Abstract: The present invention is directed to a method of inhibiting CYP3A4 induction. The method involves administering a compound of the following formula: R1—X—(CH2)n—N?C?S with R1, X, and n defined herein, binds to a Pregnane X Receptor or Steroid and Xenobiotic Receptor (SXR or NR1I2) under conditions effective to inhibit CYP3A4 gene induction. The present invention also include a method of administering a compound, described herein, together with the CYP3A4 inducer to prevent a loss of efficacy in the subject to whom the CYP3A4 inducer is repeatedly administered. In addition, such compounds can be administered to block the interaction between a CYP3A4 inducer and another drug being administered that is a substrate of CYP3A4.