Which medications can increase theophylline levels?

Cimetidine, ciprofloxacin, and erythromycin can increase theophylline levels due to their interactions with the enzymes responsible for theophylline metabolism, primarily cytochrome P450 enzymes.

Cimetidine is known to inhibit several cytochrome P450 isoenzymes, particularly CYP1A2, which is significantly involved in the metabolism of theophylline. This inhibition can lead to increased theophylline concentrations in the bloodstream, raising the risk of toxicity.

Ciprofloxacin, a fluoroquinolone antibiotic, is also known to inhibit CYP1A2 to some extent, leading to potential increases in theophylline levels when co-administered. The risk of elevated theophylline levels requires careful monitoring, especially in patients who are receiving ciprofloxacin.

Erythromycin, a macrolide antibiotic, is another potent inhibitor of CYP3A4 and can also affect other pathways that may lead to increased theophylline levels, similarly raising concerns about toxicity.

The other options, while including some medications that may have varying interactions with theophylline, do not correctly pair the three agents that have clearly established effects on increasing theophylline levels as a combination. Understanding these interactions is crucial for safe medication management in patients