Issues for Surgery
Increased risk of bronchospasm if omitted.
Advice in the Perioperative period
Elective and Emergency Surgery
Ensure that the patient is maintained on a specific manufacturer’s product (see Further Information).
For patients who may decide to quit smoking during the perioperative period see Further Information.
Restart post-operatively as soon as next dose is due.
Interaction(s) with Common Anaesthetic Agents
Theophylline and aminophylline have narrow therapeutic ranges – a small difference in serum concentrations may lead to therapeutic failure or adverse drug reactions (see Further Information).
The clinical significance of the following interactions is unclear – bear them in mind in case of an unexpected response to treatment1.
Ketamine / Esketamine
There have been case reports describing seizures in patients given ketamine and aminophylline or theophylline1, 2.
The UK manufacturer of esketamine states that it may lower the seizure threshold when used concomitantly with aminophylline or theophylline and advise that this combination should be avoided1, 3.
Although not commonly used bear in mind that resistance to pancuronium, and in one case supraventricular tachycardia, has been seen in patients taking aminophylline. Theophylline may be expected to interact similarly1.
Interaction(s) with other Common Medicines used in the Perioperative Period
Theophylline Toxicity (see Further Information)
Theophylline clearance can be reduced by erythromycin (onset may be delayed for 2 – 7 days)1, 2, 5, 6. In some cases this has led to increased theophylline levels, and toxicity may develop. Monitor theophylline levels after 48 hours and adjust the dose accordingly. Consider using an alternative antimicrobial if possible1.
In general clarithromycin does not interact with theophylline (and therefore probably not aminophylline) but there are isolated reports of possible theophylline toxicity with concomitant use1, 4, 5, 6. A clinically relevant interaction seems unlikely; however, consider the interaction if any unexplained reduction in theophylline efficacy or adverse effects (e.g. headache, nausea) occur, and monitor theophylline concentrations accordingly1.
Risk of Seizures
Seizures have developed in 2 patients taking theophylline / aminophylline when given imipenem – the general relevance of this interaction is unclear1, 2.
Macrolide Antibiotics (also see Theophylline Toxicity above)
Theophylline may cause hypokalaemia, potentially increasing the risk of torsades de pointes when given with the following4: -
Concomitant administration of theophylline and dexamethasone or hydrocortisone can increase the risk of hypokalaemia2, 4, 5, 6. This is unlikely to be an issue where corticosteroids are used as single doses to reduce post-operative nausea and vomiting or as cover for patients at risk of adrenal insufficiency. However, bear in mind should continued corticosteroid treatment be necessary post-operatively.
Monitor potassium levels closely1.
The rate of absorption from modified-release preparations can vary between brands. It is essential that a patient should be maintained on the same brand4.
Theophylline Drug Interactions, Monitoring and Toxicity
Theophylline and aminophylline have narrow therapeutic ranges – a small difference in serum concentrations may lead to therapeutic failure or adverse drug reactions. Hence, it is necessary to carefully consider concomitant prescription of any potentially interacting medication. In some cases it may be prudent to monitor serum theophylline levels.
Aminophylline is a combination of theophylline and ethylenediamine4, thus it will have the same drug interactions as theophylline alone. In addition, aminophylline levels are measured in terms of theophylline concentrations.
Quitting smoking pre-operatively improves surgical outcomes through reducing risk of post-operative complications7. If a patient decides to quit smoking during the perioperative period it must be remembered that smoking cessation can reduce theophylline clearance (potential for increased plasma theophylline levels) – dosage adjustments are likely to be necessary1, 5, 6. Consider monitoring theophylline levels.