Aminophylline
Indications
Aminophylline is used for:
Asthma, Acute bronchospasm, Chronic bronchitis, Emphysema, COPD
Adult Dose
Oral
Chronic bronchospasm
Adult: As hydrate: Initially, 225-450 mg bid, increased if necessary.
Intravenous
Acute severe bronchospasm
Adult: Loading dose: 5 mg/kg (ideal body weight) or 250-500 mg (25 mg/ml) by slow inj or infusion over 20-30 min. Maintenance infusion dose: 0.5 mg/kg/hr. Max rate: 25 mg/min.
Elderly: Dose reduction may be ncessary.
Hepatic impairment: Dose reduction may be ncessary.
Child Dose
Oral
Chronic bronchospasm
Child: >3 yr: As modified-release hydrate: 12 mg/kg daily increased to 24 mg/kg daily in 2 divided doses after 1 wk.
Intravenous
Acute severe bronchospasm
Child: Loading dose: same as adult dose. Maintenance dose: 6 mth-9 yr: 1 mg/kg/hr and 10-16 yr: 0.8 mg/kg/hr.
Renal Dose
Administration
Should be taken on an empty stomach. Take on an empty stomach at least 1 hr before or 2 hr after meals.
Contra Indications
Hypersensitivity.
Precautions
Neonates, elderly, lactation, pregnancy, cardiac/hepatic diseases, peptic ulceration, hyperthyroidism, hypertension, epilepsy, heart failure, chronic alcoholism, acute febrile illness.
Pregnancy-Lactation
Interactions
Other xanthines. Clearance reduced by allopurinol, some antiarrhythmics, cimetidine, disulfiram, fluvoxamine, interferon-alpha, macrolide antibiotics, quinolones, oral contraceptives, thiabendazole and viloxazine. Clearance increased by phenytoin, anticonvulsants, ritonavir, rifampicin, sulfinpyrazone, cigarette smoking. Corticosteroids, diuretics, beta2-agonists.
Potentially Fatal: Increased risk of cardiac arrhythmias with sympathomimetics and halothane. Tachycardia with pancuronium. beta-blockers inhibit metabolism. Increased risk of convulsion with quinolones, ketamine.
Adverse Effects
Side effects of Aminophylline :
Nausea, vomiting, abdominal pain, diarrhoea, headache, insomnia, dizziness, anxiety, restlessness; tremor, palpitations.
Potentially Fatal: Convulsions, cardiac arrhythmias, hypotension and sudden death after too rapid IV injection.
Mechanism of Action
Aminophylline is a combination of theophylline and ethylenediamine. Ethylenediamine is inactive; it increases the solubility of theophylline in water. Theophylline relaxes bronchial smooth muscle. Suggested mechanisms are an increase in intracellular cAMP through inhibition of phosphodiesterase; adenosine receptor antagonism, prostaglandin antagonism and effects on intracellular calcium.