PHYLLOCONTIN CONTINUS Prolonged release tablets Ref.[50284] Active ingredients: Aminophylline

Posology

Adults and the elderly

The usual maintenance dose is one PHYLLOCONTIN CONTINUS tablet 225 mg twice daily. This may be titrated to higher dosage as required.

Paediatric population aged 6 years and above

The usual paediatric maintenance dose is 10 mg/kg twice daily.

Some children with chronic asthma require and tolerate much higher doses (11-18 mg/kg twice daily).

Clearance is increased in children compared to values observed in adult subjects. The rapid clearance observed in children decreases towards adult values in late teens. Therefore lower doses may be required for adolescents.

Aminophylline should not be administered to children less than 6 years of age (approximately 22 kg). Other dosage forms are available that are more suitable for children less than 6 years of age.

Theophylline distributes poorly into body fat, therefore mg/kg doses should be calculated on the basis of lean (ideal) body weight.

Plasma theophylline concentrations should ideally be maintained between 5 and 12 mcg/mL. A plasma level of 5 mcg/mL probably represents the lower level of clinical effectiveness. Significant adverse reactions are usually seen at plasma theophylline levels greater than 20 mcg/mL.

Monitoring of plasma theophylline concentrations may be required when: higher doses are prescribed; patients have comorbidities resulting in impaired clearance; when aminophylline is co-administered with medication that reduces theophylline clearance.

Method of administration

Oral.

The tablets should be swallowed and not chewed.

Missed dose

If a patient forgets to take a dose but remembers within 4 hours of the time the dose was due to be taken, the tablets can be taken straight away. The next dose should be taken at the normal time. Beyond 4 hours, the prescriber may need to consider alternative treatment until the dose is due.

Theophylline has a low 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.

Over 3 g could be serious in an adult (40 mg/kg in a child). The fatal dose may be as little as 4.5 g in an adult (60 mg/kg in a child), but is generally higher.

Symptoms

Warning: Serious features may develop as long as 12 hours after overdosage with prolonged release formulations

Alimentary symptoms: Nausea, vomiting (which is often severe), epigastric pain and haematemesis. Consider pancreatitis if abdominal pain persists.

Neurological symptoms: Restlessness, hypertonia, exaggerated limb reflexes, convulsions, seizures. Coma may develop in very severe cases.

Cardiovascular symptoms: Hypotension. Sinus tachycardia is common. Ectopic beats and supraventricular and ventricular tachycardia may follow.

Metabolic symptoms: Hypokalaemia due to shift in potassium from plasma into cells is common, can develop rapidly and may be severe. Hyperglycaemia, hypomagnesaemia and metabolic acidosis may also occur. Rhabdomyolysis may also occur.

Management

Activated charcoal or gastric lavage should be considered if a significant overdose has been ingested within 1-2 hours. Repeated doses of activated charcoal given by mouth can enhance theophylline elimination. Measure the plasma potassium concentration urgently, repeat frequently and correct hypokalaemia. BEWARE! If large amounts of potassium have been given, serious hyperkalaemia may develop during recovery. If plasma potassium is low, then the plasma magnesium concentration should be measured as soon as possible.

Measure the plasma theophylline concentration regularly when severe poisoning is suspected, until concentrations are falling. Vomiting should be treated with an antiemetic such as metoclopramide or ondansetron.

In the treatment of ventricular arrhythmias, proconvulsant antiarrhythmic agents such as lignocaine (lidocaine) should be avoided because of the risk of causing or exacerbating seizures.

Tachycardia with an adequate cardiac output is best left untreated. Beta-blockers may be given in extreme cases but not if the patient is asthmatic.

Control isolated convulsions with intravenous diazepam. Exclude hypokalaemia as a cause. Particularly in the setting of theophylline overdose induced convulsions, efficacy of some anticonvulsant drugs such as benzodiazepines, may be reduced through suspected pharmacodynamic interactions.

3 years.

Do not store above 25°C.

1. Polypropylene containers with polyethylene lids containing 50, 56, 250 or 1000 tablets.
2. Aluminium foil backed PVC blister strips in cardboard cartons containing 10, 56 or 60 tablets.

Not all pack sizes may be marketed.

No special requirements.