Removing the FDA's Boxed Hepatotoxicity Warning and Liver Function Testing Requirement for Ambrisentan.

Importance: Endothelin receptor antagonists are first-line therapy for pulmonary arterial hypertension (PAH). The first 2 agents approved in the class, bosentan and ambrisentan, initially carried boxed warnings for hepatotoxicity and required monthly liver function tests (LFTs) as part of a risk evaluation and mitigation strategy (REMS); however, in 2011, as further safety data emerged on ambrisentan, the boxed hepatotoxicity warning and LFT requirements were removed. Objective: To analyze changes in the use of and LFT monitoring for ambrisentan and bosentan after changes to the ambrisentan labeling and REMS. Design, Setting, and Participants: This serial cross-sectional study used data from 3 longitudinal health care insurance claims databases-Medicaid, Optum's deidentified Clinformatics Data Mart, and Merative Marketscan-to perform an interrupted time series analysis of prescription fills and LFTs for patients taking ambrisentan and bosentan. Participants were patients filling prescriptions for ambrisentan and bosentan from July 1, 2007, to December 31, 2018. Data analysis was performed from April 2021 to August 2023. Exposure: Removal of the boxed warning for hepatotoxicity and the REMS LFT monitoring requirements on ambrisentan in March 2011. Main Outcomes and Measures: The primary outcomes were use of ambrisentan (ie, individuals with at least 1 dispensing per 1 000 000 individuals enrolled in the 3 datasets) vs bosentan and LFT monitoring (ie, proportion of initiators with at least 1 ordered test) before initiation and before the first refill. Results: A total of 10 261 patients received a prescription for ambrisentan during the study period (7442 women [72.5%]; mean [SD] age, 52.6 [17.6] years), and 11 159 patients received a prescription for bosentan (7931 women [71.1%]; mean [SD] age, 47.7 [23.7] years). Removal of the ambrisentan boxed hepatotoxicity warning and LFT monitoring requirement was associated with an immediate increase in the use of ambrisentan (1.50 patients per million enrollees; 95% CI, 1.08 to 1.92 patients per million enrollees) but no significant change in the use of bosentan. There were reductions in recorded LFTs before drug initiation (13.1% absolute decrease; 95% CI, -18.2% to -8.0%) and before the first refill (26.4% absolute decrease; 95% CI, -34.4% to -18.5%) of ambrisentan but not bosentan. Conclusions and Relevance: In this serial cross-sectional study of ambrisentan, labeling changes and removal of the REMS-related LFT requirement were associated with shifts in prescribing and testing behavior for ambrisentan but not bosentan. Further clinician education may be needed to maximize the benefits of REMS programs and labeling warnings designed to ensure the safe administration of high-risk medications.

A Multi-modal Approach to Evaluate the Impact of Risk Evaluation and Mitigation Strategy (REMS) Programs.

INTRODUCTION: Since 2007, the US Food and Drug Administration has had the authority to require risk evaluation and mitigation strategy (REMS) programs for certain medications with serious safety concerns to help ensure the benefits of the medication outweigh its risks. Such programs can include requirements for patient monitoring, restrictions on dispensing or administration, and physician and pharmacy training and certification. However, there has been only scattered evidence on the impact of REMS programs on informed decision making, medication access, or patient outcomes. OBJECTIVE: The objective of this article was to describe a study that researchers at Brigham and Women's Hospital and Harvard Medical School will conduct in partnership with the Food and Drug Administration's Office of Surveillance and Epidemiology to investigate systematically how REMS programs have operated in practice. METHODS: Investigations include health insurance claims-based analyses to understand patterns of drug use, adherence to safety requirements, and patient outcomes under REMS programs; surveys and interviews to understand physician and patient experiences with REMS; and REMS program material-based and interview-based analyses to understand the effectiveness of risk communication in REMS programs. CONCLUSIONS: These research activities will evaluate the performance of REMS programs, provide information on the benefits and burdens to patients and healthcare providers, and generate recommendations for actionable steps to improve REMS programs overall.