Drug Guide

Generic Name

Aminophylline

Brand Names Aminophyllin, Somophyllin, Aminophylline In Sodium Chloride 0.45% In Plastic Container, Truphylline, Phyllocontin, Somophyllin-df, Aminophylline Dye Free, Aminophylline In Sodium Chloride 0.45%

Classification

Therapeutic: Bronchodilator

Pharmacological: Xanthine derivative

FDA Approved Indications

Relief of bronchospasm associated with asthma, chronic obstructive pulmonary disease (COPD), and other respiratory diseases.

Mechanism of Action

Aminophylline inhibits phosphodiesterase enzymes, leading to an increase in intracellular cyclic AMP and cyclic GMP, resulting in bronchial smooth muscle relaxation, bronchodilation, and anti-inflammatory effects.

Dosage and Administration

Adult: Initial dose typically 5 mg/kg IV over 20 to 30 minutes; maintenance doses vary based on individual response and plasma drug levels.

Pediatric: Dosage determined by weight, usually 6-8 mg/kg IV; continuous or intermittent infusion can be used.

Geriatric: Start at lower doses due to reduced clearance; monitor closely.

Renal Impairment: Reduce dose and increase dosing interval.

Hepatic Impairment: Use with caution; may require dose adjustments.

Pharmacokinetics

Absorption: Limited data, often administered IV due to poor oral bioavailability.

Distribution: Widely distributed; crosses the placenta.

Metabolism: Hepatic metabolism mainly via CYP1A2; some metabolism occurs via other pathways.

Excretion: Primarily renal excretion of metabolites; small amount of unchanged drug.

Half Life: Variable; approximately 4-8 hours in healthy adults; prolonged in cardiopulmonary disease and hepatic impairment.

Contraindications

History of hypersensitivity to aminophylline or other methylxanthines.

Precautions

Cardiac arrhythmias, seizure disorders, peptic ulcer, hyperthyroidism, CYP1A2 inhibitors/inducers, concurrent use of drugs that affect CYP1A2.

Adverse Reactions - Common

Nausea, vomiting, headache, insomnia, tachycardia (Common)

Adverse Reactions - Serious

Seizures, arrhythmias, severe hypotension, hypersensitivity reactions (Serious, but less common)

Drug-Drug Interactions

Increased toxicity with cimetidine, erythromycin, ciprofloxacin; decreased efficacy with barbiturates, phenytoin, rifampin.

Drug-Food Interactions

Caffeine may enhance side effects.

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor respiratory status, heart rate, rhythm, blood pressure, and plasma aminophylline levels.

Diagnoses:

Ineffective airway clearance,

Implementation: Administer as ordered; monitor for adverse effects; drug levels to guide dosing.

Evaluation: Assess for respiratory improvement and adverse effects; maintain therapeutic plasma levels.

Patient/Family Teaching

Report symptoms of toxicity such as nausea, vomiting, seizures, or irregular heartbeat.
Do not consume excessive caffeine while on this medication.
Maintain regular blood tests to monitor drug levels.

Special Considerations

Black Box Warnings:

Significant toxicity in case of overdose; narrow therapeutic window.

Genetic Factors: Variability in metabolism may influence dosing and toxicity.

Lab Test Interference: May interfere with certain laboratory assays, including those measuring plasma cyclic nucleotides.

Overdose Management

Signs/Symptoms: Nausea, vomiting, seizures, tachyarrhythmias, hypotension.

Treatment: Discontinue drug, support vital signs, administer activated charcoal, and use benzodiazepines for seizures; dialysis in severe cases.

Storage and Handling

Storage: Store at controlled room temperature, away from moisture and light.

Stability: Stable when stored properly, check specific product labels for expiration date.