ELIXICON
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ELIXICON (ELIXICON).
Theophylline is a xanthine derivative that inhibits phosphodiesterase, leading to increased intracellular cyclic AMP levels. It also acts as a nonselective adenosine receptor antagonist, resulting in bronchodilation and anti-inflammatory effects.
| Metabolism | Primarily hepatic metabolism via cytochrome P450 1A2 (CYP1A2). Minor pathways include CYP2E1 and CYP3A4. Metabolites are excreted renally. |
| Excretion | Renal: 50% unchanged; hepatic metabolism to 3-methylxanthine, theophylline, etc. Biliary/fecal: minimal. |
| Half-life | Terminal elimination half-life: 4-6 hours in adults; 3-4 hours in children; prolonged in hepatic impairment or congestive heart failure. Context: dosing interval adjustment required in these conditions. |
| Protein binding | Approximately 40% bound, primarily to albumin. |
| Volume of Distribution | Vd: 0.3-0.5 L/kg; indicates distribution into total body water, minimal tissue binding. |
| Bioavailability | Oral immediate-release: 100%; Extended-release: 100% (well-absorbed, no first-pass metabolism). |
| Onset of Action | Oral immediate-release: 15-30 minutes; IV: rapid (within minutes); Subcutaneous: not appropriate route. |
| Duration of Action | Immediate-release: 4-6 hours; Extended-release: 8-12 hours or longer. Clinical note: monitor serum concentrations for sustained effect. |
400 mg orally every 6 hours or 600 mg orally every 8 hours; extended-release: 600-1200 mg orally every 12 hours.
| Dosage form | SUSPENSION |
| Renal impairment | GFR > 50 mL/min: no adjustment; GFR 10-50 mL/min: reduce dose by 25-50% and monitor theophylline levels; GFR < 10 mL/min: reduce dose by 50% and monitor levels. |
| Liver impairment | Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 50%; Child-Pugh Class C: reduce dose by 75% and monitor levels. |
| Pediatric use | Initial: 5 mg/kg/dose orally every 6 hours; maintenance: 100-400 mg/day in divided doses; monitor levels aggressively. |
| Geriatric use | Start at lowest effective dose (e.g., 200 mg orally every 12 hours) due to reduced clearance; monitor theophylline levels and adjust based on response and tolerability. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ELIXICON (ELIXICON).
| Breastfeeding | Excreted into breast milk; M/P ratio unknown. Caution advised, monitor infant for adverse effects. |
| Teratogenic Risk | Insufficient human data; animal studies show fetal toxicity at high doses. Avoid in first trimester unless benefit outweighs risk. Second and third trimester: use only if clearly needed. |
| Fetal Monitoring | Monitor maternal serum drug levels, liver function, renal function, and fetal growth via ultrasound. |
■ FDA Black Box Warning
Theophylline has a narrow therapeutic index; plasma levels should be monitored to avoid toxicity. Dosage should be individualized based on steady-state serum concentrations. Concurrent illness, fever, or changes in smoking habits can alter theophylline clearance.
| Serious Effects |
Hypersensitivity to theophylline or any component of the formulation; pre-existing cardiac arrhythmias (e.g., tachyarrhythmias); active seizure disorder.
| Precautions | Risk of seizures at high serum levels; may induce or worsen arrhythmias; use with caution in patients with peptic ulcer disease, hyperthyroidism, or seizure disorders; drug interactions with cimetidine, fluoroquinolones, macrolides, and allopurinol can increase theophylline levels. |
| Food/Dietary | Avoid large amounts of caffeine-containing foods and beverages such as coffee, tea, cola, and chocolate as they may increase side effects like jitteriness and insomnia. High-fat meals may affect absorption; take consistently with respect to meals. Charcoal-broiled foods may increase metabolism of theophylline, reducing efficacy. |
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| Fertility Effects | No known effects on fertility in animal studies; limited human data. |
| Clinical Pearls | ELIXICON (theophylline) requires therapeutic drug monitoring due to narrow therapeutic index of 10-20 mcg/mL. Avoid in patients with active peptic ulcer disease or seizure disorders. Use with caution in heart failure, liver disease, and elderly patients due to reduced clearance. Cigarette smoking induces metabolism, requiring dose adjustments. Common side effects include nausea, vomiting, and insomnia; toxicity presents with tachycardia, seizures, or ventricular arrhythmias. |
| Patient Advice | Take exactly as prescribed and do not change dose without consulting your doctor. · Avoid smoking and second-hand smoke as it affects how the medication works. · Limit caffeine intake (coffee, tea, chocolate, cola) as it may increase side effects. · Report symptoms of toxicity: persistent nausea, vomiting, rapid heart rate, or seizures. · Do not take this medication with other cold or asthma remedies without medical advice. |