A Case to Support the Continued Use of Rifampin in Clinical Drug–Drug Interaction Studies

Reports of 1-methyl-4-nitrosopiperazine (MNP) in rifampin products hampered the conduct of clinical DDI studies with rifampin. Since DDI studies with rifampin are typically conducted for 6 to 14 days, the assessment of acceptable intake (AI) limit of MNP using CPCA and less-than-lifetime adjustment yielded higher than the current Al limits by FDA. Therefore, in this perspective, we make a case for continued use of rifampin in clinical DDI studies based on the totality of data.