Theophylline is a substrate for which enzyme system that can cause worsening side effects when combined with certain drugs?

Theophylline is primarily metabolized by the cytochrome P450 enzymatic system, particularly through the enzymes CYP1A2 and CYP2E1. When theophylline is taken in conjunction with drugs that either inhibit or induce these CYP450 enzymes, the therapeutic levels of theophylline can be significantly altered.

Inhibition of the CYP450 enzymes can lead to increased plasma levels of theophylline, enhancing its side effects and increasing the risk of toxicity, such as gastrointestinal disturbances, seizures, and arrhythmias. Conversely, induction of these enzymes can lead to decreased levels of theophylline, resulting in reduced efficacy and potential therapeutic failure.

Understanding the interactions involving the CYP450 system is crucial for managing medications that a patient may be taking concurrently with theophylline, as this knowledge helps in optimizing therapeutic outcomes and minimizing adverse effects.