Aminophylline is indicated for the treatment and prevention of bronchospasm associated with asthma, emphysema, and chronic bronchitis. It is also used in adults for the management of cardiac asthma and left ventricular or congestive heart failure.

Aminophylline is a compound of theophylline and ethylenediamine. Ethylenediamine itself is pharmacologically inactive but enhances the solubility of theophylline in water. Theophylline works by relaxing the smooth muscles of the bronchi. Its mechanism involves increasing intracellular cAMP levels by inhibiting phosphodiesterase, blocking adenosine receptors, opposing prostaglandin activity, and influencing intracellular calcium levels.

Oral:
Chronic bronchospasm:

• Adult: As hydrate: Initially, 225-450 mg bid, increased if necessary.
• 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:

• 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.
• 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.
• Elderly: Dose reduction may be necessary.
• Hepatic impairment: Dose reduction may be necessary.

Administration
Tablets should be swallowed whole and not chewed because of the structure of the tablet.

Aminophylline should not be used in patients who are hypersensitive to xanthine derivatives or ethylenediamine. It is also contraindicated in patients with active peptic ulcer, as it can increase gastric secretion and acidity.

Common side effects include gastric irritation, nausea, vomiting, diarrhea, hematemesis, epigastric discomfort, and tremor. These are often early signs of toxicity. At higher doses, serious effects such as ventricular arrhythmias or seizures may occur. Other possible reactions include recurrence of peptic ulcer, headache, irritability, restlessness, insomnia, muscle twitching, convulsions, increased reflex activity, palpitations, tachycardia, hypotension, circulatory collapse, flushing, albuminuria, increased urination, and hematuria. Syndrome of inappropriate ADH secretion may also develop.

Use of aminophylline during pregnancy should be carefully considered by weighing the potential benefits against the risks of uncontrolled disease.

Aminophylline should be used cautiously in patients with peptic ulcer, hyperthyroidism, hypertension, cardiac arrhythmias, other cardiovascular disorders, or epilepsy, as these conditions may worsen. Caution is also required in patients with heart failure, liver dysfunction, chronic alcoholism, acute febrile illness, and in neonates and elderly patients, since reduced theophylline clearance may lead to increased blood levels and prolonged half-life.

Bronchodilator, Methylxanthine derivatives, Respiratory stimulants (analeptics), Theophylline and related drugs