AMINOPHYLLINE INJECTION BP Injection Ref.[6164] Active ingredients: Aminophylline

Aminophylline Injection BP may be given by slow intravenous injection or intravenous infusion in glucose injection or sodium chloride injection.

Aminophylline has a narrow therapeutic index, therefore cautious dosage determination is essential. Therapeutic serum concentrations of theophylline are considered to range from 10 to 20 mcg/ml and levels greater than 20 mcg/ml are often associated with toxic effects. A range of 5 to 15 mcg/ml may be effective, and associated with fewer adverse effects.

The dosage should be titrated for each individual and adjusted with caution. Serum theophylline levels should be monitored to ensure that they remain within the therapeutic range. During therapy, patients should be monitored carefully for signs of toxicity.

Elimination of theophylline in children younger than 6 months of age, especially in neonates, appears to be reduced. Because of this variation in metabolism the use of Aminophylline injection in children under 6 months of age is not recommended.

Use in patients NOT currently receiving theophylline preparations

To minimise adverse effects, IV Aminophylline should be administered slowly, at a rate not exceeding 25mg Aminophylline per minute, up to a dose of 250-500mg (5mg/kg). If patients experience acute adverse effects while loading doses are being infused, the infusion may be stopped for 5-10 minutes or administered at a slower rate.

Approximate IV Aminophylline Maintenance Doses

n.b. The use of Aminophylline IV in children under 6 months of age is not recommended.

Use in patients currently receiving theophylline preparations

In patients who are currently receiving theophylline preparations, the time, route of administration and dosage form of the patient’s last dose should be determined where possible and considered in determining a loading dose. Loading doses are based on the expectation that 0.5mg/kg (lean body weight) of theophylline will result in a 1 microgram/ml increase in serum theophylline concentration. Therefore, in patients currently receiving theophylline preparations, the loading dose should be deferred until a serum theophylline concentration can be attained or the clinician must carefully select a dose based on the potential benefits and risks.

Subsequently, the approximate IV aminophylline maintenance doses described above may be considered.

Aminophylline has a narrow therapeutic index. Theophylline toxicity is most likely to occur when serum concentrations exceed 20 micrograms/ml and becomes progressively more severe at higher serum concentrations.

Fatalities in adults have occurred during IV Aminophylline administration in large doses in patients with renal, hepatic or cardiovascular complications or where the injection has been given rapidly.

Symptoms

Tachycardia, in the absence of hypoxia, fever or administration of sympathomimetic drugs, may be an indication of theophylline toxicity.

Gastro-intestinal symptoms: Anorexia, nausea, vomiting, diarrhoea, and haematemesis.

Neurological symptoms: Restlessness, insomnia, irritability, headache, agitation, hallucinations, extreme thirst, slight fever, dilated pupils, and tinnitus. Seizures may occur even without preceding symptoms of toxicity and often result in death. Coma may develop in very severe cases.

Cardiovascular symptoms: Palpitations, arrhythmias, hypotension, supraventricular and ventricular arrhythmias may occur.

Metabolic symptoms: Hypokalaemia can develop rapidly and may be severe. Hyperglycaemia, albuminuria, hyperthermia, hypomagnesaemia, hypophosphataemia, hypercalcaemia, respiratory alkalosis and metabolic acidosis may also occur. Rhabdomyolysis may also occur.

Treatment

Treatment of overdosage is supportive and symptomatic. Serum theophylline and potassium levels should be monitored. Repeated oral administration of activated charcoal enhances the elimination of theophylline from the body even after intravenous administration. Aggressive antiemetic therapy may be required to allow administration and retention of activated charcoal.

Seizures may be treated with IV diazepam 0.1-0.3mg/kg up to 10mg. Restoration of fluid and electrolytes balance is necessary. Hypokalaemia should be corrected by intravenous infusion of potassium chloride. Sedation with diazepam may be required in agitated patients.

Propranolol may be administered intravenously to reverse extreme tachycardia, hypokalaemia and hyperglycaemia provided the patient does not suffer from asthma.

In general, theophylline is metabolised rapidly and haemodialysis is not warranted. In patients with congestive heart failure or liver disease, haemodialysis may increase theophylline clearance by as much as 2-fold.

Charcoal haemoperfusion should be considered if:

• Ileus/intestinal obstruction prevents administration of multiple dose activated charcoal.
• Plasma theophylline concentration >80mg/L (acute) or >60mg/L (chronic). In infants under 6 months of age or the elderly, charcoal haemoperfusion should be considered at theophylline concentrations >40 mg/L. Clinical features rather than theophylline concentration are the best guide for treatment.

Shelf life: 36 months.

None stated.

10ml clear glass ampoules, packed in cardboard cartons to contain 10 ampoules.

Use as directed by a physician.