氣喘(支氣管痙攣) Bronchial asthma, Bronchospasm

Nonselective phosphodiesterase enzyme Inhibitor
Aminophylline is the ethylenediamine salt of theophylline. Theophylline causes bronchodilatation, diuresis, CNS and cardiac stimulation, and gastric acid secretion by blocking phosphodiesterase which increases tissue concentrations of cyclic adenine monophosphate (cAMP) which in turn promotes catecholamine stimulation of lipolysis, glycogenolysis, and gluconeogenesis and induces release of epinephrine from adrenal medulla cells.

Metabolism:
Hepatic; involves CYP1A2, 2E1 and 3A4; forms active metabolites (caffeine and 3-methylxanthine)
Protein binding:
1. ~60%(less in neonates), primarily to albumin
2. Vd: 0.5±0.1 L/kg
Elimination half-life:
1. In adult nonsmokers: 8±2 hrs
2. In adult smokers (1-2 packs/day): 4.4 ±1 hr
3. In children 1-9 years: 7±1.1 hrs
4. In newborn infants, older patients with COPD or cor pulmonale, and patients with CHF or liver disease: >24 hrs

1. Hypersensitivity to any xanthine
2. Severe cardiac disease, peptic ulcer, renal and liver impairment

C

Avoided
The concentration of theophylline in breast milk is similar to the maternal serum concentration. Irritability may be observed in the nursing infant.

1. Common: Nausea, Vomiting, Headache, Insomnia, Tremor, Irritability, Restlessness
2. Serious: Atrial fibrillation, Tachyarrhythmia, Stevens-Johnson syndrome, Intracranial hemorrhage, Seizure

Dosage:
1. Loading dose: 6 mg/kg(ideal body weight) or 250-500 mg IV 20-30 min
2. Maintenance: followed by an infusion dose of 0.5mg/kg/hr
Adjustment:
1. Older patients and those with cor pulmonale, heart failure, or liver disease may require lower maintenance doses
2. Smokers often need higher maintenance doses