Which class of medications can cause drug interactions leading to increased levels of theophylline?

Macrolides are a class of antibiotics that can lead to significant drug interactions, particularly with theophylline. Theophylline is a drug used primarily in the management of asthma and chronic obstructive pulmonary disease (COPD). It has a narrow therapeutic index, meaning there is a small margin between therapeutic and toxic doses.

Macrolides, such as erythromycin and clarithromycin, can inhibit cytochrome P450 enzymes in the liver, specifically CYP1A2 and CYP3A4. These enzymes are responsible for metabolizing theophylline. When the activity of these enzymes is inhibited by macrolides, the metabolism of theophylline is decreased, leading to increased serum levels of theophylline. This can raise the risk of toxicity, resulting in side effects such as gastrointestinal upset, insomnia, headaches, and, in severe cases, arrhythmias or seizures.

In contrast, other medication classes listed do not have the same level of interaction with theophylline. Classical NSAIDs, for instance, do not significantly affect the metabolism of theophylline. Beta-agonists are commonly used alongside theophylline in asthma treatment but do not interact in a way that alters theophylline’s levels. Histamine receptor antagonists also do