Which of the following drugs is known to induce CYP3A4 and could lower methadone levels?

Rifampin is recognized for its strong induction effects on the CYP3A4 enzyme, which is a key player in the metabolism of many substances, including methadone. When rifampin is administered alongside methadone, it can significantly increase the metabolic clearance of methadone. This means that the presence of rifampin can lead to lower plasma levels of methadone, potentially resulting in reduced therapeutic effects and the risk of withdrawal symptoms or relapse.

In the context of drug interactions, understanding which substances induce or inhibit metabolic pathways is vital in managing dosing regimens, particularly for patients on methadone maintenance therapy. Some substances, like fluconazole, grapefruit juice, and clarithromycin, are actually known to inhibit CYP3A4 rather than induce it. Inhibitors can raise the levels of drugs metabolized by CYP3A4, whereas inducers like rifampin do the opposite, necessitating careful monitoring and possible dose adjustments for patients on methadone.