardiac arrhythmias (unless patient is undergoing monitored treatment).
Avoid high-protein or charcoal-broiled foods, as they can decrease theophylline levels. Caffeine-containing foods and beverages (e.g., coffee, tea, cola, chocolate) may increase theophylline levels and toxicity risk. Consistent dietary habits are important to maintain stable serum levels.
High-fat meals can delay absorption of aminophylline. Avoid charred meat and foods containing large amounts of caffeine. Cruciferous vegetables (broccoli, brussels sprouts) may increase metabolism. Maintain consistent dietary intake of protein and carbohydrates as changes can affect theophylline clearance.
Teratogenic risk profile: Theophylline (active ingredient in Phyllocontin) is Pregnancy Category C. First trimester: Limited data suggest no major teratogenic risk, but animal studies show potential fetal toxicity at high doses. Second and third trimesters: Theophylline crosses the placenta; fetal serum levels approximate maternal levels. Adverse effects include fetal tachycardia, jitteriness, and neonatal respiratory distress. Risk of neonatal apnea and withdrawal symptoms at delivery.
Aminophylline, a theophylline salt, is not teratogenic in humans. First trimester: No increased risk of major malformations. Second trimester: No specific fetal risks; maternal asthma control benefits outweigh risks. Third trimester: Risk of neonatal apnea, irritability, and tachycardia if maternal levels are high; avoid toxic levels.
Lactation summary: Theophylline is excreted into breast milk with an M/P ratio of approximately 0.7. Infant serum levels can reach 1-10% of maternal levels. Monitor infant for irritability, insomnia, and feeding difficulties. Generally considered compatible with breastfeeding if maternal levels are therapeutic; avoid high doses.
Aminophylline is excreted into breast milk; the M/P ratio (milk-to-plasma ratio) is approximately 0.6-0.8. Infant exposure is low (about 1-10% of maternal weight-adjusted dose). Use with caution; monitor infant for irritability and sleep disturbance. Generally considered compatible with breastfeeding.
Dosing adjustments in pregnancy: Pregnancy increases the volume of distribution and decreases hepatic clearance of theophylline, leading to reduced serum levels. Dose may need to be increased by 20-30% in the second and third trimesters. Monitor serum levels frequently and adjust to maintain therapeutic range. Postpartum, clearance returns to prepregnancy levels rapidly; reduce dose accordingly.
Pregnancy reduces theophylline clearance by 30-50% due to decreased hepatic metabolism and increased volume of distribution. Dose adjustments may be needed: reduce dose by 30% in the third trimester or monitor serum concentrations closely to maintain therapeutic levels (5-15 mcg/m L). Postpartum, clearance returns to prepregnancy levels within 4-6 weeks; readjust accordingly.
PHYLLOCONTIN (sustained-release theophylline) is a bronchodilator with a narrow therapeutic index (5-15 mcg/m L). Monitor trough levels before dose escalation. Cigarette smoking, phenytoin, and rifampin induce metabolism, requiring dose increases. Conversely, cimetidine, ciprofloxacin, and fluvoxamine inhibit metabolism, necessitating dose reductions. Use with caution in hepatic impairment, heart failure, and elderly patients due to reduced clearance.
Aminophylline is a bronchodilator composed of theophylline and ethylenediamine. The ethylenediamine component can cause hypersensitivity reactions. Monitor theophylline serum levels (target 10-20 mcg/m L). Use with caution in patients with cardiac arrhythmias, seizures, or peptic ulcer disease. Avoid in patients with porphyria. Cimetidine, ciprofloxacin, and macrolides can increase theophylline levels. Smoking induces metabolism, requiring higher doses.
Take this medication exactly as prescribed, usually every 12 hours, with or without food.,Do not crush or chew the extended-release tablets; swallow them whole.,Avoid smoking and avoid changing your smoking habits while on this medication, as it affects the drug level.,Limit or avoid caffeine-containing products (coffee, tea, cola, chocolate) as they may increase side effects.,Report symptoms of toxicity such as nausea, vomiting, insomnia, jitteriness, or rapid heartbeat to your healthcare provider immediately.,Do not change your dose or stop taking this medication without consulting your doctor.
