theophylline and clarithromycin

Clarithromycin inhibits hepatic cytochrome P450 enzymes, particularly CYP3A4 and CYP1A2, which are involved in theophylline metabolism. This inhibition reduces theophylline clearance, leading to increased plasma concentrations and potential toxicity.

Elevated theophylline levels can cause nausea, vomiting, tachycardia, cardiac arrhythmias, and seizures. The risk of toxicity is significant, particularly in patients with pre-existing cardiac or seizure disorders.

Avoid concomitant use if possible. If co-administration is necessary, monitor theophylline serum concentrations closely and adjust the dose accordingly. Patients should be observed for signs of theophylline toxicity, such as nausea, palpitations, and tremors.

Well established. Multiple case reports and clinical studies have documented increased theophylline levels and toxicity when co-administered with clarithromycin.