Aminophylline

Theophylline clearance may be increased in smokers and in those regularly exposed to tobacco smoke.

St John’s Wort may increase plasma theophylline concentrations.

Aminophylline may exhibit synergistic toxicity with ephedrine and other sympathomimetics and concurrent use may dispose the patient to cardiac arrhythmias.

Aminophylline should be given with caution to patients with cardiac failure, since clearance of aminophylline is decreased.

There is an increased risk of hypokalaemia when theophylline derivatives are given with corticosteroids or diuretics.

Aminophylline should be given with caution to patients with hepatic dysfunction, since clearance of aminophylline is decreased.

Aminophylline should be given with caution to patients with renal dysfunction , since clearance of aminophylline is decreased.

Aminophylline should be used with caution in patients with peptic ulcer, as peptic ulcer may be exacerbated.

The direct stimulatory effect of Aminophylline on the myocardium may enhance the sensitivity and toxic potential of the cardiac glycosides.

Calcium channel blockers may increase plasma theophylline concentrations.

Oral contraceptives may increase plasma theophylline concentrations.

Thyroid hormones may increase plasma theophylline concentrations.

Macrolide antibiotics may increase plasma theophylline concentrations.

Quinolone antibiotics may increase plasma theophylline concentrations and there is increased risk of convulsions.

Influenza vaccine may increase plasma theophylline concentrations.

Antiepileptics may decrease plasma theophylline concentrations.

Theophylline may reduce the effects of benzodiazepines.

In co-administration of aminophylline with beta-2 adrenergic agonists there is increased risk of arrhythmias. The hypokalaemic effects of beta₂-adrenergic agonists may be potentiated by concomitant treatment with aminophylline.

In co-administration of aminophylline with beta-blockers there is antagonism of bronchodilator effects.

Aminophylline should be used with caution in patients with hyperthyroidism, as hyperthyroidism may be exacerbated.

Aminophylline should be used with caution in patients with diabetes mellitus, as diabetes mellitus may be exacerbated.

Aminophylline should be used with caution in patients with epilepsy, as epilepsy may be exacerbated.

Aminophylline should be used with caution in patients with glaucoma, as glaucoma may be exacerbated.

The anti-arrhythmic effect of adenosine is antagonised by theophylline.

Allopurinol (high doses e.g. 600 mg daily) may increase plasma theophylline concentrations.

Aminoglutethimide may decrease plasma theophylline concentrations.

Cimetidine may increase plasma theophylline concentrations.

Disulfiram may increase plasma theophylline concentrations.

In co-administration of aminophylline with doxapram there is increased risk of d CNS stimulation.

Fluconazole may increase plasma theophylline concentrations.

The concomitant use of theophylline and fluvoxamine should usually be avoided. Where this is not possible, patients should have their theophylline dose halved and plasma theophylline should be monitored closely. Fluvoxamine may increase plasma theophylline concentrations.

Aminophylline enhances the diuretic action of thiazide diuretics and furosemide. There is an increased risk of hypokalaemia when theophylline derivatives are given with corticosteroids or diuretics.

In co-administration aminophylline with halothane there is increased risk of arrhythmias.

Interferon alfa may increase plasma theophylline concentrations.

Isoniazid may increase plasma theophylline concentrations.

In co-administration of aminophylline with ketamine there is increased risk of convulsions.

Aminophylline increases the excretion of lithium and may decrease its therapeutic effectiveness

Methotrexate may increase plasma theophylline concentrations.

Mexiletine may increase plasma theophylline concentrations.

Resistance to neuromuscular block with pancuronium has been reported in patients receiving aminophylline.

Propafenone may increase plasma theophylline concentrations.

Propranolol may increase plasma theophylline concentrations.

Rifampicin may decrease plasma theophylline concentrations.

Ritonavir may decrease plasma theophylline concentrations.

Sulfinpyrazone may decrease plasma theophylline concentrations.

In clinical trials co-administration with theophylline resulted in decreased plasma levels of zafirlukast, by approximately 30%, but with no effect on plasma theophylline levels. However, during post-marketing surveillance, there have been rare cases of patients experiencing increased theophylline levels when co-administered zafirlukast.

Aminophylline should be given with caution to patients with chronic obstructive pulmonary disease, since clearance of aminophylline is decreased.

Aminophylline should be used with caution in patients with hypertension, as hypertension may be exacerbated.

Aminophylline should be used with caution in patients with severe hypoxaemia, as severe hypoxaemia may be exacerbated.

Aminophylline should be used with caution in patients with compromised cardiac or circulatory function, as cardiac or circulatory function may be exacerbated.

Caution is also advised in patients undergoing influenza immunisation or who have active influenza infection or acute febrile illness.

Aminophylline should be given with caution to patients with chronic alcoholism, since clearance of aminophylline is decreased.

It is not known whether theophyllines can cause foetal harm when administered to pregnant women.

Although the safe use of theophylline during pregnancy has not been established relative to potential risk to the foetus, theophyllines have been used during pregnancy without teratogenicity or other adverse foetal effect. Because of the risk of uncontrolled asthma, their safety during pregnancy when clearly needed is generally not seriously questioned.

As with other drugs, aminophylline should only be used during pregnancy if considered essential by the physician. Theophylline crosses the placenta.

Theophylline is distributed into milk and may occasionally induce irritability or other signs of toxicity in nursing infants, and therefore should not be used if the mother is breast-feeding her infant.

Fertility

Animal reproduction studies have not been performed with theophyllines.

None known.