Understanding Postmarketing Requirements and Commitments for CYP3A-Mediated Drug-Drug Interactions: An Analysis of...

Addressing knowledge gaps at drug approval through drug-drug interaction (DDI)-related postmarketing requirements (PMRs) and commitments (PMCs) is essential for safe and effective use. This analysis reviewed CYP3A-related PMRs and PMCs, the most evaluated enzyme in postmarketing studies, to characterize their scope. CYP3A-related PMRs, PMCs, and labeling recommendations were identified for small-molecule new molecular entities approved by the U.S. Food and Drug Administration (2015-2024) using the Certara Drug Interaction Database (DIDB). The latest product labels from Drugs@FDA were reviewed for updates. Drugs were categorized as CYP3A substrates, inhibitors, or inducers based on PMR/PMC language. Of 332 approved drugs, 51 (15%) had CYP3A-related PMRs/PMCs, totaling 91 studies (53 PMRs, 37 PMCs, and 1 unspecified). About two-thirds were oncology drugs, including 25 kinase inhibitors. As substrates, 37 drugs had 65 requests: 26 with inhibitors (all PMRs) and 39 with inducers (30 PMCs, 8 PMRs, and 1 unspecified); 20 included physiologically based pharmacokinetic (PBPK) modeling. As precipitants, 25 drugs had 26 requests: 12 as inhibitors (11 PMRs, 1 PMC), 14 as inducers (8 PMRs, 6 PMCs), with only 1 PBPK option. Requests most often involved studies with a CYP3A substrate (N = 24), moderate inducer (N = 21), strong inducer (N = 15), strong inhibitor (N = 10), and moderate inhibitor (N = 9). Initial labeling recommendations were issued for 60 studies (65%; 35 drugs), and 53 studies (58%; 29 drugs) resulted in label updates. Overall, CYP3A-mediated DDIs remain a key focus of postmarketing evaluation, particularly for oncology drugs. PMRs and PMCs are critical for resolving uncertainties and informing label updates.