Take this medication exactly as prescribed, with or without food.,Do not crush or chew extended-release formulations.,Avoid consuming large amounts of caffeine (coffee, tea, chocolate, energy drinks) as it may increase side effects.,Report symptoms such as rapid heart rate, persistent nausea/vomiting, insomnia, or seizures immediately.,Do not stop abruptly without consulting your doctor.,Keep a regular dosing schedule to maintain consistent blood levels.
No interactions on record
"Concurrent administration of aminophylline, a xanthine derivative bronchodilator that is metabolized primarily by CYP1A2 and to a lesser extent CYP3A4, may reduce the clearance of ranolazine, an antianginal agent predominantly metabolized by CYP3A4 and to a lesser extent CYP2D6. Aminophylline can inhibit CYP3A4 activity, leading to increased ranolazine plasma concentrations, which elevates the risk of dose-dependent adverse effects such as QTc prolongation, dizziness, and syncope. This interaction is clinically significant and may necessitate dose adjustment or alternative therapy."
"Asunaprevir, a potent inhibitor of the drug transporter OATP1B1, can significantly decrease the serum concentration of aminophylline, a theophylline salt, likely by reducing its intestinal absorption or increasing its hepatic clearance. This interaction may lead to reduced therapeutic efficacy of aminophylline, potentially worsening respiratory symptoms in patients with asthma or COPD. Close monitoring and dose adjustment of aminophylline are recommended during coadministration with asunaprevir."
"Aminophylline, a bronchodilator, inhibits the metabolism of tibolone, a synthetic steroid hormone used for hormone replacement therapy, primarily through competitive inhibition of cytochrome P450 (CYP) 3A4 isoenzyme. This results in increased plasma concentrations of tibolone and its active metabolites, potentiating its hormonal effects and increasing the risk of adverse events such as thromboembolism, endometrial hyperplasia, or breast tenderness. Clinically, coadministration may require dose adjustments and careful monitoring for signs of estrogenic excess."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about PHYLLOCONTIN vs AMINOPHYLLIN, answered by our medical review team.
PHYLLOCONTIN is a Xanthine Bronchodilator that works by Sustained-release theophylline; nonselective phosphodiesterase (PDE) inhibitor, adenosine receptor antagonist, and histone deacetylase activator. Bronchodilation via relaxation of bronchial smooth muscle; also reduces airway hyperresponsiveness and inflammation.. AMINOPHYLLIN is a Xanthine Bronchodilator that works by Non-selective phosphodiesterase inhibitor, increasing intracellular c AMP and c GMP; adenosine receptor antagonist, causing bronchodilation, CNS stimulation, and positive chronotropic/inotropic effects.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between PHYLLOCONTIN and AMINOPHYLLIN depend on the specific clinical indication. These are both Xanthine Bronchodilator agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of PHYLLOCONTIN is: For chronic obstructive pulmonary disease and asthma: initial dose 225 mg orally twice daily; may increase to 450 mg twice daily. Based on theophylline, target serum concentration 5-15 mcg/m L.. The standard adult dose of AMINOPHYLLIN is: Loading dose: 6 mg/kg IV over 30 minutes (if not on theophylline); maintenance: 0.5-0.7 mg/kg/hr IV continuous infusion for adults (non-smoking), higher for smokers (0.7-0.9 mg/kg/hr). Oral: immediate-release 200-400 mg every 6 hours; sustained-release 400-600 mg every 12 hours.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between PHYLLOCONTIN and AMINOPHYLLIN in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. PHYLLOCONTIN is classified as Category C. Teratogenic risk profile: Theophylline (active ingredient in Phyllocontin) is Pregnancy Category C. First trimester: Limited data suggest no major teratogenic risk, but animal stud. AMINOPHYLLIN is classified as Category C. Aminophylline, a theophylline salt, is not teratogenic in humans. First trimester: No increased risk of major malformations. Second trimester: No specific fetal risks; maternal ast. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.