What is the effect of rifampin on methadone metabolism?

Rifampin is an antibiotic that is known to induce the cytochrome P450 enzyme system, particularly CYP3A4. This induction effect leads to an increased rate of metabolism for drugs that are substrates of CYP3A4, including methadone. As a result, rifampin lowers the serum levels of methadone, which can potentially decrease its therapeutic effects.

Patients on methadone therapy who start rifampin may require careful monitoring and possible dose adjustments due to the risk of withdrawal symptoms or failure to achieve adequate pain relief because of reduced methadone levels. Understanding the interaction between rifampin and methadone is crucial for safe and effective pain management, particularly for those being treated for opioid dependence.

The other responses do not accurately reflect the established pharmacokinetic interaction between rifampin and methadone. Thus, recognizing rifampin's role as an inducer provides essential insight for medical professionals in managing patients undergoing methadone treatment.