Which drug can interact with theophylline and decrease its effectiveness?

St. John's wort is a known inducer of certain cytochrome P450 enzymes, particularly CYP1A2, which is responsible for the metabolism of theophylline. When St. John's wort is taken alongside theophylline, it can lead to increased metabolism of theophylline in the liver, causing lower serum levels of the drug. This interaction may result in decreased effectiveness of theophylline, which is commonly prescribed for conditions like asthma or chronic obstructive pulmonary disease (COPD).

The other drugs listed do not have the same metabolic interactions with theophylline as St. John's wort does. While ibuprofen and amoxicillin are generally safe to use with theophylline, they do not induce the cytochrome P450 enzymes that affect theophylline metabolism. Prednisone, a corticosteroid, does not have a significant interaction that would decrease theophylline's effectiveness either. It is essential to be aware of such interactions, especially when managing treatments for respiratory conditions, to ensure optimal medication efficacy and patient safety.