What could potentially exacerbate the side effects of theophylline according to its interactions?

Theophylline is primarily metabolized in the liver by cytochrome P450 enzymes, particularly CYP1A2. When a patient takes a substrate that is also metabolized by these enzymes alongside a CYP450 inhibitor, the metabolism of theophylline can be significantly reduced. This reduction in clearance leads to increased plasma concentrations of theophylline, which can enhance its side effects, such as gastrointestinal disturbances, CNS stimulation, and cardiovascular effects.

By inhibiting the enzymes responsible for theophylline metabolism, the interaction raises the risk of toxicity, especially if the drug being used in conjunction is known to block the function of these metabolic pathways. Thus, the interaction between theophylline and a CYP450 inhibitor directly correlates with the potential for exacerbating the side effects associated with theophylline use.