Aminophylline
Indications
It is indicated for the treatment and
prophylaxis of bronchospasm associated with asthma, emphysema and
chronic bronchitis. Also indicated in adults for the treatment of
cardiac asthma and left ventricular or congestive cardiac failure.
Pharmacology
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.
Dosage
Oral:
Chronic bronchospasm:
Acute severe bronchospasm:
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.
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.
Contraindications
Aminophylline should not be administered to
patients with hypersensitivity to xanthines or ehylenediamine. It
should not be administered to patients with active peptic ulcer, since
it may increase the volume and acidity of gastric secretions.
Side Effects
The most common adverse effects are gastric
irritation, nausea, vomiting, diarrhea, hematemesis, epigastric pain
and tremor. These are usually early signs of toxicity; however, with
high doses, ventricular arrhythmias or seizures may be the first signs
to appear and reactivation of peptic ulcer, headache, irritability,
restlessness, insomnia, twitching, convulsion and reflex
hyperexcitability, palpitation, tachycardia, hypotension, circulatory
failure, ventricular arrhythmias, and flushing, albuminuria, diuresis
and hematuria. Also inappropriate ADH syndrome may occur.
Pregnancy & Lactation
Use of aminophylline in pregnant women should be balanced against the risk of uncontrolled disease.
Precautions & Warnings
Aminophylline should be given with caution
to patients with peptic ulceration, hyperthyroidism, hypertension,
cardiac arrhythmias or other cardiovascular disease, or epilepsy, as
these conditions may be exacerbated. They should also be given
withcaution to patients with heart failure, hepatic dysfunction, chronic
alcoholism, acute febrile illness, and to neonates and the elderly,
since in all of these circumstances theophylline clearance may be
decreased, resulting in increases in serum-theophylline concentrations
and serum half-life.
Therapeutic Class
Bronchodilator, Methyl xanthine derivatives, Respiratory stimulants: analeptics, Theophylline & related drugs
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