Theophylline (Oral Modified Release)

Usual maintenance dose for adults and the elderly. Patients vary in their response to xanthines and it may be necessary to titrate the dose individually; it may be appropriate to give a larger evening or morning dose to cover the period of worst symptoms (e.g. the morning dip in lung function). Plasma theophylline concentrations should ideally be maintained between 10 and 20 micrograms/ml, although 5 to 15 micrograms/ml may be effective; adverse effects can occur within the 10-20 micrograms/ml range and significant adverse reactions are usually seen above 20 micrograms/ml. Monitor plasma concentrations when higher doses are prescribed, when co-morbidities impair clearance, or when co-administered medicines reduce theophylline clearance. Dose reduction and monitoring may be required in the elderly and in cardiac disease/arrhythmias, hepatic disease, exacerbations of lung disease, hypothyroidism, fever, viral infection or risk of hypokalaemia; dose increase may be needed in hyperthyroidism and cystic fibrosis. Dose adjustment may be necessary if smoking is started or stopped during treatment. The SPC notes theophylline may be inappropriate as monotherapy for COPD in elderly patients because of its narrow therapeutic index. Missed dose: if remembered within 4 hours the tablets can be taken straight away and the next dose taken at the normal time. Source product: UNIPHYLLIN 200 mg prolonged release tablets. SPC sections 4.4/4.5 were truncated at the source-fetch limit, so the interaction list below may be incomplete.

Usual paediatric maintenance dose for children aged 6 years and above. Some children with chronic asthma require and tolerate much higher doses (10-16 mg/kg twice daily). Clearance is increased in children compared with adults and decreases towards adult values in late teens, so lower (adult-based) dosages may be required for adolescents. Theophylline distributes poorly into body fat, so mg/kg doses should be calculated on lean (ideal) bodyweight. Other dosage forms are available that are more suitable for children under 6 years; theophylline is contraindicated in children under 6 months. Plasma theophylline monitoring applies as for adults. Verify against a children's formulary before prescribing.