Final answer:
Taking rifampin can increase the metabolism of alprazolam, leading to decreased concentration and increased anxiety symptoms.
Step-by-step explanation:
When a patient taking alprazolam (Xanax) for anxiety starts taking rifampin, it can lead to increased anxiety symptoms. This is because rifampin can significantly increase the metabolism of alprazolam, causing it to be cleared from the body more quickly. Alprazolam is a benzodiazepine with a short half-life, so any reduction in its concentration in the body can result in a decrease in its therapeutic effects, leading to increased anxiety.